The Wetland Condition Index (WCI): Biological Indicators of Wetland Condition for Isolated Depressional Herbaceous Wetla...

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Title:
The Wetland Condition Index (WCI): Biological Indicators of Wetland Condition for Isolated Depressional Herbaceous Wetlands in Florida
Physical Description:
Report
Language:
English
Creator:
Lane, Charles R.
Brown, Mark T.
Murray-Hudson, Mike
Vivas, M. Benjamin
Publisher:
Center for Wetlands
Publication Date:

Subjects

Subjects / Keywords:
wetlands
diatoms
Florida Wetland Condition Index (FWCI)
bioassessment
biological indicators
diatoms
macroinvertebrates
Spatial Coverage:
United States -- Florida

Notes

General Note:
149 Pages

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University of Florida
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All applicable rights reserved by the source institution and holding location.
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AA00004282:00001


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The Wetland Condition Index (WCI):
Biological Indicators of Wetland Condition for Isolated Depressional Herbaceous
Wetlands in Florida







Report Submitted to the
Florida Department of Environmental Protection
under Contract #WM-683







By
Charles R. Lane
with
Mark T. Brown, Mike Murray-Hudson,
and M. Benjamin Vivas







H.T. Odum Center for Wetlands
University of Florida
Gainesville, FL 32611-6350


September 2003









ACKNOWLEDGMENTS


This research was supported under a research contract from the Florida Department
of Environmental Protection (FDEP); M.T. Brown, principal investigator. We would like
to acknowledge the support of FDEP staff, especially Russ Frydenborg, Ashley O'Neal,
Ellen McCarron, Liz Miller, Lori Wolfe, Joy Jackson, Johnny Richardson, and the FDEP
Central Laboratory in Tallahassee.
Additional acknowledgement is due to the research group of the H.T. Odum Center
for Wetlands, especially Kelly Reiss, Matt Cohen, Jim Surdick, and Susan Carstenn. We
also thank the members of the 1999 and 2000 field crew for their tireless and enthusiastic
work, especially Mark Fowlkes, Mark Otto, and Michael Stevens. Steven Doherty was an
integral part of the initial stages of this research, and his perseverance and hard work
helped to ensure this research to fruition.


































This project and the preparation of this report were funded in part by a Section 319
Nonpoint Source Management grant from the U.S. Environmental Protection Agency
through a contract with the Florida Department of Environmental Protection.
















TABLE OF CONTENTS
Page

A C K N O W L E D G M E N T S .................................................................................................. ii

LIST OF TABLES ................................................... vii

LIST OF FIGURES ........................................ .............. xi

EXECU TIVE SU M M ARY .. ................................................................. .............. xiii

CHAPTER

1 INTRODUCTION AND OVERVIEW ..................................................................

In tro d u ctio n ................................................................... .......................... ............
GIS M easurem ents and W etland M etrics......................................... ...............2...
R regional C om position ...................................................................... ...............4...
Environmental Correlates and Assemblage Response ....................................4...
B background ................................................................................ ..........................4
Wetland Trends ................. ........................................ .6
Effect of Land Use Change on Wetland Systems...................................................7...
N utrient and C hem ical L oading ....................................................... ...............9...
Selective H erbivory and Tram pling ............................................... ................ 10
Ancillary Impacts from Landscape Modification.......................................... 10
Wetland Assemblages and Biological Assessment ................................................. 11
P roje ct O v erv iew ........................................................................................................ 12

2 D IA TOM S A S BIOIND ICA TOR S....................................................... ................ 13

In tro d u ctio n ............................................................................................................... .. 1 3
M eth o d s .......................................... ... ... ........................................................ ........ 14
Site Selection and Agricultural Development Gradient ................................... 14
Field Data Collection, Sample Preparation and Laboratory Procedures............. 15
Diatoms ............... ... ... ........................... 15
Soil and water physical-chemical sampling and analysis .........................16
D ata A n aly ses ...................................................................................................... 16
Sum m ary statistics.................................................................................. 16
D iatom s-com positional tests ................................................... ................ 17
Diatoms community composition and correlation with soil and water
param eters ...................................................................................... 17
M etric D evelopm ent .................................................................... ............... 18









Sensitive and tolerant taxa....................................................... ............... 19
A utecological m etrics.............................................................. ............... 19
Constructing the Multimetric Index ...............................................................20
R results .............................................................. ........ ..................... 20
W etland D iatom C om position .......................................... ........... ................ 20
Diatom Composition and Environmental Correlates ....................................26
M etric D ev elopm ent........................................... ......................... ................ 29
R regional com position .............................................................. ................ 29
Indicator species analyses ....................... ............................................ 31
A utecological indices ........................................................ 37
T he M ultim etric Index ......................................... ........................ ................ 42
D discussion ............................................................................... ....... .............. ............... 44
Diatom Composition and Environmental Correlates ....................................44
Diatom Composition and Wetland Regions.............. ....................................46
M etric D ev elopm ent........................................... ......................... ................ 46
Indicator species analysis ........................................................ ................ 46
A utecological indices .............................................. ................ ................ 47
The Diatom Multimetric Index-Conclusion and Recommendations...............47

3 MACROPHYTES AS BIOINDICATORS ...........................................................49

In tro d u ctio n ................................................................................................................. 4 9
M e th o d s ........................................... ..... .....................................................................5 0
Site Selection and Disturbance Gradient ................ ...................................50
Field Data Collection ....................................................................... 52
D database D evelopm ent..................................... ........................ ................ 53
Species characteristics ...................................... ...... ............ ..... .............. .. 53
C oefficient of C onservatism ................................................. ................... 54
Soil and Water Physical-Chemical Sampling and Analysis.............................. 54
D ata A n a ly se s ...................................................................................................... 5 5
Sum m ary statistics....................................... .. ...... .......... .... .. ... ...... ..... 55
Macrophytes-compositional analysis ......................................................55
Macrophyte composition and soil and water parameter correlates ...........55
M etric D ev elopm ent........................................................................ ............... 55
Sensitive and tolerant species.................................................. ................ 56
E xotic species ...................................................................................... 56
A annual to perennial ratio ......................................................... ................ 56
Average Coefficient of Conservatism.....................................................56
Vegetative Index of Wetland Condition.........................................................57
R e su lts....................................................................................................... ....... .. 5 7
F field D ata ............................................................................................................ 5 7
A n cillary D ata ..................................................................................................... 5 7
C om positional A naly sis................................................................ .................. 59
Community Composition and Environmental Gradients ...............................60
M etric D ev elopm ent........................................................................ ................ 62
Sensitive and tolerant species.................................................. ................ 62
P percent exotic ...................................................................................... 69


iv









A annual to perennial ratio ......................................................... ................ 70
Average Coefficient of Conservatism ..................................... ................ 71
Vegetative Index of W etland Condition......................................... ................ 72
D iscu ssio n ................... ... .. .............................................................. ........... 7 5
Environmental Gradients and Species Distributions......................................75
M etric D ev elopm ent........................................................................ ................ 77
Sensitive and tolerant species.................................................. ................ 77
P percent exotic ...................................................................................... 78
A annual to perennial ratio ......................................................... ................ 79
Average Coefficient of Conservatism .............. .................................... 80
V egetative Index of W etland Condition......................................... ................ 81
Field D ata Collection .................................................................... 81
Conclusions and Recom m endations..................................................... 82

4 MACROINVERTEBRATES AS BIOINDICATORS .................... ..................... 83

In tro d u c tio n ................................................................................................................. 8 3
Methods ............... .. .. .. ........................................... 85
Site Selection and Agricultural Development Gradient ................................... 85
Macroinvertebrate Collection and Identification............................................85
Water and Soil Physical-Chemical Sampling and Analysis ................................ 86
Macroinvertebrate Composition and Environmental Correlates ......................... 86
M acroinvertebrate Compositional Analyses .................................. ................ 86
Sum m ary statistics............................. ........................ .. ......... ..... 86
Regional composition of macroinvertebrates.........................................86
Macroinvertebrate Metric Development ................................................87
C ategorical m etrics...................................... .. .......... ............ .. ........ .... 87
A ncillary data ...................................................................................... 88
Sensitive and tolerant species.................................................. ................ 88
Macroinvertebrate Index of Wetland Condition.............................................89
R e su lts.............................................. ......................................................... ....... .. 8 9
Wetland Macroinvertebrate Composition .................................89
Community Composition and Environmental Gradients ...............................92
M etric D ev elopm ent........................................... ......................... ................ 94
Sensitive and tolerant taxa....................................................... ................ 96
Percent predators .. .. ................. ............................................... 98
Percent O donata ............... .......... ............................. 98
Percent Orthocladiinae ........................... ............... 99
Macroinvertebrate Index of Wetland Condition..................... ...................100
D iscu ssion ........................................................ .... ...... ..... ... .... ... .. ................ 10 1
Environmental Correlates and Macroinvertebrate Composition .....................101
R regional D ata A analyses ........................................................ 104
F in al M etric s...................................................................................................... 10 4
Sensitive and tolerant genera.......................................... 105
Categorical metrics-predators...... .... .........................105
Categorical metrics-Odonates...... .... .........................105
Categorical m etrics-Orthocladiinae...... .... ...................................1... 06


v









Macroinvertebrate Index of Wetland Condition..................... ...................107
Field Sampling and Macroinvertebrate Identification................................. 107
F field sam pling .................................. .... ..................................... 107
Macroinvertebrate identification and enumeration ................ ...................108
Conclusions and Recommendations....................................... 109

5 SU M M ARY AND SYN THE SIS .......................................................................... 111

M etric Sum m ary ........................................................ ............... ..... ............. .. 111
Landscape Assessment and Index Development....................................................111
Environmental Variables Driving Wetland Composition Across Assemblages ......113
Environmental Variables and Management Concerns .................. ...................114
Conclusions and Recommendations...... ........ ..................... 114

APPENDIX

A Site D descriptions .............. .. .................. ................ .......................... ........... 116

B Soil and W ater Sampling M ethods and Results ....... ... ................................... 118

C D iatom A utecological V alues.................................. ...................... ............... 121

D Coefficient of Conservatism .................................... ...................... ............... 125

LIST O F R EFEREN CE S .. .................................................................... ............... 130















LIST OF TABLES


Table page

1-1. Landscape Development Intensity Disturbance Coefficients................................3...

1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida
landscape and concurrent increases in agricultural and urban land use..................7...

1-3. National Wetland Inventory categories and landscape abundance of freshwater
w etlan d s in F lorid a ............................................................................................ 8

2-1. Summary statistics of richness (S), evenness (E), Simpson's diversity index (H) and
Shannon diversity index (D') for benthic diatoms .............................................22

2-2. Summary statistics of richness (S), evenness (E), Simpson's diversity index (H) and
Shannon diversity index (D') for epiphytic diatoms...........................................23

2-3. Summary statistics of richness (S), evenness (E), Simpson's diversity index (H) and
Shannon diversity index (D') for phytoplanktonic diatoms................................24

2-4. Summary statistics and diatom similarities using Tukey's HSD. .............................25

2-5. Mann-Whitney U-test results of summary statistics between reference and impaired
LDI classes within benthic, epiphytic, and phytoplanktonic diatom groups. ..........25

2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland condition. ..26

2-7. MRPP analyses of the compositional similarity between benthic, epiphytic, and
phytoplanktonic diatom s. ................. ............................................................. 27

2-8. Comparison of the medians of water and soil variables between LDI classes with the
M ann-W hitney U -test ...................................................................... ................ 27

2-9. Correlations of environmental variables and ordination scores for benthic
d ia to m s ................................................................................................................ ... 3 2

2-10. Correlations of environmental variables and ordination scores for epiphytic
d ia to m s ................................................................................................................ ... 3 2

2-11. Correlations of environmental variables and ordination scores for phytoplanktonic
d ia to m s ................................................................................................................ ... 3 3









2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of
South, Central, and N orth w etland regions. ........................................ ................ 33

2-13. Reference site diatom indicator taxa identified using Indicator Species Analysis for
each w etland region ................................................................................... 34

2-14. Impaired site diatom indicator taxa identified using Indicator Species Analysis for
each w etland region ................................................................................... 35

2-15. Statewide indicators of reference conditions as determined from Indicator Species
A n a ly sis ............................................................................................................... .. 3 6

2-16. Statewide indicators of impaired conditions as determined from Indicator Species
A n a ly sis ............................................................................................................... .. 3 7

2-17. Correlations of autecological abundance data and LDI score ...............................39

2-18. Mann-Whitney U-test of autecological abundance values between impaired and
reference conditions. ............. ................ .............................................. 39

2-19. Quadrisect values and the 95th percentile data for each proposed biological
in d ic a to r ................................................................................................................ ... 4 2

2-20. Diatom Index of Wetland Condition scores for sampled sites..............................43

3-1. Advantages and disadvantages of using macrophytes as biological indicators of
wetlands condition .......................... .......... ........................ 50

3-2. Sam pling dates for each region .................................... ..................... ................ 53

3-3. Ancillary data added to the database for each plant species.................................53

3-4. Scoring Criteria for the Coefficient of Conservatism...........................................54

3-5. Summary statistics of richness (S), Simpson's diversity index (H) and Shannon
diversity index (D ') for m acrophytes ................................................. ................ 58

3-6. Co-occurrence matrices of macrophytes by region and impairment condition.........60

3-7. Simultaneous and iterative tests of community composition among regions. ..........60

3-8. MRPP comparison of the median values of water and soil variables between
reference and im paired sites ................................................................ ................ 6 1

3-9. Correlations of environmental variables and ordination scores. ..............................62

3-10. Regionally derived species indicative of reference conditions. .............................64

3-11. Regionally derived species indicative of impaired conditions ..............................65









3-12. Spearman correlations of the adundance of regional sensitive and tolerance
macrophyte species with LDI scores for each site. .............................................65

3-13. Indicator species of reference conditions derived from the peninsular dataset.......66

3-14. Indicator species of impaired conditions derived from the peninsular dataset........ 67

3-15. Exotic taxa encountered and regions) of occurrence ........................................69

3-16. Quadrisect values and 95th percentile for metric scoring. ................................72

3-17. Site scores for each metric and the summed VIWC...........................................73

4-1. Advantages and disadvantages of using macroinvertebrates in wetland
b io a sse ssm en t ........................................................................................................... 8 4

4-2. Compositional metrics, definition, and expected response. ................................... 87

4-3. Trophic metrics, definition, and expected response. ............................ ................ 88

4-4 Summary statistics of richness (S), evenness (E), Simpson's diversity index (H) and
Shannon diversity index (D') for macroinvertebrates.........................................90

4-5. Mann-Whitney U-test results of summary statistics between reference and impaired
LD I classes and betw een regional datasets. ........................................ ................ 91

4-6. MRPP analyses of the macroinvertebrate compositional similarity between South,
C central, and N orth w etland regions..................................................... ................ 91

4-7. MRPP analyses of the macroinvertebrate compositional similarity for reference sites
between South, Central, and North wetland regions...........................................92

4-8. MRPP analyses of the macroinvertebrate compositional similarity for impaired sites
between South, Central, and North wetland regions...........................................93

4-9. Comparison of the medians of water and soil variables between reference and
impaired conditions with the Mann-Whitney U-test...........................................93

4-10. Correlations of environmental variables and ordination scores for
macroinvertebrates. ... ...................... ....... ................... 94

4-11. Statewide indicators of reference conditions as determined from Indicator Species
A n a ly sis ............................................................................................................... .. 9 6

4-12. Statewide indicators of impaired conditions as determined from Indicator Species
A n a ly sis ............................................................................................................... .. 9 7

4-13. Quadrisect values and the 95th percentile data for each proposed biological
in d ic ato r.............................................................................................................. .. 1 0 0









4-14. Macroinvertebrate Index of Community Condition scores for sampled sites ......102

A-1. Site coordinates and LDI score ...... .......... .......... ..................... 116

B-1. Soil characteristics measured at each study site. .................................119

C -1. D iatom A utecological V alues ........................................................... ............... 121

D-1. Coefficient of Conservatism scores for sampled macrophytes.............................. 125















LIST OF FIGURES


Figure page

1-1. Schematic of the relationship between various ecosystem influences and biological
in te g rity .......................................................................................................... 5

1-2. Approximate landscape extent of wetlands in Florida. .......................................7...

2-1. Algal study site locations and encounter probability for isolated depressional
wetlands ................................................................. ..... 15

2-2. Hypothesized example of metric scoring using the 95th percentile of the dataset. ...21

2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly
correlated environm ental variables. ............................................... ................ 29

2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly
correlated environm ental variables. ....................... ......................................... 30

2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and
strongly correlated environm ental variables. ...................................... ................ 31

2-6. Indicator species abundance data plotted against the LDI. ..................................38

2-7. Diatom abundance for autecological metrics plotted against the LDI gradient ........30

2-8. Diatom Index of Wetland Condition scores for each site plotted against the
disturbance gradient. ............. ................ .............................................. 44

3-1. Study site locations and encounter probability for isolated depressional wetlands. .52

3-2. Transect and quadrat locations in a hypothetical depressional wetland.................52

3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted scores
for w etland m acrophytes ........................................ ......................... ................ 59

3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly correlated
environm ental variables ...................................................................... ................ 63

3-5. Abundance of sensitive species along the disturbance gradient...............................68

3-6. Abundance of tolerant species along the disturbance gradient ..................................68









3-7. Abundance of exotic taxa at each site along the disturbance gradient...................70

3-8. Annual to perennial ratio at each site along the disturbance gradient....................71

3-9. Average Coefficient of Conservatism value for each site along the disturbance
g ra d ie n t.................................................................................................................. ... 7 2

3-10. Relationship between the VIW C and the LDI................................... ................ 75

3-11. Environmental optima along a hypothetical environmental gradient................... 78

4-1. Biplot of macroinvertebrate NMDS ordination scores for each site and strongly
correlated environm ental variables. ....................... ......................................... 95

4-2. Abundance of sensitive taxa plotted against the LDI...........................................97

4-3. Abundance of tolerant taxa plotted against the LDI.............................................98

4-4. Predator abundance plotted against the LDI......................................... ................ 99

4-5. Odonata abundance plotted against the LDI......................................... ................ 99

4-6. Abundance of Orthocladiinae plotted against the LDI................. .................. 100

4-7. Macroinvertebrate Index of Wetland Condition plotted against the LDI............. 101















EXECUTIVE SUMMARY


THE WETLAND CONDITION INDEX: BIOLOGICAL INDICATORS FOR
ISOLATED DEPRESSIONAL WETLANDS IN FLORIDA

With the passage of the Water Pollution and Control Act (1972, "Clean Water
Act"), states were charged with the task to restoreoe and maintain the chemical, physical,
and biological integrity of the Nation's waters" (Water Pollution and Control Act
101 (a)). Biological integrity can be defined as, "the ability of an aquatic ecosystem to
support and maintain a balanced, integrated, adaptive community of organisms having a
species composition, diversity, and functional organization comparable to that of the
natural habitats of the region" (Karr and Dudley 1981). The State of Florida has
developed measurements of the biological integrity of freshwater aquatic systems through
the use of biological indicators, or measurable attributes of the biota that respond to
anthropogenic stressors. This has been completed for streams (Stream Condition Index,
Barbour et al. 1996) and lakes (Lake Condition Index, Gerritsen et al. 2000).
The development of the index of Florida wetland resource condition, or the
Wetland Condition Index, has followed from those earlier works assessing streams and
lakes of Florida. The goal of this project was to identify characteristics of herbaceous
wetland organismal structure, composition, and function that may serve as biological
indicators of the condition of Florida's wetland resources. Intermediate and often
concurrent goals of the project have included:

The development of a wetland classification system and geographic
regionalization to increase the sensitivity of biometrics;
The development of measures of anthropogenic disturbance affecting the
organismal assemblage of a given wetland;
The development and implementation of sampling protocols for macrophytes,
macroinvertebrates, and algal wetland assemblages;
The identification of indicators of wetland condition along the disturbance
gradient within each of the three focal assemblages;
The development of the Wetland Condition Index (WCI), an assessment method
of assemblage-specific indices of community condition for diatoms (the Diatom
Index of Wetland Condition), vegetation (the Vegetative Index of Wetland
Condition), and macroinvertebrates (the Macroinvertebrate Index of Wetland
Condition), for wetland systems throughout Florida.

This report addresses the last four of the goals described above. The first goal was
addressed in earlier reports to FDEP (see Doherty et al. 2000, Lane 2000).
The approach has included a review of technical and scientific literature,
development of a wetland classification system and crosswalk with other classifications,









wetland regionalization of Florida, and 3 years of wetland biological surveys in the
growing seasons of 1998 (pilot study), 1999, and 2000. The biological surveys were
designed to test the validity (and necessity) of the proposed wetland regions and to
identify the appropriate biological indicator taxa.
The wetland classification scheme was organized with major classes defined from
three variables: 1) dominant vegetation (forested, shrub, herbaceous); 2) geomorphic
position (stream channel (floodplain), flat topography, sloped topography, lake fringe,
depressional); and 3) primary water source (rainfall, surface water, ground water).
Subclasses are discriminated by modifiers (hydroperiod and plant community
associations). Eleven wetland classes were identified: forested (river swamp,
slough/strand/seepage swamp, lake swamp, depression swamp, flatland swamp); shrub
dominated (shrub-scrub swamp); and herbaceous (river marsh, wet prairie, lake marsh,
depressional marsh, seepage marsh). An HTML electronic data base has been completed
and delivered to the FDEP that cross walks existing wetland classifications to the new
simplified, classification scheme developed for the bio-assessment project.
Regionalization of the State was considered necessary since there is significant
variation in climatic and physical features of the Florida peninsula and it was believed
that these regional differences could equate to variations in biological indicator "signals."
Map coverages of physical and climatic variables of the Florida landscape were used to
develop regions that had different characteristic driving energies and landscape structural
characteristics (see Lane 2000).
The map coverages were combined with GIS map algebra to create a spatial
hydrologic budget equation for the State. The equation modeled the movement of water
on the landscape during the ecologically sensitive spring growing season. The output of
the model was a Potential Soil Moisture Index (PSMI). The PSMI was separated into
four regions based on both the critical depth of saturation and on a statistical clustering of
the PSMI values. The classified regions were tested for similarities and differences to
determine if between region variation in wetland type and environmental variables was
greater than within region variations.
A quantitative index of the human disturbance gradient has been developed using
energy intensity of land uses as the metric. Called a Landscape Development Intensity
index (LDI), the LDI is a land use based index of human disturbance. It is calculated
spatially from aerial photographs of each site using coefficients applied to land uses
within a 100 meter buffer surrounding the wetlands. Development intensity factors are a
function of the energy use per unit area of land use. A total area weighted LDI is
calculated for the 100-meter area of influence (see Brown and Vivas submitted).
Three years of biological surveys of wetlands through out the state were designed
to test regionalization as well as for metric and bio-indicator development. A 1998 pilot
study involved surveying 24 herbaceous and forested depression wetlands in north and
central Florida. Major taxonomic assemblages were characterized and ranked along a
gradient of disturbances. Sites were located within multiple land uses such as parks,
preserves, pasture, farm fields, well fields, silviculture plots, and urban matrix. Impacts
that were assessed included hydrological modifications, nutrient loading, and altered
hydroperiod. The first year's sampling resulted in development of standardized sampling
procedures, design and implementation of a statewide sampling program, and
identification of community attributes and candidate metrics.









In the second and third year's field seasons, 75 herbaceous, depressional wetlands
were surveyed in three regions (22 sites in the North, 30 in the Central, and 23 in the
South region, see Figures 2-1 and 3-1). Approximately half of the wetlands were located
in developed landscapes (i.e. agricultural setting) and half were reference locations.
Many of the sites were paired sites (impacted and reference at close proximity).
Three indices of wetland integrity were developed based on measurable attributes
metricss) of the assemblages sampled from the 75 isolated depressional wetlands (see
table below): the Diatom Index of Wetland Condition (DIWC, 14 metrics), Vegetative
Index of Wetland Condition (VIWC, 5 metrics), and Macroinvertebrate Index of Wetland
Condition (MIWC, 5 metrics). These indices were not regionally dependent and were
thus applicable to the entire peninsula. Each index was significantly correlated
(Spearman's r> 0.751, p<0.0001) with an independent geographic information systems-
based measure of human landscape modification, the Landscape Development Intensity
index (see Brown and Vivas submitted).


Diatom Index of Wetland
Condition
% Sensitive Spp.
% Tolerant Spp.
% Sensitive Elevated pH
% Tolerant Elevated pH
% Sensitive Elevated
Salinity
% Tolerate Elevated Salinity
% Sensitive Elevated
Nitrogen
% Tolerate Elevated
Nitrogen
% Sensitive Low D.O.
% Tolerate Low D.O.
% Meso- & Polysaprobous
% Oligotrophic
% Eutrophic
% Pollution Tolerant


Vegetative Index of
Wetland Condition
% Sensitive Spp.
% Tolerant Spp.
% Exotic Taxa
Annual: Perennial Ratio
Average Coefficient of
Conservatism Score


Macroinvertebrate Index
of Wetland Condition
% Sensitive Genera
% Tolerant Genera
% Predators
% Odonata
% Orthocladiinae


An ancillary goal of this research was to elucidate the various landscape and
soil/water physio-chemical constituents responsible for determining the community
composition of the sampled wetlands, as understanding the driving forces may aid in
managing wetland resources. Four variables were strongly associated with community
composition across all three assemblages diatomss, macrophytes, and macroinvertebrates)
sampled: soil pH, water column specific conductivity, water column total phosphorous,
and Landscape Development Intensity index score. In addition, water color and latitude
were also associated with macroinvertebrate and macrophyte community composition,
respectively.
The indices of biotic integrity developed from this research may be used to provide
quantitative and objective measurement of the wetland resources of peninsular Florida
and may form the scientific basis for an objective and quantifiable rapid assessment
procedure. In addition, results from this study suggested that efforts to restore









community composition and associated processes and functions should focus on
amending inflows and fluxes of water, materials, and energy that affect soil pH, specific
conductivity, and water TP, as well as decreasing the abundance of human-developed
lands within 100m of wetlands.














CHAPTER 1
INTRODUCTION AND OVERVIEW

Introduction

Wetlands are defined as "areas that are inundated or saturated by surface or ground
water at a frequency and duration to support, and that under normal circumstances do
support, a prevalence of vegetation typically adapted for life in saturated soil conditions"
(42 Fed. Reg. 37, 125-126, 37128-29; July 19, 1977). Wetlands on the landscape provide
many important functions, including biogeochemical cycling, wildlife habitat, floodwater
attenuation, and water quality improvement. In the mid-1970s the United States
Environmental Protection Agency (U.S. EPA) mandated that wetlands, as protected
under the Clean Water Act (Clean Water Act 101(a)), required biological monitoring
and assessment to ensure that the biological integrity (sensu Karr 1981) of these systems
was not diminished. Wetland biological monitoring and assessment, as differing from
synoptic water or soil chemistry sampling, characterizes the wetland flora and fauna to
measure the relative state of wetland resources.
The use of biotic characteristics, including taxonomic composition and the
abundance of functional guilds (i.e., "scrapers"), has provided robust assessments of the
relative state of various aquatic systems (see Barbour et al. 1996, Gerritsen and White
1997), as organisms integrate exogenous perturbations that occur at local (i.e., nutrient
loading) and landscape scales (i.e., increases in residential land use) (Karr and Chu
1999). These observations have led to the development of indices of biological integrity
(IBIs, Karr 1981), which relate measured attributes (or metrics) of various assemblages
measured on-site to changes in human disturbance (Karr and Chu 1999, U.S. EPA
2002a).
Often, the human disturbance gradient is interpreted subjectively (i.e., best
professional judgment Adamus et al. 1991, Miller and Gunsalus 1997) or confounded
through circular logic (i.e., a metric correlated to the disturbance gradient may also be
directly incorporated into scoring the disturbance gradient Miller and Gunsalus 1997).
To decrease these problems associated with on-site assessments, as well as the costs and
logistics related to on-site visits, techniques have also been developed to examine
biological response to landscape scale measurements through the use of geographic
information systems (GIS) analysis (O'Conner et al. 2000, Cuffney et al. 2000). As
compared with gradients assessed on-site that examine conditions l i/hin the system,
landscape scale measurements assume a direct relationship between land use surrounding
an aquatic body and the composition and relative condition of the system (Galatowitsch
et al. 1999a). For example, studies have related biological data (e.g., richness) to the
abundance of particular land use measurements (e.g., percent impervious surface meters -
Doberstein et al. 2000, percent agricultural land use within watershed Roth et al. 1996).
However, GIS based analyses are subject to errors of land use interpretation from aerial
photos, as well as delays (often of several years) between flight dates and available geo-









rectified and digitized information, which can affect their accuracy. On the other hand,
GIS based analyses of relative condition do not require an on-site visit, which decreases
sampling effort and thus increases the number of sites quantifiable. In addition, GIS
based analyses have been reported as generally precise and correlated with biological
conditions within nested systems (Roth et al. 1996, Galatowitsch et al. 1999a, Karr and
Chu 1999). These attributes increase the allure of GIS based analyses in assessing the
relative condition of isolated depressional herbaceous wetlands on the Florida landscape.
However, a disconnection may exist between the wetland system and the GIS-
based assessment method due to the assumption of causal mechanisms between land use
within a given distance from the wetland and relative wetland condition. For instance, a
site may be perched on the landscape and thus not as highly affected by inputs from
surrounding lands as a site in a low-lying area within the same land use. In this example,
the expected variance in the biological data vis-a-vis the two hypothetical sites would not
be assessed through GIS analyses as such biological analyses would be at too coarse a
scale for spatial analyses. However, incorporating on-site measurements of biota,
although more difficult than GIS analyses due to sampling and identification efforts,
provides additional information germane to accurately assessing relative wetland
condition (Karr and Chu 1999). In addition, combining GIS analyses with on-site
biological data can improve the accuracy, precision, and sensitivity of spatial metrics by
providing causal pathways to perceived variance in the dataset, and may instigate future
improvements in assessment methods.
These observations lead to the following goals of this report. First, to identify
measurable attributes (or metrics, such as the abundance of exotic taxa) of the flora
diatomss and macrophytes) and fauna (macroinvertebrates) of isolated depressional
marshes in Florida that are highly correlated with a GIS based measurement of landscape
modification, the Landscape Development Intensity index, which is described below.
Second, to test interregional compositional differences attributed to
latitudinal/physiological gradients between the organisms sampled from within three
wetland regions of peninsular Florida (after Lane 2000) that, if present, may necessitate
the development of unique measurable attributes for each wetland region. Third, to
identify significant associations between floral and faunal assemblage composition and
measured soil and/or water parameters collected from sampled wetlands to aid in
synecological understanding and resource management.

GIS Measurements and Wetland Metrics

The Landscape Development Intensity index (LDI, Brown and Vivas submitted)
was used to assess the development intensity of lands within 100m around each sampled
wetland, independent of the wetland biota. The LDI was developed by Brown and Vivas
(submitted) and assesses the intensity of various land uses by measuring the annual non-
renewable energy flow, given in terms of emergy, or embodied energy (Odum 1995), for
each land use. They calculated their emergy values by identifying the energy pathways
for each land use (land use data obtained from local water management districts, based on
1995 aerial photos), obtaining the value in joules/year from published sources, and
multiplying the joules/year value by solar-emjoules/joule (sej/J, Odum 1995) to relate the
amount of energy to a solar unit per year (see Brown and Vivas submitted). The use of an
independent energy-based spatial measurement in this study permitted the incorporation









of many disparate processes (e.g., pesticide use, water diversion and ditching, plowing,
road building) into a single, agglomerative value. The actual LDI calculation was made
for a 100m buffer directly surrounding each wetland using the following equation: LDI =
Z (LDC % LU); where LDI is the Landscape Development Intensity index, LDC is the
Landscape Development Coefficient (Table 1-1), the %LU is the percent of each land use
within the 100m buffer directly surrounding each wetland. The relationship of land use
intensity with other buffer sizes (18m, 250, 500m, 1000m) is currently being investigated
(M.B. Vivas, Department of Environmental Engineering Sciences, University of Florida,
personal communication).

Table 1-1. Landscape Development Intensity Disturbance Coefficients.
Non-Renewable Ln
Empower Density Non-Renewable LDI
Land Use (E14 sej/ha/yr) Empower Density Coefficients
Natural System 0 1.00
Natural Open water 0 1.00
Pine Plantation 5.10 1.63 1.58
Woodland Pasture
(with livestock) 8.00 2.08 2.02

Pasture (Bahia) (without
livestock) 17.20 2.84 2.77

Recreational / Open Space
(Low-intensity) 17.20 2.84 2.77

Low Intensity Pasture
(Bahia) (with livestock) 33.31 3.51 3.41

Citrus 44.00 3.78 3.68
High Intensity Pasture
(Bahia, with livestock) 46.74 3.84 3.74

Row crops 107.13 4.67 4.54
Single Family Residential
(Low-density) 1077.00 6.98 6.79

Recreational / Open Space
(High-intensity) 1230.00 7.11 6.92

High Intensity Agriculture 1349.20 7.21 7.00
(Dairy farm)
Note: Modified from Brown and Vivas (submitted).









Strong correlations between measured wetland attributes and the LDI would
suggest a connection between surrounding land use and nested community composition
(Roth et al. 1996, Brown and Vivas submitted). The relationship between any given
metric and the LDI would be further strengthened through evidence of accuracy,
precision, and sensitivity to changes in the LDI. High variance within metric responses
for any given LDI could suggest causal mechanisms affecting community composition
that were not accurately captured by the LDI, such as sources of stress not visible to GIS
analyses (i.e., low relief ditch from degraded water source). An examination of metric
sensitivity to LDI values would permit the development of land use thresholds for various
assemblages, and furthermore may provide predictive ability for future wetland
composition in areas undergoing land use change.

Regional Composition

Testing the effects of physiographic and/or climatic regions on wetland community
composition can provide germane information on the development of ground-based
biometrics. Lane (2000) delineated freshwater wetlands of Florida into four regions based
on a climatic and physiographic model. Composition may differ between regions due to
physiographic and climatic differences and possibly render biometrics developed in one
area of the state impotent in another wetland region.

Environmental Correlates and Assemblage Response

Strong correlations between LDI values and community composition would
suggest a causal mechanism and may assist in explaining metric relationships with the
LDI. Developing an understanding of water and soil environmental parameters correlated
with community composition may also provide the means for environmental managers to
address specific ecosystem driving forces affecting wetland systems. In addition, strong
correlations between environmental parameters and community composition can advance
the knowledge of autecological relationships for diatom, macrophyte, and
macroinvertebrate taxa.

Background

With passage of the Clean Water Act (1972, "Water Pollution and Control Act"),
states were charged with the task to "restore and maintain the chemical, physical, and
biological integrity of the Nation's waters," including wetlands (Water Pollution and
Control Act 101 (a), Danielson 1998). Adhering to this mandate for wetland systems
required first that a working definition for wetland biological integrity be defined, and
second that a method to ascertain the relative ecological state of wetlands be developed.
Integrity, as it has been applied to Clean Water Act mandates and thus may be
applied to Florida's wetlands, has been defined as "the ability of an aquatic ecosystem to
support and maintain a balanced, integrated, adaptive community of organisms having a
species composition, diversity, and functional organization comparable to that of the
natural habitats of the region" (Karr and Dudley 1981, pg. 60). Implicit within this
definition is maintenance of ecosystem driving forces that operate at different spatial and
temporal scales to maintain the resilience and pattern of the ecosystem, such as the proper











Transformations Conductivity

Organics
Chemical Organics
pH Variables Exogenous
chemicals
Nutrients
Alkalinity Turbidity D.O.


Competition Life Stages

Feeding
Biotic Factors )
Disease

Keystone
Species Reproduction Parasitism


O.M. Inputs


Sunlight


Nutrients


Land Use Endogenous
Land Use e m
extremes
Duration

Hydrology Precipitation
Depth


Runoff I Groundwater


Buffer Size
Substrate
Composition Ha


Water Flow


Canopy

Erosion


10 & 20 Seasonal Vegetation Topography
Production Cycles
Figure 1-1. Schematic of the relationship between various ecosystem influences and
biological integrity. (Modified from U.S. EPA 2002a).

hydrology, fire regime, and cross-scale community interactions (Figure 1-1, Peterson et
al. 1998, Gunderson and Pritchard 2002).
Historically, aquatic monitoring and assessment inferred ecosystem condition from
either toxicity samples or ambient water quality monitoring (Karr 1981, 1993, McCarron
and Frydenborg 1997). At best, these data were rudimentary in their ability to reflect
more than a temporal constituent concentration within the water body. If a toxicity
parameter was not specifically targeted for detection, then the water body could be


BIOLOGICAL
INTEGRITY









considered "clean" yet replete with undetected toxics, metals, or physically altered such
that it no longer resembled a fully functioning water body. Additionally, synergisms
within water bodies from multiple impacts or "spike" loading events were typically not
accounted for in toxicity or ambient monitoring programs (Karr 1993, Karr and Chu
1997).
In the late 1980s, the United States Environmental Protection Agency realized the
potential of biological criteria to assess the Nation's waters and mandated states to use
biological indicators to achieve the goals of the Clean Water Act (United States General
Accounting Office 1988, U.S. EPA 1990, Karr 1995). A premise behind the use of
biological indicators versus synoptic physical or chemical sampling to assess aquatic
condition was that due to their intricate relationship with their environment, organisms in
situ reflect current conditions as well as integrate cumulative impacts (Karr 1981,
Hunsaker and Carpenter 1990, Karr and Chu 1999). Biological criteria and monitoring
programs embraced by the U.S. EPA have since been utilized to assess lakes and streams
throughout the United States (Barbour et al. 1996, Karr and Chu 1999, Barbour et al.
1999, Gerritsen et al. 2000). Only recently have efforts be undertaken to assess wetland
condition using biological criteria (U.S. EPA 2002a).
While other assessment methods exist, such as the hydrogeomorphic (HGM)
approach (Brinson and Reinhardt 1996), or rapid, "best scientific judgment" approaches
(e.g., Wetland Evaluation Technique-WET, Adamus et al. 1991; Wetland Rapid
Assessment Procedure-WRAP, Miller and Gunsalus 1997), the U.S. EPA has supported
the use of multimetric indices of biotic integrity, or IBIs (sensu Karr 1981), to assess the
condition of wetland resources (U.S. EPA 2002a). A multimetric index of biotic integrity
combines measured biological attributes (or metrics) of trophic, community, and/or
functional structure of various species assemblages within a wetland ecosystem into a
single value. Ideal metrics are accurate, highly sensitive to change, and precise. The
developed index can then be compared to either a reference condition (a suite of
previously characterized wetlands located in undisturbed landscapes such as state parks
and preserves) or along a gradient defined by changes in land use (Reynoldson et al.
1997, Karr and Chu 1999, Brown and Vivas submitted). The condition of the aquatic
system in question is based on the relative similarity of the metric value obtained from
that system vis-a-vis previously measured metrics in similar aquatic systems located in
"reference conditions."

Wetland Trends

Wetlands on the Florida landscape provide services to the state including water
retention and flood attenuation, water quality improvement and nutrient immobilization,
aquifer recharge, biogeochemical processes, wildlife habitat, and climate regulation.
Historically, wetlands covered more than half of Florida, approximately 8.2 million
hectares (Figure 1-2). Ditching and filling for agricultural operations, water control, and
urban development over the past 200 years have substantially decreased the abundance
and functional capacity (i.e., habitat, water storage) of wetlands on the Florida landscape
(Dahl 1990, Kautz 1993). A historical perspective of the areal extent of marshes in
Florida and concurrent increases in agricultural and urban landscapes from 1936 1987
is presented in Table 1-2. Approximately 23% of Florida (3.6 million ha) is currently
classified as inland freshwater wetlands by the National Wetlands Inventory (Table 1-3),












IE


200 0 200 400 Kilometers

Figure 1-2. Approximate landscape extent of wetlands in Florida. Riverine, palustrine,
and estuarine wetlands are indicated in black on the map. (Modified from
Lane 2000).

Table 1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida
landscape and concurrent increases in agricultural and urban land use.
Land Use 1936 1949 1959 1970 1980 1987
Marsh 2.82 2.15 2.45 1.48 1.23 1.25
Agriculture 2.45 2.73 3.29 4.13 4.38 4.17
Urban 0.29 0.43 0.72 1.16 1.46 1.89
Notes: Values from 1936 are estimates. Modified from Kautz (1993).

of which greater than 34% are palustrine emergent marshes, the focal wetland class for
this study (Doherty et al. 2000).
Wetlands are typically found in topographic lows in the landscape and tend to
accumulate nutrients, metals, and toxins from up-slope sources as rainfall percolates
through the wetland basin (Kirkman et al. 1998, Mitsch and Gosselink 2000). The
constituents of surface and sub-surface flow, if transported into down-slope wetlands, can
result in changes in processes and floral and faunal composition of receiving wetlands.

Effect of Land Use Change on Wetland Systems

Changes in land use within wetland watersheds hydrologicc units where
precipitation falling within will move via percolation and interstitial flow or overland









Table 1-3. National Wetland Inventory categories and landscape abundance of freshwater
wetlands in Florida.


NWI
Code
R2AB
R2EM
R3AB
R4 SB
L1AB
L2AB
L2EM
P AB3
P AB4
P EM
P SS
P FO 1
P F02
P F03
P F04
P F06
P F07


% NWI inland freshwater wetlands
% upland area
% other (estuarine) wetlands and deepwater habitats
State total area
Source: Doherty et al. (2000)


flow to the wetland) can cause significant changes in wetland structure and function.
Some of these changes are: 1) increased nutrient (mainly phosphorus) and chemical
loading from lands shifted into production (Flaig and Reddy 1995, Bedford 1999, Daoust
and Childers 1999, Maul and Cooper 2000), 2) selective herbivory and trampling from
cattle (Winchester et al. 1985, Long et al. 1986, Blanch and Brock 1994, van Oene et al.
1999, Grace and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000), 3) altered
hydroperiod due to ditching or filling (Anderson and Vondracek 1999, Euliss and Mushet
1999, Kirkman et al. 2000, Babbit and Tanner 2000), 4) increased sedimentation due to
ditching or removing topsoil (Martin and Hartman 1987, Freeland et al. 1999, Shutler et
al. 2000), 5) colonization of invasive exotic organisms (Bedford 1999), 6) destruction of
wetland/upland transition zones (Winchester et al. 1985), and 7) alteration of landscape-
level processes such as fire frequency (Moss 1992, Kirkman et al. 1998, Bedford 1999,
Semlitsch 2000). Of particular relevance to this study are the effects of nutrient and
chemical loading, selective herbivory and trampling by cattle, and ancillary effects of


Wetland Class Description
Riverine, Lower Perennial, Aquatic Bed
Riverine, Lower Perennial, Emergent, non-persistent
Riverine, Upper Perennial, Aquatic Bed
Riverine, Intermittent, Streambed
Lacustrine, Limnetic, Aquatic Bed
Lacustrine, Littoral, Aquatic Bed
Lacustrine, Littoral, Emergent, non-persistent
Palustrine, Aquatic Bed, Rooted Vascular
Palustrine, Aquatic Bed, Floating Vascular
Palustrine, Emergent
Palustrine, Scrub Shrub
Palustrine, Forested, Broad-Leaved Deciduous
Palustrine, Forested, Needle-Leaved Deciduous
Palustrine, Forested, Broad-Leaved Evergreen
Palustrine, Forested, Needle-Leaved Evergreen
Palustrine, Forested, Deciduous (mixed)
Palustrine, Forested, Evergreen (mixed)


% % State
Wetland Area Area
<1 <1
<1 <1
<1 <1
<1 <1
<1 <1
1 <1
<1 <1
1 <1
<1 <1
34 8
11 3
6 1
9 2
5 1
11 2
<1 <1
22 5
-100









changes in wetland watershed land use. As such, a review of those three effects is
provided below.

Nutrient and Chemical Loading

Nutrient and chemical loading of wetland systems alters community composition
(Davis and Ogden 1994, Freeland et al. 1999, Doherty et al. 2000). Changes in land use
development surrounding wetlands can create large stores of exogenous nutrients, which
can act as potential sources for ecosystem-altering nutrients and chemicals. Graetz and
Nair (1995), studying dairy and beef ranching lands in Okeechobee County, Florida,
found mean concentrations of total phosphorus (TP) in the soil of 5300-6500 ug/kg,
approximately 40% of which was soluble reactive phosphorus readily available to
organisms. Graetz and Nair (1995) also found significant differences in soil phosphorus
along a gradient of grazing intensity from 79 kg/ha in natural areas (zero grazing
pressure) to 4939 kg/ha in intensely grazed dairy feedlots. Rainfall and the subsequent
movement of surface and sub-surface flows through phosphorus (P) laden landscapes can
mobilize and deliver P into wetlands and other aquatic systems, resulting in alterations in
community composition, structure, and function with potential effects on food web
dynamics (Winchester et al. 1985, Moss 1992, Flaig and Reddy 1995, Daoust and
Childers 1999, Freeland et al. 1999, Maul and Cooper 2000). For instance, Freeland et al.
(1999) reported that periphyton assimilating increased exogenous P caused shifts in
macrophyte species composition (Freeland et al. 1999). In studies in the Everglades
(Davis and Ogden 1994), higher plants, such as Typha spp. tolerate nutrient loading and
out-compete other less tolerant macrophytes, such as Cladium jamaicense. Likewise,
floating plants Lemna spp., which grow readily in nutrient enriched waters, can become
so prolific to create oxygen stress for aquatic communities in the water column (e.g., fish,
macroinvertebrates, microbes, macrophytes) through shading of photosynthetic, oxygen-
producing algae and other macrophytes (Dierberg and Brezonik 1984).
The direct nutrient loading of wetland systems can also occur as a result of land use
development intensity in the surrounding wetland watershed (Graetz and Nair 1995).
Tanner et al. (1984) tracked cattle movements on a South Florida rangeland and found
that cattle spent the majority of time in herbaceous wetlands (fall months) or
upland/herbaceous wetland ecotones (summer months). They also reported no significant
difference in cattle defecation/urination location among herbaceous wetlands,
upland/herbaceous wetland ecotones, canal banks, or flat woods, suggesting near constant
landscape loading of available nutrients. Several authors suggested encouraging cattle to
graze in marshes during summer as Panicum spp. and Andropogon spp. typically have
the highest crude protein levels of any available forage during that period (Tanner et al.
1984, Kalmbacher et al. 1984, Long et al. 1986). Direct grazing within the marsh could
lead to higher concentrations of P and N as there would be no biochemical degradation of
the nutrient constituents in the process of overland or interstitial flow before their
deposition in the wetland.
Reddy et al. (1996) reported that the uptake of available phosphorous by wetland
vegetation was estimated at 28%-70% of the available P transported to the wetland. This
P uptake is dependent upon plant growth rate, growth structure (woody or herbaceous
material), P concentration in the soil, and the physical and chemical characteristics of the
soil (Agami et al. 1990, Flaig and Reddy 1995). However, aquatic plant storage of P is a









temporary phenomenon as approximately 80% of the nutrients are released to the water
column by decaying vegetation (Agami et al. 1990, Reddy et al. 1996), suggesting that
wetland plants are nutrient storage, and not sinks.
Agrochemical application within a wetland basin may also affect wetland processes
and functions. Movement of pesticides, herbicides, and agrochemical fertilizers into
wetlands is generally related to either direct or drift application or absorption of the
chemical onto soil particles, which are subsequently mobilized into the wetlands during
rainfall events (Anderson and Vondracek 1999, Freeland et al. 1999). Martin and
Hartman (1987) reported influx of sediments to wetlands in cultivated landscapes at twice
the rate from uncultivated landscapes. Euliss and Mushet (1999) noted that chemicals and
chemical-laden soil particles transported from uplands into wetlands could be toxic to
zooplankton and reduce foraging and food assimilation rates of aquatic invertebrates.
Semlitsch (2000) and Shutler et al. (2000) reported impacts to non-target wetland
organisms from pesticides. Several authors found changes in wetland community
assemblages due to agrochemical loading (Anderson and Vondracek 1999, Bedford 1999,
Kolozsvary and Swihart 1999, Maul and Cooper 1999).

Selective Herbivory and Trampling

While low-density grazing in rangeland (native forage) maintains species richness
and mimics natural processes, such as foraging by deer or other herbivores (Blanch and
Brock 1994), high-density herbivory by cattle can alter native upland and wetland
vegetation communities and have long-term successional consequences (Dobkin et al.
1998). Tanner et al. (1984) and others (Kalmbacher et al. 1984, Long et al. 1986) noted
that cattle selectively graze wetland plants on the landscape, thus altering community
composition. Van Oene et al. (1999) found that grazing prevented dominance of tall
wetland species of grasses, shrubs, and trees, as they were selectively harvested by cattle,
which led to structural and functional changes in the wetland, such as decreased wildlife
habitat. Vulink et al. (2000) reported that wetland vegetation community changes
occurred due to modifications of light availability as livestock consumed the shading
vegetation. Additionally, Vulink et al. (2000) found that grazing substantially impacted
plants with apical meristems within the reach of livestock, which altered community
composition and structure.
Reader and Craft (1999) and Vulink et al. (2000) demonstrated that the trampling
and physical destruction of wetland vegetation by livestock directly altered community
structure and composition. In addition, several authors have noted increased fluxes of
nutrient and sediment flow into wetlands through destruction of vegetative buffers, such
as the fringing Hypericum spp. or Serenoa repens (Winchester et al. 1985, Blanch and
Brock 1994, Vulink et al. 2000).

Ancillary Impacts from Landscape Modification

Changes in landscape level processes as a result of modification of wetland
watershed land use have effects on wetland composition and function (Bedford 1999).
Wetlands in cultivated and urban landscapes have highly variable water-level fluxes
compared to wetlands in non-developed landscapes, which can affect soil anoxia and
wildlife habitat (Rushton and Carr 1993, Tilley and Brown 1998, Euliss and Mushnet









1999). In order to facilitate movement of water off the landscape, wetlands in agricultural
land use matrices are often inter-connected by ditches that can decrease the hydroperiod
of all wetlands if attached to an outflow (such as a canal or stream), which can provide
conditions for colonization by upland taxa. If not connected to an outflow, an increased
hydroperiod may result from ditching as water is rapidly shunted off the landscape and
into the wetland, instead of moving slowly via overland and sub-surface flows. In some
cases, canals and streams can back-flood connected marshes, altering hydrology and
possibly allowing marsh access to stream/canal species (such as predatory fish), with
potential impacts to wetland fauna that require fish-free habitat for breeding (Babbit and
Tanner 2000).
Florida ecosystems have evolved with fire as a driving force to the extent that some
organisms require fire for reproductive success (Ewel 1990). In wetland watersheds used
for agricultural purposes, fire is typically excluded (Kirkman et al. 1998). Whereas the
fire season in Florida is related to lightning strikes, which are highest in summer,
prescribed burns currently occur in spring (Kirkman et al. 1998). This alteration to the
timing and extent of natural processes may affect reproduction and foraging success of
wetland organisms, which have evolved with seasonal fire.
Wetland diversity across the landscape (i.e., the number of wetlands in a given
area) is also affected through alterations of wetland watershed land use that include
ditching, draining, and filling (Kirkman et al. 1996, Kirkman et al. 1998, Kolozsvary and
Swihart 1999). Whereas depressional marshes may be scattered on the landscape and
provide metapopulation dynamics (i.e., increased gene flow) of organisms between
wetlands, loss of wetlands on the landscape decreases landscape diversity and can cause
increased crowding and subsequent decreases in population as organisms compete for
decreasing resources and space (Pearlstine et al. 1997).

Wetland Assemblages and Biological Assessment

Various assemblages (i.e., macrophytes, macroinvertebrates, microbes, birds, etc.)
within an ecosystem have been used as biological indicators for aquatic systems,
including wetlands (U.S. EPA 2002b-e). Appropriate indicator assemblages are those that
measurably respond to the gradient defined along the abscissa (i.e., land use change, total
phosphorus, etc.), and ideal indicator assemblages are also composed of organisms
relatively easy to identify, abundant, and available for sampling or mensuration for an
extended period (Karr and Chu 1999). Appropriate metrics derived from indicator
assemblages are accurate, exhibit high precision, and are likewise sensitive to increases in
change along the abscissa (Karr and Chu 1999).
As most aquatic assemblages respond to alterations occurring at both large (i.e.,
abundance of croplands in a wetland basin) and small scales (i.e., pH alterations; Allan
and Johnson 1997), determining the particular stressor or component of anthropogenic
disturbance that an aquatic assemblage responds to is often difficult. Various scales of
temporal response further compound the identification of stressors. Incorporating
multiple assemblages (i.e., macrophytes and macroinvertebrates) can assist in
determining sources of perturbations, especially if the autecological requirements of the
selected assemblages are well established (e.g., Reed 1986, Lenat 1993, Van Dam et al.
1994). Characterizing various edaphic, hydrologic or landscape variables and identifying
trends can also assist in elucidating sources of wetland perturbation.









By including multiple assemblages in the initial development of biological
indicators, the likelihood increases that a suite of potential metrics can be identified that
are strongly correlated with the abscissa. In addition, sampling multiple assemblages
permits an examination of the temporal responses of wetland organisms to perturbations,
which, depending on the speed of community change, has the potential to alter
conclusions. For instance, diatoms respond extremely rapidly to environmental
conditions, on the order of a few hours to a few days, macroinvertebrates respond slower
(with turnover times ranging from hours to years), and macrophytes generally react the
slowest to alterations (responses occur over days to decades). Substantial information
also exists on the natural history and autecological requirements of diatoms (Bahls 1993,
Van Dam et al. 1994), macroinvertebrates (Hilsenhoff 1988, Lenat 1993, Barbour et al.
1999), and macrophytes (Reed 1997, Taft et al. 1997).

Project Overview

In this study, diatoms, macrophytes, and macroinvertebrates were sampled from
isolated depressional herbaceous wetlands located within human-modified land use
matrices throughout peninsular Florida. Compositional differences among sampled
assemblages driven by latitudinal or physiographical regions were examined to ascertain
the importance in developing regionally specific biological assessment metrics. Analysis
of water and soil physical-chemical parameters and land use identified variables affecting
the composition and structure of sampled biotic assemblages in the study wetlands. GIS
analyses assigned empirically derived values to each wetland based on the abundance (%
area) and land use intensity of developed lands within a 100m boundary around each
wetland site. Compositional and functional attributes, or metrics, that correlated with the
empirically derived GIS land use measure were identified from each assemblage and
combined into three unique assemblage-specific field based indices of biological
integrity. In addition, the ability of the GIS land use measure to accurately and precisely
reflect the environmental conditions on-site was assessed through examination of the
variance within metric responses. Conclusions on the use of the wetland organisms and
GIS based measures of relative wetland condition and suggestions for improvements
were made.















CHAPTER 2
DIATOMS AS BIOINDICATORS

Introduction

Diatoms (Class Bacillariophyceae) are important components of wetlands and other
aquatic systems and provide several functions including: 1) primary production, 2)
nutrient and biogeochemical cycling, 3) oxygen cycling, and 4) water chemistry
regulation (Rader and Richardson 1992, Stevenson et al. 1996, Goldsborough and
Robinson 1996, McCormick et al. 1997, Doherty et al. 2000, U.S. EPA 2002e). Stream
and lake researchers, and more recently wetland researchers, noted the response of
diatoms to land use changes, increases in nutrient loading, alterations in pH, and changes
in specific conductivity (Lange-Bertalot 1979, Whitmore 1989, Bahls 1993, Van Dam et
al. 1994, Pan and Stevenson 1996, McCormick and Cairns 1997, Danielson 1998,
Barbour et al. 1999, Stevenson 2001, U.S. EPA 2002e). The U.S. EPA (2002e, p.2)
reports diatoms as "amongst the most widely used indicators of biological integrity and
physico-chemical conditions in aquatic ecosystems." Changes in diatom taxonomic
composition correlated with changes in physical-chemical parameters have been noted in
the Florida Everglades (Raschke 1993), prairie potholes (Adamus 1996), riverine
bottomland wetlands, marshes, swamps, and bogs (Pan and Stevenson 1996, Stevenson et
al. 1999), streams (Bahls 1993, McCormick and Cairns 1997, Barbour et al. 1999, Winter
and Duthie 2000, Munn et al. 2002), large rivers (Fore and Grafe 2002), lakes in Florida
(Whitmore 1989), and other systems (see McCormick and Cairns 1997). The diatom
community response has also been examined for heavy metals (Charles et al. 1996), pH
(Pan and Stevenson 1996), saprobity levels (Lange-Bertalot 1979), nutrient and physical-
chemical parameters (Van Dam et al. 1994), and other perturbations (see reviews in
Stoermer and Smol 1999).
In this chapter, diatoms community attributes were correlated with the Landscape
Development Intensity index (LDI, Brown and Vivas submitted). Strongly correlated
attributes (or metrics) identified through regression with the LDI were scaled so disparate
metrics could be combined. The scaled metrics were summed to create the Diatom Index
of Wetland Condition (DIWC). Analysis of measured abiotic and biotic environmental
data identified parameters strongly correlated with diatom composition to advance
synecological understanding on driving forces affecting the distribution and composition
of wetland diatoms. Variance within diatom metrics was examined to explore
relationships between landscape scale measurements and local, wetland specific
responses.











Methods

Site Selection and Agricultural Development Gradient

Seventy isolated depressional marshes throughout peninsular Florida were sampled
a single time in landscape matrices with varying amounts of human-modified land uses
during summer 1999 (n=35) and 2000 (n=35). Using best scientific judgment, sites were
initially stratified into reference (no obvious human modified landscapes within >100m),
and impaired (obvious human landscape modification within 100m) categories. The
Landscape Development Intensity index (LDI, Brown and Vivas submitted) was later
independently calculated through GIS analyses for each site by identifying varying land
use abundance within each wetland basin (100m around wetland edge). LDI scores of
<2.0 were characteristic of minimally disturbed ("reference") wetlands and allowed the
reference condition to incorporate small disturbances such as low density park paths.
Slightly less than half the sites (33) were defined as reference sites, which were generally
located in state and federal parks, preserves, and state forests. The remaining 37 wetlands
were located within agricultural landscape matrices and were considered "impaired" sites
(LDI > 2.0). Twenty-seven impaired sites were located in cattle ranches of varying
stocking densities, 7 were located in truck crops (tomatoes, peppers), 2 were in citrus
groves, and 1 was sampled in a silvicultural forest. All sites selected were hydrated when
sampled. Site coordinates and LDI score for each sampled wetland may be found in
Appendix A.
As isolated depressional marshes are not uniformly distributed throughout Florida,
the sites were likewise generally located in counties with the proper wetland hydrology
and geomorphic setting (Lane 2000, Figure 2-1). The sites were initially stratified into
three peninsular wetland regions, or areas of similar climatic and physiographic
conditions (after Lane 2000). A compositional test, the multiple response permutation
procedures (MRPP) available in PCOrd (MjM Software, Gleneden Beach, Oregon,
version 4.10) was used to identify the ecological significance of the modeled wetland
regions for diatom distribution. MRPP (Mielke 1984, Mielke and Berry 2000) provides a
rank-based non-parametric multivariate test of the difference between n samples based on
a distance matrix calculated between sites in ordinate space. The Sorensen distance
measure was used for this test, as it is an effective distance measure for use in community
data (McCune and Grace 2002). MRPP returns a statistic, A, which is the "chance-
corrected within group agreement" (McCune et al. 2002). Zero values for A indicate that
heterogeneity within groups equals that expected by chance, and values of 1.0 indicate
perfect agreement between groups (McCune and Grace 2002, McCune et al. 2002).
MRPP also returns a Tvalue test statistic. The more negative the test statistic Tthe
greater the separation between test groups (McCune and Grace 2002). The probability
value, p, is based on the calculated possibility of finding differences as or more extreme
than the observed group differences (Lesica et al. 1991). MRPP was calculated to
compare composition across all regions (e.g., South versus Central versus North), and
was also iteratively calculated to compare between individual wetland regions (e.g.,
South region composition versus North region composition). Significance for this test, as
for all tests unless otherwise noted, was set at the conventional significance of 0.05.













A NORTH


Rank by county (n = 67)
of depressional marsh
prevelance. CENTRAL
CENTRAL
6
11
16
21
26
31
w E 36

46
51 SOUTH
56
61
66

w Impacted

O Reference -


150 0 150 300 km
Figure 2-1. Algal study site locations and encounter probability for isolated depressional
wetlands. Counties shaded darker have a higher density of isolated
depressional wetlands
Field Data Collection, Sample Preparation and Laboratory Procedures

Diatoms

Diatom, soil, and water physical-chemical samples were taken at each wetland, and
care was exercised to ensure minimal cross-sample contamination of diatom
communities. Three different types of diatoms were sampled: benthic, epiphytic, and
phytoplanktonic. Benthic diatoms were collected from wetland sediments. Epiphyton was
collected from submerged portions of macrophytes. Phytoplankton was sampled from the
water column.
Benthic diatoms were sampled throughout hydrated areas of each wetland. Ten
samples were proportionally distributed in a randomized fashion among the vegetation
zones and a composite sample fixed. For each sample, a hollow cylinder with a diameter
of approximately 10 cm was placed on the substrate, and a bulb pipette was used to









mobilize the material at the water/sediment interface. A 10mL sample was taken with the
bulb pipette and placed in a composite sampling jar. The total sampled volume in the
composite sample was approximately 100mL. Epiphytic diatoms were sampled at ten
locations in the wetland by snipping representative submersed and floating vegetation
and placing the samples into a 3.8L Ziploc bag. Approximately 0.5L of wetland water
was added and the bag gently kneaded to mobilize the epiphyton. A 10mL sample was
obtained using a bulb pipette rinsed with wetland water and placed into a composite
sampling jar. Total volume of the composite sample was approximately 100mL.
Phytoplanktonic diatoms were sampled at ten different locations through the wetland in
areas of at least 10cm of water. A sealed 100mL cylinder was placed under the surface of
the water, the cap was removed and the cylinder filled. The cap was replaced underwater,
the cylinder removed, and a composite sample taken. The total volume of the composite
phytoplankton sample was approximately IL. Once all ten samples were taken of each
diatom type, the composite samples were preserved using M3 (APHA 1995): 5mL for
benthic and epiphytic diatoms, and 20mL for phytoplanktonic diatoms.
All samples were homogenized prior to subsampling for identification. To clean
organic matter from the diatom frustules for identification the subsamples were digested
following Hasle and Fryxell (1970). The samples were rinsed using distilled water and
mounted on microscope slides using Naphrax (Northern Biological Supplies Limited,
Ipswich, England). Following FDEP procedures (SOP #AB-03.1, available at
www.dep.state.fl.us/labs/sop/), 250 diatom valves were then counted along microscope
transects and identified to the lowest taxonomic level possible (usually species). For
samples that were sparse (i.e., phytoplankton), sampling effort was capped at 1 hour.
Diatom data were combined and entered into the FDEP database for further analysis.

Soil and water physical-chemical sampling and analysis

To relate the distribution of wetland diatoms to environmental parameters, soil and
water physical and chemical parameters were obtained at each site and determined in the
laboratory as described in Appendix B. The following soil chemistry parameters were
determined in the lab: total phosphorous (soil TP, mg/kg), percent total nitrogen (%TN),
percent total carbon (%TC), percent organic matter (%OM), and pH. The following water
chemistry parameters were obtained from samples collected from each site: color (PCU),
specific conductivity (umhos/cm), turbidity (NTU), pH, ammonia (mg/L), nitrate/nitrite
(mg/L), total Kjeldahl Nitrogen (TKN, mg/L), and total Phosphorus (water TP, mg/L). In
the event that the constituent measured was below detection levels, the value was entered
for analysis was half of the lowest detectable level. See Appendix B for additional
information.

Data Analyses

Summary statistics

Summary measures of sample richness, evenness, Shannon diversity, and Simpson
diversity were calculated for each site and diatom type and provided information on the
distribution of species vis-a-vis land use. Richness is a measure of the total number of
taxa found in a sample (Whittaker 1972). Evenness is a measure of distribution among










taxa at a site. Shannon diversity and Simpson diversity indices measure the diversity of a
site based on the abundance and total number of taxa (Brower et al. 1990). Two
additional diversity indices were also calculated from the diatom data and compared
between LDI classes of <2.0 or > 2.0: beta and gamma diversity (Ricklefs 1990, McCune
and Grace 2002). Gamma diversity, or species richness over a range of habitat (i.e.,
reference conditions, Whittaker 1972), was calculated as the total richness of a class of
samples (LDI classes of <2.0 or > 2.0). Beta diversity incorporates gamma diversity and
indicates compositional variation in a sample. Beta diversity was calculated as gamma
diversity divided by the average richness at a site (McCune and Grace 2002).

Diatoms-compositional tests

The Percent Similarity Index (PSI, Wolda 1981) and MRPP were used to assess the
fidelity of habitat types for each of the three types of diatoms sampled. PSI (Wolda 1981)
provides an index of overlap between diatom types and was calculated as
PSI = [ I (minimum pij, ) ] 100
where PSI is the percentage similarity between diatom types and k (for instance benthic
and epiphytic diatoms), pij is the percentage of species i in diatom typej, and Pik is the
percentage of species i in diatom type k. PSI was calculated to compare local, within-site
diatom community composition (i.e., benthic, epiphytic, and phytoplanktonic diatom
types from a single site) and for a global comparison (i.e., the abundance of all benthic,
epiphytic, and phytoplanktonic diatoms identified were compared across all sites). While
no significance was calculated, PSI values greater than 0.70 are generally considered
highly similar (Matthews et al. 1988).
MRPP, using the Sorensen distance measure, was also used to identify global group
differences and provided a measure of the significance of the difference. Differences in
summary statistics, such as evenness and diversity indices, were examined between
landscape development classes (i.e., LDI <2.0 and LDI > 2.0) with the Mann-Whitney U-
test, and among diatom types using Tukey's Honest Significant Difference (HSD) test
(Zar 1999). The Mann-Whitney U-test and Tukey's HSD test are non-parametric
comparison procedures that test for equal medians between groups. The Mann-Whitney
U-test was performed using two classes (i.e., LDI <2.0 and LDI > 2.0) and Tukey's HSD
was calculated for tests of more than two classes (i.e., South, Central, and North regions).

Diatoms community composition and correlation with soil and water parameters

The following soil variables were arcsine square root transformed to decrease
measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Log1o
transformations were completed on soil TP, color, specific conductivity, turbidity,
ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity
among environmental variables, described as strong correlations between independent
variables (Zar 1999), was tested using two multicolinearity diagnostic statistics available
through linear regression analysis in SAS, the variance inflation factor and tolerance
(SAS 1990). While no formal cutoff value exists, a conservative measure was used, and
variables were considered collinear if they had a variance inflation factor (VIF) of >5.0
and a tolerance of <0.20 (ter Braak 1987, SAS 1990). The Mann-Whitney U-test was









used to test the null hypothesis of equal medians between reference and impaired classes
for each environmental variable (Zar 1999).
The relationship between measured environmental values (including LDI score)
and species composition was examined with the Mantel test (Mantel 1967) and with non-
metric multidimensional scaling (NMDS; Kruskal 1964, Mather 1976), both available in
PCOrd. A Mantel test, which evaluates the correlation between distance measures of two
matrices (McCune and Grace 2002), was computed to test the null hypothesis of no
relationship between the arcsine square root transformed diatom species abundance and
measured environmental parameters. The Sorensen distance measure was used for the
abundance matrix, and the Euclidean distance measure was utilized for the second matrix
due to the negative values of the log-transformed environmental parameters. The
significance of the hypothesis of no relationship between the matrices was tested with a
Monte Carlo simulation of 9999 randomizations. The standardized Mantel statistic
(Mantel's r), a t statistic, and the significance of the relationship were calculated for each
test.
NMDS was used to ordinate the samples based on arcsine square root transformed
species abundances and to correlate environmental parameters to sites in ordination
space. NMDS is an ordination method well suited for data that are non-normal, as it uses
ranked distances to avoid the assumption of linear relationships among variables
(Waichler et al. 2001, McCune and Grace 2002). To decrease chances of finding local
minima, twenty-five runs with random seeds were made using six-dimensional starting
space and the Sorensen distance measure. The instability criterion was set at 0.00001, the
maximum number of iterations to find a stable solution was set to 400, 50 runs were
conducted with real data, and 50 randomized runs were completed to calculate ap-value
of the solution. The number of dimensions that accurately described the data set was
obtained as a measure of the "stress" (or fit) of the ordination. A final run was made with
the starting seed that provided the best final fit. A two-dimension solution was selected
for benthic and epiphytic diatoms, and a three-dimension solution was selected for
phytoplanktonic diatoms, as increased dimensionality only marginally improved the fit.
The final NMDS solution was repeated several times to ensure stability of the solution.
Pearson's correlation coefficients between site scores and environmental parameters,
including LDI score, were calculated. A bi-plot of environmental parameters with
Pearson correlations to site scores >0.30 was constructed.

Metric Development

Diatom metrics were developed using literature sources and iterative tests (i.e.,
Bahls 1993, Van Dam et al. 1994, McCormick and Cairns 1997, Stevenson 2001, U.S.
EPA 2002e, Fore and Grafe 2002, Fore 2003) and correlated using Spearman's r with the
Landscape Development Intensity index (Brown and Vivas submitted). Final metrics
were those with significance values of <0.05 and Spearman correlations of >|0.501 with
the LDI. Final metrics were also tested for bivariate correlation using Spearman's r.
Metrics with bivariate correlations (r > |0.801) reduced to one metric based on the strength
of the correlations with the LDI. All metric evaluation were conducted with SAS (SAS
Institute, Cary N.C., version 8.02).










Sensitive and tolerant taxa

The use of Indicator Species Analysis (ISA) as a method of identifying species with
specificity (i.e., exclusive to a given group) and fidelity (i.e., always present within a
given group) to ecological conditions is growing in ecological literature (Chytry et al.
2002). The randomization test and the corresponding p-value provide a statistically
rigorous and defensible presentation of identified species (McCune and Grace 2002).
Indicator Species Analysis (Dufrene and Legendre 1997) with non-transformed
abundance data identified species with significant association to LDI classification of
impaired or reference conditions.
ISA, available in PCOrd, contrasts the fidelity of species between a priori defined
groups (in this case, sites with LDI<2.0 or LDI>2.0) using the algorithms of Dufrene and
Legendre (1997). First, the mean abundance (xkj) of species in group k was calculated
by examining the proportional abundance of species in group k relative to species in all
groups. Second, the relative abundance (RAkj) of species in group k was calculated by
dividing the mean abundance (xkj) by abundance in each group. The proportional
frequency (RFkj) of species in group k was then calculated by summing the total
occurrences (presence) of species in group k and dividing by the number of sample units
in group k. The two proportions (RAkj and RFkj) combined in the following equation that
solves for IndValkj, the indicator value of species for group k:
IndValkj = 100 (RAkj RFkj)
As RA and RF are multiplied, both must be high for IndVal to be high. Additional
descriptions of ISA may be found in McCune and Grace (2002). A Monte Carlo test with
10,000 permutations and p-value of 0.10 was used to test significance of the indicator
species for a particular group k (i.e., sites with LDI<2.0 or LDI>2.0). The abundance of
species with significant specificity and fidelity to reference or impaired conditions (i.e.,
sensitive and tolerant taxa) was assessed for each site and correlated with the LDI.

Autecological metrics

An ecological indicator value based on published tolerances to particular
physical/chemical condition for each diatom species identified was determined using a
coded checklist of autecological guilds (Appendix C; Bahls 1993, Van Dam et al.
1994). Bahls (1993) categorized diatoms in Montana streams as very tolerant, tolerant, or
sensitive to pollution based on initial classifications of Lange-Bertalot (1979) and Lowe
(1974). Van Dam et al. (1994) provided a list of attributes describing the tolerance of
European diatoms to varying pH, salinity, dissolved oxygen content, nutrient enrichment,
and saprobic conditions, which Fore (2003) and Fore and Grafe (2002) used to develop
indicators for streams in Mid-Atlantic states and large rivers in Idaho, respectively.
As agricultural operations can increase soil alkalinity through fertilizer application,
and evaporative salts from irrigation can be transported into wetlands through
precipitation (Leland and Porter 2000, Fore and Grafe 2002), it was expected that
alkaliphilous diatoms and diatoms that tolerate higher salinity would increase with
increasing agricultural operations (and hence LDI scores). Agrochemical fertilizers, as
well as direct application of cattle wastes on the landscape, increase nutrient loading into
aquatic systems (Flaig and Reddy 1995, Reddy et al. 1996, Reddy et al. 1998). It was









therefore anticipated that diatoms tolerant of higher nutrient levels and saprobity (or
biodegradable organic matter and low dissolved oxygen levels), as well as higher trophic
state (driven by high levels of inorganic nutrients), would increase with increasing LDI
scores. In contrast, acidophilous diatoms and those indicative of low salinity would be
expected to dominate wetlands in reference conditions. Similarly, diatoms sensitive to
nutrient enrichment, low dissolved oxygen and saprobic conditions would be expected to
decrease with increasing LDI scores.
For each of the autecological guilds identified by Van Dam et al. (1994) and the
pollution tolerance value of Bahls (1993), diatoms were coded (guilds with between 3
and 7 categories) to denote tolerance to environmental variables. The ordinal trophic
classes of Van Dam et al. (1994), "oligotraphentic" and "oligo-mesotraphentic," were
combined into a single class as these diatoms indicative of low-trophic status were
expected to respond in a similar fashion to increasing LDI scores. The abundance of
diatoms for each class was determined for each autecological index. The abundance of
diatoms for each class was then correlated (Spearman's r) with the LDI score for each
site. Bivariate correlations between taxa guild values were assessed using Spearman's r,
and a tolerance ofr > |0.801 was arbitrarily established to delimit highly correlated guild
values. Guilds having lower correlations with the LDI were parsed. The median
abundances for potential metrics based on autecological indices between LDI classes
were tested with the Mann-Whitney U-test.

Constructing the Multimetric Index

To complete development of the multimetric index of wetland condition based on
diatom metrics, it was necessary to scale the metrics to a uniform ranking so they could
be added together and a single value representative of wetland condition be obtained
(Karr and Chu 1999). In this study, metrics were scored into four categories: 0,3,7, and
10, based on quartile scores for the 95th percentile of each metric (Mack 2001). A
hypothetical example of this scoring is presented in Figure 2-2. Using the 95th percentile
decreases the influence of outliers on metric scoring (Mack 2001). For measures that
decreased in abundance with increasing LDI scores, the lowest quartile was given a 0, the
next quartile a 3, the third a 7, and the highest and last quartile a 10. This scale was
inverted for measures that increased in abundance with increasing LDI scores.

Results

Wetland Diatom Composition

Seventy herbaceous depressional wetlands throughout peninsular Florida with
standing water were sampled in 1999 and 2000. Twenty-three were sampled in the South
region, thirty in the Central region, and seventeen in the North region. Based on the
dominant land use around the wetland, twelve sites sampled in the South region were a
priori considered impaired, sixteen in the Central region, and eight in the North region.
Two hundred ninety-nine diatom taxa from the combined three diatom types were
identified. Seventy benthic and sixty-nine epiphytic and phytoplanktonic samples were
enumerated and identified, as data were incomplete for two sites: (IFASII epiphyton and
CMWRef- phytoplankton). The average count of frustules for benthic diatoms was














60





30 30 ------- W -- Score: 7





0 ________Score: 0

1 2 3 4


Figure 2-2. Hypothesized example of metric scoring using the 95th percentile of the
dataset. The scoring would switch for metric that increase with increasing

LDI scores.

261.6 (+/- 19.7) and for epiphytic diatoms, 265.5 (+/- 31.9). The sparse nature of the
phytoplanktonic diatoms resulted in an average of 67.9 diatoms identified in each sample
and a high standard deviation of 57.7. One hundred ninety-five diatom taxa were
identified in the benthic samples, one hundred seventy-four in the epiphytic samples, and
two hundred forty-four in the phytoplankton samples.
Summary measures of sample richness, evenness, Shannon diversity, and Simpson
diversity were calculated for each site (Brower et al. 1990). Summary statistics are
presented in Tables 2-1 to 2-3. Tukey's HSD results (Table 2-4) indicated that richness
was significantly higher in phytoplankton and benthic diatoms than in epiphyton. No
significant differences were found for measures of evenness and Simpson's diversity
measure, but phytoplankton and benthic diatoms, and benthic diatoms and epiphytic
diatoms, did not significantly differ for Shannon diversity values (see Table 2-4). No
significant differences were found for measures of richness, evenness, Shannon diversity,
or Simpson's diversity between impaired and reference sites for all diatom types (Mann-
Whitney U-test, Table 2-5).
Alpha (richness), beta, and gamma diversity values for each diatom type and
wetland condition are given in Table 2-6. Beta and gamma diversity were higher in
phytoplankton samples than at the other samples despite the low numbers of diatoms
identified at each site. Beta diversity was higher in impaired sites for epiphytic and
phytoplanktonic diatoms, while gamma diversity in impaired sites was higher than in
reference sites for all three diatom types sampled.
















Table 2-1. Summary statistics of richness (S), evenness (E), Simpson's diversity index
(H) and Shannon diversity index (D') for benthic diatoms.


Name
Audubon
BearScat
BigCow
BRSebastian
CabPatch
Caravelle
Chuluota
CLBayard
CLCove
CMWPast
CMWRef
COBurgle
COHole
Crew
Deerfly
DEMelon
Garber
GbarE
GLDonut
GLPont
Goethe
GreenSwamp
Haguel
Haguell
HalfMoon
HARare
HEBad
HEL2
HEOkay
HighPast
HighRef
HillsRef
HuntCamp
IFASI
IFASII


E
0.824
0.884
0.866
0.791
0.705
0.884
0.817
0.752
0.805
0.820
0.760
0.827
0.848
0.799
0.899
0.661
0.734
0.751
0.797
0.797
0.820
0.893
0.812
0.894
0.827
0.766
0.796
0.768
0.869
0.828
0.882
0.914
0.879
0.802
0.791


H
2.176
3.064
3.028
2.088
1.623
2.731
2.561
1.928
2.370
2.606
2.277
2.518
2.622
2.540
2.737
1.912
2.122
2.171
2.654
2.597
2.165
2.800
2.346
3.126
2.294
2.255
1.748
2.129
2.605
2.597
2.726
2.865
2.989
2.173
1.966


D'
0.8380
0.9336
0.9296
0.8246
0.6885
0.9194
0.8862
0.8053
0.8694
0.8885
0.8359
0.8887
0.8872
0.8654
0.9171
0.7495
0.8230
0.7914
0.8967
0.8624
0.8536
0.9212
0.8759
0.9424
0.8711
0.8575
0.7885
0.8178
0.8998
0.8884
0.9160
0.9322
0.9298
0.8431
0.8210


\ / /


Name S
Immokalee 23
IRBlueCypress 21
IRCanal 12
IROJ 28
JD6 14
KellyPark 11
LCork 26
LEGo 17
LESuwan 20
LLeeCounty 21
MALudy 16
MASpray 15
McArthur 23
MNElmer 16
MNOcala 14
MRPepper 26
Myakka 14
OKCara 17
OKKISS 14
OKPast 22
PacificTom 17
PallMar 14
PBCorbett 11
PBEnjay 10
Penner 13
POWales 10
POWeowak 19
RiceCreek 20
SandhillCrane 11
SANorthMya 11
SAOscer 12
Savannas 16
STCow 14
UNHealthy 19
Weikiva 9


E
0.879
0.627
0.675
0.857
0.818
0.847
0.847
0.864
0.861
0.828
0.712
0.643
0.666
0.725
0.862
0.813
0.827
0.861
0.842
0.807
0.825
0.717
0.745
0.738
0.483
0.757
0.816
0.895
0.661
0.815
0.733
0.811
0.672
0.846
0.481


H
2.756
1.908
1.676
2.857
2.159
2.031
2.759
2.449
2.579
2.522
1.973
1.741
2.089
2.009
2.275
2.649
2.182
2.439
2.221
2.493
2.338
1.892
1.787
1.698
1.240
1.744
2.404
2.680
1.585
1.954
1.820
2.250
1.773
2.491
1.057


D'
0.9206
0.6833
0.6772
0.9191
0.8373
0.8318
0.8962
0.8913
0.9081
0.8769
0.7781
0.7564
0.7236
0.7628
0.8769
0.8819
0.8504
0.8854
0.8476
0.8791
0.8697
0.7778
0.7686
0.7783
0.4755
0.7956
0.8797
0.9178
0.6512
0.8178
0.7762
0.8412
0.7398
0.8915
0.4270












Table 2-2. Summary statistics of richness (S), evenness (E), Simpson's diversity index
(H) and Shannon diversity index (D') for epiphytic diatoms.


Name
Audubon
BearScat
BigCow
BRSebastian
CabPatch
Caravelle
Chuluota
CLBayard
CLCove
CMWPast
CMWRef
COBurgle
COHole
CREW
Deerfly
DEMelon
Garber
GbarE
GLdonut
GLpont
Goethe
GreenSwamp
Haguel
Haguell
HalfMoon
HARare
HEBad
HEL2
HEOkay
HighPast
HighRef
HillsRef
HuntCamp
IFASI
Immokalee


E H D'
0.736 1.943 0.7716
0.858 2.526 0.8888
0.862 2.841 0.9220
0.784 1.806 0.7785
0.916 3.201 0.9493
0.833 2.309 0.8732
0.756 1.878 0.7772
0.713 1.388 0.7151
0.760 1.669 0.7463
0.756 1.879 0.7944
0.846 2.445 0.8841
0.706 1.912 0.7493
0.759 1.885 0.8026
0.888 2.705 0.9168
0.792 2.197 0.8366
0.802 2.516 0.8770
0.642 1.779 0.6725
0.437 1.086 0.4106
0.774 2.097 0.8129
0.866 2.287 0.8775
0.798 2.106 0.8367
0.895 2.588 0.9078
0.750 2.031 0.8071
0.902 3.006 0.9359
0.826 2.118 0.8475
0.853 2.250 0.8660
0.793 1.544 0.7242
0.678 1.960 0.7955
0.818 2.409 0.8620
0.806 2.285 0.8490
0.767 2.258 0.8243
0.788 2.471 0.8733
0.747 1.856 0.7757
0.752 2.036 0.8096
0.880 2.188 0.8668


Name S
IRBlueCypress 16
IRCanal 20
IROJ 18
JD6 14
KellyPark 11
LCork 13
LEgo 11
LESuwan 20
LLeeCounty 20
MALudy 16
MASpray 8
McArthur 14
MNElmer 13
MNOcala 14
MRPepper 28
Myakka 16
OKCara 18
OKKiss 13
OKPast 21
PacificTom 19
PallMar 10
PBCorbet 20
PBenjay 11
Penner 9
POWales 7
POWeowak 16
RiceCreek 16
SandhillCrane 25
SANorthmya 17
SAOscer 13
Savannas 12
STCow 18
UNHealthy 12
Weikiva 11


E H D'
0.673 1.865 0.7372
0.753 2.255 0.8312
0.813 2.350 0.8597
0.754 1.989 0.8054
0.733 1.758 0.7610
0.716 1.836 0.7423
0.920 2.206 0.8808
0.883 2.645 0.9126
0.870 2.607 0.9034
0.705 1.954 0.7649
0.662 1.376 0.7101
0.602 1.589 0.6392
0.769 1.973 0.8199
0.817 2.156 0.8464
0.834 2.778 0.8810
0.802 2.224 0.8477
0.828 2.394 0.8739
0.736 1.889 0.7722
0.709 2.159 0.7994
0.837 2.465 0.8755
0.818 1.884 0.8183
0.786 2.355 0.8742
0.815 1.955 0.8175
0.507 1.114 0.4502
0.889 1.730 0.8078
0.847 2.349 0.8795
0.766 2.123 0.8107
0.821 2.642 0.8872
0.796 2.257 0.8646
0.583 1.494 0.6955
0.633 1.574 0.7035
0.758 2.191 0.8224
0.794 1.973 0.8097
0.573 1.373 0.5789











Table 2-3.


Name
Audubon
BearScat
BigCow
BRSebastian
CabPatch
Caravelle
Chuluota
CLBayard
CLCove
CMWPast
COBurgle
COHole
CREW
Deerfly
DEMelon
Garber
GbarE
GLDonut
GLPont
Goethe
GreenSwamp
Haguel
Haguell
HalfMoon
HARare
HABad
HEL2
HEOkay
HighPast
HighRef
HillsRef
HuntCamp
IFASI
IFASII
Immokalee


Summary statistics of richness (S), evenness (E), Simpson's diversity index
(H) and Shannon diversity index (D') for phvtoplanktonic diatoms.


E
0.739
0.874
0.864
0.712
0.925
0.960
0.998
0.709
0.651
1.000
0.748
0.813
0.968
0.922
0.781
1.000
0.651
0.719
0.816
0.986
0.940
0.974
1.000
0.871
0.710
0.690
0.774
0.883
0.660
0.887
0.781
0.702
0.663
0.992
0.939


H
2.137
2.881
3.096
1.879
3.290
3.129
3.680
1.819
1.718
3.296
1.920
2.394
3.116
2.850
2.299
2.944
1.804
1.948
2.521
2.670
2.949
2.918
3.178
2.300
1.923
1.434
2.356
2.973
1.372
2.203
2.378
1.542
1.590
3.233
2.985


D'

0.8197
0.9152
0.9344
0.7611
0.9541
0.9486
0.9744
0.7172
0.6958
0.9630
0.7610
0.8667
0.9506
0.9304
0.8441
0.9474
0.6838
0.7634
0.8902
0.9273
0.9275
0.9408
0.9583
0.8773
0.7543
0.6892
0.8325
0.9313
0.6048
0.8715
0.8048
0.6503
0.6957
0.9592
0.9348


Name
IRBlueCypress
IRCanal
IROJ
JD6
KellyPark
LCork
LEGo
LESuwan
LLeeCounty
MALudy
MASpray
McArthur
MNElmer
MNOcala
MRPepper
Myakka
OKCara
OKKiss
OKPast
PacificTom
PallMar
PBCorbett
PBEnjay
Penner
POWales
POWeowak
RiceCreek
SandhillCrane
SANorthMya
SAOscer
Savannas
STCow
UNHealthy
Weikiva


E
0.864
0.749
0.868
0.728
0.446
0.704
0.858
0.907
0.824
0.732
0.625
0.439
0.748
0.838
1.000
0.878
0.852
0.975
0.917
0.952
0.812
0.793
0.838
0.750
0.835
0.801
0.833
0.893
0.827
0.402
0.736
0.771
0.818
0.924


H
2.671
1.862
2.760
1.921
1.143
2.109
2.201
2.569
2.285
2.230
1.439
1.189
1.919
2.211
3.219
2.631
2.462
3.377
2.835
3.410
2.250
2.199
2.081
1.979
1.922
2.358
2.453
3.005
2.056
0.883
2.128
2.183
2.215
2.296


D'

0.9004
0.7750
0.8998
0.7687
0.4485
0.7544
0.8565
0.9078
0.8569
0.7943
0.6719
0.4819
0.7845
0.8381
0.9600
0.9061
0.8854
0.9612
0.9211
0.9595
0.8086
0.8473
0.8379
0.7628
0.7937
0.8736
0.8782
0.9326
0.8262
0.3623
0.8048
0.8442
0.8473
0.8852


\ / /


\ / | |









Table 2-4. Summary statistics and diatom similarities using Tukey's HSD.
Standard
Variable Algal Type N Mean Median Deviation
S Benthic a 70 18.4 18.0 5.9
Epiphyticb 69 15.7 15.0 5.2
Phyto.a 69 18.8 18.0 7.1

E Benthica 70 0.792 0.814 0.087
Epiphytica 69 0.773 0.788 0.094
Phyto.a 69 0.815 0.827 0.132

H Benthicab 70 2.280 2.276 0.431
Epiphyticb 69 2.101 2.118 0.418
Phyto.a 69 2.236 2.296 0.609

D' Benthica 70 0.834 0.860 0.095
Epiphytica 69 0.808 0.820 0.097
Phyto.a 69 0.831 0.857 0.124
Note: Diatom types (Benthic, Epiphytic, Phytoplanktonic) with a similar letter superscript
were not significantly different atp=0.05.

Table 2-5. Mann-Whitney U-test results of summary statistics between reference and
impaired LDI classes within benthic, epiphytic, and phytoplanktonic diatom
groups.
Benthic Epiphytic Phytoplanktonic
Diatoms Diatoms Diatoms
S -1.515 -1.780 -1.175
(Richness) (0.130) (0.075) (0.240)

E 1.306 0.560 0.595
(Evenness) (0.192) (0.576) (0.551)

H -0.077 -0.746 -0.169
(Shannon Diversity) (0.939) (0.456) (0.866)

D' 0.435 0.048 -0.078
(Simpson's Diversity) (0.663) (0.962) (0.938)

Comparisons of the fidelity of species to particular habitats benthicc, epiphytic, and
phytoplanktonic) were made using PSI and MRPP. For benthic versus epiphytic diatoms,
within site PSI ranged from 6% to 89%, and averaged 55% (+/- 17.2%).
Within site PSI ranged from 2% to 78%, and averaged 42% (+/- 19.0%) for benthic
versus phytoplanktonic diatoms. The range between epiphytic and phytoplanktonic
diatoms was 1% to 77%, and averaged 46% (+/- 19.4%). Global comparisons using
pooled data (i.e., all benthic diatoms from all sites pooled into a benthicc" heading versus
all epiphytic diatoms from all sites pooled into an "epiphytic" heading) indicated a










Table 2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland
condition.
Alpha Diversity Beta Diversity Gamma Diversity

All Benthic (n=70) 18.4 10.60 195
Impaired 19.4 7.94 154
Reference 17.4 8.05 140

All Epiphyton (n=69) 15.7 11.08 174
Impaired 16.9 8.70 147
Reference 14.4 6.81 98

All Phytoplankton (n=69) 18.8 12.98 244
Impaired 19.5 10.00 195
Reference 17.9 9.11 163

remarkable lack of fidelity to specific habitats among the diatom community as the
benthic and epiphytic communities were 84% similar, the benthic and phytoplanktonic
communities were 75% similar, and the epiphytic and phytoplanktonic communities were
76% similar. MRPP results supported the lack of uniqueness between benthic, epiphytic,
and phytoplanktonic communities. MRPP analyses (Table 2-7), were completed using
both abundance data and simple presence data, and were calculated for both a
simultaneous comparison of all three diatom types and an iterative comparison of one
type versus another. In all cases, MRPP results indicated no significant differences
between the benthic, epiphytic, and phytoplanktonic communities at the conventional p-
value of 0.05.

Diatom Composition and Environmental Correlates

As a lack of habitat fidelity was demonstrated by the benthic, epiphytic, and
phytoplanktonic communities, it was necessary to select one community to pursue the
development of biological indicators of wetland condition. Selecting multiple
communities would "double-count" the effect of landscape influences on the wetland
environment. The criterion for further metric development was to identify the diatom
community with the strongest relationship to the environmental parameters, including the
LDI score. This was accomplished by examining matrix correlations between abundance
values and environmental parameters using the Mantel test, and by examining the NMDS
ordination of the abundance values for each diatom community and the correlation of site
scores with environmental parameters.
Including the LDI, fourteen environmental variables were measured at each site.
The measured water and soil parameters are given in Appendix B. Significant differences
between impaired and reference conditions, as measured by the Mann-Whitney U-test,
were found for the following parameters: soil pH, soil TP, specific conductivity, water
pH, ammonia, TKN, and water TP (Table 2-8). Water color was significantly lower in
reference conditions at p<0.10. Colinearity among the variables was recognized for %TC,










Table 2-7. MRPP analyses of the compositional similarity between benthic, epiphytic,
and phytoplanktonic diatoms.
Test A T p-value

Abundance B vs. E vs. P -0.0005 0.321 0.558
Global
Test


resence B vs. E vs. P -0.0008 -0.492 0.262
Global
Test

Abundance B vs. E -0.0020 1.186 0.994
Iterative B vs. P 0.0013 -0.841 0.166
Tests E vs. P -0.0004 0.252 0.503

Presence B vs. E -0.0019 1.012 0.916
Iterative B vs. P 0.0021 -1.262 0.108
Tests E vs. P 0.0016 -0.951 0.151


Note: Abbreviations are B benthicc), E (epiphyton), P (phytoplankton). Global tests refer
to simultaneous multivariate tests of the pooled diatoms from all benthic, epiphytic, and
phytoplanktonic samples. Iterative tests exclude one group (of three) during the MRPP
procedure.

Table 2-8. Comparison of the medians of water and soil variables between LDI classes
with the Mann-Whitney U-test.
Water Values Statistic (Z) p-value
Color -1.868 0.062
Specific Conductivity -3.919 <0.001
Turbidity -1.524 0.127
Water pH -4.677 <0.001
Ammonia -2.690 0.007
Nitrates/Nitrites 0.771 0.441
TKN -2.932 0.003
TP -4.836 <0.001


Soil Values Statistic (Z) p-value
Soil pH -3.036 0.002
%TC -0.818 0.414
%OM -1.253 0.210
%TN -1.147 0.251
%TP -2.771 0.006










TKN, and water pH following regression analyses of the transformed data (SAS 1990).
These variables were removed.
The Mantel test was used to test the hypothesis of no relationship between the
abundance data for benthic, epiphytic, and phytoplanktonic diatoms and the measured
environmental parameters and LDI score. The relationship between the matrices was
strongest for epiphytic diatoms (Mantel's r=0.49, p<0.001). Benthic diatoms (Mantel's
r=0.39, p<0.001) and phytoplanktonic diatoms (Mantel's r=0.30,p<0.001) were also
significantly correlated to the environmental parameters, albeit not as strongly as the
epiphyton.
NMDS ordinations of the diatom community abundance data were able to capture
approximately equal total variance in the dataset for each of the three diatom types (total
variance for Benthic: 81.1%; Epiphyton: 77.4%; Phytoplankton 80.1%). The stress, or
"goodness of fit" of the ordination was also approximately equal, and indicated an
adequate and representative decreased dimensionality of the dataset (Kruskal 1964,
Clarke 1993). The calculated stress for each diatom was: benthic diatoms: 16.68;
epiphytic diatoms: 18.45; phytoplanktonic diatoms: 15.66. Site scores for each diatom
community type, overlaid by a vector diagram of environmental variables with strong
(r2>0.30) correlations to the first two axes, are presented in Figures 2-3 to 2-5. A two-
dimensional solution was identified for benthic and epiphytic diatoms, and a three
dimensional solution was identified for phytoplankton. Total variance accounted for by
the ordination of the diatoms was approximately equal between types. The benthic
diatom ordination accounted for 81.1% of the variation in the dataset (first axis: 26.2%,
second axis 54.9%); 77.4% of the variation in the epiphytic diatom dataset was accounted
for by the ordination (first axis: 49.2%, second axis: 28.2%); and 80.1% of the variation
was reflected in the ordination of the phytoplankton (first axis: 28.7%, second axis:
36.5%, third axis: 14.8%). The relationship between the first two axes for phytoplankton
are shown in Figure 2-5 as the third axis, despite accounting for approximately 15% of
the variation in the dataset, had no strongly correlated environmental variables.
Correlations of environmental variables with the ordination score for benthic,
epiphytic, and phytoplanktonic diatoms are presented in Tables 2-9 to 2-11. Four
environmental variables were correlated >0.30 with the ordination scores of benthic and
epiphytic diatoms (LDI, soil pH, specific conductivity, and water TP). Three variables
were correlated with phytoplanktonic diatoms (LDI, specific conductivity, and soil pH).
None of the environmental variables were correlated > 0.50 for phytoplanktonic diatoms,
while one of four were >0.50 for benthic diatoms and three of four were >0.50 for
epiphytic diatoms.
Based on results of the Mantel tests and the NMDS ordination scores and
correlations, as well as the lack of significant differences between the benthic, epiphytic,
and phytoplanktonic communities as measured by MRPP and indicated by high PSI
values, a decision to base bioassessment metric development on the epiphytic community
was made. The results of the Mantel test indicated that the epiphytic diatom community
had a stronger relationship with the measured environmental parameters than either the
benthic diatoms or phytoplankton. NMDS ordinations also suggested stronger
correlations between epiphytic diatoms and environmental parameters, notably LDI score
and water TP, than were found with benthic diatoms, although goodness of fit and
percent of variance explained were slightly lower. Phytoplanktonic diatoms were









removed from consideration due to the low Mantel statistic values and weaker NMDS
correlations with environmental parameters, most notably the LDI score, as compared to
epiphyton or benthic diatoms.

Metric Development

Regional composition

MRPP analyses of the arcsine square root transformed abundance data were
completed for epiphytic diatoms to determine if regional factors contributed to epiphyton
community composition. When simultaneously compared (i.e., South vs. Central vs.
North), diatom distribution did not differ significantly (at p<0.05). However, when


0 Reference Sites
Impaired Sites
Cond wTP
U wTP






o E 0 A xis 1:
0 _0
0 0 OD 0
0 0
o rn0 o





Co o0

Figure 2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly
correlated environmental variables. The vectors are shown at 150% of
original length for clarity. The percent variance explained by each axis is
noted on the axis. The length of the vectors represents the strength of the
correlation (all >|0.301) and the angle represents the direction of maximum
change. Four variables are shown: pH (soil pH), Cond (specific conductivity),
TP (water total phosphorus), and LDI (Landscape Development Intensity
index).











iteratively tested, diatom distribution differed significantly (p<0.05) between the South
and North regions, but the differences were insignificant between the South and Central,
and the Central and North regions. This was examined further by testing the regional
distribution of reference sites and impaired sites. When simultaneously tested, the
reference sites differed across all regions (Table 2-12). Reference sites also differed
between South and Central regions, and South and North regions, but not between
Central and North regions. In contrast, the impaired sites did not differ when
simultaneously compared, nor when regions were contrasted, indicating similar species
composition across peninsular Florida in disturbed landscapes.

0
0 0 0
U
o 800
08 o 0

0 0, Axis 1:
S i 0 49.2%
LDI 0TPe 00S
o
_Cond
0 0

0g 0
0


sp 0





0 Reference Sites 0
0 Impaired Sites .co 0
x N
Figure 2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly
correlated environmental variables. The vectors are shown at 125% of the
original length for clarity. The percent of variance explained by each axis is
given on each axis. Four environmental variables were strongly (r>|0.30|)
correlated with NMDS ordination scores: pH (soil pH), Cond (specific
conductivity), TP (water TP), and LDI.











0 Reference Sites
* Impaired Sites


*
U


0


0


0


o00 0
o1C%


0 CO


Figure 2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and
strongly correlated environmental variables. The vectors are shown at 200%
of the original length for clarity. The percent of variance explained by each
axis is given on each axis. Three environmental variables were strongly
(r>|0.30|) correlated with NMDS ordination scores: Cond (specific
conductivity), TP (water TP), and LDI.

Indicator species analyses

Indicator Species Analysis was used to identify species that exhibited specificity
and fidelity to LDI scores of <2.0 (i.e., "reference indicators") and >2.0 (i.e., "impaired
indicators") for each region. The significant species for reference indicators and impaired
indicators are presented in Tables 2-13 and 2-14, respectively. Ten indicators of reference
conditions were identified in the South region, 12 in the Central region and 4 in the North
region. Five impaired indicators were identified in the South region, 12 in the Central
region, and 6 in the North region. There was substantial overlap of indicator species
between regions.


0

U U


Axis 1:
28.7%
0


0
0
0

0
O










Table 2-9. Correlations of environmental variables and ordination scores for benthic
diatoms.
Axis 1 (26.2%) Axis 2 (54.9%)
Parameter r2 tau r2 tau
Soil pH 0.62 -0.55 0.20 0.25
% TN 0.03 0.08 0.02 0.17
TP (mg/kg) 0.01 0.07 0.09 0.23
% OM 0.07 0.14 0.01 0.14
Color (PCU) 0.18 0.25 0.05 0.18
Spec. Cond. (umhos/cm) 0.28 -0.39 0.48 0.51
Turbidity (NTU) <0.01 -0.02 0.06 0.17
Ammonia (mg/L) <0.01 -0.09 0.05 0.19
Nitrate/Nitrite (mg/L) 0.02 0.10 0.02 -0.08
Water TP (mg/L) <0.01 -0.04 0.42 0.49
LDI Score 0.06 -0.20 0.42 0.36
Note: Underlined correlations were > 0.30 and were considered strongly correlated with
NMDS ordination scores. Kendal's tau, a non-parametric measure of association, is also
given.

Table 2-10. Correlations of environmental variables and ordination scores for epiphytic
diatoms.
Axis 1 (49.2%) Axis 2 (28.2%)
Parameter r2 tau r2 tau
Soil pH 0.23 -0.34 0.59 -0.58
% TN <0.01 -0.07 0.03 0.08
TP (mg/kg) 0.11 -0.24 <0.01 0.06
% OM <0.01 -0.07 0.08 0.14
Color (PCU) 0.07 -0.17 0.22 0.26
Spec. Cond. (umhos/cm) 0.46 -0.50 0.19 -0.32
Turbidity (NTU) 0.06 -0.15 0.02 0.06
Ammonia (mg/L) 0.03 -0.21 0.02 <-0.01
Nitrate/Nitrite (mg/L) <0.01 <-0.01 0.03 0.17
Water TP (mg/L) 0.53 -0.55 <0.01 0.05
LDI Score 0.63 -0.50 0.02 -0.11
Note: Underlined correlations were r2 > 0.30 and were considered strongly correlated
with NMDS ordination scores for each site. Kendal's tau, a non-parametric measure of
association, is also given.














Table 2-11. Correlations of environmental variables and ordination scores for
phytoplanktonic diatoms.


Parameter
Soil pH
% TN
TP (mg/kg)
% OM
Color (PCU)
Spec. Cond. (umhos/cm)
Turbidity (NTU)
Ammonia (mg/L)
Nitrate/Nitrite (mg/L)
Water TP (mg/L)
LDI Score


Axis 1 (28.7%)


r2
0.40
<0.01
<0.01
<0.01
0.13
0.19
<0.01
<0.01
0.03
<0.01
0.11


tau
-0.49
0.02
<-0.01
0.03
0.20
-0.34
-0.02
-0.06
0.12
-0.08
-0.25


Axis 2 (36.5%)


r2
0.16
<0.01
0.02
0.02
0.03
0.35
<0.01
<0.01
0.04
0.28
0.38


tau
0.27
0.09
0.11
0.01
0.15
0.45
0.03
0.18
-0.15
-0.22
0.38


Axis 3 (14.8%)
r2 tau
0.06 0.15
0.040 -0.11
0.05 -0.15
0.05 -0.17
0.19 -0.27
0.02 0.11
0.07 -0.24
0.01 -0.03
0.05 -0.18
0.11 -0.27
0.05 -0.15


Note: Underlined correlations were > 0.30 and were considered strongly correlated with
NMDS ordination scores for each site. Kendal's tau, a non-parametric measure of
association, is also given.

Table 2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of
South, Central, and North wetland regions.


Simultaneous
Tests


Abundance
Iterative
Tests

Presence
Iterative
Tests


Test
%: S vs. C vs. N
P/A: S vs. C vs. N


S vs. C
S vs. N
C vs. N

S vs. C
S vs. N
C vs. N


A
0.0056
0.0096


0.0045
0.0113
-0.0015

0.0086
0.0195
-0.0040


T
-1.254
-1.794


-1.080
-2.038
0.320

-1.843
-2.818
0.662


p-value
0.111
0.057


0.132
0.045
0.533

0.057
0.019
0.711













Table 2-13. Reference site diatom indicator taxa identified using Indicator Species
Analysis for each wetland region.


Region
South
Reference


Central
Reference













North
Reference


Indicator Species
(LDI <2.0)
Anomoeneis serians acuta
Anomoeneis serians brachysira
Anomoeneis serians
Anomoeneis vitrea
Eunotia bilunaris mucophila
Eunotia flexuosa eurycephala
Eunotia naegelii
Frustulia rhomboides crassinerva
Frustulia rhomboides saxonica
Navicula mediocris

Anomoeneis serians acuta
Anomoeneis serians brachysira
Desmogonium rabenhorstianum
Eunotia bilunaris mucophila
Eunotia denticulata
Eunotia paludosa
Eunotia paludosa trinacria
Eunotia pirla
Eunotia soleirolii
Eunotia zygodon
Frustulia rhomboides
Frustulia rhomboides saxonica

Desmogonium rabenhorstianum
Frustulia rhomboides
Frustulia rhomboides saxonica
Pinnularia subcapitata


Observed
Ind. Value
45.5
43.8
27.3
59.5
45.8
27.3
63.0
32.0
70.2
36.4


38.5
45.9
44.0
43.1
23.1
53.8
46.2
38.5
30.8
38.5
50.3
81.2

50.0
58.7
72.0
68.3


p-value
0.013
0.046
0.092
0.015
0.054
0.091
0.014
0.084
0.006
0.035

0.009
0.016
0.016
0.033
0.069
0.001
0.002
0.009
0.027
0.010
0.021
<0.001

0.081
0.024
0.050
0.098










Table 2-14. Impaired site diatom indicator taxa identified using Indicator Species
Analysis for each wetland region.

Indicator Species Observed
Region (LDI >2.0) Ind. Value p-value
South Gomphonema parvulum 58.3 0.005
Impaired Navicula confervacea 58.3 0.005
Nitzschia palea debilis 85.2 <0.001
Nitzschia sociabilis 41.7 0.038
Pinnularia acrosphaeria 33.3 0.094

Central Gomphonema angustatum 29.4 0.054
Impaired Gomphonema gracile 52.9 0.002
Gomphonema parvulum 60.1 0.004
Navicula confervacea 70.3 0.001
Navicula minima 33.9 0.060
Navicula seminulum 45.8 0.018
Nitzschiafrustulum 35.3 0.038
Nitzschia gracilis 29.4 0.072
Nitzschia palea 52.2 0.026
Nitzschia palea debilis 77.0 <0.001
Nitzschia sociabilis 30.8 0.089
Pinnularia gibba 37.3 0.067

North Gomphonemaparvulum 62.5 0.026
Impaired Navicula difficillima 62.5 0.027
Navicula minima 49.2 0.080
Navicula seminulum 50.0 0.081
Nitzschia palea 58.3 0.033
Nitzschia palea debilis 63.3 0.066

ISA was also used to identify significant indicator species for impaired and
reference sites for the combined peninsular regions (South, Central, and North regions;
n=69). A total of 43 indicator species were identified for the combined analysis, 22
reference condition indicators and 21 impaired condition indicators (Tables 2-15 and 2-
16, respectively). With the exception of two indicators of reference conditions (Eunotia
soleirolii and Pinnularia subcapita) and two indicators of impaired conditions (Nitzschia
frustulum and N. gracilis) found in regional analyses, there was complete overlap of
regional and peninsular indicator species. This was not unexpected considering the lack
of significance when composition between regions was simultaneously tested with
MRPP. The larger n allowed for greater statistical power in the analysis of indicator
species, thus 5 reference indicator species and 9 impaired indicator species were













identified using the peninsular (n=69) dataset that were not in any regional indicator
species. Little additional information was garnered from identifying regionally specific
indicator species, and 14 additional indicator species were identified using the peninsular
dataset. Furthermore, no significant difference was found in the simultaneous
multivariate MRPP test of regional significance of community composition. Thus, it was
concluded that the remaining analyses would utilize the peninsular dataset. Therefore
metrics developed are not regionally specific but apply throughout peninsular Florida.
Using the peninsular dataset of indicator species (n=43), the abundance of the
indicator species for both impaired and reference conditions were calculated for each site
and correlated with the LDI using Spearman's r (Figure 2-6). Correlations for the
abundance of reference indicators and impaired indicators are: % Reference Indicators r
= -0.66, p<0.001; % Impaired Indicators r = 0.60, p<0.001. The abundance of reference
indicators demonstrated a highly variable distribution, especially for LDI values of
approximately <3.2. In general, sites with LDI scores of >3.2 were composed of <10%
reference indicators. The abundance of impaired indicators suggested a low correlation

Table 2-15. Statewide indicators of reference conditions as determined from Indicator
Species Analysis.


Indicator Species
(LDI <2.0)
Anomoeneis serians acuta
Anomoeneis serians brachysira
Anomoeneis serians
Anomoeneis vitrea
Desmogonium rabenhorstianum
Eunotia bilunaris mucophila
Eunotia denticulata
Eunotia flexuosa
Eunotia flexuosa eurycephala
Eunotia monodon
Eunotia naegelii
Eunotia paludosa
Eunotia paludosa trinacria
Eunotia pirla
Eunotia rhomboidea
Eunotia zygodon
Frustulia rhomboides
Frustulia rhomboides crassinerva
Frustulia rhomboides saxonica
Navicula mediocris
Navicula subtilissima
Stauroneis kriezeri


Observed
Ind. Value
34.4
39.1
9.4
22.0
26.6
41.4
17.5
20.2
9.4
9.4
59.5
29.4
29.7
27.7
37.0
23.1
46.3
17.8
75.1
25.0
17.3
16.6


p-value
<0.001
<0.001
0.099
0.052
0.027
0.003
0.021
0.099
0.093
0.095
0.002
0.007
0.017
0.005
0.029
0.015
<0.001
0.046
<0.001
0.001
0.030
0.084










Table 2-16. Statewide indicators of impaired
Species Analysis.

Indicator Species
(LDI >2.0)
Caloneis bacillum
Gomphonema angustatum
Gomphonema gracile
Gomphonema lanceolatum
Gomphonema parvulum
Melosira italica
Navicula confervacea
Navicula difficillima
Navicula minima
Navicula molestiformis
Navicula pupula rectangularis
Navicula seminulum
Nitzschia amphibia
Nitzschia microcephala
Nitzschia palea
Nitzschia palea debilis
Nitzschia palea tenuirostris
Nitzschia perminuta
Nitzschia sociabilis
Pinnularia acrosphaeria
Pinnularia gibba


conditions as determined from Indicator


Observed
Ind. Value
16.2
22.8
46.4
21.6
60.9
18.9
59.3
35.4
33.8
13.5
15.9
42.2
21.2
13.5
48.4
76.3
15.5
12.3
32.8
21.6
27.5


p-value
0.030
0.020
0.002
0.005
<0.001
0.014
<0.001
0.001
0.002
0.053
0.057
<0.001
0.041
0.058
0.005
<0.001
0.065
0.010
0.002
0.006
0.036


with increasing LDI scores until a threshold at approximately 3.7 was reached. At that
point, the abundance of impaired indicators increased markedly.

Autecological indices

One hundred thirty-four of the 174 epiphyton diatom taxa (approximately 77%)
had one or more autecological, or ecological indicator, values obtained from Van Dam et
al. (1994) and Bahls (1993). On a site-by-site basis, approximately 82% of diatoms found
at a given site had ecological indicator values. This ranged from approximately 56% to
100% of the diatoms found in the 69 sampled wetlands.
The abundance of each class for the autecological indicator guilds of Van Dam et
al. (1994) and Bahls (1993) was calculated for each site and correlated (Spearman's r)
with the LDI. Responsive metrics were those with correlations of>|0.501 and significant
(p<0.05) correlation coefficients. Bivariate correlations using Spearman's r were
calculated for the autecological indices having negative (n=6 metrics) and positive (n=7
metrics) responses with increasing LDI scores. The abundance of diatoms sensitive to
nitrogen levels, or "tolerating very small concentrations of organically bound nitrogen,"
was strongly (r = 0.86) correlated with oligosaprobous diatoms (Van Dam et al. 1994, p.













100 -
# A

0
U**


5 *0





*
0 l *- *

1 2 3 4 5 6
LDI






100 -
B
90 -
S80 .
o 70 *0
a 60 r
S50 -
S40 -
3 30- *
0 00
I) .6
0 20-
10- .
0 1* ** *

1 2 3 4 5 6
LDI


Figure 2-6. Indicator species abundance data plotted against the LDI. A) Abundance of
Reference Indicators vs. the LDI. B) Abundance of Impaired Indicators vs. the
LDI.










120). The percent of diatoms sensitive to elevated nitrogen levels index was maintained,
as the abundance of nitrogen-sensitive diatoms was more strongly correlated with the
LDI than the abundance of oligosaprobous diatoms (Spearman's r = -0.67 for percent
nitrogen sensitive diatoms, r = -0.58 for oligosaprobous taxa). The remaining
autecological indices of Van Dam et al. (1994) and Bahls (1993) were significantly
(p<0.001) correlated (Spearman's r) > |0.501 with the LDI (Table 2-17). A plot of the
abundance of diatoms for each uncorrelated metric along the disturbance gradient is

Table 2-17. Correlations of autecological abundance data and LDI score.


Metric
% Tolerate High pH
% Require Low pH
% Require Low Salinity
% Tolerate High Salinity
% Sensitive High Nitrogen
% Tolerate High Nitrogen
% Require Elevated D.O.
% Tolerant Low D.O.
% Meso- & Polysaprobous
% Oligotrophic
% Eutrophic
% Pollution Tolerant


Spearman's
r
0.65
-0.68
-0.51
0.62
-0.66
0.68
-0.63
0.64
0.69
-0.59
0.67
0.67


p-value
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001


Notes
VD 3
VD Class 1
VD Class 1
VD Class 3
VD Class 1
VD Class 3
VD Class 1
VD Class 4
VD Class 4
VD Classes 1 & 2
VD Class 5
Bahls Class 1


Note: VD Class and Bahls class represent the autecological index value from Van Dam et
al. (1994) and Bahls (1993).


Table 2-18. Mann-Whitney U-test of autecological abundance values
and reference conditions.


between impaired


Metric
% Tolerate High pH
% Require Low pH
% Require Low Salinity
% Tolerate High Salinity
% Sensitive High Nitrogen
% Tolerate High Nitrogen
% Require Elevated D.O.
% Tolerant Low D.O.
% Meso- & Polysaprobous
% Oligotrophic
% Eutrophic
% Pollution Tolerant


Statistic (Z)
-5.288
5.433
4.067
-5.171
5.475
-5.595
5.379
-5.287
-5.381
5.048
-5.580
-5.474


p-value
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001






























: *. %



1 2 3 4 5 6
LDI



A) % Sensitive Elevated pH


S

S



S.


*.





*





1 2 3 4 5 6
LDI


B) % Tolerate Elevated pH


80
70
60
50 -
40 -
30 -
20
10 -
D 1 l, +


*


. 3
r 3 *
* *Z
*+.*
*


2 3 4 5 6
LDI


C) % Salinity Sensitive


S.
ta


4. .


2 1 1
2 3 4


5 6


et -

* X: :


1 2 3 4 5 6
LDI


D) % Salinity Tolerant


* ja.


4 5 6


1 2


E) % Sensitive Elevated Nitrogen


F) % Tolerant Elevated Nitrogen


Figure 2-7. Diatom abundance for autecological metrics plotted against the LDI

gradient. A) % Sensitive Elevated pH, B) % Tolerate Elevated pH, C) %

Salinity Sensitive, D) % Salinity Tolerant, E) % Sensitive Elevated

Nitrogen, F) % Tolerant Elevated Nitrogen, G) % Sensitive Low D.O.,

H) % Tolerant Low D.O., I) % Oligotrophic, J) % Eutrophic, K) %

Meso-Polysaprobous, L) % Pollution Tolerant.


t.
*


3
3























.. *




..** .


1 2 3 4 5 6
LDI



G) % Sensitive Low D.O.


.1




* 3.
* S.
* p


2 3 4 5 6
LDI


I) % Oligotrophic


~4O



0


10

0


4.;


1 2 3 4 5 6
LDI



K) % Meso-Polysaprobous


:., .



1 2 3 4 5 6
LDI



H) % Tolerant Low D.O.










*




o*



1 2 3 4 5 6
LDI


J) % Eutrophic


a



* S



1 2 3 4 5 6
LDI



L) % Pollution Tolerant


50

V
s o
Q

M 30

020

10

D


Figure 2-7 (Continued).










presented in Figure 2-7. The Mann-Whitney U-test (Table 2-18) indicated that
all medians were significantly different (p<0.001) between reference and impaired sites.
In general, autecological metrics that decreased with increasing LDI values
appeared to have a greater goodness of fit and to be less sensitive to changes in the LDI.
The results suggest metrics that increase with increasing LDI score approach a threshold
near approximately 3.8. Thereafter, the abundance of the various metrics increases
markedly, but with a high variance.

The Multimetric Index

Two metrics derived from indicator species analysis (Dufrene and Legendre 1997),
one metric based on pollution tolerance (Bahls 1993) and eleven metrics identified from
autecological indicator values of Van Dam et al. (1994), were selected as final metrics
based on the significance and strength of the correlations with the LDI. The quartile
values of 95th percentile and the corresponding values of 0,3,7,10 for each metric are
given in Table 2-19. The fourteen metrics were summed to create the Diatom Index of
Wetland Condition (DIWC), with a possible range of value from 0 to 140. One site had a
summed DIWC value of zero, and one site scored a perfect 140 (Table 2-20). Reference
sites averaged 114.5 points, with a standard deviation of 26.3 points and a median value
of 122.5. Impaired sites averaged 42.1 points (+/- 38.3) and had a median value of 33.0.
DIWC scores were correlated with the LDI Score for each site: Spearman's r = 0.79, p
< 0.001 (Figure 2-8). However, similar to the metrics that comprised the index, the results
appear to be highly variable for any given LDI score. Metric sensitivity appears to
increase near LDI scores of 3.2. Mann-Whitney U-test results indicate a significant
difference between DIWC scores for impaired and reference sites (Z=5.991, p<0.001).

Table 2-19. Quadrisect values and the 95th percentile data for each proposed biological
indicator.

95th 0 3 7 10
Metric Percentile Scores Scores Scores Scores
% Reference Indicators 0.789 <0.0279 0.0279 0.2328 >0.2328 0.5620 >0.5620
% Impaired Indicators 0.934 >0.5512 >0.1094 0.5512 0.0001 0.1094 0
% Sensitive Elevated pH 0.445 0 0.0001 0.0234 >0.0234 0.2000 >0.2000
% Tolerant Elevated pH 0.818 >0.4820 >0.2300 0.4820 0.0571 0.2300 <0.0571
% Sensitive Elevated Salinity 0.840 <0.2361 0.2361 0.4221 >0.4221 0.5889 >0.5889
% Tolerate Elevated Salinity 0.405 >0.1000 >0.035 0.1000 0.0001 0.035 0
% Sensitive Elevated Nitrogen 0.811 <0.1349 0.1349 0.3506 >0.3506 0.5590 >0.5590
% Tolerate Elevated Nitrogen 0.589 >0.1622 >0.0118 0.1622 0.0001 0.0118 0
% Sensitive Low D.O. 0.840 <0.1471 0.1471 0.3274 >0.3274 0.5551 >0.5551
% Tolerate Low D.O. 0.350 >0.1195 >0.0228 0.1195 0.0001 0.0228 0
% Meso- & Polysaprobous 0.209 >0.1400 >0.0250 0.1400 0.0001 0.0250 0
% Oligotrophic 0.932 <0.2830 0.2830 0.4582 >0.4582 0.6667 >0.6667
% Eutrophic 0.592 >0.2101 >0.0152 0.2101 0.0001 0.0152 0
% Pollution Tolerant 0.368 >0.1594 >0.0239 0.1594 0.0001 0.0239 0









Table 2-20. Diatom Index of Wetland Condition scores for sampled sites.
Sites DIWC Sites DIWC
Audubon 36 IRBlueCypress 53
BearScat 72 IRCanal 41
BigCow 18 IROJ 48
BRSebastian 137 JD6 140
CabPatch 28 KellyPark 91
Caravelle 39 LCork 100
Chuluota 131 LLeeCounty 70
CLBayard 100 LEGo 106
CLCove 16 LESuwan 49
CMWPast 111 MALudy 9
CMWRef 134 MASpray 124
COBurgle 15 McArthur 6
COHole 70 MNElmer 55
Crew 118 MNOcala 140
DEMelon 9 MRPepper 35
Deerfly 105 Myakka 100
Garber 86 OKCara 21
Gbare 20 OKKiss 137
GLDonut 9 OKPast 36
GLPont 3 PacificTom 43
Goethe 106 PallMar 140
GreenSwamp 113 PBCorbett 96
HARare 3 PBEnjay 137
Haguel 3 Penner 140
Haguell 22 POWales 137
HalfMoon 134 POWeowak 134
HEBad 29 RiceCreek 93
HEL2 6 SANorthMya 115
HEOkay 49 SAOscer 127
Highpast 33 SandhillCrane 103
HighRef 87 Savannas 140
HillsRef 83 STCow 0
HuntCamp 137 UNHealthy 13
IFASI 128 Weikiva 140
Immokalee 110






44






150
tM:0 *

0 ** *
100 0



50 *



0 0O0

1 2 3 4 5 6
LDI


Figure 2-8. Diatom Index of Wetland Condition scores for each site plotted against the
disturbance gradient.

Discussion

Diatom Composition and Environmental Correlates

It was anticipated that environmental variables would drive the wetland community
composition such that low overlap (as measured by PSI and MRPP) would occur between
benthic, epiphytic, and phytoplanktonic diatoms, as reported by Pan and Stevenson
(1996) and U.S. EPA (2002e). Benthic diatoms were expected to respond strongly to the
nutrient and chemical condition of the wetland sediments (Stevenson 2001). Epiphytic
diatoms were expected to respond to nutrients from both the soils and water column, as
"nutrients taken up by plants from sediments are released and readily absorbed by
epiphytic biofilms" (Stevenson 2001, p. 121). Phytoplanktonic diatoms were expected to
respond most strongly to the nutrients and physical/chemical characteristics of the
enveloping waters. However, as found by Van Meter-Kasanof (1973), Moss (1981), de
Jonge and van Beusekom (1992), there was substantial overlap for each of the wetland
diatom communities, indicating a similar response to forcing functions (i.e., pH, specific
conductivity, nutrients).
The similarities may also be a result of the spatial location of the sampled diatoms.
The benthic community, due to the spatial position at the bottom of the water column,
likely integrated not only benthic, but also epiphytic and phytoplanktonic diatoms. This
purported ability of benthic diatoms to integrate a longer temporal signature of wetland









conditions vis-a-vis the epiphytic or phytoplanktonic diatoms is a reflection of their
position within the wetland and could be considered an advantage to using diatoms for
biological assessment (Stevenson 2001, U.S. EPA 2002e). Benthic diatoms were thus
likely composed not only diatoms of the benthos, but also of the rain of dead and
sloughed-off diatoms from the phytoplankton and epiphyton communities. Epiphytic
diatoms were composed not only of the diatoms equipped to thrive on macrophytes, but
also of phytoplanktonic and mobilized benthic diatoms that became entangled in the often
thick web of tendrils of soft algae growing from the macrophytes. U.S. EPA (2002e, p.
6) considers wetland epiphytic diatoms a reflection of the "last couple of months" -
generally meaning the hydrated period for the wetland, although many of the diatoms
may persist during periods of drought. The phytoplankton community was composed of
diatoms evolved to move within the water column, as well as organisms mobilized from
the sediments and plant matter by wind action or disturbances from vertebrates. The
phytoplanktonic diatoms generally reflect the shortest period of wetland conditions, as
once they fall from suspension, they become assimilated into the benthos (U.S. EPA
2002e).
While high similarities (>75%) existed on a global level between diatoms found in
benthic, epiphytic, and phytoplanktonic communities, a moderate -50% within-site
similarity was identified (using PSI) for the sampled diatom assemblages. These results
may be indicative of temporal variations of within-site species abundances, perhaps a
reflection of slower or faster responses of diatoms within a particular community to
hydrologic or physical/chemical parameters.
Strong correlations were found for soil pH, specific conductivity, and LDI score for
the sampled assemblages, and benthic and epiphytic diatoms were also strongly
correlated with water TP (see Tables 2-9 to 2-11). It is well established that pH and
specific conductivity have a controlling effect on diatom species composition (Lowe
1974, Pan and Stevenson 1996, U.S. EPA 2002e), and that these variables are altered by
anthropogenic disturbances such as agro-fertilizer application and hydrologic
modifications (Fore and Grafe 2002, U.S. EPA 2002e). Likewise, the link between
phosphorus and diatom composition is well established (Lowe 1974, Pan and Stevenson
1996, Stevenson et al. 1999 Barbour et al 1999), and a link would be expected between a
general impairment indicator (LDI score), which reflects the physical, chemical, and
nutrient alterations to the landscape, and wetland diatom species composition (Carpenter
and Waite 2000, O'Conner et al. 2000, Cuffney et al. 2000, Munn et al. 2002, Fore and
Grafe 2002, Fore 2003).
Despite the high similarity identified with PSI and MRPP, and similar driving
forces identified with NMDS, a much stronger relationship with environmental variables
(as measured by Mantel tests) was identified with epiphyton than with benthic or
phytoplanktonic diatoms. These results (Mantel's r values for each assemblage) do not
change by more than 0.01 when species that occur in <2 sites are removed (C. Lane,
unpublished data). This suggests that the higher richness found in phytoplanktonic and
benthic assemblages do not affect the relationship between a particular assemblage and
the measured environmental variables through the addition of ecological "noise" from
rare species (Marchant 2002). These results further support the use of epiphytic diatoms
as the selected diatom assemblage for analyses.









Diatom Composition and Wetland Regions

The lack of significant differences in the composition of epiphytic diatoms between
regions, when simultaneously tested with MRPP, was driven by the lack of significant
differences in the composition of impaired sites (see Table 2-12). It is theorized that once
a wetland crossed a threshold of impairment (e.g., McCormick and Stevenson 1998),
whatever effect physiographic (i.e., mineral or organic soil) or climatic variables may
have on the community is muted by the driving energies of the impairment (i.e.,
alterations to specific conductivity, pH, or phosphorus levels). Thus, there were no
significant differences among epiphytic diatoms in impaired sites throughout peninsular
Florida, but a significant difference between diatoms found in reference conditions in
each region was identified. The environmental driving forces strongly were specific
conductivity, soil pH, water color, and TP (C. Lane, unpublished data). Adding latitude
and longitude of each site to the second (environmental variables) matrix resulted in the
addition of latitude as a strongly correlated variable (C. Lane, unpublished data). These
results again distinguish the importance of specific conductivity, pH, and TP as driving
variables of diatom community composition, and also suggest that physiographic or
climatic variables associated with the North to South axis of peninsular Florida affect the
distribution of diatoms located in reference conditions. The addition of water color as a
driving variable in diatom communities follows from the negative effect of darker waters
on photosynthesis rates, and the necessity of adaptations to such environments.

Metric Development

Indicator species analysis

Indicator species analysis identified 43 taxa with specificity and fidelity to LDI
scores of <2.0 and >2.0. Using the abundance of these taxa provided a metric to measure
the relationship between the land use around the wetland and the identified sensitive or
tolerant taxa within the wetland. Increased sampling would likely affect the composition
of the sensitive and tolerant taxa lists as additional taxa would be found that were
significantly related to reference or impaired conditions, while some taxa currently listed
as sensitive or tolerant would likely be not significantly related to either classification due
to increased sampling size clarifying the relationships in the data.
The highly variable abundance of reference indicators, when plotted along the LDI,
suggests that reference indicators are likewise highly variable in assessing wetland
condition, at least until a threshold of LDI scores of approximately 3.2. After that
threshold of measured disturbance is reached, the abundance of reference indicators
plummets. Impaired indicator abundance appears to react similarly to increasing LDI
values, with a similar threshold of approximately 3.4. However, the accuracy and
precision of the impaired indicator abundance at LDI values greater than 3.4, appears to
be improved vis-a-vis the abundance of reference indicators at low development intensity
values.









Autecological indices

The indices of Van Dam et al. (1994) and Bahls (1993) combined autecological
values for diatoms of European and the Mountain-west environments, respectively. That
the indices developed elsewhere appear to be valid for diatoms of herbaceous
depressional wetlands in peninsular Florida is not surprising, considering their use in
identifying various disturbance gradients in large rivers of Idaho (Fore and Grafe 2002),
streams of the mid-Atlantic states (Fore 2003), Wyoming (Peterson and Porter 2002), and
Maine wetlands (U.S. EPA 2002e-see case studies). Not only are many of the diatoms
cosmopolitan in their worldwide distribution, but they also exhibit fidelity of response to
disturbance gradients throughout the world.
As in the abundance of indicator taxa, a threshold near 3.2-3.4 appears to
dramatically affect the distribution of site scores. For instance, the abundance of diatoms
that tolerate elevated pH, salinity, nitrogen, low D.O., and pollution, as well as the
eutrophic and meso-polysaprobous all increase markedly in that range, although there are
highly variable distributions for any given LDI above a 3.0. This suggests a threshold of
tolerance exists up to approximate LDI values of 3.2.
Most metrics that decrease with increasing development intensity do so with
accuracy and precision (albeit low), especially when compared with metrics that increase
with increasing development intensity. A highly variable response is nevertheless
evident for those six metrics, although it appears that the highest variability in the data
exists near values of 1.0, as well as around LDI values of 3.2.

The Diatom Multimetric Index-Conclusion and Recommendations

The DIWC, which combines species composition and autecological response for
diatoms of herbaceous depressional marshes in Florida, was correlated |>0.751 (p<0.001)
with increasing land use modification scores. The high number of metrics (14) provided
for a wide-range of responses to various possible perturbations from hydrologic
alterations to nutrient loading. However, the metric responses, including that of the
DIWC, highlighted discrepancies within the distribution of values along the LDI. The
highly variable distribution of metrics for any given LDI value was exhibited by all
identified metrics. Thresholds appeared to exists at LDI values near 1.0 and 3.3, although
these threshold were muted in the DIWC. These results suggest that LDI values of less
than 3.2 could most likely be grouped together into a suite of highly variable reference
sites little structure in the data (i.e., correlation with the LDI) appeared to be manifested
for values of <3.2. Similarly, the rapid increase in most metric values after 3.2 was also
highly variable by site.
The sites analyzed in the development of this multimetric index were sampled
during the late summer. Research on seasonal and annual variation in the distribution of
diatoms, and of the variation in the DIWC for diatoms sampled in different years and
seasons is currently underway. In addition, the current DIWC requires that the wetland be
hydrated for sampling. However, in this study it was unknown how long a given wetland
had been hydrated prior to sampling. Thus, although diatoms may respond very quickly
to hydration (Stoermer and Smol 1999), sampling response and subsequent analyses may
be confounded by temporal variation in hydration. Current research underway (K. Reiss,
University of Florida Department of Environmental Engineering Sciences, personal






48


communication) will determine the utility of benthic diatoms sampled during dry periods
to adequately and accurately reflect the condition of the wetland in question. Should the
benthic diatoms prove to be year-round indicators of community condition, this
multimetric index constructed on epiphytic diatoms should be reassessed.
Finally, epiphytic diatoms are generally expected to change in community
composition depending on the macrophytes species to which they are attached
(Stevenson 2001). It would be well worth examining, in laboratory settings, community
variations among epiphytic diatoms when several different wetland macrophytes species
common in both impaired and reference conditions are available for colonization.














CHAPTER 3
MACROPHYTES AS BIOINDICATORS

Introduction

Wetland macrophytes are well suited for use as reliable biological indicators of the
relative condition of Florida freshwater depressional marshes. Defined as plants "growing
in water or on a substrate that is at least periodically deficient in oxygen as a result of
excess water"(Cowardin et al. 1979, pg. 40), wetland macrophytes are ubiquitous and
identifying features of marshes throughout Florida. Since wetland plants are sessile (save
for a few free-floating species), they are unable to actively avoid perturbations through
flight mechanisms. Thus, the community composition of marsh macrophytes,
"...reflect[s] the temporal, spatial, chemical, physical, and biological dynamics of a
[wetland] system"(Fennessy et al. 2001, pg. 3), and changes in wetland macrophyte
community composition may be used to indicate both past perturbations and current
conditions (Doherty et al. 2000, Adamus et al. 2001, Fennessy et al. 2001).
Reliable biological indicators provide information on the condition of a resource
relative to "reference," or least disturbed conditions, within an ecologically meaningful
region (Barbour et al. 1996, Karr and Chu 1999). Wetland macrophytes possess many
advantages for use as reliable biological indicators, most notably their prevalence in
wetland systems and response to land use changes (Table 3-1). Wetland macrophytes
respond to hydrologic, nutrient, and chemical perturbations associated with increased
development to wetland landscape matrices (Adamus and Brant 1990, Adamus 1996,
Doherty et al. 2000, Fennessy et al. 2001, Adamus et al. 2001). Changes in wetland
macrophyte species abundance and composition along nutrient gradients have been noted
Bedford et al. 1999). Compositional changes due to chemical loading (i.e., herbicides;
McIntyre et al. 1988), hydrologic alterations (Wood and Tanner 1990, Rochow 1994,
David 1994, Busch et al. 1998, MaGee et al. 1999) and to destruction of habitat (Blanch
and Brock 1994, Winchester et al. 1995, Dobkin et al. 1998, van Oene et al. 1999, Grace
and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000) have also been described for
wetland macrophytes. Additionally, well-documented collection methods exist for
wetland plants (e.g., Brown 1991, Peet et al. 1996, Fennessy et al. 2001), and definitive
identification texts abound that permit identification to the species level in most cases
(e.g., Godfrey and Wooten 1979, 1981, Wunderlin 1998). Moreover, unlike typical
macroinvertebrate and algal indicators, standing water need not be present for the
collection of wetland macrophytes, thus increasing the sampling opportunities for
wetland assessment.
The use of macrophytes as biological indicators is not without disadvantages. There
are seasonal differences in species composition and potential lag times between
perturbations and responses (Fennessy et al. 2001). While most wetland plants are easily
identified with basic field training, some species may lack diagnostic parts during the
sampling window or require expert skills to identify. While detractions from using









Table 3-1. Advantages and disadvantages of using macrophytes as biological indicators
of wetlands condition.
Advantages of Macrophyte Biological Indicators
Ubiquitous Features of Wetlands
Sessile Organisms
Established Taxonomy
Great Diversity of Species
Ecological Tolerances Well-Known
Well-developed Sampling Techniques

Disadvantages of Macrophyte Indicators
Possible lag time between disturbance and response
Field Identification Difficult in Certain Seasons
Sampling Window May Only Be the Growing Season
Some Species Non-responsive to Perturbations
Few Published Documentations of Response to Certain Stressors

Note: Modified from Cronk and Fennessy (2001).

macrophytes exist (see Table 3-1), wetland macrophytes nevertheless "...provide clear
and robust signals of human disturbance" (Cronk and Fennessy 2001, p. 373).
Recognizing the ability and sensitivity of macrophyte bioindicators to differentiate
wetland condition along a gradient of landscape modification, several states have
included or are exploring the use of macrophytes in their wetland biological assessment
programs (e.g., Ohio: Mack 2001, Montana: Apfelbeck 2000, Minnesota: Gernes and
Helgen 1999, Galatowitsch et al. 1999a, North Dakota: Mushet et al. 2002). Additionally,
the U.S. Environmental Protection Agency's Biological Assessment of Wetlands
Working Group (BAWWG) has supported development of biological assessment criteria,
including macrophytes, through funding for state initiatives, workshops, and technical
publications (e.g., Doherty et al. 2000, Fennessy et al. 2001, U.S. EPA 2002a).
In this chapter, details regarding methods of data analyses and final choices for
macrophyte metrics for use in developing biological indicators of wetland condition were
given. Analyses of environmental parameters measured (both abiotic and biotic) were
also conducted to assess the environmental variables that affected the distribution of
macrophyte taxa within wetlands. In addition, metric variation for a given LDI score for
the macrophyte metrics was also examined to assess the accuracy and precision of the
LDI.

Methods

Site Selection and Disturbance Gradient

Seventy-five isolated depressional marshes (Figure 3-1) were sampled a single
timefor macrophyte community composition throughout peninsular Florida in the
summers of 1999 (n=35) and 2000 (n=40). Using best scientific judgment, sites were














NORTH


Encounter probability rank
for depressional marshes
by County
1 CENTRAL
6

16
21
26
313

41

56 SOUTH
61
66

U Impacted

OReference ,'

150 0 150 300 km
Figure 3-1. Study site locations and encounter probability for isolated depressional
wetlands. Counties shaded darker have a higher density of isolated depressional wetlands

initially stratified into reference (no obvious human modified landscapes within >100m),
and impaired (obvious human landscape modification within 100m) categories. Site
condition was independently assessed later with the LDI (Brown and Vivas submitted), as
noted in the diatom methods section (Chapter 2: Site Selection and Agricultural
Development Gradient). Slightly less than half the sites (35) were considered reference
sites, generally located in state and federal parks, preserves, and state forests. Wetlands
that comprised the remaining 40 sites were located within agricultural landscape matrices
and were considered impaired sites (LDI > 2.0). Thirty impaired sites were located in
cattle ranches of varying stocking densities, 7 in truck crops (tomatoes, peppers), 2 in
citrus groves, and 1 was sampled in a silvicultural forest. Site coordinates and LDI score
for each sampled wetland are found in Appendix A. All but five sites were hydrated when
sampled.









Field Data Collection

Wetland macrophytes were identified and counted in Im x 5m quadrats along four
belt transects. Transects were laid out along each cardinal direction (North, South, East,
West) beginning at the wetland edge and extending to the center of the wetland (Figure 3-
2). The wetland/upland boundary was determined in the field through plant status (i.e.,
facultative, obligate, upland) from Tobe et al. (1998) and hydric soil parameters (see U.S.
Department of Agriculture 1998). In 1999, the transects continued from the wetland edge
until the center was reached or until 15m2 (3 consecutive quadrats) did not change in
species composition. (Approximately 2% of the sites had transects not reaching the
measured center of the wetland in 1999.) This was changed in 2000 to ensure full
characterization of the wetland macrophyte community by collecting data along the entire
length of each transect. The presence of living plants was noted within 0.5m along each
side of the transect tape for each quadrat from the wetland edge to the center of the
wetland. Unknown species were collected, labelled, and pressed for later identification by
David Hall of the University of Florida. All collected species were stored in the Howard
T. Odum Center for Wetlands herbarium.

N


Figure 3-2. Transect and quadrat locations in a hypothetical depressional wetland.









Drought conditions during 1999 and 2000 field seasons forced the sampling period
to be both delayed in its onset and extended in duration to ensure hydration of the
sampled wetlands (Table 3-2). Thus, some species encountered lacked the fruiting bodies,
flowers, and other parts requisite for identification due to seasonal vagaries in
reproduction or growth. All macrophytes found were identified to the lowest level
possible, generally species, and entered into the database for further use in metric
development. This study focused on taxa identified to species.

Table 3-2. Sampling dates for each region.
Earliest Date Latest Date Earliest Date Latest Date
Region 1999 1999 2000 2000
South August 3 November 4 August 29 October 25
Central July 23 August 17 September 9 October 26
North July 28 November 11 October 16 November 1

Database Development

Field data sheets denoting presence of macrophytes within each Im x 5m quadrat
along each of the four transects were transcribed into Microsoft Excel spreadsheets and a
Microsoft Access database and error-checked by two people: the person who originally
transcribed the data into Microsoft Excel, and another person who reread the original
datasheet back to the original transcriber who reviewed the Microsoft Excel output. A
master plant list of all plants identified was developed, and ancillary species'
characteristics from the literature, as well as Coefficient of Conservatism scores
(described below), were added to the list. The plant database was linked in such a way
that all characteristics could be analyzed by site, transect, or quadrat.

Species characteristics

Plant species characteristics (listed in Table 3-3) were taken from the literature for
use in developing biological indicators. The primary source for these data was Wunderlin
(1998), but other sources were also consulted, including Godfrey and Wooten (1979,
1981), Tobe et al. (1998), and the internet-based Atlas of Florida Vascular Plants
(Wunderlin and Hansen 2000).

Table 3-3. Ancillary data added to the database for each plant species.

Family
Annual or perennial (biennial plants were incorporated in the annuals)
Form: grass, sedge, rush, forbs, vine, fern, tree, shrub, aquatic
Deciduous or evergreen
Native or exotic
Coefficient of Conservatism score









Coefficient of Conservatism

Ten expert botanists (Anthony Arcuri, Keith Bradley, Kathy Burks, David Hall,
Ashley O'Neal, Jim Poppleton, Nina Raymond, Bruce Tatje, John Tobe, and Wendy
Zomlefer) were enlisted to assist in identifying species characteristics for use in
developing a Coefficient of Conservatism score. The Coefficient of Conservatism (CC)
was developed by Wilhelm and Ladd (1988) as part of the Floristic Quality Assessment
Index, a method of assessing vegetation in the Chicago area based on expert botanists'
opinion on the fidelity of a plant species to particular environments. Since its inception,
this method has been utilized to assess wetland condition based upon species present in
numerous studies (Herman et al. 1997, Fennessey et al. 1998, Mack 2001, Mushet et al.
2002, Cohen et al. submitted). To determine CC scores, the botanists were sent the full
list of species encountered during the two sampling seasons (n=397), and were asked to
score the plants using the coefficients and definitions given in Table 3-4. The botanists
were also asked to weight the confidence of their answers on a 1-3 scale (3 being the
most confident). Subsequently, each botanist's CC value for each plant was multiplied by
each botanist's confidence weight for that plant, increasing the proportional
representation for extremely confident scores. The score for each plant after confidence
weighting was summed and averaged across all botanists, and normalized to a 1-10 scale.
See Cohen et al. (submitted) for additional information.

Table 3-4. Scoring Criteria for the Coefficient of Conservatism.
C of C Description
0 Alien taxa and those native taxa that are opportunistic invaders or
common components of disturbed communities.
1 3 Widespread taxa that are found in a variety of communities, including
disturbed sites.
4 6 Taxa that display fidelity to a particular community, but tolerant of
moderate disturbance to that community.
7 8 Taxa that are typical of well-established communities that have
sustained only minor disturbances.
9- 10 Taxa that exhibit a high degree of fidelity to a narrow set of ecological
conditions.


Soil and Water Physical-Chemical Sampling and Analysis

To relate the distribution of wetland macrophytes to environmental parameters, soil
and water physical and chemical parameters were measured at each site as described in
Chapter 2 (Methods: Field Data Collection, Sample Preparation and Laboratory
Procedures) and Appendix B.









Data Analyses

Summary statistics

Summary measures of sample richness, Shannon diversity, Simpson diversity, beta,
and gamma diversity were calculated for each site and provided information on species
distributions vis-a-vis land use as described in Chapter 2: Data Analyses.

Macrophytes-compositional analysis

While wetlands throughout peninsular Florida were sampled, the sites were initially
stratified into three peninsular wetland regions, or areas of similar climatic and
physiographic conditions (after Lane 2000, see Figure 3-1). Through examination of data
at the regional level, it was expected that variations in species assemblages due to
climatic or physiographic differences between sites within a given region would be
minimized (Gerritsen et al. 2000, Smogor and Angermeier 2001). To test the significance
of the modeled wetland regions on species distribution, a compositional test, the multiple
response permutation procedures (MRPP,) available in PCOrd (MjM Software, Gleneden
Beach, Oregon, version 4.10) and described in Chapter 2 (Methods: Site Selection and
Agricultural Development Gradient), was used.

Macrophyte composition and soil and water parameter correlates

The following soil variables were arcsine square root transformed to decrease
measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Logio
transformations were completed on soil TP, color, specific conductivity, turbidity,
ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity
among the environmental variables, described as strong correlations between independent
variables (Zar 1999), was tested for using the variance inflation factor and tolerance,
described in Chapter 2 (Methods: Data Analyses). The non-parametric Mann-Whitney U-
test was used to test the null hypothesis of equal medians between reference and impaired
classes for each environmental variable (Zar 1999).
The relationship between measured environmental values (including LDI score)
and species composition was examined with the Mantel test (Mantel 1967) and with non-
metric multidimensional scaling (NMDS, Kruskal 1974, Mather 1976), both available in
PCOrd and described in Chapter 2 (Methods: Data Analyses). A two-dimension NMDS
solution was selected for macrophyte taxa as increased dimensionality only marginally
improved the fit. Correlations of site scores with environmental parameters, including
LDI score and latitude and longitude (decimal degrees), were calculated and a bi-plot of
parameters with correlations (Pearson's r2> 0.30) to site scores was constructed.

Metric Development

Macrophyte metrics were identified from the literature (e.g., Wilhelm and Ladd
1988, Adamus and Brant 1990, Andreas and Lichvar 1995, Adamus 1996, Kantrud and
Newton 1996, Gernes and Helgen 1999, Cronk and Fennessy 2001, Mack 2001, Fennessy
et al. 2001) or developed from iterative analyses of data response. Metrics were selected









for inclusion in the preliminary Vegetative Index of Wetland Condition (VIWC) if they
demonstrated a constant and predictable change with increasing Landscape Development
Intensity (LDI) scores as measured by the Spearman correlation coefficient. Final metrics
were those with significant (p<0.05) Spearman's correlations >|0.50| with the LDI.
Metrics were also tested for their ability to discern between the classification of sampled
wetlands in impaired (LDI >2.0) and reference (LDI <2.0) landscapes using the
nonparametric Mann-Whitney U-test. Additionally, to normalize wetlands of different
sizes, metrics that incorporated the enumeration of species (such as the count of exotic
species encountered at a site) were changed into abundance values by dividing the sum of
the metric by the total number of plants identified to species at a site. All evaluations of
potential metrics were conducted with SAS (SAS Institute, Cary N.C., version 8.02).
Based on preliminary data analysis and the strength of the metric correlation with the
LDI, the macrophyte metrics described below were selected for inclusion in each wetland
region.

Sensitive and tolerant species

Indicator Species Analysis (ISA, Dufrene and Legendre 1997) was utilized to
identify species with a significant association with LDI classification of impaired
(LDI>2.0) or reference conditions (LDI<2.0) as described in Chapter 2 (Metric
Development).

Exotic species

The percent of total species exotic to Florida at a wetland site was calculated by
dividing the number of exotic species encountered by the total number of species found at
the site. Native or exotic plant status was determined using Tobe et al. (1998), Wunderlin
(1998), Godfrey and Wooten (1979, 1981), Langeland and Burks (1998), and Wunderlin
and Hansen (various dates 2000). In general, exotic species were those thought to have
not been present in Florida before European settlement of North America. The abundance
of exotic species was expected to increase with increasing development of the landscape
surrounding the wetland (Fennessy et al. 2001).

Annual to perennial ratio

The ratio of annual to perennial (A:P) species was calculated for each wetland. The
trend expected was that as development increased in a wetland landscape matrix, the
proportion of "weedy," or annual species versus perennial species would increase
(Edwards and Weakley 2001). Life-history status (i.e., annual/perennial) was determined
from the literature for each species identified, and a ratio was determined for each
wetland.

Average Coefficient of Conservatism

To obtain an average CC score for each wetland sampled, the sum of the
confidence weighted CC values for each plant found at the sampled wetland was divided
by the total number of plants sampled. The resultant CC score provided an estimate of the









conservatism of the plants encountered. As development increased within the wetland
landscape matrix, the CC score for the wetland was expected to decrease, indicating the
presence of both plants with more general habitat requirements and exotics.

Vegetative Index of Wetland Condition

To create a multi-metric index of wetland condition based on metrics that were
strongly correlated with the LDI, it was necessary to score the proposed metrics. Scoring
allows the disparate metrics (i.e., such as ratios and relative abundance metrics) to be
summed to provide a numerical score for the condition of the wetland to compare vis-a-
vis a set of reference wetlands within a given region (Karr and Chu 1997). Scoring
methods are described in Chapter 2 (Methods: Constructing the Multimetric Index).
Following the metric scoring, the Vegetative Index of Wetland Condition was determined
for each wetland sampled by summing the scored metrics.

Results

Field Data

Seventy-five herbaceous depressional wetlands throughout peninsular Florida were
sampled in 1999 and 2000. Twenty-three were sampled in the South region, thirty in the
Central region, and twenty-two in the North region. Based on the predominant land use
around the wetland, twelve of the sites sampled in the South region were a priori
considered impaired, sixteen in the Central region, and eight in the North region.
Three hundred and ninety-seven different taxa from 207 plant genera representing
111 families were identified during the 1999 and 2000 field seasons. Two hundred
twenty-six taxa were identified in the South region, 270 taxa were identified in the
Central region, and 242 taxa were identified in the North region; many species were
found in more than one region.
Summary measures of sample richness, Shannon diversity, and Simpson diversity
were calculated for each site (Brower et al. 1990). Summary statistics are presented in
Table 3-5. Mann-Whitney U-tests indicated no significant difference between reference
and impaired sites for richness, Shannon diversity, or Simpson diversity (all tests Z = -
0.005, p = 0.996). Two additional indices were also calculated from the macrophyte data:
beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Beta and gamma
diversity were higher in impaired sites than in reference sites (impaired sites average
richness: 31.60, beta diversity: 9.81, gamma diversity: 310; reference sites average
richness: 31.66, beta diversity: 8.18, gamma diversity: 259).

Ancillary Data

A histogram of the distribution of CC scores for the species identified is given in
Figure 3-3. As the data were normalized, the mean of the distribution is 5.0, while the
median value is 5.56, and the standard deviation is 2.57. The plant with the highest
conservatism score (10) was Coelorachis tuberculosa. In general, exotic species and
invasive native species were given scores of zero. However, several exotic species, such
as Xyrisjupicai (CC = 3.51), were given higher scores by the botanists, indicating a











Table 3-5. Summary statistics of richness (S), Simpson's diversity index (H) and


Shannon diversity index (D') for macrophytes.


Site Name S
ALPaynes 28
Audobon 16
Bear Scat 39
Big Cow 34
BRSebastian 24
CabPatch 34
Caravelle 22
Chuluota 41
CLBayard 20
CLCove 34
CMWPast 39
CMWRef 21
COBurgle 16
COHole 25
Crew 31
DEMelon 41
Deerfly 31
GarberRanch 22
GBarE 28
GLDonut 24
GLPont 20
Goethe 24
GreenSwamp 34
HaRare 33
Haguel 27
Haguell 21
Half Moon 37
HEBad 37
HEL2 18
HEOKAY 46
HighPast 16
HighRef 23
HillsRef 43
Hunt Camp 26
IFASI 26
IFASII 27
Immokalee 26
IRBlueCvpress 42


H D'
3.332 0.9643
2.773 0.9375
3.664 0.9744
3.526 0.9706
3.178 0.9583
3.526 0.9706
3.091 0.9545
3.714 0.9756
2.996 0.95
3.526 0.9706
3.664 0.9744
3.045 0.9524
2.773 0.9375
3.219 0.96
3.434 0.9677
3.714 0.9756
3.434 0.9677
3.091 0.9545
3.332 0.9643
3.178 0.9583
2.996 0.95
3.178 0.9583
3.526 0.9706
3.497 0.9697
3.296 0.963
3.045 0.9524
3.611 0.973
3.611 0.973
2.89 0.9444
3.829 0.9783
2.773 0.9375
3.135 0.9565
3.761 0.9767
3.258 0.9615
3.258 0.9615
3.296 0.963
3.258 0.9615
3.738 0.9762


Site Name S
IRCanal 22
IROJ 43
JD6 33
Kelly Park 27
LCork 48
LLeeCounty 58
LEGo 41
LESuwan 42
MALudy 54
MASpray 24
McArthur 29
MNElmer 45
MNErik 38
MNOcala 38
MRPepper 46
Myakka 35
OKCara 47
OKKiss 37
OKPast 28
PacificTom 37
Pall-Mar 17
PBCorbett 33
PBEnjay 43
Penner 14
POWales 18
POWeowak 44
PUPond 19
RiceCreek 16
SANorthMya 31
SAOscer 38
SandhillCrane 35
Savannas 41
STCow 40
SUVaca 37
SUWarhol 33
UNHealthy 30
Wekiva 15


H
3.091
3.761
3.497
3.296
3.871
4.06
3.714
3.738
3.989
3.178
3.367
3.807
3.638
3.638
3.829
3.555
3.85
3.611
3.332
3.611
2.833
3.497
3.761
2.639
2.89
3.784
2.944
2.773
3.434
3.638
3.555
3.714
3.689
3.611
3.497
3.401
2.708


D'
0.9545
0.9767
0.9697
0.963
0.9792
0.9828
0.9756
0.9762
0.9815
0.9583
0.9655
0.9778
0.9737
0.9737
0.9783
0.9714
0.9787
0.973
0.9643
0.973
0.9412
0.9697
0.9767
0.9286
0.9444
0.9773
0.9474
0.9375
0.9677
0.9737
0.9714
0.9756
0.975
0.973
0.9697
0.9667
0.9333











40 -


30 -

LI.




10
20 -1 1








0 5 10
C of C Scores


Figure 3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted
scores for wetland macrophytes.

perceived higher fidelity to a narrower set of ecological conditions. A list of species
identified and their corresponding CC scores is given in Appendix D.

Compositional Analysis

A matrix of the co-occurrence of identified species in the wetland regions of
Florida is presented in Table 3-6. The co-occurrence of species found in reference and
impaired sites for the three wetland regions are also given in Table 3-6. The South and
North regions shared the fewest species, slightly more than half, while approximately
60% of the plants found in the Central region were also found in the North or South
regions. The Central region was also most similar to the North and the South regions for
both impaired and reference plants.
Tests of compositional similarities between wetland regions (Lane 2000) were
conducted using MRPP (Table 3-7). Significant differences in compositional similarity
among wetland regions were identified for both simultaneous (i.e., South vs. Central vs.
North) and iterative tests (i.e., South vs. Central, South vs. North, Central vs. North).
When reference sites were compared, significant differences were also identified for both
simultaneous and iterative tests. Tests of impaired sites indicated significant differences
when simultaneously tested, however, iterative tests found only significant difference
between impaired sites of the South and North regions at p<0.05. The iterative tests of
impaired sites between all regions were significantly different at p<0.10.









Table 3-6. Co-occurrence matrices of macrophytes by region and impairment condition.
Condition Region South Central North
All Sites South 100.0 % 61.9% 52.3 %
(n=75) Central 73.4 % 100.0 % 66.9 %
North 56.6 % 60.0 % 100.0 %


Reference
(n=35)


Impaired
(n=40)


South
Central
North

South
Central
North


100.0 %
58.1 %
43.2 %

100.0 %
67.9 %
56.2 %


54.4 %
100.0 %
55.7%

58.2 %
100.0 %
56.1 %


47.8 %
65.7 %
100.0 %

47.9 %
55.8 %
100.0 %


Table 3-7. Simultaneous and iterative tests of community composition among regions.
Test Comparison A T p-value
Simultaneous
Tests: All Sites S vs. C vs. N 0.0211 -6.235 < 0.001

Simultaneous
Reference Only S vs. C vs. N 0.0502 -7.198 < 0.001

Simultaneous
Impaired Only S vs. C vs. N 0.0176 -3.137 0.005

Iterative S vs. C 0.0120 -3.330 0.010
Tests: S vs. N 0.0323 -8.066 < 0.001
All Sites C vs. N 0.0075 -2.156 0.039

Iterative S vs. C 0.0300 -4.156 0.001
Tests: S vs. N 0.0690 -7.492 < 0.001
Reference Only C vs. N 0.0204 -2.961 0.010

Iterative S vs. C 0.0094 -1.703 0.060
Tests: S vs. N 0.0022 -3.096 0.009
Impaired Only C vs. N 0.0110 -1.873 0.050
Note: S = South region, C = Central region, N= North region

Community Composition and Environmental Gradients

Including the LDI, fourteen environmental variables were measured at each site.
The measured water and soil parameters are given in the Appendix B. Significant
differences between impaired and reference conditions, as measured by the Mann-
Whitney U-test, were found for the following parameters: soil pH, soil TP, specific
conductivity, water pH, ammonia, TKN, and water TP (Table 3-8). Water color was
significant lower in reference conditions at p<0.10.









Table 3-8. MRPP comparison of the median values of water and soil variables between
reference and impaired sites.
Water Values Statistic (Z) p-value
Color -1.868 0.066
Specific Conductivity -3.919 < 0.001
Turbidity -1.524 0.127
Water pH -4.700 < 0.001
Ammonia -2.707 0.007
Nitrates/Nitrites 0.782 0.437
TKN -2.932 0.003
TP -4.836 < 0.001

Soil Values Statistic (Z) p-value
Soil pH -2.894 0.004
%TC -0.616 0.538
%OM -1.105 0.269
%TN -0.924 0.356
%TP -2.719 0.008

Colinearity among variables, which was identified as a VIF>5.0 and a tolerance of
<0.20, was recognized for %TC, TKN, and water pH following regression analyses of the
transformed data (SAS 1990). These variables were removed. The Mantel test was used
to test the hypothesis of no relationship between the identified macrophytes and the
measured environmental parameters, including LDI score. Results indicated a strong and
significant relationship (Mantel's r = 0.49, p=0.001).
An NMDS ordination was completed to examine the underlying structure of the
sites in ordination space and to ascertain the environmental variables driving the
composition of sites sampled. Correlations for all measured environmental variables are
presented in Table 3-9, and a biplot of site ordination overlaid with vectors representing
the environmental variables is presented in Figure 3-4. The stress, or "goodness of fit" of
the ordination was 21.11 and indicated a marginally adequate and representative
decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). Likewise, the final
instability after 400 iterations was 0.00399, which was higher than the ideal instability
(<0.001) but nevertheless a generally acceptable instability value (McCune and Grace
2002). The ordination indicated that 74.5% of the variance in the dataset was captured by
the two dimensional ordination (first axis: 42.5%, second axis:33.0%). The ordination
scores for each site were linearly correlated (Pearson's r) with the measured
environmental values, including LDI, latitude, and longitude. Correlations (Pearson's r2)
> 0.30 were found for LDI: 0.66, soil pH 0.57, water TP: 0.48, latitude: 0.39, and specific
conductivity: 0.33, indicating their importance in driving the structure of the wetland
macrophyte community.











Table 3-9. Correlations of environmental variables and ordination scores.
Axis 1 (42.5%) Axis 2 (33.0%)
Parameter r2 tau r2 tau
Soil pH 0.14 0.26 0.57 0.57
% TN <0.01 0.14 0.16 -0.21
TP (mg/kg) 0.20 0.32 0.05 -0.13
% OM 0.02 0.14 0.22 -0.27
Color (PCU) 0.11 0.21 0.08 -0.17
Spec. Cond. (umhos/cm) 0.33 0.40 0.10 0.23
Turbidity (NTU) 0.07 0.15 0.01 -0.05
Ammonia (mg/L) 0.07 0.24 0.03 -0.07
Nitrate/Nitrite (mg/L) <0.01 -0.05 0.05 -0.20
Water TP (mg/L) 0.48 0.52 <0.01 -<0.01
LDI Score 0.66 0.56 0.11 0.22
Latitude (decimal degrees) 0.01 0.07 0.39 -0.45
Longitude (decimal degrees) 0.01 0.04 0.03 -0.14

Metric Development

Significant regional differences were identified in species composition, hence
initial metric development focused on identifying regionally specific bioindicators with
strong correlations with the LDI. It was anticipated that due to the regionally distinct
composition of the isolated depressional herbaceous wetlands, the final metrics would
likewise vary for each region. However, though the composition of the wetlands varied
between regions, the suite of final metrics that had significant correlations with p-values
<0.05 and Spearman's correlation coefficients of r >|0.501 with the LDI gradient (%
Sensitive, % Tolerant, % Exotic, Average CC, and A:P ratio) did not vary, indicating a
common response of wetland systems to increases in land use development.

Sensitive and tolerant species

Indicator species analysis (ISA) identified 39 taxa as indicative of reference
conditions and 26 taxa as indicative of impaired conditions (Tables 3-10 and 3-11,
respectively). Thirty-four were identified in the South region (22 reference, 12 impaired),
45 in the Central region (27 reference, 18 impaired), and 8 in the North region (2
reference, 6 impaired). Correlations of the abundance of species indicative of reference
conditions (% Sensitive) and impaired conditions (% Tolerant) with the LDI were
significant (p<0.001) and >|0.701 for all regions (Table 3-12). There was moderate
overlap of indicator species between regions, with 33.9% (22/65) occurring in more than
one region.











soil pH


U*


* 0


* 0


O


0 O 0
0 0 0
o OO
O U


iter TP


*


C
0 cO 0
oM 0 Reference Sites
O
0 .- U Impaired Sites

Figure 3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly
correlated environmental variables. The vectors are shown at 150% of
original length for clarity. The percent variance explained by each axis is
noted on the axis. The length of the vectors represents the strength of the
correlation (all >10.301) and the angle represents the direction of maximum
change. Five variables are shown: soil pH, Cond (specific conductivity),
water TP, latitude, and LDI.

ISA was also used to identify species with specificity and fidelity to reference and
impaired conditions using the peninsular dataset (n=75). While compositional differences
existed between regions, it was hypothesized that some taxa would be robust indicators
throughout peninsular Florida. It was also hypothesized that increasing the n of the
dataset would provide additional power in identifying indicator species. Forty-six species
were identified as reference indicator species and 36 were identified as impaired
indicators using the peninsular dataset (Tables 3-13 and 3-14, respectively). There was
substantial overlap between regional and peninsular indicator species. Three regional
impaired indicator species (South Region: Axonopusfurcatus, Central Region:










Table 3-10. Regionally derived species indicative of reference conditions.

Reference Indicator Species
(Sensitive Species) South Central North
Amphicarpum muhlenbergianum (50.1, 0.074)
Andropogon virginicus (49.9, 0.010) (61.1, 0.019)
Aristida purpurascens (38.5, 0.007)
Blechnum serrulatum (47.3, 0.026)
Cassythafiliformis (27.3, 0.095)
Cladiumjamaicense (38.4, 0.070)
Eriocaulon decangulare (41.8, 0.086) (69.2, <0.001)
Eupatorium leptophyllum (36.4, 0.039)
Fuirena scirpoidea (62.7, <0.001)
Gratiola ramosa (45.5, 0.015) (38.5, 0.011)
Hedyotis uniflora (23.1, 0.074)
Hypericum brachyphylum (38.5, 0.008)
Hypericumfasciculatum (41.8, 0.088) (61.5, <0.001)
Ilex glabra (27.3, 0.087) (38.5, 0.009)
Ipomoea sagittata (27.3, 0.090)
Iva microcephala (27.3, 0.096)
Lachnanthes caroliniana (44.5, 0.062) (49.5, 0.084)
Ludwigia linifolia (30.8, 0.027)
Lycopodium appressum (27.3, 0.087)
Lyonia lucida (23.1, 0.071)
Oxypolisfiliformis (38.4, 0.069)
Panicum erectifolium (85.7, <0.001) (48.5, 0.005)
Panicum rigidulum (38.4, 0.069) (30.8, 0.026)
Panicum spretum (23.1, 0.073)
Panicum tenerum (48.5, 0.005)
Paspalum monostachyum (27.3, 0.090)
Pinus elliottii (54.5, 0.003) (73.6, 0.002)
Proserpinaca pectinata (66.7, <0.001)
Rhynchosporafascicularis (23.1, 0.070)
Rhynchosporafilifolia (36.4, 0.037) (30.8, 0.028)
Rhynchospora tracyi (50.4, 0.037) (40.9, 0.027)
Scleria baldwinii (23.1, 0.077)
Serenoa repens (53.8, 0.001)
\'l/, i iM ,i aquatica (45.5, 0.015)
'li ,... ',,iii iflavidulus (33.4, 0.056)
Utricularia purpurea (23.1, 0.072)
Woodwardia virginica (58.9, 0.007)
Xyris elliottii (23.1, 0.068)
Xyrisjupicai (38.4, 0.066) (38.5, 0.009)
Note: Calculated indicator values and the significance of the indicator value for each
species, respectively, are given in parentheses.










Table 3-11. Regionally derived species indicative of impaired conditions.


Impaired Indicator Species
(Tolerant Species)
Alternanthera philoxeroides
Axonopus furcatus
Bacopa monnieri
Centella asiatica
Commelina diffusa
Cuphea c.,, il,.. i,io.. i ,
Cyperus haspan
Cyperus odoratus
Cyperus polystachyos
Cyperus surinamensis
Diodia virginiana
Eclipta prostrata
Eupatorium capillifolium
Hydrochloa caroliniensis
Juncus e tt1u. u.
Lindernia granwdilora
Ludwigia octovalvis
Ludwigia peruviana
Panicum repens
Paspalum notatum
Paspalum urvillei
Phyla nodiflora
Polygonum hydropiperoides
Polygonum punctatum
Pontederia cordata
Setaria parviflora


South


(33.3, 0.087)
(41.7, 0.036)

(50, 0.014)
(50, 0.013)









(33.3, 0.093)

(33.3, 0.090)
(33.3, 0.092)
(33.3, 0.095)




(42.3, 0.070)

(47.3, 0.099)
(68.7, 0.005)
(41.7, 0.040)


Central


(64.3, 0.002)
(41.2, 0.01)
(41.2, 0.010)
(40.4, 0.036)
(41.2, 0.009)
(58.8, 0.001)
(29.4, 0.050)
(70.6, <0.001)
(52.9, 0.003)
(42.2, 0.072)

(75.3, <0.001)



(41.2, 0.010)
(41.2, 0.009)
(41.2, 0.010)
(41.2, 0.010)
(47.1, 0.010)

(41.2, 0.010)

(29.4, 0.050)


North
(36.4, 0.090)


(45.5, 0.034)

(46.8, 0.062)




(54.5, 0.011)







(36.4, 0.086)

(52.9, 0.088)


Note: Calculated indicator values and the significance of the indicator value for each
species, respectively, are given in parentheses.


Table 3-12. Spearman correlations of the adundance of regional sensitive
macrophyte species with LDI scores for each site.


and tolerance


Region Comparison Spearman's r p-value


South % Sensitive Spp. -0.75 < 0.001
% Tolerant Spp. 0.72 < 0.001


Central % Sensitive Spp. -0.77 < 0.001
% Tolerant Spp. 0.78 < 0.001


North % Sensitive Spp. -0.73 < 0.001
% Tolerant Spp. 0.86 < 0.001










Table 3-13. Indicator species of reference conditions derived from the peninsular dataset.


Reference Indicator
Species
(Sensitive Species)
Amphicarpum muhlenbergianum
Andropogon virginicus
Aristida purpurascens
Brasenia schreberi %
Drosera capillaris %
Eriocaulon decangulare
Fuirena scirpoidea
Gratiola ramosa
Hypericum brachyphylum
Hypericum fasciculatum
Ilex glabra
Iva microcephala
Lachnocaulon anceps %
Lachnanthes caroliniana
Lachnocaulon minus %
Ludwigia linifolia
Lycopodium appressum
Nymphaea odorata %
Nyssa biflora %
Oxypolis filiformis
Panicum chamaelonche %
Panicum erectifolium
Panicum hemitomon I


Observed
Ind. Val.
37.5
56.2
22.6
11.4
11.4
39.3
39.8
28.6
24.3
44.0
29.1
11.4
8.6
37.0
11.4
18.8
11.4
19.9
16.0
22.6
12.2
45.3
52.5


p-
value
0.023
<0.001
0.034
0.043
0.042
<0.001
0.007
<0.001
0.011
<0.001
<0.001
0.046
0.094
0.007
0.040
0.036
0.040
0.089
0.076
0.029
0.094
<0.001
0.027


Reference Indicator
Species
(Sensitive Species)
Panicum rigidulum
Panicum tenerum
Paspalum monostachyum
Paspalum praecox %
Pinus elliottii
Proserpinaca pectinata
Rhexia mariana %
Rhexia nashii %
Rhynchospora filifolia
Rhynchospora rariflora %
Rhynchospora tracyi
Rhynchospora ,1 i ,i, ,
Scleria baldwinii
Scleria reticularis %
Serenoa repens
N, ii, ,11 aquatica
l\ ,i.-.',i,,ihii ,flavidulus
Utricularia purpurea
Viola lanceolata %
Woodwardia virginica
Xyris elliottii
Xyris jupicai
Xyris smalliana I


Observed p-
Ind. Val. value
27.1 0.004
29.3 0.007
8.6 0.097
8.6 0.100
47.7 <0.001
47.6 <0.001
30.5 0.009
8.6 0.097
22.9 0.002
14.3 0.019
29.3 0.005
8.6 0.098
12.2 0.089
30.4 0.024
30.9 0.002
14.3 0.019
19.9 0.059
12.2 0.094
8.6 0.099
38.4 0.002
17.8 0.025
27.1 0.005
16.0 0.073


Note: Taxa marked () were not significant indicator species at the regional level.
Calculated indicator values and the significance of the indicator value for each species
are also presented.

Eupatorium capillifolium, and North Region: Polygonum hydropiperoides), all of which
have a statewide distribution (Tobe et al. 1998), were not calculated to be peninsular-
wide indicator species. Nine regional reference indicator species (South Region:
Blechnum serrulatum, Cassytha filiformis, Cladium jamaicense, Eupatorium
leptophyllum, and Ipomea sagittata, Central Region: Hedyotis uniflora, Lyonia
lucida,Panicum spretum, and Rhyncosporafascicularis), all of which have statewide
distributions (with the exception of Cassythafiliformis, which is limited to south and
central Florida Wunderlin 1998, Tobe et al. 1998), were not significant indicator
species using the peninsular dataset. However, 88.5% (23 of 26) of the regional impaired
indicator species and 76.9% (30 of 39) of the regional reference indicator species were
also indicator species with the peninsular dataset. The additional power from combining
the regional data into a peninsular dataset also allowed for an additional 17 species to be
identified as indicator species of reference (7 species) or impaired (10 species) conditions
(noted in Tables 3-13 and 3-14).










Table 3-14. Indicator species of impaired conditions derived from


Impaired Indicator
Species
(Tolerant Species)
Alternanthera philoxeroides
Aster subulatus %
Bacopa monnieri
Carex albolutescens %
Centella asiatica
Commelina dimttU.at
Cuphea c,, ihol.. oi,. o i %a
Cynodon dactylon %
Cyperus haspan
Cyperus odoratus
Cyperus polystachyos
Cyperus retrorsus %
Cyperus surinamensis
Diodia virginiana
Eclipta prostrata
Galium uniflorum %
Hydrochloa caroliniensis
Juncus effusus


Observed p-
Ind. Val. value
20.0 0.007
27.4 0.002
21.7 0.086
12.5 0.059
43.4 0.032
39.8 <0.001
37.3 <0.001
12.5 0.057
24.0 0.052
20.0 0.006
45.0 <0.001
12.5 0.055
20.0 0.006
53.8 <0.001
30.0 <0.001
12.5 0.060
24.0 0.050
52.3 <0.001


Impaired Indicator
Species
(Tolerant Species)
Kyllinga brevifolia %
Lindernia griandillora
Ludwigia octovalvis
Ludwigia peruviana
Ludwigia repens %
Melochia corchorifolia %
Panicum repens
Paspalum acuminatum %
Paspalum notatum
Paspalum urvillei
Phyla nodiflora
Polygonum punctatum
Pontederia cordata
Sacciolepis striata %
Sesbania herbacea %
Setaria parviflora
Thelypteris interrupta %
Tvpha latifolia i


Note: Taxa marked (f) were not significant indicator species at the regional level.
Calculated indicator values and the significance of the indicator value for each species
are also presented.

Using the peninsular indicator species (n=82 species), the abundance of indicator
species for both reference (% Sensitive) and impaired (% Tolerant) conditions was
calculated for each site and correlated with the LDI. A plot of the relationship between
LDI score and % Sensitive and % Tolerant species are presented in Figures 3-5 and 3-6,
respectively. The Spearman's correlation coefficients were significantly and highly
correlated with the LDI (% Sensitive r = -0.76, p<0.001; % Tolerant r = 0.75, p<0.001).
The abundance of sensitive taxa plotted in Figure 3-5 suggested a relatively accurate and
precise distribution, with fair goodness of fit. There was substantial variation in the data
for sites with LDI scores of approximately 1.0, but a noticeable and linear decreasing
trend with increasing LDI values was evident. Distribution of the % Tolerant data
indicated a low correlation between the LDI and the % Tolerant until LDI scores of
approximately 3.5. At that point, substantial variation in the dataset was evident, with
abundance values ranging from approximately 10% to 75%.
The peninsular dataset was utilized to identify the proposed bioassessment
metrics. The apparent advantage of utilizing the peninsular dataset lay in the higher
number of significant indicator species identified for community condition assessment
and the strength and significance of the correlations with the LDI. The combined dataset
provided 48 additional indicator species in the South region, 37 additional indicators in
the Central region, and 74 additional significant indicators in the North region. However,
as the number of reference and impaired sites sampled was not equal for the regions
(South reference = 11, Central reference = 13, North reference = 11; South impaired =


Observed
Ind. Val.
12.5
20.0
24.9
35.0
33.4
12.5
32.4
20.0
30.0
24.9
37.3
38.3
43.4
26.7
15.0
25.0
12.5
12.5


p-
value
0.058
0.007
0.005
<0.001
0.014
0.058
0.006
0.015
0.004
0.003
<0.001
<0.001
0.057
0.080
0.029
<0.001
0.058
0.056


the peninsular dataset.
















70 -


60 -


50 -


40 -


30


20


10 -

0-


LDI

Figure 3-5. Abundance of sensitive species along the disturbance gradient.


80 -

70

60 -

50 -

40 -

30 -

20 -

10 -

0 -


LDI


Figure 3-6. Abundance of tolerant species along the disturbance gradient.


00
0

0
* 00 0
000 0
*0

2
00 .0
0
0
0 0
0 0
0
0
0
0 0 0 .i~7. 0 0 0
0
CI: .0 0
0
no o 0


**

.*
0*
0
.


:
***
0 0
0*
0 0*

0

) ,*** **
$4* *:. *\
0 *
* *.0*10


* *

*










12, Central impaired = 17, North reference = 11), Kruskal-Wallis tests were employed to
ensure that the median abundance of sensitive and impaired indicators were equal for
each region. The Kruskal-Wallis test null hypothesis was equal medians for all groups.
Unequal medians would indicate a regional bias in the distribution of indicator species
and likely predispose a reference or impaired site in a particular region to lower
assessment values vis-a-vis reference or impaired sites in the other regions. No
significant difference in median values between regions for either % Sensitive or %
Tolerant species were identified using the Kruskal-Wallis test (% Sensitive H=0.076,
p=0.963, % Tolerant H=1.598, p=0.450). Thus, the abundance of sensitive and tolerant
species identified using ISA and the peninsular dataset were selected as metrics.


Table 3-15. Exotic taxa encountered and regions) of occurrence.


Exotic Species
Aeschynomene indica
Alternanthera philoxeroides
Alternanthera sessilis
Alternanthera tenella
Amaranthus blitum
Amaranthus spinosus
Caperonia palustris
Chenopodium ambrosioides
Cuphea carthagenensis
Cynodon dactylon
Cyperus lanceolatus
Desmodium triflorum
Digitaria bicornis
Echinochloa colona
Echinochloa crusgalli
Eichhornia crassipes
Eleusine indica
Eragrostis atrovirens
Fimbristylis miliacea
Gomphrena serrata
Hedyotis corymbosa
Hymenachne amplexicaulis
Ipomoea quamoclit
Kyllinga brevifolia
Ludwigia peruviana
Lygodium microphyllum


S C
*


*0


*
*




*
* *
*
*
*
* *


N Exotic Species
Macroptilium 1,ath)i ,i, A,
* Melaleuca quinquenervia
Melochia corchorifolia
Mollugo verticillata
* Murdannia keisak
* Murdannia nudiflora
Panicum maximum
* Panicum repens
* Paspalum acuminatum
* Paspalum notatum
Paspalum urvillei
Phyllanthus urinaria
Polygonum lapathifolium
* Portulaca amilis
* Richardia scabra
* Sacciolepis indica
* Salvinia minima
Schinus terebinthifolius
Scleria vaginata
Senna occidentalis
Solanum viarum
Sporobolus indicus
* Urena lobata
* Verbena bonariensis
* Xyrisjupicai


S C N
*


* *
*
*
*
*
* *
*
* *
* *
*


*
* *


Percent exotic

Fifty-one exotic species were identified throughout peninsular Florida (Table 3-
15). Exotics, which included pasture grasses planted for forage, were significantly more
abundant in impaired conditions than in reference conditions (peninsular dataset, Mann-
Whitney U-test Z= -5.379, p<0.001). Median values between regions did not differ







70


(Kruskal-Wallis H = 0.740, p=0.691), nor were significant differences identified when
the abundance of exotic species was compared between regions for both impaired sites
(Kruskal-Wallis H=0.247, p=0.884) and reference sites (Kruskal-Wallis H=0.998,
p=0.607). The abundance of exotic species was significantly correlated with the LDI in
each region (Spearman's r: South = 0.71, p=<0.001; Central = 0.54, p=0.002; North=
0.74, p<0.001). The Spearman correlation coefficient was also calculated for the
abundance of exotic species and the LDI using the peninsular data set (Spearman's r =
0.67, p<0.001, Figure 3-7).
The abundance of exotic taxa appeared to not be strongly correlated with
increases in LDI value until a threshold of approximately 3.5 was reached. Many sites
before LDI values of approximately 3.5 appeared to have "background" values for exotic
taxa of less than 10%, suggesting a nearly universal distribution of exotic taxa throughout
Florida. Near LDI values of 3.5, however, marked increases in the abundance of exotic
taxa suggested a threshold value had been crossed, although substantial variation in the
dataset remained.


50


40 -


30 -


20-


10 -


0 -


0
0

0


0-* *0
0 *


0
0


LDI


Figure 3-7. Abundance of exotic taxa at each site along the disturbance gradient.


Annual to perennial ratio

The median annual to perennial ratio was significantly higher in impaired
conditions versus reference conditions for the peninsular dataset (Mann-Whitney U-test Z
= -5.122, p<0.001). The correlation between the A:P ratio and the LDI was significant


0
0
0%

Ix
0
0
0


0
* 0O







71


when the peninsular dataset was examined (Spearman's r = 0.65, p< 0.001, Figure 3-8).
Spearman's correlation coefficient between the A:P ratio and the LDI was also significant
for each region: South r = 0.60, p=0.002; Central r = 0.69, p<0.001; North r = 0.65,
p=0.001. The median value for the A:P ratio did not differ between regions (Kruskal-
Wallis H = 0.938, p=0.626), nor did median values differ between regions for reference
conditions (Kruskal-Wallis H = 2.130, p=0.344) or impaired conditions (Kruskal-Wallis
H = 0.114, p=0.945).
Variance in the A:P ratio dataset, as well as sensitivity and accuracy appeared to
be minimal until a threshold value of approximately 3.2 was passed. At that point, the
ratio increased, as did the variance in the data.


0.7

0.6 -

0.5 -

0.4

0.3 -

0.2 -

0.1 -

0.0 -


LDI


Figure 3-8. Annual to perennial ratio at each site along the disturbance gradient.

Average Coefficient of Conservatism

Significant differences in the median CC value between reference and impaired
conditions using the peninsular dataset were identified (Mann-Whitney U-test Z = 6.510,
p< 0.001). A significant correlation was calculated between the peninsular dataset
average CC and the LDI score (Spearman's r = -0.78, p< 0.001, Figure 3-9). Median
values between regions were not significantly different (Kruskal-Wallis H = 0.501, p=
0.778). Kruskal-Wallis tests also indicated that the median average CC value did not
differ between regions for reference sites (H = 0.501, p= 0.778) or impaired sites (H=
0.140, p= 0.932). Significant (Spearman's r) correlations between the LDI and the
average CC were identified for each region (South r = -0.74, p< 0.001; Central r = -0.75,
p< 0. 001, North r = -0.76, p< 0.001). The average CC appeared to be sensitive to
increases in LDI value once a threshold of approximately 3.0 was passed. Marked


*
*




0 *

*
0* *
* 0 0** *
* t 0
OO *
?I







72


increases in variance within the dataset followed, although in general a trend of
decreasing average CC values continued.


7-


6-


5-


4-


3-


2-


***
0* *


*\ .* *
0 0 .
a..
*..
.* *
*

1
*
0
*
*

I I I 4 5
1 2 3 4 5 6


LDI


Figure 3-9. Average Coefficient of Conservatism value for each site along the
disturbance gradient.

Vegetative Index of Wetland Condition

The Vegetative Index of Wetland Condition (VIWC) was calculated for each site
by scoring the 95th percentile of each metric based on the peninsula dataset (n=75). The
peninsular dataset was utilized as no significant regional effects were found in the
distribution of the five metrics between reference and impaired conditions, as previously
described. The 95th percentile and the scoring breaks for each metric are given in Table 3-
16, and the scores for each site and metric are given in Table 3-17. The scored metrics
were summed to calculate the VIWC. The relationship between the LDI and the VIWC
for each site is presented in Figure 3-10. The VIWC ranged from 0 (the lowest score

Table 3-16. Quadrisect values and 95th percentile for metric scoring.
95th 0 3 7 10
Metric
Percentile Scores Scores Scores Scores
% Sensitive Spp. 0.5834 < 0.0820 0.0820 0.2308 > 0.2308 0.4474 > 0.4474
% Tolerant Spp. 0.6321 > 0.3723 > 0.1081 0.3723 0.0597 0.1081 < 0.0597
% Exotic Taxa 0.2742 > 0.1198 > 0.0385 0.1198 0.0001 0.0385 0
A:P Ratio 0.3105 > 0.1231 > 0.0625 0.1231 0.0352 0.0625 < 0.0352
Average CC 6.352 < 3.7015 3.7015 5.4085 > 5.4085 5.8874 > 5.8874











Table 3-17. Site scores for each metric and the summed VIWC.
% Exotic Average
Site % Sensitive % Tolerant Spp. CC A:P Ratio VIWC
ALPaynes 7 7 10 10 7 41
Audobon 3 0 0 0 0 3
Bear Scat 3 7 10 10 10 40
Big Cow 0 3 3 3 0 9
BRSebastian 10 10 3 10 7 40
CabPatch 3 3 3 3 7 19
Caravelle 3 3 3 3 7 19
Chuluota 7 10 7 10 7 41
CLBayard 7 10 10 7 10 44
CLCove 0 0 0 0 0 0
CMMPas 7 7 10 10 10 44
CMWRef 7 3 10 10 10 40
COBurgle 0 0 0 3 0 3
COHole 3 7 10 3 7 30
Crew 10 7 7 10 3 37
DEMelon 3 0 0 0 0 3
Deerfly 7 10 7 7 3 34
Garber 3 0 3 3 10 19
GbarE 0 0 0 3 0 3
GLDonut 0 3 0 0 3 6
GLPont 0 0 0 0 0 0
Goethe 10 7 10 7 7 41
GreenSwamp 10 10 10 7 10 47
HaRare 0 0 0 0 0 0
Haguel 0 3 0 0 0 3
Haguell 0 0 0 0 0 0
HalfMoon 7 7 10 10 10 44
HEBad 0 0 0 0 0 0
HEL2 0 0 0 0 0 0
HEOKAY 7 3 3 7 3 23
HighRef 7 7 10 7 7 38
HighPast 0 0 0 0 3 3
HillsRef 10 7 10 7 10 44
Hunt Camp 10 10 10 7 7 44
IFAS I 3 3 7 10 10 33
IFAS II 7 10 7 10 7 41
Immokalee 10 7 10 7 7 41
IRBlueCypress 3 0 3 3 3 12
IRCanal 0 0 0 0 0 0
IROJ 0 0 0 3 0 3
JD6 10 10 7 10 10 47







74


Table 3-17. Continued.

% Exotic Average
Site % Sensitive % Tolerant Spp. CC A:P Ratio VIWC
Kelly Park 3 3 10 3 0 19
Lcork 7 7 7 7 3 31
LLeeCounty 7 7 3 3 3 23
LEGo 7 3 10 7 10 37
LESuwan 3 3 10 7 7 30
MALudy 3 0 0 0 0 3
MASpray 7 3 10 3 7 30
McArthur 3 0 3 0 0 6
MNElmer 3 3 7 3 3 19
MNErik 7 7 3 3 3 23
MNOcala 7 7 10 7 10 41
MRPepr 3 3 0 3 3 12
Myakka 10 3 10 10 7 40
OKCara 3 0 0 3 0 6
OKKiss 10 7 10 10 7 44
OKPast 3 0 3 3 3 12
PacTom 0 0 0 0 3 3
Pall-Mar 10 10 10 10 10 50
PBCorbett 10 7 7 10 3 37
PBEnjay 10 10 7 10 3 40
Penner 10 10 10 10 10 50
POWales 10 10 3 10 7 40
POWeowak 10 10 10 10 7 47
PUPond 10 10 3 10 3 36
RiceCreek 10 7 3 7 3 30
SANorthMya 10 10 3 7 10 40
SAOscer 7 7 3 7 7 31
SandhillCrane 3 3 3 3 0 12
Savannas 10 10 7 10 10 47
STCow 0 0 0 0 0 0
SUVaca 7 10 10 7 10 44
SUWarhol 0 3 0 0 0 3
UNHealthy 0 0 0 0 0 0
Wekiva 10 10 10 10 10 50

possible) to 50 (the highest possible score), with 9 sites scoring 0 and 3 scoring 50. The
nine low-scoring sites were all located in cattle pastures with high densities (C. Lane,
personal observation) in the South (3 sites), Central (3 sites), and North (3 sites) regions.
The three high-scoring sites were also evenly distributed with one in each region: South
(on conservation lands owned by the South Florida Water Management District), Central
(in a state park), and North (in a national forest). The VIWC was significantly correlated
to the LDI score (Spearman's r = -0.75, p< 0.001) and was significantly different
between reference and impaired classes (Mann-Whitney U-test Z = 6.496, p< 0.001). No
difference between regions was found for the summed VIWC (Kruskal-Wallis H = 0.865,










p= 0.649), nor between regions and impaired sites (Kruskal-Wallis H = 0.438, p= 0.804)
or between regions and reference sites (Kruskal-Wallis H = 4.534, p= 0.104).
As in the metrics that comprised the VIWC, variance within the dataset appeared
to be manifested most strongly at approximate LDI values of 3.5. In addition, higher
variance than was expected was also evident at LDI values of approximately 1.0, based
on the distribution of the metric values that comprised the VIWC.


50 -


40 -


30 -


20 -


10 -


0 -


LDI


Figure 3-10. The relationship between the VIWC and the LDI.


Discussion

Correlations between metrics and LDI scores suggested landscape modification
affected that the composition and structure of the wetland flora, although the variance in
the dataset was substantial, especially for LDI values near 3.5. Five metrics were
correlated >10.501 with the LDI: abundance of sensitive and tolerant taxa, abundance of
exotic taxa, annual to perennial ratio, and average coefficient of conservatism score. The
VIWC, which combines the macrophyte metrics into a single value, defined the condition
of each wetland such that the lowest scoring wetlands tended to have the highest
landscape development intensity scores, while the wetlands with the highest VIWC
scores were in areas with lower LDI values.

Environmental Gradients and Species Distributions

Macrophytes respond strongly to anthropogenic modifications of wetland
ecosystems and surrounding landscapes (Doherty et al. 2000, Adamus et al. 2001),
including alterations in community composition due to hydrology (van der Valk 1981,
David 1996), nutrient loading (Koch and Reddy 1992, Doren et al. 1997, Bedford et al.
1999), physical/chemical alteration (Latham et al. 1994, Adamus et al. 2001),


* *


hme


03 C
** B
see *
8**** *4 *





C SO


su a *
eS
*









sedimentation (Waldrop and Brooks 1998), and other factors such as selective herbivory
(Reader and Craft 1999), trampling (Blanch and Brock 1994), or modification of fire
regime (Bayley and Odum 1976, Winchester et al. 1985, Newman et al. 1998). The
wetlands sampled in this study were subjected to a myriad of anthropogenic
modifications, with the strongest gradient being of increased agricultural land use
intensity and associated nutrient loading and chemical modification, along with
hydrologic alterations and herbivory/trampling. These vectors of disturbance were
manifested by significant differences between the constituents measured (Table 3-8).
Five measured constituents or calculated values were of particular importance in driving
community structure based on the relationship (Pearson's r2> 0.30) between the NMDS
ordination scores and the LDI, site soil pH, water TP, specific conductivity, and latitude
(Table 3-9).
Macrophyte composition was most strongly correlated with the LDI score, which
is an agglomerative disturbance index capturing landscape modification due to altered
hydrology, nutrient loading, and predicted agrochemical application and other
disturbances associated with various land uses (Brown and Vivas submitted). As the LDI
captures many disturbance vectors, the strength of the relationship between macrophyte
distribution and LDI score was not surprising. The ordination results buttress the use of
GIS-based independent measures of general impairment, such as the LDI, in identifying
modifications to landscapes and predicting wetland community condition (Johnson 1994,
Adamus and Bergman 1995, Roth et al. 1996, Miller et al. 1997, Cuffney et al. 2000, 106
Carpenter and Waite 2000, O'Conner et al. 2000, Munn et al. 2002, Fore and Grafe 2002,
Fore 2003). The strength of the relationship between site ordination structure and the LDI
also supported the metrics developed with the LDI as the abscissa, or measured
disturbance gradient.
The ordination scores were also correlated with soil pH, specific conductivity, and
water TP. Wetlands are generally low-lying landscape features, which predisposes these
ecosystems to down-slope accumulations of nutrients from cattle grazing (Reddy et al.
1998) and crop and citrus agrochemical application and drift (Euliss and Mushet 1999,
Anderson and Vondracek 1999). In a south-central Florida study by Graetz and Nair
(1995), nutrient augmentation through fertilizers and cattle wastes in pastureland soils
augmented background levels, such that approximately 40% of the phosphorous became
bioavailable (labile), whereas only 2% was bioavailable in native areas. These massive
loading rates may allow nutrients to be moved directly or indirectly into wetland systems
from overland or interstitial flow, and can be manifested by drastic alterations in wetland
community composition (Craft et al. 1995, Newman et al. 1998, Mitsch and Gosselink
2000). Beyond altering species composition in wetland systems directly down-slope of
anthropogenic land uses, sufficient nutrient loading of wetland systems can occur such
that wetlands, rather than being nutrient sinks (Flaig and Reddy 1995), may end up as
nutrient sources for water bodies farther down-slope including wetlands, streams, and
lakes (Agami et al. 1990). Alterations in soil pH, specific conductivity, and available
nutrients, among other changes, may be indicative of wetland loading from agrochemical
fertilizers and cattle wastes (Fore and Grafe 2002, U.S. EPA 2002e).
In addition to the LDI and physical/chemical determinants of community
composition from the NMDS ordination, a latitudinal gradient affecting species
composition was also correlated with ordination scores. The Florida peninsula, which juts









into the Gulf of Mexico and Atlantic Ocean, is tempered from climatic extremes by the
heat absorbing/desorbing nature of water. This protects many species that have evolved
in south Florida's sub-tropical environment. Northern Florida, however, is somewhat
exposed to the temperate climate of mainland North America, with many freezing days
and different precipitation patterns than southern Florida (Fernald and Purdum 1998). As
suggested by significant compositional differences (Table 3-7) between wetland
macrophytes of northern, central, and southern Florida, different species have
autecological requirements associated with latitudinal changes.

Metric Development

The results suggested that while macrophytes responded to increased
development intensity, as measured by increased LDI values, substantial variance was
evidenced by the five metrics that comprised the VIWC. In addition, the metrics appeared
to be marginally sensitive to changes in LDI values until an LDI score of approximately
3.5 was reached. Throughout peninsular Florida, the metrics appeared able to
approximate the condition of the sampled wetlands along increases in landscape
modification, however, the substantial variance within each of the metric values,
especially after LDI values of approximately 3.5, indicated that additional information
relating the plant metrics to the landscape metrics was required to more fully understand
the relationship between plant metrics and landscape development. The results of the
analysis for each of the final metrics are described below.

Sensitive and tolerant species

It is generally accepted that most organisms have autecological optima, or
environmental conditions most suited for the highest possible productivity and/or fitness
(Ricklefs 1990, Gaiser et al.1998, Stevenson et al. 1999, U.S. EPA 2002e). These
conditions can include adequate water, nutrients, photoperiod, and temperature. A
hypothetical gradient (Figure 3-11) is thus likely to exist for each species. As optima
exist, there are likewise extremes where conditions are unfavorable for growth, let alone
survival, for species not adapted to the environment. Environmental extremes can include
altered salinity, pH, hydropatterns, nutrients, physical disturbances, chemical
disturbances, anoxia, or photoperiod. In this study, the environmental conditions
generally found at reference sites were significantly different in many physical/chemical
constituents than those found in impaired sites (Table 3-8). A review of the literature
suggests that other constituents of the soil and water, such as metals or
pesticides/herbicides, likely differ between reference and impaired conditions (Purvis et
al. 1991, Euliss and Mushet 1999, Mitsch and Gosselink 2000). Likewise, though not
quantified, pressures associated with browsing and selective grazing were likely
significantly different in reference than in impaired conditions. The abiotic and biotic
factors listed above could be considered to define the range of environmental conditions
acceptable for the plants identified in this study. The LDI was utilized in Indicator
Species Analysis as an analog for the acceptable environmental conditions of various
species. Species with significant fidelity and specificity to low LDI scores were thus
considered to have optima within the range of environmental conditions often found in











maximum response






0)


Q.
C
0
C.
on



Environmental
Soptima


Hypothetical environmental gradient
Figure 3-11. Environmental optima along a hypothetical environmental gradient.

reference sites. Those species indicative of higher LDI values were conversely considered
to have optima within the range of conditions expressed by impaired sites. It is beyond
the scope of this research to explore the autecologies of the sensitive and tolerant plants
listed in Tables 3-13 and 3-14 further, but the significance of the relationship suggests
proclivities towards particular environmental conditions for those indicator macrophytes.
In this study, Indicator Species Analysis was able to discern 82 plants with
fidelity and specificity to a particular landscape development condition throughout
peninsular Florida. The abundance of these sensitive and tolerant plants was correlated
with the LDI (Spearman's r >10.701), and not significantly affected by regional vagaries in
species composition. However, the highly variable relationship between the abundance of
sensitive and tolerant plants and the LDI indicated limitations to conclusions drawn. The
abundance of sensitive plants demonstrated high variance throughout the plot along the
LDI, although lower values appeared near LDI scores of approximately 3.5. Tolerant
plants, which expressed a minimal relationship with the LDI until a threshold of
approximately 3.5 was reach, were also highly variable, although not as sensitive to
changes in LDI values for the low scores.

Percent exotic

Increased development has the potential of promoting the spread of exotic species
into wetlands where they can alter community composition, patterns, processes, and even
functioning (Leibowitz and Brown 1990, Hobbs and Huenneke 1992, Cronk and
Fennessy 2001). Disturbance within the wetland itself from activities such as cattle
grazing provides a pathway for exotic propagules through cattle feces or by seeds









adhering to the coats of domestic herbivores. The heavy machinery used in typical
cropping or citrus operations can also provide a pathway for propagules. The trampling
associated with cattle grazing can provide patches of bare ground for colonization of
exotic species. Drift of herbicides into wetlands from agricultural practices can alter the
composition or fitness of wetland flora and create patches of bare ground, which can
subsequently be colonized by exotic species. Drainage of landscapes for development can
provide direct conduits to wetlands for exotic species, if those drainages directly link to
the wetland (Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). Altering the natural
sheet flow pattern through landscape level drainages can also affect the species
composition of wetlands by providing drier conditions conducive to colonization by
exotic annual species (David 1999). Increased development that affects the landscape
surrounding the wetland may also cause a potential increase in exotic propagules entering
the wetland system through the increase in the proportion of the perimeter of the wetland
that is subjected to seed sources of exotic species.
The results, however, suggested that the abundance of exotic taxa was marginally
sensitive to increases in land development intensity until a threshold had been crossed,
approximately 3.2. Once that threshold had been passed, substantial variance was
manifested in the dataset, which suggested additional processes not captured by the LDI
were affecting the distribution of exotic taxa throughout peninsular Florida. These
processes may be further understood through the collection of additional data (i.e.,
requesting planting history from land owners) or through additional observations (i.e., the
distance from the nearest road to the wetland, or the existence of perches within the site;
both would potentially increase the abundance of propagules).
Several species found in the wetlands sampled are on the Florida Exotic Pest
Plant Council's list of "Category I" exotics (Eichornia crassipes, Hymenachne
amplexicaulis, Lygodium microphyllum, Melaleuca quinquenervia, Panicum repens,
Schinus terebinthifolius, and Solanum viarum). Category I exotic species are those
considered to alter native plant communities by directly displacing native species,
changing the structures or ecological functions within a community, or hybridizing with
native species (FLEPPC 2003). Two plants identified were FLEPPC Category II exotic
species (Alternantheraphiloxeroides and Urena lobata). These plants are increasing in
abundance throughout Florida but have not yet affected the natural areas, as have
Category I exotics (FLEPPC 2003). It is interesting that not all of the exotic species
found appear to possess such damning traits. Richard's yellow-eyed grass, Xyrisjupicai,
native to French Guiana (Wunderlin and Hansen 2000), is one such species. This species
was found frequently enough in reference conditions to be considered a sensitive
indicator species.

Annual to perennial ratio

As hydrologic conditions in wetlands are dynamic, many wetland plants have
evolved life-history traits to maintain themselves during periods of endogenous
environmental perturbations. In an adaptation that enables wetland plants to combine
reproductive structures with storage devices, most wetland plants are vegetatively
reproducing perennials (Galatowitsch et al. 1999b, Cronk and Fennessy 2001). Perennial
plants, by dint of their storage/reproductive structures such as rhizomes, tubers, and
corms, are thus better able to pass through the Gleasonian sieve that regulates the









presence and abundance of species within the confines of the wetland system (van der
Valk 1981). However, exogenous perturbations that disrupt natural processes, such as
hydroperiod alterations, nutrient loading, and trampling, may provide opportunities for
the generally faster-growing annual species to out-compete perennial species for
nutrients, water, and light. Annual species (often considered "weedy" species) increase in
wetlands undergoing anthropogenic perturbations, while perennial species decline
(Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). The results of the annual to
perennial ratio metric generally support the conclusions from the literature, as the ratio of
annuals to perennials increases with increasing development.
However, at low levels of measured disturbance (LDI scores), the results
suggested that the A:P ratio was marginally sensitive to change. Only once an LDI
threshold of approximately 3.2 was passed were changes evident in A:P ratio. This
suggests that wetland processes maintain A:P ratios until development intensity increases
sufficiently to alter those processes, for instance through decreased hydroperiod as a
result of ditching and draining associated with higher LDI values.

Average Coefficient of Conservatism

Since its inception by Wilhelm and Ladd (1988) as a method to measure the
"quality" of the vegetation in the Chicago area, the Floristic Quality Assessment Index
(FQAI, originally called the Natural Area Index), and the associated Coefficient of
Conservatism have found widespread use in a variety of different ecosystems (Southern
Ontario Woodlands: Francis et al. 2000; Illinois uplands, flatwoods, and prairies: Taft et
al. 1997; North Dakota wetlands: Mushet et al. 2002). Many authors have utilized the
FQAI, calculated as the average CC value for the site multiplied by the square root of the
total number of species at a site. This inherently rewards systems richer in species and
assumes that such a system is more ecologically desirable (Fennessy et al. 1998, Cohen et
al. submitted). Like Francis et al. (2000), in this study the average CC score was utilized
as a metric. This decreased the influence of species richness on the site score and more
accurately reflected the ecological data collected as the average species richness for sites
with an LDI score of less than 2.0 (31.70 +/- 10.80) was not significantly different
(Mann-Whitney U-test Z = -0.005, p= 0.990) than those sites scoring greater than 2.0
(31.68 +/- 9.51). The lack of richer systems in reference wetlands may be a function of
the strong hydrological driving forces maintained on the minimally developed landscape.
Whereas developed landscapes often drain the wetland area, which can allow species into
the wetland proper that would otherwise be excluded due to anoxic soil conditions, the
wetlands located in reference landscapes generally have zones where species tolerant of
different hydroperiods and anoxia can thrive. Thus the richness found in developed sites
may be an artifact of the drainage associated with development.
Landscape drainage may have also affected the highly variable distribution of CC
values associated with LDI scores of approximately 3.5. As noted, drainage increases the
area available for colonization by upland and facultative plants due to decreases in soil
anoxia. However, the slope and additional site-specific factors (e.g., the presence of
perches, as discussed in the % Exotic metric) may have decreased the opportunity for
plants with low CC scores to colonize wetland zones.









Vegetative Index of Wetland Condition

The VIWC, developed for isolated depressional herbaceous wetlands in
peninsular Florida, combined five biological measurements into a single score to
ascertain the relative condition of a sampled wetland vis-a-vis a suite of reference
wetlands located in low development landscapes (Karr and Chu 1999). While
significantly correlated with the disturbance gradient, the VIWC appeared to be highly
variable for any given LDI score, especially scores located near LDI values of 1.0 and
3.5. The high variance in each of the metrics, as well as in the final correlation between
the LDI and VIWC may have been in locations with a time delay between impairment
activity and the manifestation of that impairment in the wetland macrophyte community
(i.e., a field, long held fallow, that is now in crop rotation). Conversely, LDI scores,
based on landscape values, may not have accurately quantified the condition of a site that
was in rotation or grazed that was sampled months or years after such deleterious
activities had ceased. While ground-verification occurred, in some cases accurate land
use maps or site histories could not be obtained, and best scientific judgment was
employed in spatial off-site GIS analysis. While a few outliers appeared to exist in the
relationship between the LDI and VIWC, the focus of this analysis was on the utility of
macrophytes as indicators of wetland condition. An assumption inherent in this study, as
in most analyses utilizing bioindicators, was that should environmental conditions be
such that the macrophytic community was characteristic of sites in reference conditions,
then the integrity (c.f. PL 92-500, Clean Water Act, 101 (a)) of the site was not suspect.
On the other hand, sites with vegetation characteristic of impaired conditions were
assumed to be under various degrees of human modification of deterministic, driving
variables. In this manner, the VIWC, which directly compares wetland vegetation, may
be best employed as an accurate assessment tool for isolated depressional herbaceous
wetlands in Florida.

Field Data Collection

Florida was in the midst of a significant drought during the study period
(Lawrimore et al. 2001), which was manifested by decreased hydroperiod, extent, and
depth of inundation in many of the sampled wetlands. Many wetlands identified as
potential sites were not sampled during the study period due to the lack of standing water
- originally a prerequisite for inclusion that was slackened as the sampling season waned
in 2000. Five of the ephemeral wetlands sampled in this study (all in the North region)
were not hydrated during the sampling window, and may not have been hydrated to the
point of standing water at any point during the study period. In addition, the hydroperiod
may have been significantly decreased in many, if not all, of the wetlands sampled. This
may have affected the species composition in both reference and impaired wetlands for
instance through the increased abundance of weedy annuals such as Eupatorium
capillifolium. The effect of the drought on the macrophytes identified would likely have
been most pronounced on the wetland fringe, as macrophytes typically found in more
upland conditions may have colonized the non-hydrated wetland fringe and out-competed
typical (i.e., obligate or facultative) wetland plants. As the drought was endogenous in
nature and pervasive throughout Florida, the effects were likely evenly distributed in both
impaired and reference sites. It was noted, however, that sites in impaired landscapes









often expressed modified hydrological functioning due to drainage ditches (C. Lane,
personal observation) that may have caused a greater response to the effects of the
drought.
As mentioned, the sampling protocol was modified between sampling years. The
slight changes in the sampling protocols between 1999 and 2000 were not expected to
have had a noticeable effect on the accurate characterization of the 2% of sampled
wetlands without 4 full transects from the wetland edge to the center. No wetland had all
4 transects halted before the center, and the additional information possibly gathered
from the extended transects after 15m2 had been sampled without a change in species
composition would likely be minimal.

Conclusions and Recommendations

This chapter of the study quantified the condition of sampled wetlands through an
assessment of the structure and composition of the wetland macrophyte community.
However, the VIWC, should be seen as a model that must be verified and calibrated to
decrease the variability between metric response and the LDI. A recommended
calibration for the proposed metrics and the VIWC that is currently underway (C. Lane,
unpublished results) includes re-sampling a number of study wetlands to ascertain yearly
fluctuations in species assemblages and the subsequent effect on the VIWC. To sample
study wetlands twice within a given year but during different seasons would provide the
opportunity to examine seasonal effects on the composition and structure of wetlands and
the corresponding alterations to the individual metrics and VIWC. Model verification
would also increase the value of the proposed VIWC. Florida, by nature of rainfall and
topography, is a state rich in wetland resources. Increasing the number of sampled
wetlands across all landscape types would increase the power, precision, and accuracy of
the individual metrics as well as the multi-metric VIWC. The addition of larger isolated
herbaceous wetland systems into the calibration and verification of the VIWC would also
permit the expression of the VIWC across wetlands of different scales.














CHAPTER 4
MACROINVERTEBRATES AS BIOINDICATORS

Introduction

Shallow, isolated depressional wetlands typically support a variety of aquatic,
semi-aquatic, and terrestrial invertebrates that are important components of wetland and
local terrestrial food webs (Kushlan 1990, Evans 1996, Sharitz and Batzer 1999, Evans et
al. 1999, Leslie et al. 1999). Because of the nature of depressional wetlands, invertebrates
associated with these ecosystems are regularly subjected to endogenous environmental
stresses such as anoxia, wide salinity fluxes, and hydroperiod fluctuations. Invertebrates
in depressional wetlands may be further stressed by exogenous (human-induced) factors
such as nutrient and organic loading, contaminant toxicity, acidification, salinization,
sedimentation, changes in vegetation cover, thermal alteration, dehydration, hydrologic
alterations, and habitat fragmentation (Adamus and Brandt 1990, Adamus 1996,
Danielson 1998, Doherty et al. 2000). Measured changes in invertebrate community
structure and function relative to these exogenic perturbations may be used to assess the
ecological condition of the depressional wetland ecosystem through development of a
multimetric index of biologic integrity (Adamus 1996, Danielson 1998, Galatowitsch et
al. 1999a, Karr and Chu 1999, Kashian and Burton 2000).
Multimetric indices utilizing macroinvertebrates have been used in biological
monitoring to determine the relative quality of lentic and lotic aquatic ecosystems
throughout the country (Hellawell 1986, Plafkin et al. 1989, Cairns and Pratt 1993,
Kerans and Karr 1994, Rosenberg and Resh 1996, Karr and Chu 1999). As of 1997,
forty-eight states, including Florida, have implemented or have begun developing
macroinvertebrate assessment methods for lakes or streams (Karr and Chu 1999). In
Florida, the Florida Department of Environmental Protection (FDEP) combined metrics
that measure diversity, composition, and functional feeding groups in the development of
the Stream Condition Index (SCI) for the evaluation of lotic systems (Barbour et al.
1996). Metrics were likewise identified by the FDEP to assess the biological integrity of
lakes in the state (Gerritsen and White 1997, Gerritsen et al. 2000). Macroinvertebrate
assemblages in Florida have also been utilized to develop a bio-monitoring program in
southern Florida canal systems (Snyder et al. 1998, in Doherty et al. 2000), for evaluating
the success of restoration projects (e.g., Merritt et al. 1999) constructed wetlands (e.g.,
Erwin et al. 1997, Crisman et al. 1997), and for assessing the impact of human-induced
disturbances on cypress domes and the Everglades (i.e., Brightman 1984, Leslie et al.
1999, Rader 1999).
Multimetric assessments of wetland condition using macroinvertebrates as
indicator organisms have been conducted in a growing number of states and agencies
(e.g., Yoder and Rankin 1995, Danielson 1998, Burton et al. 1999, Gernes and Helgen
1999, Ludden and Hauer 2000). Macroinvertebrates are well suited for the effective
measurement of the spatial and temporal impacts of human-induced disturbances (Table









Table 4-1. Advantages and disadvantages of using macroinvertebrates in wetland
bioassessment.
Advantages Disadvantages
Widely distributed in wetlands Some are extremely difficult to
Easily sampled and generally identify
abundant Many short-lived
Some organisms have known Identification is labor intensive
response to perturbations May be sparse in some wetlands
Many are sedentary within a or seasonally abundant
single wetland Hydrated wetlands generally
Important components of trophic required
webs Poor taxonomic knowledge of
Respond quickly to perturbations some groups
Some are long-lived Some taxa migrate from other
water bodies
Sources: Danielson (1998), Doherty et al. (2000), U.S. EPA (2002c)

4-1). Macroinvertebrates are typically abundant in wetlands, easily sampled, and
relatively easily identified (Rosenberg and Resh 1993). Additionally, there is ample
literature on various sampling methods (Cheal et al. 1993, Adamus 1996), taxonomic
keys (i.e., Merrit and Cummins 1996), and macroinvertebrate tolerance values for
pollutants in lotic environments (Hilsenhoff 1987, Lenat 1993, Barbour et al. 1996), as
well as a growing array of metrics that have responded to the effects of episodic or
constant human disturbances on aquatic systems (see Yoder and Rankin 1995, Barbour et
al. 1996, Gerritsen and White 1997, Galatowitsch et al. 1999a, Karr and Chu 1999,
Gernes and Helgen 1999, Kashian and Burton 2000, Ludden and Hauer 2000, Doherty et
al. 2000, U.S. EPA 2002c).
While the advantages of macroinvertebrates have dictated their use in biological
assessments throughout the country, disadvantages to using them in biological
assessments exist (see Table 4-1). Detailed taxonomic keys are necessary to identify most
organisms to genus or species levels, and often the keys do not address the diagnostic
features of larvae or instars. Sample processing time is large with macroinvertebrates
(e.g., sorting, subsampling, enumeration and identification) and some families (e.g.,
Chironomidae) require mounting specimens on slides for identification. Most wetland
macroinvertebrates emerge after the wetland has hydrated, thus requiring adequate
rainfall and/or standing water, which typically is seasonal in Florida. The time since the
wetland was hydrated will also affect the sampled community composition (e.g.,
predators typically emerge later than their prey). Additionally, many macroinvertebrate
responses to perturbations in the literature are from lotic or lentic systems as data on
macroinvertebrate responses to perturbations in wetland systems are sparse, but growing
(Danielson 1998, Adamus et al. 2001, U.S. EPA 2002c).
In this chapter, results of testing and evaluating community structural and
functional measurements for macroinvertebrates (insect and non-insect taxa) of isolated
herbaceous depressional wetlands in peninsular Florida are given. The goal was to
identify metrics, or measurable components of the wetland macroinvertebrate




Full Text

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The Wetland Condition Index (WCI): Biological Indicators of Wetland Condition for Isolated Depressional Herbaceous Wetlands in Florida Report Submitted to the Florida Department of E nvironmental Protection under Contract #WM-683 By Charles R. Lane with Mark T. Brown, Mike Murray-Hudson, and M. Benjamin Vivas H.T. Odum Center for Wetlands University of Florida Gainesville, FL 32611-6350 September 2003

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ACKNOWLEDGMENTS This research was supported under a research contract from the Florida Department of Environmental Protection (FDEP); M.T. Brown, principal investigator. We would like to acknowledge the support of FDEP staff, especially Russ Frydenborg, Ashley ONeal, Ellen McCarron, Liz Miller, Lori Wolfe, Joy Jackson, Johnny Richardson, and the FDEP Central Laboratory in Tallahassee. Additional acknowledgement is due to the research group of the H.T. Odum Center for Wetlands, especially Kelly Reiss, Matt Cohen, Jim Surdick, and Susan Carstenn. We also thank the members of the 1999 and 2000 field crew for their tireless and enthusiastic work, especially Mark Fowlkes, Mark Otto, and Michael Stevens. Steven Doherty was an integral part of the initial stages of this research, and his perseverance and hard work helped to ensure this research to fruition. This project and the preparation of this report were funded in part by a Section 319 Nonpoint Source Management grant from the U.S. Environmental Protection Agency through a contract with the Florida Department of Environmental Protection. ii

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TABLE OF CONTENTS Page ACKNOWLEDGMENTS..................................................................................................ii LIST OF TABLES............................................................................................................vii LIST OF FIGURES...........................................................................................................xi EXECUTIVE SUMMARY.............................................................................................xiii CHAPTER 1 INTRODUCTION AND OVERVIEW........................................................................1 Introduction...................................................................................................................1 GIS Measurements and Wetland Metrics..............................................................2 Regional Composition...........................................................................................4 Environmental Correlates and Assemblage Response..........................................4 Background...................................................................................................................4 Wetland Trends.............................................................................................................6 Effect of Land Use Change on Wetland Systems.........................................................7 Nutrient and Chemical Loading............................................................................9 Selective Herbivory and Trampling....................................................................10 Ancillary Impacts from Landscape Modification................................................10 Wetland Assemblages and Biological Assessment....................................................11 Project Overview........................................................................................................12 2 DIATOMS AS BIOINDICATORS............................................................................13 Introduction.................................................................................................................13 Methods......................................................................................................................14 Site Selection and Agricultural Development Gradient......................................14 Field Data Collection, Sample Preparation and Laboratory Procedures.............15 Diatoms........................................................................................................15 Soil and water physical-chemical sampling and analysis............................16 Data Analyses......................................................................................................16 Summary statistics........................................................................................16 Diatoms-compositional tests........................................................................17 Diatoms community composition and correlation with soil and water parameters...............................................................................................17 Metric Development............................................................................................18 iii

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Sensitive and tolerant taxa............................................................................19 Autecological metrics...................................................................................19 Constructing the Multimetric Index....................................................................20 Results.........................................................................................................................20 Wetland Diatom Composition.............................................................................20 Diatom Composition and Environmental Correlates..........................................26 Metric Development............................................................................................29 Regional composition...................................................................................29 Indicator species analyses............................................................................31 Autecological indices...................................................................................37 The Multimetric Index.........................................................................................42 Discussion...................................................................................................................44 Diatom Composition and Environmental Correlates..........................................44 Diatom Composition and Wetland Regions........................................................46 Metric Development............................................................................................46 Indicator species analysis.............................................................................46 Autecological indices...................................................................................47 The Diatom Multimetric IndexConclusion and Recommendations..................47 3 MACROPHYTES AS BIOINDICATORS................................................................49 Introduction.................................................................................................................49 Methods......................................................................................................................50 Site Selection and Disturbance Gradient.............................................................50 Field Data Collection...........................................................................................52 Database Development........................................................................................53 Species characteristics..................................................................................53 Coefficient of Conservatism.........................................................................54 Soil and Water Physical-Chemical Sampling and Analysis................................54 Data Analyses......................................................................................................55 Summary statistics........................................................................................55 Macrophytes-compositional analysis...........................................................55 Macrophyte composition and soil and water parameter correlates..............55 Metric Development............................................................................................55 Sensitive and tolerant species.......................................................................56 Exotic species...............................................................................................56 Annual to perennial ratio..............................................................................56 Average Coefficient of Conservatism..........................................................56 Vegetative Index of Wetland Condition..............................................................57 Results.........................................................................................................................57 Field Data............................................................................................................57 Ancillary Data.....................................................................................................57 Compositional Analysis.......................................................................................59 Community Composition and Environmental Gradients....................................60 Metric Development............................................................................................62 Sensitive and tolerant species.......................................................................62 Percent exotic...............................................................................................69 iv

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Annual to perennial ratio..............................................................................70 Average Coefficient of Conservatism..........................................................71 Vegetative Index of Wetland Condition..............................................................72 Discussion...................................................................................................................75 Environmental Gradients and Species Distributions...........................................75 Metric Development............................................................................................77 Sensitive and tolerant species.......................................................................77 Percent exotic...............................................................................................78 Annual to perennial ratio..............................................................................79 Average Coefficient of Conservatism..........................................................80 Vegetative Index of Wetland Condition..............................................................81 Field Data Collection...........................................................................................81 Conclusions and Recommendations....................................................................82 4 MACROINVERTEBRATES AS BIOINDICATORS...............................................83 Introduction.................................................................................................................83 Methods......................................................................................................................85 Site Selection and Agricultural Development Gradient......................................85 Macroinvertebrate Collection and Identification.................................................85 Water and Soil Physical-Chemical Sampling and Analysis................................86 Macroinvertebrate Composition and Environmental Correlates.........................86 Macroinvertebrate Compositional Analyses.......................................................86 Summary statistics........................................................................................86 Regional composition of macroinvertebrates...............................................86 Macroinvertebrate Metric Development......................................................87 Categorical metrics.......................................................................................87 Ancillary data...............................................................................................88 Sensitive and tolerant species.......................................................................88 Macroinvertebrate Index of Wetland Condition..................................................89 Results.........................................................................................................................89 Wetland Macroinvertebrate Composition...........................................................89 Community Composition and Environmental Gradients....................................92 Metric Development............................................................................................94 Sensitive and tolerant taxa............................................................................96 Percent predators..........................................................................................98 Percent Odonata...........................................................................................98 Percent Orthocladiinae.................................................................................99 Macroinvertebrate Index of Wetland Condition................................................100 Discussion.................................................................................................................101 Environmental Correlates and Macroinvertebrate Composition.......................101 Regional Data Analyses....................................................................................104 Final Metrics......................................................................................................104 Sensitive and tolerant genera......................................................................105 Categorical metricspredators....................................................................105 Categorical metricsOdonates....................................................................105 Categorical metricsOrthocladiinae...........................................................106 v

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Macroinvertebrate Index of Wetland Condition................................................107 Field Sampling and Macroinvertebrate Identification.......................................107 Field sampling............................................................................................107 Macroinvertebrate identification and enumeration...........................................108 Conclusions and Recommendations..................................................................109 5 SUMMARY AND SYNTHESIS.............................................................................111 Metric Summary.......................................................................................................111 Landscape Assessment and Index Development......................................................111 Environmental Variables Driving Wetland Composition Across Assemblages......113 Environmental Variables and Management Concerns.............................................114 Conclusions and Recommendations.........................................................................114 APPENDIX A Site Descriptions.......................................................................................................116 B Soil and Water Sampling Methods and Results.......................................................118 C Diatom Autecological Values...................................................................................121 D Coefficient of Conservatism.....................................................................................125 LIST OF REFERENCES.................................................................................................130 vi

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LIST OF TABLES Table page 1-1. Landscape Development Intensity Disturbance Coefficients......................................3 1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida landscape and concurrent increases in agricultural and urban land use.....................7 1-3. National Wetland Inventory categories and landscape abundance of freshwater wetlands in Florida.....................................................................................................8 2-1. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for benthic diatoms...................................................22 2-2. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for epiphytic diatoms................................................23 2-3. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for phytoplanktonic diatoms.....................................24 2-4. Summary statistics and diatom similarities using Tukeys HSD..............................25 2-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes within benthic, epiphytic, and phytoplanktonic diatom groups...........25 2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland condition...26 2-7. MRPP analyses of the compositional similarity between benthic, epiphytic, and phytoplanktonic diatoms..........................................................................................27 2-8. Comparison of the medians of water and soil variables between LDI classes with the Mann-Whitney U-test...............................................................................................27 2-9. Correlations of environmental variables and ordination scores for benthic diatoms.....................................................................................................................32 2-10. Correlations of environmental variables and ordination scores for epiphytic diatoms.....................................................................................................................32 2-11. Correlations of environmental variables and ordination scores for phytoplanktonic diatoms.....................................................................................................................33 vii

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2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of South, Central, and North wetland regions..............................................................33 2-13. Reference site diatom indicator taxa identified using Indicator Species Analysis for each wetland region..................................................................................................34 2-14. Impaired site diatom indicator taxa identified using Indicator Species Analysis for each wetland region..................................................................................................35 2-15. Statewide indicators of reference conditions as determined from Indicator Species Analysis....................................................................................................................36 2-16. Statewide indicators of impaired conditions as determined from Indicator Species Analysis....................................................................................................................37 2-17. Correlations of autecological abundance data and LDI score.................................39 2-18. Mann-Whitney U-test of autecological abundance values between impaired and reference conditions.................................................................................................39 2-19. Quadrisect values and the 95 th percentile data for each proposed biological indicator....................................................................................................................42 2-20. Diatom Index of Wetland Condition scores for sampled sites................................43 3-1. Advantages and disadvantages of using macrophytes as biological indicators of wetlands condition....................................................................................................50 3-2. Sampling dates for each region.................................................................................53 3-3. Ancillary data added to the database for each plant species......................................53 3-4. Scoring Criteria for the Coefficient of Conservatism................................................54 3-5. Summary statistics of richness (S), Simpsons diversity index (H) and Shannon diversity index (D) for macrophytes.......................................................................58 3-6. Co-occurrence matrices of macrophytes by region and impairment condition.........60 3-7. Simultaneous and iterative tests of community composition among regions...........60 3-8. MRPP comparison of the median values of water and soil variables between reference and impaired sites.....................................................................................61 3-9. Correlations of environmental variables and ordination scores................................62 3-10. Regionally derived species indicative of reference conditions...............................64 3-11. Regionally derived species indicative of impaired conditions................................65 viii

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3-12. Spearman correlations of the adundance of regional sensitive and tolerance macrophyte species with LDI scores for each site...................................................65 3-13. Indicator species of reference conditions derived from the peninsular dataset.......66 3-14. Indicator species of impaired conditions derived from the peninsular dataset........67 3-15. Exotic taxa encountered and region(s) of occurrence.............................................69 3-16. Quadrisect values and 95th percentile for metric scoring.......................................72 3-17. Site scores for each metric and the summed VIWC................................................73 4-1. Advantages and disadvantages of using macroinvertebrates in wetland bioassessment...........................................................................................................84 4-2. Compositional metrics, definition, and expected response.......................................87 4-3. Trophic metrics, definition, and expected response..................................................88 4-4 Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for macroinvertebrates..............................................90 4-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes and between regional datasets..............................................................91 4-6. MRPP analyses of the macroinvertebrate compositional similarity between South, Central, and North wetland regions..........................................................................91 4-7. MRPP analyses of the macroinvertebrate compositional similarity for reference sites between South, Central, and North wetland regions................................................92 4-8. MRPP analyses of the macroinvertebrate compositional similarity for impaired sites between South, Central, and North wetland regions................................................93 4-9. Comparison of the medians of water and soil variables between reference and impaired conditions with the Mann-Whitney U-test................................................93 4-10. Correlations of environmental variables and ordination scores for macroinvertebrates...................................................................................................94 4-11. Statewide indicators of reference conditions as determined from Indicator Species Analysis....................................................................................................................96 4-12. Statewide indicators of impaired conditions as determined from Indicator Species Analysis....................................................................................................................97 4-13. Quadrisect values and the 95 th percentile data for each proposed biological indicator..................................................................................................................100 ix

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4-14. Macroinvertebrate Index of Community Condition scores for sampled sites.......102 A-1. Site coordinates and LDI score...............................................................................116 B-1. Soil characteristics measured at each study site.....................................................119 C-1. Diatom Autecological Values.................................................................................121 D-1. Coefficient of Conservatism scores for sampled macrophytes...............................125 x

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LIST OF FIGURES Figure page 1-1. Schematic of the relationship between various ecosystem influences and biological integrity. ....................................................................................................................5 1-2. Approximate landscape extent of wetlands in Florida. ..............................................7 2-1. Algal study site locations and encounter probability for isolated depressional wetlands. ..................................................................................................................15 2-2. Hypothesized example of metric scoring using the 95 th percentile of the dataset. ...21 2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly correlated environmental variables. ........................................................................29 2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly correlated environmental variables..........................................................................30 2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and strongly correlated environmental variables............................................................31 2-6. Indicator species abundance data plotted against the LDI........................................38 2-7. Diatom abundance for autecological metrics plotted against the LDI gradient........30 2-8. Diatom Index of Wetland Condition scores for each site plotted against the disturbance gradient.................................................................................................44 3-1. Study site locations and encounter probability for isolated depressional wetlands..52 3-2. Transect and quadrat locations in a hypothetical depressional wetland....................52 3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted scores for wetland macrophytes..........................................................................................59 3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly correlated environmental variables...........................................................................................63 3-5. Abundance of sensitive species along the disturbance gradient................................68 3-6. Abundance of tolerant species along the disturbance gradient..................................68 xi

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3-7. Abundance of exotic taxa at each site along the disturbance gradient......................70 3-8. Annual to perennial ratio at each site along the disturbance gradient.......................71 3-9. Average Coefficient of Conservatism value for each site along the disturbance gradient.....................................................................................................................72 3-10. Relationship between the VIWC and the LDI.........................................................75 3-11. Environmental optima along a hypothetical environmental gradient......................78 4-1. Biplot of macroinvertebrate NMDS ordination scores for each site and strongly correlated environmental variables..........................................................................95 4-2. Abundance of sensitive taxa plotted against the LDI................................................97 4-3. Abundance of tolerant taxa plotted against the LDI..................................................98 4-4. Predator abundance plotted against the LDI..............................................................99 4-5. Odonata abundance plotted against the LDI..............................................................99 4-6. Abundance of Orthocladiinae plotted against the LDI............................................100 4-7. Macroinvertebrate Index of Wetland Condition plotted against the LDI................101 xii

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EXECUTIVE SUMMARY THE WETLAND CONDITION INDEX: BIOLOGICAL INDICATORS FOR ISOLATED DEPRESSIONAL WETLANDS IN FLORIDA With the passage of the Water Pollution and Control Act (1972, Clean Water Act), states were charged with the task to [r]estore and maintain the chemical, physical, and biological integrity of the Nations waters (Water Pollution and Control Act (a)). Biological integrity can be defined as, the ability of an aquatic ecosystem to support and maintain a balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of the natural habitats of the region (Karr and Dudley 1981). The State of Florida has developed measurements of the biological integrity of freshwater aquatic systems through the use of biological indicators, or measurable attributes of the biota that respond to anthropogenic stressors. This has been completed for streams (Stream Condition Index, Barbour et al. 1996) and lakes (Lake Condition Index, Gerritsen et al. 2000). The development of the index of Florida wetland resource condition, or the Wetland Condition Index, has followed from those earlier works assessing streams and lakes of Florida. The goal of this project was to identify characteristics of herbaceous wetland organismal structure, composition, and function that may serve as biological indicators of the condition of Floridas wetland resources. Intermediate and often concurrent goals of the project have included: The development of a wetland classification system and geographic regionalization to increase the sensitivity of biometrics; The development of measures of anthropogenic disturbance affecting the organismal assemblage of a given wetland; The development and implementation of sampling protocols for macrophytes, macroinvertebrates, and algal wetland assemblages; The identification of indicators of wetland condition along the disturbance gradient within each of the three focal assemblages; The development of the Wetland Condition Index (WCI), an assessment method of assemblage-specific indices of community condition for diatoms (the Diatom Index of Wetland Condition), vegetation (the Vegetative Index of Wetland Condition), and macroinvertebrates (the Macroinvertebrate Index of Wetland Condition), for wetland systems throughout Florida. This report addresses the last four of the goals described above. The first goal was addressed in earlier reports to FDEP (see Doherty et al. 2000, Lane 2000). The approach has included a review of technical and scientific literature, development of a wetland classification system and crosswalk with other classifications, xiii

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wetland regionalization of Florida, and 3 years of wetland biological surveys in the growing seasons of 1998 (pilot study), 1999, and 2000. The biological surveys were designed to test the validity (and necessity) of the proposed wetland regions and to identify the appropriate biological indicator taxa. The wetland classification scheme was organized with major classes defined from three variables: 1) dominant vegetation (forested, shrub, herbaceous); 2) geomorphic position (stream channel (floodplain), flat topography, sloped topography, lake fringe, depressional); and 3) primary water source (rainfall, surface water, ground water). Subclasses are discriminated by modifiers (hydroperiod and plant community associations). Eleven wetland classes were identified: forested (river swamp, slough/strand/seepage swamp, lake swamp, depression swamp, flatland swamp); shrub dominated (shrub-scrub swamp); and herbaceous (river marsh, wet prairie, lake marsh, depressional marsh, seepage marsh). An HTML electronic data base has been completed and delivered to the FDEP that cross walks existing wetland classifications to the new simplified, classification scheme developed for the bio-assessment project. Regionalization of the State was considered necessary since there is significant variation in climatic and physical features of the Florida peninsula and it was believed that these regional differences could equate to variations in biological indicator signals. Map coverages of physical and climatic variables of the Florida landscape were used to develop regions that had different characteristic driving energies and landscape structural characteristics (see Lane 2000). The map coverages were combined with GIS map algebra to create a spatial hydrologic budget equation for the State. The equation modeled the movement of water on the landscape during the ecologically sensitive spring growing season. The output of the model was a Potential Soil Moisture Index (PSMI). The PSMI was separated into four regions based on both the critical depth of saturation and on a statistical clustering of the PSMI values. The classified regions were tested for similarities and differences to determine if between region variation in wetland type and environmental variables was greater than within region variations. A quantitative index of the human disturbance gradient has been developed using energy intensity of land uses as the metric. Called a Landscape Development Intensity index (LDI), the LDI is a land use based index of human disturbance. It is calculated spatially from aerial photographs of each site using coefficients applied to land uses within a 100 meter buffer surrounding the wetlands. Development intensity factors are a function of the energy use per unit area of land use. A total area weighted LDI is calculated for the 100-meter area of influence (see Brown and Vivas submitted). Three years of biological surveys of wetlands through out the state were designed to test regionalization as well as for metric and bio-indicator development. A 1998 pilot study involved surveying 24 herbaceous and forested depression wetlands in north and central Florida. Major taxonomic assemblages were characterized and ranked along a gradient of disturbances. Sites were located within multiple land uses such as parks, preserves, pasture, farm fields, well fields, silviculture plots, and urban matrix. Impacts that were assessed included hydrological modifications, nutrient loading, and altered hydroperiod. The first years sampling resulted in development of standardized sampling procedures, design and implementation of a statewide sampling program, and identification of community attributes and candidate metrics. xiv

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In the second and third years field seasons, 75 herbaceous, depressional wetlands were surveyed in three regions (22 sites in the North, 30 in the Central, and 23 in the South region, see Figures 2-1 and 3-1). Approximately half of the wetlands were located in developed landscapes (i.e. agricultural setting) and half were reference locations. Many of the sites were paired sites (impacted and reference at close proximity). Three indices of wetland integrity were developed based on measurable attributes (metrics) of the assemblages sampled from the 75 isolated depressional wetlands (see table below): the Diatom Index of Wetland Condition (DIWC, 14 metrics), Vegetative Index of Wetland Condition (VIWC, 5 metrics), and Macroinvertebrate Index of Wetland Condition (MIWC, 5 metrics). These indices were not regionally dependent and were thus applicable to the entire peninsula. Each index was significantly correlated (Spearmans r|0.75|, p<0.0001) with an independent geographic information systems-based measure of human landscape modification, the Landscape Development Intensity index (see Brown and Vivas submitted). Diatom Index of Wetland Condition Vegetative Index of Wetland Condition Macroinvertebrate Index of Wetland Condition % Sensitive Spp. % Sensitive Spp. % Sensitive Genera % Tolerant Spp. % Tolerant Spp. % Tolerant Genera % Sensitive Elevated pH % Exotic Taxa % Predators % Tolerant Elevated pH Annual:Perennial Ratio % Odonata % Sensitive Elevated Salinity Average Coefficient of Conservatism Score % Orthocladiinae % Tolerate Elevated Salinity % Sensitive Elevated Nitrogen % Tolerate Elevated Nitrogen % Sensitive Low D.O. % Tolerate Low D.O. % Meso& Polysaprobous % Oligotrophic % Eutrophic % Pollution Tolerant An ancillary goal of this research was to elucidate the various landscape and soil/water physio-chemical constituents responsible for determining the community composition of the sampled wetlands, as understanding the driving forces may aid in managing wetland resources. Four variables were strongly associated with community composition across all three assemblages (diatoms, macrophytes, and macroinvertebrates) sampled: soil pH, water column specific conductivity, water column total phosphorous, and Landscape Development Intensity index score. In addition, water color and latitude were also associated with macroinvertebrate and macrophyte community composition, respectively. The indices of biotic integrity developed from this research may be used to provide quantitative and objective measurement of the wetland resources of peninsular Florida and may form the scientific basis for an objective and quantifiable rapid assessment procedure. In addition, results from this study suggested that efforts to restore xv

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community composition and associated processes and functions should focus on amending inflows and fluxes of water, materials, and energy that affect soil pH, specific conductivity, and water TP, as well as decreasing the abundance of human-developed lands within 100m of wetlands. xvi

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CHAPTER 1 INTRODUCTION AND OVERVIEW Introduction Wetlands are defined as areas that are inundated or saturated by surface or ground water at a frequency and duration to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (42 Fed. Reg. 37, 125-126, 37128-29; July 19, 1977). Wetlands on the landscape provide many important functions, including biogeochemical cycling, wildlife habitat, floodwater attenuation, and water quality improvement. In the mid-1970s the United States Environmental Protection Agency (U.S. EPA) mandated that wetlands, as protected under the Clean Water Act (Clean Water Act 1(a)), required biological monitoring and assessment to ensure that the biological integrity (sensu Karr 1981) of these systems was not diminished. Wetland biological monitoring and assessment, as differing from synoptic water or soil chemistry sampling, characterizes the wetland flora and fauna to measure the relative state of wetland resources. The use of biotic characteristics, including taxonomic composition and the abundance of functional guilds (i.e., scrapers), has provided robust assessments of the relative state of various aquatic systems (see Barbour et al. 1996, Gerritsen and White 1997), as organisms integrate exogenous perturbations that occur at local (i.e., nutrient loading) and landscape scales (i.e., increases in residential land use) (Karr and Chu 1999). These observations have led to the development of indices of biological integrity (IBIs, Karr 1981), which relate measured attributes (or metrics) of various assemblages measured on-site to changes in human disturbance (Karr and Chu 1999, U.S. EPA 2002a). Often, the human disturbance gradient is interpreted subjectively (i.e., best professional judgment Adamus et al. 1991, Miller and Gunsalus 1997) or confounded through circular logic (i.e., a metric correlated to the disturbance gradient may also be directly incorporated into scoring the disturbance gradient Miller and Gunsalus 1997). To decrease these problems associated with on-site assessments, as well as the costs and logistics related to on-site visits, techniques have also been developed to examine biological response to landscape scale measurements through the use of geographic information systems (GIS) analysis (OConner et al. 2000, Cuffney et al. 2000). As compared with gradients assessed on-site that examine conditions within the system, landscape scale measurements assume a direct relationship between land use surrounding an aquatic body and the composition and relative condition of the system (Galatowitsch et al. 1999a). For example, studies have related biological data (e.g., richness) to the abundance of particular land use measurements (e.g., percent impervious surface meters Doberstein et al. 2000, percent agricultural land use within watershed Roth et al. 1996). However, GIS based analyses are subject to errors of land use interpretation from aerial photos, as well as delays (often of several years) between flight dates and available geo1

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2 rectified and digitized information, which can affect their accuracy. On the other hand, GIS based analyses of relative condition do not require an on-site visit, which decreases sampling effort and thus increases the number of sites quantifiable. In addition, GIS based analyses have been reported as generally precise and correlated with biological conditions within nested systems (Roth et al. 1996, Galatowitsch et al. 1999a, Karr and Chu 1999). These attributes increase the allure of GIS based analyses in assessing the relative condition of isolated depressional herbaceous wetlands on the Florida landscape. However, a disconnection may exist between the wetland system and the GIS-based assessment method due to the assumption of causal mechanisms between land use within a given distance from the wetland and relative wetland condition. For instance, a site may be perched on the landscape and thus not as highly affected by inputs from surrounding lands as a site in a low-lying area within the same land use. In this example, the expected variance in the biological data vis--vis the two hypothetical sites would not be assessed through GIS analyses as such biological analyses would be at too coarse a scale for spatial analyses. However, incorporating on-site measurements of biota, although more difficult than GIS analyses due to sampling and identification efforts, provides additional information germane to accurately assessing relative wetland condition (Karr and Chu 1999). In addition, combining GIS analyses with on-site biological data can improve the accuracy, precision, and sensitivity of spatial metrics by providing causal pathways to perceived variance in the dataset, and may instigate future improvements in assessment methods. These observations lead to the following goals of this report. First, to identify measurable attributes (or metrics, such as the abundance of exotic taxa) of the flora (diatoms and macrophytes) and fauna (macroinvertebrates) of isolated depressional marshes in Florida that are highly correlated with a GIS based measurement of landscape modification, the Landscape Development Intensity index, which is described below. Second, to test interregional compositional differences attributed to latitudinal/physiological gradients between the organisms sampled from within three wetland regions of peninsular Florida (after Lane 2000) that, if present, may necessitate the development of unique measurable attributes for each wetland region. Third, to identify significant associations between floral and faunal assemblage composition and measured soil and/or water parameters collected from sampled wetlands to aid in synecological understanding and resource management. GIS Measurements and Wetland Metrics The Landscape Development Intensity index (LDI, Brown and Vivas submitted) was used to assess the development intensity of lands within 100m around each sampled wetland, independent of the wetland biota. The LDI was developed by Brown and Vivas (submitted) and assesses the intensity of various land uses by measuring the annual non-renewable energy flow, given in terms of emergy, or embodied energy (Odum 1995), for each land use. They calculated their emergy values by identifying the energy pathways for each land use (land use data obtained from local water management districts, based on 1995 aerial photos), obtaining the value in joules/year from published sources, and multiplying the joules/year value by solar-emjoules/joule (sej/J, Odum 1995) to relate the amount of energy to a solar unit per year (see Brown and Vivas submitted). The use of an independent energy-based spatial measurement in this study permitted the incorporation

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3 of many disparate processes (e.g., pesticide use, water diversion and ditching, plowing, road building) into a single, agglomerative value. The actual LDI calculation was made for a 100m buffer directly surrounding each wetland using the following equation: LDI = (LDC % LU); where LDI is the Landscape Development Intensity index, LDC is the Landscape Development Coefficient (Table 1-1), the %LU is the percent of each land use within the 100m buffer directly surrounding each wetland. The relationship of land use intensity with other buffer sizes (18m, 250, 500m, 1000m) is currently being investigated (M.B. Vivas, Department of Environmental Engineering Sciences, University of Florida, personal communication). Table 1-1. Landscape Development Intensity Disturbance Coefficients. Land Use Non-Renewable Empower Density(E14 sej/ha/yr) Ln Non-Renewable Empower Density LDI Coefficients Natural System 0 1.00 Natural Open water 0 1.00 Pine Plantation 5.10 1.63 1.58 Woodland Pasture (with livestock) 8.00 2.08 2.02 Pasture (Bahia) (without livestock) 17.20 2.84 2.77 Recreational / Open Space (Low-intensity) 17.20 2.84 2.77 Low Intensity Pasture (Bahia) (with livestock) 33.31 3.51 3.41 Citrus 44.00 3.78 3.68 High Intensity Pasture (Bahia, with livestock) 46.74 3.84 3.74 Row crops 107.13 4.67 4.54 Single Family Residential (Low-density) 1077.00 6.98 6.79 Recreational / Open Space (High-intensity) 1230.00 7.11 6.92 High Intensity Agriculture (Dairy farm) 1349.20 7.21 7.00 Note: Modified from Brown and Vivas (submitted).

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4 Strong correlations between measured wetland attributes and the LDI would suggest a connection between surrounding land use and nested community composition (Roth et al. 1996, Brown and Vivas submitted). The relationship between any given metric and the LDI would be further strengthened through evidence of accuracy, precision, and sensitivity to changes in the LDI. High variance within metric responses for any given LDI could suggest causal mechanisms affecting community composition that were not accurately captured by the LDI, such as sources of stress not visible to GIS analyses (i.e., low relief ditch from degraded water source). An examination of metric sensitivity to LDI values would permit the development of land use thresholds for various assemblages, and furthermore may provide predictive ability for future wetland composition in areas undergoing land use change. Regional Composition Testing the effects of physiographic and/or climatic regions on wetland community composition can provide germane information on the development of ground-based biometrics. Lane (2000) delineated freshwater wetlands of Florida into four regions based on a climatic and physiographic model. Composition may differ between regions due to physiographic and climatic differences and possibly render biometrics developed in one area of the state impotent in another wetland region. Environmental Correlates and Assemblage Response Strong correlations between LDI values and community composition would suggest a causal mechanism and may assist in explaining metric relationships with the LDI. Developing an understanding of water and soil environmental parameters correlated with community composition may also provide the means for environmental managers to address specific ecosystem driving forces affecting wetland systems. In addition, strong correlations between environmental parameters and community composition can advance the knowledge of autecological relationships for diatom, macrophyte, and macroinvertebrate taxa. Background With passage of the Clean Water Act (1972, Water Pollution and Control Act), states were charged with the task to restore and maintain the chemical, physical, and biological integrity of the Nations waters, including wetlands (Water Pollution and Control Act (a), Danielson 1998). Adhering to this mandate for wetland systems required first that a working definition for wetland biological integrity be defined, and second that a method to ascertain the relative ecological state of wetlands be developed. Integrity, as it has been applied to Clean Water Act mandates and thus may be applied to Floridas wetlands, has been defined as the ability of an aquatic ecosystem to support and maintain a balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of the natural habitats of the region (Karr and Dudley 1981, pg. 60). Implicit within this definition is maintenance of ecosystem driving forces that operate at different spatial and temporal scales to maintain the resilience and pattern of the ecosystem, such as the proper

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5 Figure 1-1. Schematic of the relationship between various ecosystem influences and biological integrity. (Modified from U.S. EPA 2002a). hydrology, fire regime, and cross-scale community interactions (Figure 1-1, Peterson et al. 1998, Gunderson and Pritchard 2002). Historically, aquatic monitoring and assessment inferred ecosystem condition from either toxicity samples or ambient water quality monitoring (Karr 1981, 1993, McCarron and Frydenborg 1997). At best, these data were rudimentary in their ability to reflect more than a temporal constituent concentration within the water body. If a toxicity parameter was not specifically targeted for detection, then the water body could be

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6 considered clean yet replete with undetected toxics, metals, or physically altered such that it no longer resembled a fully functioning water body. Additionally, synergisms within water bodies from multiple impacts or spike loading events were typically not accounted for in toxicity or ambient monitoring programs (Karr 1993, Karr and Chu 1997). In the late 1980s, the United States Environmental Protection Agency realized the potential of biological criteria to assess the Nations waters and mandated states to use biological indicators to achieve the goals of the Clean Water Act (United States General Accounting Office 1988, U.S. EPA 1990, Karr 1995). A premise behind the use of biological indicators versus synoptic physical or chemical sampling to assess aquatic condition was that due to their intricate relationship with their environment, organisms in situ reflect current conditions as well as integrate cumulative impacts (Karr 1981, Hunsaker and Carpenter 1990, Karr and Chu 1999). Biological criteria and monitoring programs embraced by the U.S. EPA have since been utilized to assess lakes and streams throughout the United States (Barbour et al. 1996, Karr and Chu 1999, Barbour et al. 1999, Gerritsen et al. 2000). Only recently have efforts be undertaken to assess wetland condition using biological criteria (U.S. EPA 2002a). While other assessment methods exist, such as the hydrogeomorphic (HGM) approach (Brinson and Reinhardt 1996), or rapid, best scientific judgment approaches (e.g., Wetland Evaluation TechniqueWET, Adamus et al. 1991; Wetland Rapid Assessment ProcedureWRAP, Miller and Gunsalus 1997), the U.S. EPA has supported the use of multimetric indices of biotic integrity, or IBIs (sensu Karr 1981), to assess the condition of wetland resources (U.S. EPA 2002a). A multimetric index of biotic integrity combines measured biological attributes (or metrics) of trophic, community, and/or functional structure of various species assemblages within a wetland ecosystem into a single value. Ideal metrics are accurate, highly sensitive to change, and precise. The developed index can then be compared to either a reference condition (a suite of previously characterized wetlands located in undisturbed landscapes such as state parks and preserves) or along a gradient defined by changes in land use (Reynoldson et al. 1997, Karr and Chu 1999, Brown and Vivas submitted). The condition of the aquatic system in question is based on the relative similarity of the metric value obtained from that system vis--vis previously measured metrics in similar aquatic systems located in reference conditions. Wetland Trends Wetlands on the Florida landscape provide services to the state including water retention and flood attenuation, water quality improvement and nutrient immobilization, aquifer recharge, biogeochemical processes, wildlife habitat, and climate regulation. Historically, wetlands covered more than half of Florida, approximately 8.2 million hectares (Figure 1-2). Ditching and filling for agricultural operations, water control, and urban development over the past 200 years have substantially decreased the abundance and functional capacity (i.e., habitat, water storage) of wetlands on the Florida landscape (Dahl 1990, Kautz 1993). A historical perspective of the areal extent of marshes in Florida and concurrent increases in agricultural and urban landscapes from 1936 1987 is presented in Table 1-2. Approximately 23% of Florida (3.6 million ha) is currently classified as inland freshwater wetlands by the National Wetlands Inventory (Table 1-3),

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7 Figure 1-2. Approximate landscape extent of wetlands in Florida. Riverine, palustrine, and estuarine wetlands are indicated in black on the map. (Modified from Lane 2000). Table 1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida landscape and concurrent increases in agricultural and urban land use. Land Use 1936 1949 1959 1970 1980 1987 Marsh 2.82 2.15 2.45 1.48 1.23 1.25 Agriculture 2.45 2.73 3.29 4.13 4.38 4.17 Urban 0.29 0.43 0.72 1.16 1.46 1.89 Notes : Values from 1936 are estimates. Modified from Kautz (1993). of which greater than 34% are palustrine emergent marshes, the focal wetland class for this study (Doherty et al. 2000). Wetlands are typically found in topographic lows in the landscape and tend to accumulate nutrients, metals, and toxins from up-slope sources as rainfall percolates through the wetland basin (Kirkman et al. 1998, Mitsch and Gosselink 2000). The constituents of surface and sub-surface flow, if transported into down-slope wetlands, can result in changes in processes and floral and faunal composition of receiving wetlands. Effect of Land Use Change on Wetland Systems Changes in land use within wetland watersheds (hydrologic units where precipitation falling within will move via percolation and interstitial flow or overland

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8 Table 1-3. National Wetland Inventory categories and landscape abundance of freshwater wetlands in Florida. NWI Code Wetland Class Description % Wetland Area % State Area R 2 AB Riverine, Lower Perennial, Aquatic Bed <1 <1 R 2 EM Riverine, Lower Perennial, Emergent, non-persistent <1 <1 R 3 AB Riverine, Upper Perennial, Aquatic Bed <1 <1 R 4 SB Riverine, Intermittent, Streambed <1 <1 L 1 AB Lacustrine, Limnetic, Aquatic Bed <1 <1 L 2 AB Lacustrine, Littoral, Aquatic Bed 1 <1 L 2 EM Lacustrine, Littoral, Emergent, non-persistent <1 <1 P AB 3 Palustrine, Aquatic Bed, Rooted Vascular 1 <1 P AB 4 Palustrine, Aquatic Bed, Floating Vascular <1 <1 P EM Palustrine, Emergent 34 8 P SS Palustrine, Scrub Shrub 11 3 P FO 1 Palustrine, Forested, Broad-Leaved Deciduous 6 1 P FO 2 Palustrine, Forested, Needle-Leaved Deciduous 9 2 P FO 3 Palustrine, Forested, Broad-Leaved Evergreen 5 1 P FO 4 Palustrine, Forested, Needle-Leaved Evergreen 11 2 P FO 6 Palustrine, Forested, Deciduous (mixed) <1 <1 P FO 7 Palustrine, Forested, Evergreen (mixed) 22 5 ~100 % NWI inland freshwater wetlands 23 % upland area 63 % other (estuarine) wetlands and deepwater habitats 14 State total area 100 Source : Doherty et al. (2000) flow to the wetland) can cause significant changes in wetland structure and function. Some of these changes are: 1) increased nutrient (mainly phosphorus) and chemical loading from lands shifted into production (Flaig and Reddy 1995, Bedford 1999, Daoust and Childers 1999, Maul and Cooper 2000), 2) selective herbivory and trampling from cattle (Winchester et al. 1985, Long et al. 1986, Blanch and Brock 1994, van Oene et al. 1999, Grace and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000), 3) altered hydroperiod due to ditching or filling (Anderson and Vondracek 1999, Euliss and Mushet 1999, Kirkman et al. 2000, Babbit and Tanner 2000), 4) increased sedimentation due to ditching or removing topsoil (Martin and Hartman 1987, Freeland et al. 1999, Shutler et al. 2000), 5) colonization of invasive exotic organisms (Bedford 1999), 6) destruction of wetland/upland transition zones (Winchester et al. 1985), and 7) alteration of landscape-level processes such as fire frequency (Moss 1992, Kirkman et al. 1998, Bedford 1999, Semlitsch 2000). Of particular relevance to this study are the effects of nutrient and chemical loading, selective herbivory and trampling by cattle, and ancillary effects of

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9 changes in wetland watershed land use. As such, a review of those three effects is provided below. Nutrient and Chemical Loading Nutrient and chemical loading of wetland systems alters community composition (Davis and Ogden 1994, Freeland et al. 1999, Doherty et al. 2000). Changes in land use development surrounding wetlands can create large stores of exogenous nutrients, which can act as potential sources for ecosystem-altering nutrients and chemicals. Graetz and Nair (1995), studying dairy and beef ranching lands in Okeechobee County, Florida, found mean concentrations of total phosphorus (TP) in the soil of 5300 ug/kg, approximately 40% of which was soluble reactive phosphorus readily available to organisms. Graetz and Nair (1995) also found significant differences in soil phosphorus along a gradient of grazing intensity from 79 kg/ha in natural areas (zero grazing pressure) to 4939 kg/ha in intensely grazed dairy feedlots. Rainfall and the subsequent movement of surface and sub-surface flows through phosphorus (P) laden landscapes can mobilize and deliver P into wetlands and other aquatic systems, resulting in alterations in community composition, structure, and function with potential effects on food web dynamics (Winchester et al. 1985, Moss 1992, Flaig and Reddy 1995, Daoust and Childers 1999, Freeland et al. 1999, Maul and Cooper 2000). For instance, Freeland et al. (1999) reported that periphyton assimilating increased exogenous P caused shifts in macrophyte species composition (Freeland et al. 1999). In studies in the Everglades (Davis and Ogden 1994), higher plants, such as Typha spp. tolerate nutrient loading and out-compete other less tolerant macrophytes, such as Cladium jamaicense. Likewise, floating plants Lemna spp., which grow readily in nutrient enriched waters, can become so prolific to create oxygen stress for aquatic communities in the water column (e.g., fish, macroinvertebrates, microbes, macrophytes) through shading of photosynthetic, oxygen-producing algae and other macrophytes (Dierberg and Brezonik 1984). The direct nutrient loading of wetland systems can also occur as a result of land use development intensity in the surrounding wetland watershed (Graetz and Nair 1995). Tanner et al. (1984) tracked cattle movements on a South Florida rangeland and found that cattle spent the majority of time in herbaceous wetlands (fall months) or upland/herbaceous wetland ecotones (summer months). They also reported no significant difference in cattle defecation/urination location among herbaceous wetlands, upland/herbaceous wetland ecotones, canal banks, or flat woods, suggesting near constant landscape loading of available nutrients. Several authors suggested encouraging cattle to graze in marshes during summer as Panicum spp. and Andropogon spp. typically have the highest crude protein levels of any available forage during that period (Tanner et al. 1984, Kalmbacher et al. 1984, Long et al. 1986). Direct grazing within the marsh could lead to higher concentrations of P and N as there would be no biochemical degradation of the nutrient constituents in the process of overland or interstitial flow before their deposition in the wetland. Reddy et al. (1996) reported that the uptake of available phosphorous by wetland vegetation was estimated at 28%-70% of the available P transported to the wetland. This P uptake is dependent upon plant growth rate, growth structure (woody or herbaceous material), P concentration in the soil, and the physical and chemical characteristics of the soil (Agami et al. 1990, Flaig and Reddy 1995). However, aquatic plant storage of P is a

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10 temporary phenomenon as approximately 80% of the nutrients are released to the water column by decaying vegetation (Agami et al. 1990, Reddy et al. 1996), suggesting that wetland plants are nutrient storages, and not sinks. Agrochemical application within a wetland basin may also affect wetland processes and functions. Movement of pesticides, herbicides, and agrochemical fertilizers into wetlands is generally related to either direct or drift application or absorption of the chemical onto soil particles, which are subsequently mobilized into the wetlands during rainfall events (Anderson and Vondracek 1999, Freeland et al. 1999). Martin and Hartman (1987) reported influx of sediments to wetlands in cultivated landscapes at twice the rate from uncultivated landscapes. Euliss and Mushet (1999) noted that chemicals and chemical-laden soil particles transported from uplands into wetlands could be toxic to zooplankton and reduce foraging and food assimilation rates of aquatic invertebrates. Semlitsch (2000) and Shutler et al. (2000) reported impacts to non-target wetland organisms from pesticides. Several authors found changes in wetland community assemblages due to agrochemical loading (Anderson and Vondracek 1999, Bedford 1999, Kolozsvary and Swihart 1999, Maul and Cooper 1999). Selective Herbivory and Trampling While low-density grazing in rangeland (native forage) maintains species richness and mimics natural processes, such as foraging by deer or other herbivores (Blanch and Brock 1994), high-density herbivory by cattle can alter native upland and wetland vegetation communities and have long-term successional consequences (Dobkin et al. 1998). Tanner et al. (1984) and others (Kalmbacher et al. 1984, Long et al. 1986) noted that cattle selectively graze wetland plants on the landscape, thus altering community composition. Van Oene et al. (1999) found that grazing prevented dominance of tall wetland species of grasses, shrubs, and trees, as they were selectively harvested by cattle, which led to structural and functional changes in the wetland, such as decreased wildlife habitat. Vulink et al. (2000) reported that wetland vegetation community changes occurred due to modifications of light availability as livestock consumed the shading vegetation. Additionally, Vulink et al. (2000) found that grazing substantially impacted plants with apical meristems within the reach of livestock, which altered community composition and structure. Reader and Craft (1999) and Vulink et al. (2000) demonstrated that the trampling and physical destruction of wetland vegetation by livestock directly altered community structure and composition. In addition, several authors have noted increased fluxes of nutrient and sediment flow into wetlands through destruction of vegetative buffers, such as the fringing Hypericum spp. or Serenoa repens (Winchester et al. 1985, Blanch and Brock 1994, Vulink et al. 2000). Ancillary Impacts from Landscape Modification Changes in landscape level processes as a result of modification of wetland watershed land use have effects on wetland composition and function (Bedford 1999). Wetlands in cultivated and urban landscapes have highly variable water-level fluxes compared to wetlands in non-developed landscapes, which can affect soil anoxia and wildlife habitat (Rushton and Carr 1993, Tilley and Brown 1998, Euliss and Mushnet

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11 1999). In order to facilitate movement of water off the landscape, wetlands in agricultural land use matrices are often inter-connected by ditches that can decrease the hydroperiod of all wetlands if attached to an outflow (such as a canal or stream), which can provide conditions for colonization by upland taxa. If not connected to an outflow, an increased hydroperiod may result from ditching as water is rapidly shunted off the landscape and into the wetland, instead of moving slowly via overland and sub-surface flows. In some cases, canals and streams can back-flood connected marshes, altering hydrology and possibly allowing marsh access to stream/canal species (such as predatory fish), with potential impacts to wetland fauna that require fish-free habitat for breeding (Babbit and Tanner 2000). Florida ecosystems have evolved with fire as a driving force to the extent that some organisms require fire for reproductive success (Ewel 1990). In wetland watersheds used for agricultural purposes, fire is typically excluded (Kirkman et al. 1998). Whereas the fire season in Florida is related to lightning strikes, which are highest in summer, prescribed burns currently occur in spring (Kirkman et al. 1998). This alteration to the timing and extent of natural processes may affect reproduction and foraging success of wetland organisms, which have evolved with seasonal fire. Wetland diversity across the landscape (i.e., the number of wetlands in a given area) is also affected through alterations of wetland watershed land use that include ditching, draining, and filling (Kirkman et al. 1996, Kirkman et al. 1998, Kolozsvary and Swihart 1999). Whereas depressional marshes may be scattered on the landscape and provide metapopulation dynamics (i.e., increased gene flow) of organisms between wetlands, loss of wetlands on the landscape decreases landscape diversity and can cause increased crowding and subsequent decreases in population as organisms compete for decreasing resources and space (Pearlstine et al. 1997). Wetland Assemblages and Biological Assessment Various assemblages (i.e., macrophytes, macroinvertebrates, microbes, birds, etc.) within an ecosystem have been used as biological indicators for aquatic systems, including wetlands (U.S. EPA 2002b-e). Appropriate indicator assemblages are those that measurably respond to the gradient defined along the abscissa (i.e., land use change, total phosphorus, etc.), and ideal indicator assemblages are also composed of organisms relatively easy to identify, abundant, and available for sampling or mensuration for an extended period (Karr and Chu 1999). Appropriate metrics derived from indicator assemblages are accurate, exhibit high precision, and are likewise sensitive to increases in change along the abscissa (Karr and Chu 1999). As most aquatic assemblages respond to alterations occurring at both large (i.e., abundance of croplands in a wetland basin) and small scales (i.e., pH alterations; Allan and Johnson 1997), determining the particular stressor or component of anthropogenic disturbance that an aquatic assemblage responds to is often difficult. Various scales of temporal response further compound the identification of stressors. Incorporating multiple assemblages (i.e., macrophytes and macroinvertebrates) can assist in determining sources of perturbations, especially if the autecological requirements of the selected assemblages are well established (e.g., Reed 1986, Lenat 1993, Van Dam et al. 1994). Characterizing various edaphic, hydrologic or landscape variables and identifying trends can also assist in elucidating sources of wetland perturbation.

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12 By including multiple assemblages in the initial development of biological indicators, the likelihood increases that a suite of potential metrics can be identified that are strongly correlated with the abscissa. In addition, sampling multiple assemblages permits an examination of the temporal responses of wetland organisms to perturbations, which, depending on the speed of community change, has the potential to alter conclusions. For instance, diatoms respond extremely rapidly to environmental conditions, on the order of a few hours to a few days, macroinvertebrates respond slower (with turnover times ranging from hours to years), and macrophytes generally react the slowest to alterations (responses occur over days to decades). Substantial information also exists on the natural history and autecological requirements of diatoms (Bahls 1993, Van Dam et al. 1994), macroinvertebrates (Hilsenhoff 1988, Lenat 1993, Barbour et al. 1999), and macrophytes (Reed 1997, Taft et al. 1997). Project Overview In this study, diatoms, macrophytes, and macroinvertebrates were sampled from isolated depressional herbaceous wetlands located within human-modified land use matrices throughout peninsular Florida. Compositional differences among sampled assemblages driven by latitudinal or physiographical regions were examined to ascertain the importance in developing regionally specific biological assessment metrics. Analysis of water and soil physical-chemical parameters and land use identified variables affecting the composition and structure of sampled biotic assemblages in the study wetlands. GIS analyses assigned empirically derived values to each wetland based on the abundance (% area) and land use intensity of developed lands within a 100m boundary around each wetland site. Compositional and functional attributes, or metrics, that correlated with the empirically derived GIS land use measure were identified from each assemblage and combined into three unique assemblage-specific field based indices of biological integrity. In addition, the ability of the GIS land use measure to accurately and precisely reflect the environmental conditions on-site was assessed through examination of the variance within metric responses. Conclusions on the use of the wetland organisms and GIS based measures of relative wetland condition and suggestions for improvements were made.

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CHAPTER 2 DIATOMS AS BIOINDICATORS Introduction Diatoms (Class Bacillariophyceae) are important components of wetlands and other aquatic systems and provide several functions including: 1) primary production, 2) nutrient and biogeochemical cycling, 3) oxygen cycling, and 4) water chemistry regulation (Rader and Richardson 1992, Stevenson et al. 1996, Goldsborough and Robinson 1996, McCormick et al. 1997, Doherty et al. 2000, U.S. EPA 2002e). Stream and lake researchers, and more recently wetland researchers, noted the response of diatoms to land use changes, increases in nutrient loading, alterations in pH, and changes in specific conductivity (Lange-Bertalot 1979, Whitmore 1989, Bahls 1993, Van Dam et al. 1994, Pan and Stevenson 1996, McCormick and Cairns 1997, Danielson 1998, Barbour et al. 1999, Stevenson 2001, U.S. EPA 2002e). The U.S. EPA (2002e, p.2) reports diatoms as amongst the most widely used indicators of biological integrity and physico-chemical conditions in aquatic ecosystems. Changes in diatom taxonomic composition correlated with changes in physical-chemical parameters have been noted in the Florida Everglades (Raschke 1993), prairie potholes (Adamus 1996), riverine bottomland wetlands, marshes, swamps, and bogs (Pan and Stevenson 1996, Stevenson et al. 1999), streams (Bahls 1993, McCormick and Cairns 1997, Barbour et al. 1999, Winter and Duthie 2000, Munn et al. 2002), large rivers (Fore and Grafe 2002), lakes in Florida (Whitmore 1989), and other systems (see McCormick and Cairns 1997). The diatom community response has also been examined for heavy metals (Charles et al. 1996), pH (Pan and Stevenson 1996), saprobity levels (Lange-Bertalot 1979), nutrient and physical-chemical parameters (Van Dam et al. 1994), and other perturbations (see reviews in Stoermer and Smol 1999). In this chapter, diatoms community attributes were correlated with the Landscape Development Intensity index (LDI, Brown and Vivas submitted). Strongly correlated attributes (or metrics) identified through regression with the LDI were scaled so disparate metrics could be combined. The scaled metrics were summed to create the Diatom Index of Wetland Condition (DIWC). Analysis of measured abiotic and biotic environmental data identified parameters strongly correlated with diatom composition to advance synecological understanding on driving forces affecting the distribution and composition of wetland diatoms. Variance within diatom metrics was examined to explore relationships between landscape scale measurements and local, wetland specific responses. 13

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14 Methods Site Selection and Agricultural Development Gradient Seventy isolated depressional marshes throughout peninsular Florida were sampled a single time in landscape matrices with varying amounts of human-modified land uses during summer 1999 (n=35) and 2000 (n=35). Using best scientific judgment, sites were initially stratified into reference (no obvious human modified landscapes within >100m), and impaired (obvious human landscape modification within 100m) categories. The Landscape Development Intensity index (LDI, Brown and Vivas submitted) was later independently calculated through GIS analyses for each site by identifying varying land use abundance within each wetland basin (100m around wetland edge). LDI scores of <2.0 were characteristic of minimally disturbed (reference) wetlands and allowed the reference condition to incorporate small disturbances such as low density park paths. Slightly less than half the sites (33) were defined as reference sites, which were generally located in state and federal parks, preserves, and state forests. The remaining 37 wetlands were located within agricultural landscape matrices and were considered impaired sites (LDI > 2.0). Twenty-seven impaired sites were located in cattle ranches of varying stocking densities, 7 were located in truck crops (tomatoes, peppers), 2 were in citrus groves, and 1 was sampled in a silvicultural forest. All sites selected were hydrated when sampled. Site coordinates and LDI score for each sampled wetland may be found in Appendix A. As isolated depressional marshes are not uniformly distributed throughout Florida, the sites were likewise generally located in counties with the proper wetland hydrology and geomorphic setting (Lane 2000, Figure 2-1). The sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions (after Lane 2000). A compositional test, the multiple response permutation procedures (MRPP) available in PCOrd (MjM Software, Gleneden Beach, Oregon, version 4.10) was used to identify the ecological significance of the modeled wetland regions for diatom distribution. MRPP (Mielke 1984, Mielke and Berry 2000) provides a rank-based non-parametric multivariate test of the difference between n samples based on a distance matrix calculated between sites in ordinate space. The Sorensen distance measure was used for this test, as it is an effective distance measure for use in community data (McCune and Grace 2002). MRPP returns a statistic, A, which is the chance-corrected within group agreement (McCune et al. 2002). Zero values for A indicate that heterogeneity within groups equals that expected by chance, and values of 1.0 indicate perfect agreement between groups (McCune and Grace 2002, McCune et al. 2002). MRPP also returns a T value test statistic. The more negative the test statistic T the greater the separation between test groups (McCune and Grace 2002). The probability value, p, is based on the calculated possibility of finding differences as or more extreme than the observed group differences (Lesica et al. 1991). MRPP was calculated to compare composition across all regions (e.g., South versus Central versus North), and was also iteratively calculated to compare between individual wetland regions (e.g., South region composition versus North region composition). Significance for this test, as for all tests unless otherwise noted, was set at the conventional significance of 0.05.

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15 Figure 2-1. Algal study site locations and encounter probability for isolated depressional wetlands. Counties shaded darker have a higher density of isolated depressional wetlands <1ha (from U.S. Fish and Wildlife Service 2000). Field Data Collection, Sample Preparation and Laboratory Procedures Diatoms Diatom, soil, and water physical-chemical samples were taken at each wetland, and care was exercised to ensure minimal cross-sample contamination of diatom communities. Three different types of diatoms were sampled: benthic, epiphytic, and phytoplanktonic. Benthic diatoms were collected from wetland sediments. Epiphyton was collected from submerged portions of macrophytes. Phytoplankton was sampled from the water column. Benthic diatoms were sampled throughout hydrated areas of each wetland. Ten samples were proportionally distributed in a randomized fashion among the vegetation zones and a composite sample fixed. For each sample, a hollow cylinder with a diameter of approximately 10 cm was placed on the substrate, and a bulb pipette was used to

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16 mobilize the material at the water/sediment interface. A 10mL sample was taken with the bulb pipette and placed in a composite sampling jar. The total sampled volume in the composite sample was approximately 100mL. Epiphytic diatoms were sampled at ten locations in the wetland by snipping representative submersed and floating vegetation and placing the samples into a 3.8L Ziploc bag. Approximately 0.5L of wetland water was added and the bag gently kneaded to mobilize the epiphyton. A 10mL sample was obtained using a bulb pipette rinsed with wetland water and placed into a composite sampling jar. Total volume of the composite sample was approximately 100mL. Phytoplanktonic diatoms were sampled at ten different locations through the wetland in areas of at least 10cm of water. A sealed 100mL cylinder was placed under the surface of the water, the cap was removed and the cylinder filled. The cap was replaced underwater, the cylinder removed, and a composite sample taken. The total volume of the composite phytoplankton sample was approximately 1L. Once all ten samples were taken of each diatom type, the composite samples were preserved using M3 (APHA 1995): 5mL for benthic and epiphytic diatoms, and 20mL for phytoplanktonic diatoms. All samples were homogenized prior to subsampling for identification. To clean organic matter from the diatom frustules for identification the subsamples were digested following Hasle and Fryxell (1970). The samples were rinsed using distilled water and mounted on microscope slides using Naphrax (Northern Biological Supplies Limited, Ipswich, England). Following FDEP procedures (SOP #AB-03.1, available at www.dep.state.fl.us/labs/sop/), 250 diatom valves were then counted along microscope transects and identified to the lowest taxonomic level possible (usually species). For samples that were sparse (i.e., phytoplankton), sampling effort was capped at 1 hour. Diatom data were combined and entered into the FDEP database for further analysis. Soil and water physical-chemical sampling and analysis To relate the distribution of wetland diatoms to environmental parameters, soil and water physical and chemical parameters were obtained at each site and determined in the laboratory as described in Appendix B. The following soil chemistry parameters were determined in the lab: total phosphorous (soil TP, mg/kg), percent total nitrogen (%TN), percent total carbon (%TC), percent organic matter (%OM), and pH. The following water chemistry parameters were obtained from samples collected from each site: color (PCU), specific conductivity (umhos/cm), turbidity (NTU), pH, ammonia (mg/L), nitrate/nitrite (mg/L), total Kjeldahl Nitrogen (TKN, mg/L), and total Phosphorus (water TP, mg/L). In the event that the constituent measured was below detection levels, the value was entered for analysis was half of the lowest detectable level. See Appendix B for additional information. Data Analyses Summary statistics Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity were calculated for each site and diatom type and provided information on the distribution of species vis--vis land use. Richness is a measure of the total number of taxa found in a sample (Whittaker 1972). Evenness is a measure of distribution among

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17 taxa at a site. Shannon diversity and Simpson diversity indices measure the diversity of a site based on the abundance and total number of taxa (Brower et al. 1990). Two additional diversity indices were also calculated from the diatom data and compared between LDI classes of <2.0 or 2.0: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Gamma diversity, or species richness over a range of habitat (i.e., reference conditions, Whittaker 1972), was calculated as the total richness of a class of samples (LDI classes of <2.0 or 2.0). Beta diversity incorporates gamma diversity and indicates compositional variation in a sample. Beta diversity was calculated as gamma diversity divided by the average richness at a site (McCune and Grace 2002). Diatoms-compositional tests The Percent Similarity Index (PSI, Wolda 1981) and MRPP were used to assess the fidelity of habitat types for each of the three types of diatoms sampled. PSI (Wolda 1981) provides an index of overlap between diatom types and was calculated as PSI = [ (minimum pij, ) ] 100 where PSI is the percentage similarity between diatom types j and k (for instance benthic and epiphytic diatoms), p ij is the percentage of species i in diatom type j, and p ik is the percentage of species i in diatom type k. PSI was calculated to compare local, within-site diatom community composition (i.e., benthic, epiphytic, and phytoplanktonic diatom types from a single site) and for a global comparison (i.e., the abundance of all benthic, epiphytic, and phytoplanktonic diatoms identified were compared across all sites). While no significance was calculated, PSI values greater than 0.70 are generally considered highly similar (Matthews et al. 1988). MRPP, using the Sorensen distance measure, was also used to identify global group differences and provided a measure of the significance of the difference. Differences in summary statistics, such as evenness and diversity indices, were examined between landscape development classes (i.e., LDI <2.0 and LDI 2.0) with the Mann-Whitney U-test, and among diatom types using Tukeys Honest Significant Difference (HSD) test (Zar 1999). The Mann-Whitney U-test and Tukeys HSD test are non-parametric comparison procedures that test for equal medians between groups. The Mann-Whitney U-test was performed using two classes (i.e., LDI <2.0 and LDI 2.0) and Tukeys HSD was calculated for tests of more than two classes (i.e., South, Central, and North regions). Diatoms community composition and correlation with soil and water parameters The following soil variables were arcsine square root transformed to decrease measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Log 10 transformations were completed on soil TP, color, specific conductivity, turbidity, ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity among environmental variables, described as strong correlations between independent variables (Zar 1999), was tested using two multicolinearity diagnostic statistics available through linear regression analysis in SAS, the variance inflation factor and tolerance (SAS 1990). While no formal cutoff value exists, a conservative measure was used, and variables were considered collinear if they had a variance inflation factor (VIF) of 5.0 and a tolerance of <0.20 (ter Braak 1987, SAS 1990). The Mann-Whitney U-test was

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18 used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). The relationship between measured environmental values (including LDI score) and species composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS; Kruskal 1964, Mather 1976), both available in PCOrd. A Mantel test, which evaluates the correlation between distance measures of two matrices (McCune and Grace 2002), was computed to test the null hypothesis of no relationship between the arcsine square root transformed diatom species abundance and measured environmental parameters. The Sorensen distance measure was used for the abundance matrix, and the Euclidean distance measure was utilized for the second matrix due to the negative values of the log-transformed environmental parameters. The significance of the hypothesis of no relationship between the matrices was tested with a Monte Carlo simulation of 9999 randomizations. The standardized Mantel statistic (Mantels r), a t statistic, and the significance of the relationship were calculated for each test. NMDS was used to ordinate the samples based on arcsine square root transformed species abundances and to correlate environmental parameters to sites in ordination space. NMDS is an ordination method well suited for data that are non-normal, as it uses ranked distances to avoid the assumption of linear relationships among variables (Waichler et al. 2001, McCune and Grace 2002). To decrease chances of finding local minima, twenty-five runs with random seeds were made using six-dimensional starting space and the Sorensen distance measure. The instability criterion was set at 0.00001, the maximum number of iterations to find a stable solution was set to 400, 50 runs were conducted with real data, and 50 randomized runs were completed to calculate a p-value of the solution. The number of dimensions that accurately described the data set was obtained as a measure of the stress (or fit) of the ordination. A final run was made with the starting seed that provided the best final fit. A two-dimension solution was selected for benthic and epiphytic diatoms, and a three-dimension solution was selected for phytoplanktonic diatoms, as increased dimensionality only marginally improved the fit. The final NMDS solution was repeated several times to ensure stability of the solution. Pearsons correlation coefficients between site scores and environmental parameters, including LDI score, were calculated. A bi-plot of environmental parameters with Pearson correlations to site scores >0.30 was constructed. Metric Development Diatom metrics were developed using literature sources and iterative tests (i.e., Bahls 1993, Van Dam et al. 1994, McCormick and Cairns 1997, Stevenson 2001, U.S. EPA 2002e, Fore and Grafe 2002, Fore 2003) and correlated using Spearmans r with the Landscape Development Intensity index (Brown and Vivas submitted). Final metrics were those with significance values of <0.05 and Spearman correlations of |0.50| with the LDI. Final metrics were also tested for bivariate correlation using Spearmans r. Metrics with bivariate correlations (r |0.80|) reduced to one metric based on the strength of the correlations with the LDI. All metric evaluation were conducted with SAS (SAS Institute, Cary N.C., version 8.02).

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19 Sensitive and tolerant taxa The use of Indicator Species Analysis (ISA) as a method of identifying species with specificity (i.e., exclusive to a given group) and fidelity (i.e., always present within a given group) to ecological conditions is growing in ecological literature (Chytry et al. 2002). The randomization test and the corresponding p-value provide a statistically rigorous and defensible presentation of identified species (McCune and Grace 2002). Indicator Species Analysis (Dufrene and Legendre 1997) with non-transformed abundance data identified species with significant association to LDI classification of impaired or reference conditions. ISA, available in PCOrd, contrasts the fidelity of species between a priori defined groups (in this case, sites with LDI<2.0 or LDI2.0) using the algorithms of Dufrene and Legendre (1997). First, the mean abundance (xkj) of species j in group k was calculated by examining the proportional abundance of species j in group k relative to species j in all groups. Second, the relative abundance (RAkj) of species j in group k was calculated by dividing the mean abundance (xkj) by abundance in each group. The proportional frequency (RFkj) of species j in group k was then calculated by summing the total occurrences (presence) of species j in group k and dividing by the number of sample units in group k. The two proportions (RAkj and RFkj) combined in the following equation that solves for IndValkj, the indicator value of species j for group k: IndValkj = 100 (RAkj RFkj) As RA and RF are multiplied, both must be high for IndVal to be high. Additional descriptions of ISA may be found in McCune and Grace (2002). A Monte Carlo test with 10,000 permutations and p-value of 0.10 was used to test significance of the indicator species for a particular group k (i.e., sites with LDI<2.0 or LDI2.0). The abundance of species with significant specificity and fidelity to reference or impaired conditions (i.e., sensitive and tolerant taxa) was assessed for each site and correlated with the LDI. Autecological metrics An ecological indicator value based on published tolerances to particular physical/chemical condition for each diatom species identified was determined using a coded checklist of autecological guilds (Appendix C; Bahls 1993, Van Dam et al. 1994). Bahls (1993) categorized diatoms in Montana streams as very tolerant, tolerant, or sensitive to pollution based on initial classifications of Lange-Bertalot (1979) and Lowe (1974). Van Dam et al. (1994) provided a list of attributes describing the tolerance of European diatoms to varying pH, salinity, dissolved oxygen content, nutrient enrichment, and saprobic conditions, which Fore (2003) and Fore and Grafe (2002) used to develop indicators for streams in Mid-Atlantic states and large rivers in Idaho, respectively. As agricultural operations can increase soil alkalinity through fertilizer application, and evaporative salts from irrigation can be transported into wetlands through precipitation (Leland and Porter 2000, Fore and Grafe 2002), it was expected that alkaliphilous diatoms and diatoms that tolerate higher salinity would increase with increasing agricultural operations (and hence LDI scores). Agrochemical fertilizers, as well as direct application of cattle wastes on the landscape, increase nutrient loading into aquatic systems (Flaig and Reddy 1995, Reddy et al. 1996, Reddy et al. 1998). It was

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20 therefore anticipated that diatoms tolerant of higher nutrient levels and saprobity (or biodegradable organic matter and low dissolved oxygen levels), as well as higher trophic state (driven by high levels of inorganic nutrients), would increase with increasing LDI scores. In contrast, acidophilous diatoms and those indicative of low salinity would be expected to dominate wetlands in reference conditions. Similarly, diatoms sensitive to nutrient enrichment, low dissolved oxygen and saprobic conditions would be expected to decrease with increasing LDI scores. For each of the autecological guilds identified by Van Dam et al. (1994) and the pollution tolerance value of Bahls (1993), diatoms were coded (guilds with between 3 and 7 categories) to denote tolerance to environmental variables. The ordinal trophic classes of Van Dam et al. (1994), oligotraphentic and oligo-mesotraphentic, were combined into a single class as these diatoms indicative of low-trophic status were expected to respond in a similar fashion to increasing LDI scores. The abundance of diatoms for each class was determined for each autecological index. The abundance of diatoms for each class was then correlated (Spearmans r) with the LDI score for each site. Bivariate correlations between taxa guild values were assessed using Spearmans r, and a tolerance of r |0.80| was arbitrarily established to delimit highly correlated guild values. Guilds having lower correlations with the LDI were parsed. The median abundances for potential metrics based on autecological indices between LDI classes were tested with the Mann-Whitney U-test. Constructing the Multimetric Index To complete development of the multimetric index of wetland condition based on diatom metrics, it was necessary to scale the metrics to a uniform ranking so they could be added together and a single value representative of wetland condition be obtained (Karr and Chu 1999). In this study, metrics were scored into four categories: 0,3,7, and 10, based on quartile scores for the 95th percentile of each metric (Mack 2001). A hypothetical example of this scoring is presented in Figure 2-2. Using the 95 th percentile decreases the influence of outliers on metric scoring (Mack 2001). For measures that decreased in abundance with increasing LDI scores, the lowest quartile was given a 0, the next quartile a 3, the third a 7, and the highest and last quartile a 10. This scale was inverted for measures that increased in abundance with increasing LDI scores. Results Wetland Diatom Composition Seventy herbaceous depressional wetlands throughout peninsular Florida with standing water were sampled in 1999 and 2000. Twenty-three were sampled in the South region, thirty in the Central region, and seventeen in the North region. Based on the dominant land use around the wetland, twelve sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. Two hundred ninety-nine diatom taxa from the combined three diatom types were identified. Seventy benthic and sixty-nine epiphytic and phytoplanktonic samples were enumerated and identified, as data were incomplete for two sites: (IFASII epiphyton and CMWRef phytoplankton). The average count of frustules for benthic diatoms was

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21 4321 6050403020100 LDI Proposed Metric Score: 10Score: 7Score: 3Score: 0 Figure 2-2. Hypothesized example of metric scoring using the 95 th percentile of the dataset. The scoring would switch for metrics that increase with increasing LDI scores. 261.6 (+/19.7) and for epiphytic diatoms, 265.5 (+/31.9). The sparse nature of the phytoplanktonic diatoms resulted in an average of 67.9 diatoms identified in each sample and a high standard deviation of 57.7. One hundred ninety-five diatom taxa were identified in the benthic samples, one hundred seventy-four in the epiphytic samples, and two hundred forty-four in the phytoplankton samples. Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity were calculated for each site (Brower et al. 1990). Summary statistics are presented in Tables 2-1 to 2-3. Tukeys HSD results (Table 2-4) indicated that richness was significantly higher in phytoplankton and benthic diatoms than in epiphyton. No significant differences were found for measures of evenness and Simpsons diversity measure, but phytoplankton and benthic diatoms, and benthic diatoms and epiphytic diatoms, did not significantly differ for Shannon diversity values (see Table 2-4). No significant differences were found for measures of richness, evenness, Shannon diversity, or Simpsons diversity between impaired and reference sites for all diatom types (Mann-Whitney U-test, Table 2-5). Alpha (richness), beta, and gamma diversity values for each diatom type and wetland condition are given in Table 2-6. Beta and gamma diversity were higher in phytoplankton samples than at the other samples despite the low numbers of diatoms identified at each site. Beta diversity was higher in impaired sites for epiphytic and phytoplanktonic diatoms, while gamma diversity in impaired sites was higher than in reference sites for all three diatom types sampled.

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22 Table 2-1. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for benthic diatoms. Name S E H D` Name S E H D` Audubon 14 0.824 2.176 0.8380 Immokalee 23 0.879 2.756 0.9206 BearScat 32 0.884 3.064 0.9336 IRBlueCypress 21 0.627 1.908 0.6833 BigCow 33 0.866 3.028 0.9296 IRCanal 12 0.675 1.676 0.6772 BRSebastian 14 0.791 2.088 0.8246 IROJ 28 0.857 2.857 0.9191 CabPatch 10 0.705 1.623 0.6885 JD6 14 0.818 2.159 0.8373 Caravelle 22 0.884 2.731 0.9194 KellyPark 11 0.847 2.031 0.8318 Chuluota 23 0.817 2.561 0.8862 LCork 26 0.847 2.759 0.8962 CLBayard 13 0.752 1.928 0.8053 LEGo 17 0.864 2.449 0.8913 CLCove 19 0.805 2.370 0.8694 LESuwan 20 0.861 2.579 0.9081 CMWPast 24 0.820 2.606 0.8885 LLeeCounty 21 0.828 2.522 0.8769 CMWRef 20 0.760 2.277 0.8359 MALudy 16 0.712 1.973 0.7781 COBurgle 21 0.827 2.518 0.8887 MASpray 15 0.643 1.741 0.7564 COHole 22 0.848 2.622 0.8872 McArthur 23 0.666 2.089 0.7236 Crew 24 0.799 2.540 0.8654 MNElmer 16 0.725 2.009 0.7628 Deerfly 21 0.899 2.737 0.9171 MNOcala 14 0.862 2.275 0.8769 DEMelon 18 0.661 1.912 0.7495 MRPepper 26 0.813 2.649 0.8819 Garber 18 0.734 2.122 0.8230 Myakka 14 0.827 2.182 0.8504 GbarE 18 0.751 2.171 0.7914 OKCara 17 0.861 2.439 0.8854 GLDonut 28 0.797 2.654 0.8967 OKKISS 14 0.842 2.221 0.8476 GLPont 26 0.797 2.597 0.8624 OKPast 22 0.807 2.493 0.8791 Goethe 14 0.820 2.165 0.8536 PacificTom 17 0.825 2.338 0.8697 GreenSwamp 23 0.893 2.800 0.9212 PallMar 14 0.717 1.892 0.7778 HagueI 18 0.812 2.346 0.8759 PBCorbett 11 0.745 1.787 0.7686 HagueII 33 0.894 3.126 0.9424 PBEnjay 10 0.738 1.698 0.7783 HalfMoon 16 0.827 2.294 0.8711 Penner 13 0.483 1.240 0.4755 HARare 19 0.766 2.255 0.8575 POWales 10 0.757 1.744 0.7956 HEBad 9 0.796 1.748 0.7885 POWeowak 19 0.816 2.404 0.8797 HEL2 16 0.768 2.129 0.8178 RiceCreek 20 0.895 2.680 0.9178 HEOkay 20 0.869 2.605 0.8998 SandhillCrane 11 0.661 1.585 0.6512 HighPast 23 0.828 2.597 0.8884 SANorthMya 11 0.815 1.954 0.8178 HighRef 22 0.882 2.726 0.9160 SAOscer 12 0.733 1.820 0.7762 HillsRef 23 0.914 2.865 0.9322 Savannas 16 0.811 2.250 0.8412 HuntCamp 30 0.879 2.989 0.9298 STCow 14 0.672 1.773 0.7398 IFASI 15 0.802 2.173 0.8431 UNHealthy 19 0.846 2.491 0.8915 IFASII 12 0.791 1.966 0.8210 Weikiva 9 0.481 1.057 0.4270

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23 Table 2-2. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for epiphytic diatoms. Name S E H D` Name S E H D` Audubon 14 0.736 1.943 0.7716 IRBlueCypress 16 0.673 1.865 0.7372 BearScat 19 0.858 2.526 0.8888 IRCanal 20 0.753 2.255 0.8312 BigCow 27 0.862 2.841 0.9220 IROJ 18 0.813 2.350 0.8597 BRSebastian 10 0.784 1.806 0.7785 JD6 14 0.754 1.989 0.8054 CabPatch 33 0.916 3.201 0.9493 KellyPark 11 0.733 1.758 0.7610 Caravelle 16 0.833 2.309 0.8732 LCork 13 0.716 1.836 0.7423 Chuluota 12 0.756 1.878 0.7772 LEgo 11 0.920 2.206 0.8808 CLBayard 7 0.713 1.388 0.7151 LESuwan 20 0.883 2.645 0.9126 CLCove 9 0.760 1.669 0.7463 LLeeCounty 20 0.870 2.607 0.9034 CMWPast 12 0.756 1.879 0.7944 MALudy 16 0.705 1.954 0.7649 CMWRef 18 0.846 2.445 0.8841 MASpray 8 0.662 1.376 0.7101 COBurgle 15 0.706 1.912 0.7493 McArthur 14 0.602 1.589 0.6392 COHole 12 0.759 1.885 0.8026 MNElmer 13 0.769 1.973 0.8199 CREW 21 0.888 2.705 0.9168 MNOcala 14 0.817 2.156 0.8464 Deerfly 16 0.792 2.197 0.8366 MRPepper 28 0.834 2.778 0.8810 DEMelon 23 0.802 2.516 0.8770 Myakka 16 0.802 2.224 0.8477 Garber 16 0.642 1.779 0.6725 OKCara 18 0.828 2.394 0.8739 GbarE 12 0.437 1.086 0.4106 OKKiss 13 0.736 1.889 0.7722 GLdonut 15 0.774 2.097 0.8129 OKPast 21 0.709 2.159 0.7994 GLpont 14 0.866 2.287 0.8775 PacificTom 19 0.837 2.465 0.8755 Goethe 14 0.798 2.106 0.8367 PallMar 10 0.818 1.884 0.8183 GreenSwamp 18 0.895 2.588 0.9078 PBCorbet 20 0.786 2.355 0.8742 HagueI 15 0.750 2.031 0.8071 PBenjay 11 0.815 1.955 0.8175 HagueII 28 0.902 3.006 0.9359 Penner 9 0.507 1.114 0.4502 HalfMoon 13 0.826 2.118 0.8475 POWales 7 0.889 1.730 0.8078 HARare 14 0.853 2.250 0.8660 POWeowak 16 0.847 2.349 0.8795 HEBad 7 0.793 1.544 0.7242 RiceCreek 16 0.766 2.123 0.8107 HEL2 18 0.678 1.960 0.7955 SandhillCrane 25 0.821 2.642 0.8872 HEOkay 19 0.818 2.409 0.8620 SANorthmya 17 0.796 2.257 0.8646 HighPast 17 0.806 2.285 0.8490 SAOscer 13 0.583 1.494 0.6955 HighRef 19 0.767 2.258 0.8243 Savannas 12 0.633 1.574 0.7035 HillsRef 23 0.788 2.471 0.8733 STCow 18 0.758 2.191 0.8224 HuntCamp 12 0.747 1.856 0.7757 UNHealthy 12 0.794 1.973 0.8097 IFASI 15 0.752 2.036 0.8096 Weikiva 11 0.573 1.373 0.5789 Immokalee 12 0.880 2.188 0.8668

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24 Table 2-3. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for phytoplanktonic diatoms. Name S E H D` Name S E H D` Audubon 18 0.739 2.137 0.8197 IRBlueCypress 22 0.864 2.671 0.9004 BearScat 27 0.874 2.881 0.9152 IRCanal 12 0.749 1.862 0.7750 BigCow 36 0.864 3.096 0.9344 IROJ 24 0.868 2.760 0.8998 BRSebastian 14 0.712 1.879 0.7611 JD6 14 0.728 1.921 0.7687 CabPatch 35 0.925 3.290 0.9541 KellyPark 13 0.446 1.143 0.4485 Caravelle 26 0.960 3.129 0.9486 LCork 20 0.704 2.109 0.7544 Chuluota 40 0.998 3.680 0.9744 LEGo 13 0.858 2.201 0.8565 CLBayard 13 0.709 1.819 0.7172 LESuwan 17 0.907 2.569 0.9078 CLCove 14 0.651 1.718 0.6958 LLeeCounty 16 0.824 2.285 0.8569 CMWPast 27 1.000 3.296 0.9630 MALudy 21 0.732 2.230 0.7943 COBurgle 13 0.748 1.920 0.7610 MASpray 10 0.625 1.439 0.6719 COHole 19 0.813 2.394 0.8667 McArthur 15 0.439 1.189 0.4819 CREW 25 0.968 3.116 0.9506 MNElmer 13 0.748 1.919 0.7845 Deerfly 22 0.922 2.850 0.9304 MNOcala 14 0.838 2.211 0.8381 DEMelon 19 0.781 2.299 0.8441 MRPepper 25 1.000 3.219 0.9600 Garber 19 1.000 2.944 0.9474 Myakka 20 0.878 2.631 0.9061 GbarE 16 0.651 1.804 0.6838 OKCara 18 0.852 2.462 0.8854 GLDonut 15 0.719 1.948 0.7634 OKKiss 32 0.975 3.377 0.9612 GLPont 22 0.816 2.521 0.8902 OKPast 22 0.917 2.835 0.9211 Goethe 15 0.986 2.670 0.9273 PacificTom 36 0.952 3.410 0.9595 GreenSwamp 23 0.940 2.949 0.9275 PallMar 16 0.812 2.250 0.8086 HagueI 20 0.974 2.918 0.9408 PBCorbett 16 0.793 2.199 0.8473 HagueII 24 1.000 3.178 0.9583 PBEnjay 12 0.838 2.081 0.8379 HalfMoon 14 0.871 2.300 0.8773 Penner 14 0.750 1.979 0.7628 HARare 15 0.710 1.923 0.7543 POWales 10 0.835 1.922 0.7937 HABad 8 0.690 1.434 0.6892 POWeowak 19 0.801 2.358 0.8736 HEL2 21 0.774 2.356 0.8325 RiceCreek 19 0.833 2.453 0.8782 HEOkay 29 0.883 2.973 0.9313 SandhillCrane 29 0.893 3.005 0.9326 HighPast 8 0.660 1.372 0.6048 SANorthMya 12 0.827 2.056 0.8262 HighRef 12 0.887 2.203 0.8715 SAOscer 9 0.402 0.883 0.3623 HillsRef 21 0.781 2.378 0.8048 Savannas 18 0.736 2.128 0.8048 HuntCamp 9 0.702 1.542 0.6503 STCow 17 0.771 2.183 0.8442 IFASI 11 0.663 1.590 0.6957 UNHealthy 15 0.818 2.215 0.8473 IFASII 26 0.992 3.233 0.9592 Weikiva 12 0.924 2.296 0.8852 Immokalee 24 0.939 2.985 0.9348

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25 Table 2-4. Summary statistics and diatom similarities using Tukeys HSD. Standard Deviation Variable Algal Type N Mean Median S Benthic a 70 18.4 18.0 5.9 Epiphytic b 69 15.7 15.0 5.2 Phyto. a 69 18.8 18.0 7.1 E Benthic a 70 0.792 0.814 0.087 Epiphytic a 69 0.773 0.788 0.094 Phyto. a 69 0.815 0.827 0.132 H Benthic ab 70 2.280 2.276 0.431 Epiphytic b 69 2.101 2.118 0.418 Phyto. a 69 2.236 2.296 0.609 D Benthic a 70 0.834 0.860 0.095 Epiphytic a 69 0.808 0.820 0.097 Phyto. a 69 0.831 0.857 0.124 Note: Diatom types (Benthic, Epiphytic, Phytoplanktonic) with a similar letter superscript were not significantly different at p=0.05. Table 2-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes within benthic, epiphytic, and phytoplanktonic diatom groups. Benthic Diatoms Epiphytic Diatoms Phytoplanktonic Diatoms S (Richness) -1.515 (0.130) -1.780 (0.075) -1.175 (0.240) E 1.306 0.560 0.595 (Evenness) (0.192) (0.576) (0.551) H -0.077 -0.746 -0.169 (Shannon Diversity) (0.939) (0.456) (0.866) D 0.435 0.048 -0.078 (Simpsons Diversity) (0.663) (0.962) (0.938) Comparisons of the fidelity of species to particular habitats (benthic, epiphytic, and phytoplanktonic) were made using PSI and MRPP. For benthic versus epiphytic diatoms, within site PSI ranged from 6% to 89%, and averaged 55% (+/17.2%). Within site PSI ranged from 2% to 78%, and averaged 42% (+/19.0%) for benthic versus phytoplanktonic diatoms. The range between epiphytic and phytoplanktonic diatoms was 1% to 77%, and averaged 46% (+/19.4%). Global comparisons using pooled data (i.e., all benthic diatoms from all sites pooled into a benthic heading versus all epiphytic diatoms from all sites pooled into an epiphytic heading) indicated a

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26 Table 2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland condition. Alpha Diversity Beta Diversity Gamma Diversity All Benthic (n=70) 18.4 10.60 195 Impaired 19.4 7.94 154 Reference 17.4 8.05 140 All Epiphyton (n=69) 15.7 11.08 174 Impaired 16.9 8.70 147 Reference 14.4 6.81 98 All Phytoplankton (n=69) 18.8 12.98 244 Impaired 19.5 10.00 195 Reference 17.9 9.11 163 remarkable lack of fidelity to specific habitats among the diatom community as the benthic and epiphytic communities were 84% similar, the benthic and phytoplanktonic communities were 75% similar, and the epiphytic and phytoplanktonic communities were 76% similar. MRPP results supported the lack of uniqueness between benthic, epiphytic, and phytoplanktonic communities. MRPP analyses (Table 2-7), were completed using both abundance data and simple presence data, and were calculated for both a simultaneous comparison of all three diatom types and an iterative comparison of one type versus another. In all cases, MRPP results indicated no significant differences between the benthic, epiphytic, and phytoplanktonic communities at the conventional p-value of 0.05. Diatom Composition and Environmental Correlates As a lack of habitat fidelity was demonstrated by the benthic, epiphytic, and phytoplanktonic communities, it was necessary to select one community to pursue the development of biological indicators of wetland condition. Selecting multiple communities would double-count the effect of landscape influences on the wetland environment. The criterion for further metric development was to identify the diatom community with the strongest relationship to the environmental parameters, including the LDI score. This was accomplished by examining matrix correlations between abundance values and environmental parameters using the Mantel test, and by examining the NMDS ordination of the abundance values for each diatom community and the correlation of site scores with environmental parameters. Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in Appendix B. Significant differences between impaired and reference conditions, as measured by the Mann-Whitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 2-8). Water color was significantly lower in reference conditions at p<0.10. Colinearity among the variables was recognized for %TC,

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27 Table 2-7. MRPP analyses of the compositional similarity between benthic, epiphytic, and phytoplanktonic diatoms. Test A T p-value Abundance Global Test B vs. E vs. P -0.0005 0.321 0.558 Presence Global Test B vs. E vs. P -0.0008 -0.492 0.262 Abundance B vs. E -0.0020 1.186 0.994 Iterative B vs. P 0.0013 -0.841 0.166 Tests E vs. P -0.0004 0.252 0.503 Presence B vs. E -0.0019 1.012 0.916 Iterative B vs. P 0.0021 -1.262 0.108 Tests E vs. P 0.0016 -0.951 0.151 Note : Abbreviations are B (benthic), E (epiphyton), P (phytoplankton). Global tests refer to simultaneous multivariate tests of the pooled diatoms from all benthic, epiphytic, and phytoplanktonic samples. Iterative tests exclude one group (of three) during the MRPP procedure. Table 2-8. Comparison of the medians of water and soil variables between LDI classes with the Mann-Whitney U-test. Water Values Statistic (Z) p-value Color -1.868 0.062 Specific Conductivity -3.919 <0.001 Turbidity -1.524 0.127 Water pH -4.677 <0.001 Ammonia -2.690 0.007 Nitrates/Nitrites 0.771 0.441 TKN -2.932 0.003 TP -4.836 <0.001 Soil Values Statistic (Z) p-value Soil pH -3.036 0.002 %TC -0.818 0.414 %OM -1.253 0.210 %TN -1.147 0.251 %TP -2.771 0.006

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28 TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the abundance data for benthic, epiphytic, and phytoplanktonic diatoms and the measured environmental parameters and LDI score. The relationship between the matrices was strongest for epiphytic diatoms (Mantels r=0.49, p<0.001). Benthic diatoms (Mantels r=0.39, p<0.001) and phytoplanktonic diatoms (Mantels r=0.30,p<0.001) were also significantly correlated to the environmental parameters, albeit not as strongly as the epiphyton. NMDS ordinations of the diatom community abundance data were able to capture approximately equal total variance in the dataset for each of the three diatom types (total variance for Benthic: 81.1%; Epiphyton: 77.4%; Phytoplankton 80.1%). The stress, or goodness of fit of the ordination was also approximately equal, and indicated an adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). The calculated stress for each diatom was: benthic diatoms: 16.68; epiphytic diatoms: 18.45; phytoplanktonic diatoms: 15.66. Site scores for each diatom community type, overlaid by a vector diagram of environmental variables with strong (r20.30) correlations to the first two axes, are presented in Figures 2-3 to 2-5. A two-dimensional solution was identified for benthic and epiphytic diatoms, and a three dimensional solution was identified for phytoplankton. Total variance accounted for by the ordination of the diatoms was approximately equal between types. The benthic diatom ordination accounted for 81.1% of the variation in the dataset (first axis: 26.2%, second axis 54.9%); 77.4% of the variation in the epiphytic diatom dataset was accounted for by the ordination (first axis: 49.2%, second axis: 28.2%); and 80.1% of the variation was reflected in the ordination of the phytoplankton (first axis: 28.7%, second axis: 36.5%, third axis: 14.8%). The relationship between the first two axes for phytoplankton are shown in Figure 2-5 as the third axis, despite accounting for approximately 15% of the variation in the dataset, had no strongly correlated environmental variables. Correlations of environmental variables with the ordination score for benthic, epiphytic, and phytoplanktonic diatoms are presented in Tables 2-9 to 2-11. Four environmental variables were correlated 0.30 with the ordination scores of benthic and epiphytic diatoms (LDI, soil pH, specific conductivity, and water TP). Three variables were correlated with phytoplanktonic diatoms (LDI, specific conductivity, and soil pH). None of the environmental variables were correlated 0.50 for phytoplanktonic diatoms, while one of four were 0.50 for benthic diatoms and three of four were 0.50 for epiphytic diatoms. Based on results of the Mantel tests and the NMDS ordination scores and correlations, as well as the lack of significant differences between the benthic, epiphytic, and phytoplanktonic communities as measured by MRPP and indicated by high PSI values, a decision to base bioassessment metric development on the epiphytic community was made. The results of the Mantel test indicated that the epiphytic diatom community had a stronger relationship with the measured environmental parameters than either the benthic diatoms or phytoplankton. NMDS ordinations also suggested stronger correlations between epiphytic diatoms and environmental parameters, notably LDI score and water TP, than were found with benthic diatoms, although goodness of fit and percent of variance explained were slightly lower. Phytoplanktonic diatoms were

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29 removed from consideration due to the low Mantel statistic values and weaker NMDS correlations with environmental parameters, most notably the LDI score, as compared to epiphyton or benthic diatoms. Metric Development Regional composition MRPP analyses of the arcsine square root transformed abundance data were completed for epiphytic diatoms to determine if regional factors contributed to epiphyton community composition. When simultaneously compared (i.e., South vs. Central vs. North), diatom distribution did not differ significantly (at p<0.05). However, when Figure 2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of original length for clarity. The percent variance explained by each axis is noted on the axis. The length of the vectors represents the strength of the correlation (all >|0.30|) and the angle represents the direction of maximum change. Four variables are shown: pH (soil pH), Cond (specific conductivity), TP (water total phosphorus), and LDI (Landscape Development Intensity index).

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30 iteratively tested, diatom distribution differed significantly (p<0.05) between the South and North regions, but the differences were insignificant between the South and Central, and the Central and North regions. This was examined further by testing the regional distribution of reference sites and impaired sites. When simultaneously tested, the reference sites differed across all regions (Table 2-12). Reference sites also differed between South and Central regions, and South and North regions, but not between Central and North regions. In contrast, the impaired sites did not differ when simultaneously compared, nor when regions were contrasted, indicating similar species composition across peninsular Florida in disturbed landscapes. Figure 2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 125% of the original length for clarity. The percent of variance explained by each axis is given on each axis. Four environmental variables were strongly (r>|0.30|) correlated with NMDS ordination scores: pH (soil pH), Cond (specific conductivity), TP (water TP), and LDI.

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31 Figure 2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 200% of the original length for clarity. The percent of variance explained by each axis is given on each axis. Three environmental variables were strongly (r>|0.30|) correlated with NMDS ordination scores: Cond (specific conductivity), TP (water TP), and LDI. Indicator species analyses Indicator Species Analysis was used to identify species that exhibited specificity and fidelity to LDI scores of <2.0 (i.e., reference indicators) and 2.0 (i.e., impaired indicators) for each region. The significant species for reference indicators and impaired indicators are presented in Tables 2-13 and 2-14, respectively. Ten indicators of reference conditions were identified in the South region, 12 in the Central region and 4 in the North region. Five impaired indicators were identified in the South region, 12 in the Central region, and 6 in the North region. There was substantial overlap of indicator species between regions.

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32 Table 2-9. Correlations of environmental variables and ordination scores for benthic diatoms. Axis 1 (26.2%) Axis 2 (54.9%) Parameter r 2 tau r 2 tau Soil pH 0.62 -0.55 0.20 0.25 % TN 0.03 0.08 0.02 0.17 TP (mg/kg) 0.01 0.07 0.09 0.23 % OM 0.07 0.14 0.01 0.14 Color (PCU) 0.18 0.25 0.05 0.18 Spec. Cond. (umhos/cm) 0.28 -0.39 0.48 0.51 Turbidity (NTU) <0.01 -0.02 0.06 0.17 Ammonia (mg/L) <0.01 -0.09 0.05 0.19 Nitrate/Nitrite (mg/L) 0.02 0.10 0.02 -0.08 Water TP (mg/L) <0.01 -0.04 0.42 0.49 LDI Score 0.06 -0.20 0.42 0.36 Note : Underlined correlations were 0.30 and were considered strongly correlated with NMDS ordination scores. Kendals tau, a non-parametric measure of association, is also given. Table 2-10. Correlations of environmental variables and ordination scores for epiphytic diatoms. Axis 1 (49.2%) Axis 2 (28.2%) Parameter r 2 tau r 2 tau Soil pH 0.23 -0.34 0.59 -0.58 % TN <0.01 -0.07 0.03 0.08 TP (mg/kg) 0.11 -0.24 <0.01 0.06 % OM <0.01 -0.07 0.08 0.14 Color (PCU) 0.07 -0.17 0.22 0.26 Spec. Cond. (umhos/cm) 0.46 -0.50 0.19 -0.32 Turbidity (NTU) 0.06 -0.15 0.02 0.06 Ammonia (mg/L) 0.03 -0.21 0.02 <-0.01 Nitrate/Nitrite (mg/L) <0.01 <-0.01 0.03 0.17 Water TP (mg/L) 0.53 -0.55 <0.01 0.05 LDI Score 0.63 -0.50 0.02 -0.11 Note : Underlined correlations were r 2 0.30 and were considered strongly correlated with NMDS ordination scores for each site. Kendals tau, a non-parametric measure of association, is also given.

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33 Table 2-11. Correlations of environmental variables and ordination scores for phytoplanktonic diatoms. Axis 1 (28.7%) Axis 2 (36.5%) Axis 3 (14.8%) Parameter r 2 tau r 2 tau r 2 tau Soil pH 0.40 -0.49 0.16 0.27 0.06 0.15 % TN <0.01 0.02 <0.01 0.09 0.040 -0.11 TP (mg/kg) <0.01 <-0.01 0.02 0.11 0.05 -0.15 % OM <0.01 0.03 0.02 0.01 0.05 -0.17 Color (PCU) 0.13 0.20 0.03 0.15 0.19 -0.27 Spec. Cond. (umhos/cm) 0.19 -0.34 0.35 0.45 0.02 0.11 Turbidity (NTU) <0.01 -0.02 <0.01 0.03 0.07 -0.24 Ammonia (mg/L) <0.01 -0.06 <0.01 0.18 0.01 -0.03 Nitrate/Nitrite (mg/L) 0.03 0.12 0.04 -0.15 0.05 -0.18 Water TP (mg/L) <0.01 -0.08 0.28 -0.22 0.11 -0.27 LDI Score 0.11 -0.25 0.38 0.38 0.05 -0.15 Note : Underlined correlations were 0.30 and were considered strongly correlated with NMDS ordination scores for each site. Kendals tau, a non-parametric measure of association, is also given. Table 2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of South, Central, and North wetland regions. Test A T p-value Simultaneous %: S vs. C vs. N 0.0056 -1.254 0.111 Tests P/A: S vs. C vs. N 0.0096 -1.794 0.057 Abundance S vs. C 0.0045 -1.080 0.132 Iterative S vs. N 0.0113 -2.038 0.045 Tests C vs. N -0.0015 0.320 0.533 Presence S vs. C 0.0086 -1.843 0.057 Iterative S vs. N 0.0195 -2.818 0.019 Tests C vs. N -0.0040 0.662 0.711

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34 Table 2-13. Reference site diatom indicator taxa identified using Indicator Species Analysis for each wetland region. Region Indicator Species (LDI <2.0) Observed Ind. Value p-value South Anomoeneis serians acuta 45.5 0.013 Reference Anomoeneis serians brachysira 43.8 0.046 Anomoeneis serians 27.3 0.092 Anomoeneis vitrea 59.5 0.015 Eunotia bilunaris mucophila 45.8 0.054 Eunotia flexuosa eurycephala 27.3 0.091 Eunotia naegelii 63.0 0.014 Frustulia rhomboides crassinerva 32.0 0.084 Frustulia rhomboides saxonica 70.2 0.006 Navicula mediocris 36.4 0.035 Central Anomoeneis serians acuta 38.5 0.009 Reference Anomoeneis serians brachysira 45.9 0.016 Desmogonium rabenhorstianum 44.0 0.016 Eunotia bilunaris mucophila 43.1 0.033 Eunotia denticulata 23.1 0.069 Eunotia paludosa 53.8 0.001 Eunotia paludosa trinacria 46.2 0.002 Eunotia pirla 38.5 0.009 Eunotia soleirolii 30.8 0.027 Eunotia zygodon 38.5 0.010 Frustulia rhomboides 50.3 0.021 Frustulia rhomboides saxonica 81.2 <0.001 North Desmogonium rabenhorstianum 50.0 0.081 Reference Frustulia rhomboides 58.7 0.024 Frustulia rhomboides saxonica 72.0 0.050 Pinnularia subcapitata 68.3 0.098

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35 Table 2-14. Impaired site diatom indicator taxa identified using Indicator Species Analysis for each wetland region. Region Indicator Species (LDI 2.0) Observed Ind. Value p-value South Gomphonema parvulum 58.3 0.005 Impaired Navicula confervacea 58.3 0.005 Nitzschia palea debilis 85.2 <0.001 Nitzschia sociabilis 41.7 0.038 Pinnularia acrosphaeria 33.3 0.094 Central Gomphonema angustatum 29.4 0.054 Impaired Gomphonema gracile 52.9 0.002 Gomphonema parvulum 60.1 0.004 Navicula confervacea 70.3 0.001 Navicula minima 33.9 0.060 Navicula seminulum 45.8 0.018 Nitzschia frustulum 35.3 0.038 Nitzschia gracilis 29.4 0.072 Nitzschia palea 52.2 0.026 Nitzschia palea debilis 77.0 <0.001 Nitzschia sociabilis 30.8 0.089 Pinnularia gibba 37.3 0.067 North Gomphonema parvulum 62.5 0.026 Impaired Navicula difficillima 62.5 0.027 Navicula minima 49.2 0.080 Navicula seminulum 50.0 0.081 Nitzschia palea 58.3 0.033 Nitzschia palea debilis 63.3 0.066 ISA was also used to identify significant indicator species for impaired and reference sites for the combined peninsular regions (South, Central, and North regions; n=69). A total of 43 indicator species were identified for the combined analysis, 22 reference condition indicators and 21 impaired condition indicators (Tables 2-15 and 2-16, respectively). With the exception of two indicators of reference conditions (Eunotia soleirolii and Pinnularia subcapita) and two indicators of impaired conditions (Nitzschia frustulum and N. gracilis) found in regional analyses, there was complete overlap of regional and peninsular indicator species. This was not unexpected considering the lack of significance when composition between regions was simultaneously tested with MRPP. The larger n allowed for greater statistical power in the analysis of indicator species, thus 5 reference indicator species and 9 impaired indicator species were

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36 identified using the peninsular (n=69) dataset that were not in any regional indicator species. Little additional information was garnered from identifying regionally specific indicator species, and 14 additional indicator species were identified using the peninsular dataset. Furthermore, no significant difference was found in the simultaneous multivariate MRPP test of regional significance of community composition. Thus, it was concluded that the remaining analyses would utilize the peninsular dataset. Therefore metrics developed are not regionally specific but apply throughout peninsular Florida. Using the peninsular dataset of indicator species (n=43), the abundance of the indicator species for both impaired and reference conditions were calculated for each site and correlated with the LDI using Spearmans r (Figure 2-6). Correlations for the abundance of reference indicators and impaired indicators are: % Reference Indicators r = -0.66, p<0.001; % Impaired Indicators r = 0.60, p<0.001. The abundance of reference indicators demonstrated a highly variable distribution, especially for LDI values of approximately <3.2. In general, sites with LDI scores of >3.2 were composed of <10% reference indicators. The abundance of impaired indicators suggested a low correlation Table 2-15. Statewide indicators of reference conditions as determined from Indicator Species Analysis. Indicator Species (LDI <2.0) Observed Ind. Value p-value Anomoeneis serians acuta 34.4 <0.001 Anomoeneis serians brachysira 39.1 <0.001 Anomoeneis serians 9.4 0.099 Anomoeneis vitrea 22.0 0.052 Desmogonium rabenhorstianum 26.6 0.027 Eunotia bilunaris mucophila 41.4 0.003 Eunotia denticulata 17.5 0.021 Eunotia flexuosa 20.2 0.099 Eunotia flexuosa eurycephala 9.4 0.093 Eunotia monodon 9.4 0.095 Eunotia naegelii 59.5 0.002 Eunotia paludosa 29.4 0.007 Eunotia paludosa trinacria 29.7 0.017 Eunotia pirla 27.7 0.005 Eunotia rhomboidea 37.0 0.029 Eunotia zygodon 23.1 0.015 Frustulia rhomboides 46.3 <0.001 Frustulia rhomboides crassinerva 17.8 0.046 Frustulia rhomboides saxonica 75.1 <0.001 Navicula mediocris 25.0 0.001 Navicula subtilissima 17.3 0.030 Stauroneis kriegeri 16.6 0.084

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37 Table 2-16. Statewide indicators of impaired conditions as determined from Indicator Species Analysis. Indicator Species (LDI 2.0) Observed Ind. Value p-value Caloneis bacillum 16.2 0.030 Gomphonema angustatum 22.8 0.020 Gomphonema gracile 46.4 0.002 Gomphonema lanceolatum 21.6 0.005 Gomphonema parvulum 60.9 <0.001 Melosira italica 18.9 0.014 Navicula confervacea 59.3 <0.001 Navicula difficillima 35.4 0.001 Navicula minima 33.8 0.002 Navicula molestiformis 13.5 0.053 Navicula pupula rectangularis 15.9 0.057 Navicula seminulum 42.2 <0.001 Nitzschia amphibia 21.2 0.041 Nitzschia microcephala 13.5 0.058 Nitzschia palea 48.4 0.005 Nitzschia palea debilis 76.3 <0.001 Nitzschia palea tenuirostris 15.5 0.065 Nitzschia perminuta 12.3 0.010 Nitzschia sociabilis 32.8 0.002 Pinnularia acrosphaeria 21.6 0.006 Pinnularia gibba 27.5 0.036 with increasing LDI scores until a threshold at approximately 3.7 was reached. At that point, the abundance of impaired indicators increased markedly. Autecological indices One hundred thirty-four of the 174 epiphyton diatom taxa (approximately 77%) had one or more autecological, or ecological indicator, values obtained from Van Dam et al. (1994) and Bahls (1993). On a site-by-site basis, approximately 82% of diatoms found at a given site had ecological indicator values. This ranged from approximately 56% to 100% of the diatoms found in the 69 sampled wetlands. The abundance of each class for the autecological indicator guilds of Van Dam et al. (1994) and Bahls (1993) was calculated for each site and correlated (Spearmans r) with the LDI. Responsive metrics were those with correlations of >|0.50| and significant (p<0.05) correlation coefficients. Bivariate correlations using Spearmans r were calculated for the autecological indices having negative (n=6 metrics) and positive (n=7 metrics) responses with increasing LDI scores. The abundance of diatoms sensitive to nitrogen levels, or tolerating very small concentrations of organically bound nitrogen, was strongly (r = 0.86) correlated with oligosaprobous diatoms (Van Dam et al. 1994, p.

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38 A B Figure 2-6. Indicator species abundance data plotted against the LDI. A) Abundance of Reference Indicators vs. the LDI. B) Abundance of Impaired Indicators vs. the LDI.

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39 120). The percent of diatoms sensitive to elevated nitrogen levels index was maintained, as the abundance of nitrogen-sensitive diatoms was more strongly correlated with the LDI than the abundance of oligosaprobous diatoms (Spearmans r = -0.67 for percent nitrogen sensitive diatoms, r = -0.58 for oligosaprobous taxa). The remaining autecological indices of Van Dam et al. (1994) and Bahls (1993) were significantly (p<0.001) correlated (Spearmans r) |0.50| with the LDI (Table 2-17). A plot of the abundance of diatoms for each uncorrelated metric along the disturbance gradient is Table 2-17. Correlations of autecological abundance data and LDI score. Metric Spearman s r p-value Notes % Tolerate High pH 0.65 <0.001 VD 3 % Require Low pH -0.68 <0.001 VD Class 1 % Require Low Salinity -0.51 <0.001 VD Class 1 % Tolerate High Salinity 0.62 <0.001 VD Class 3 % Sensitive High Nitrogen -0.66 <0.001 VD Class 1 % Tolerate High Nitrogen 0.68 <0.001 VD Class 3 % Require Elevated D.O. -0.63 <0.001 VD Class 1 % Tolerant Low D.O. 0.64 <0.001 VD Class 4 % Meso& Polysaprobous 0.69 <0.001 VD Class 4 % Oligotrophic -0.59 <0.001 VD Classes 1 & 2 % Eutrophic 0.67 <0.001 VD Class 5 % Pollution Tolerant 0.67 <0.001 Bahls Class 1 Note : VD Class and Bahls class represent the autecological index value from Van Dam et al. (1994) and Bahls (1993). Table 2-18. Mann-Whitney U-test of autecological abundance values between impaired and reference conditions. Metric Statistic (Z) p-value % Tolerate High pH -5.288 <0.001 % Require Low pH 5.433 <0.001 % Require Low Salinity 4.067 <0.001 % Tolerate High Salinity -5.171 <0.001 % Sensitive High Nitrogen 5.475 <0.001 % Tolerate High Nitrogen -5.595 <0.001 % Require Elevated D.O. 5.379 <0.001 % Tolerant Low D.O. -5.287 <0.001 % Meso& Polysaprobous -5.381 <0.001 % Oligotrophic 5.048 <0.001 % Eutrophic -5.580 <0.001 % Pollution Tolerant -5.474 <0.001

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40 A) % Sensitive Elevated pH B) % Tolerate Elevated pH C) % Salinity Sensitive D) % Salinity Tolerant E) % Sensitive Elevated Nitrogen F) % Tolerant Elevated Nitrogen Figure 2-7. Diatom abundance for autecological metrics plotted against the LDI gradient. A) % Sensitive Elevated pH, B) % Tolerate Elevated pH, C) % Salinity Sensitive, D) % Salinity Tolerant, E) % Sensitive Elevated Nitrogen, F) % Tolerant Elevated Nitrogen, G) % Sensitive Low D.O., H) % Tolerant Low D.O., I) % Oligotrophic, J) % Eutrophic, K) % Meso-Polysaprobous, L) % Pollution Tolerant.

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41 G) % Sensitive Low D.O. H) % Tolerant Low D.O. I) % Oligotrophic J) % Eutrophic K) % Meso-Polysaprobous L) % Pollution Tolerant Figure 2-7 (Continued).

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presented in Figure 2-7. The Mann-Whitney U-test (Table 2-18) indicated that all medians were significantly different (p0.001) between reference and impaired sites. In general, autecological metrics that decreased with increasing LDI values appeared to have a greater goodness of fit and to be less sensitive to changes in the LDI. The results suggest metrics that increase with increasing LDI score approach a threshold near approximately 3.8. Thereafter, the abundance of the various metrics increases markedly, but with a high variance. The Multimetric Index Two metrics derived from indicator species analysis (Dufrene and Legendre 1997), one metric based on pollution tolerance (Bahls 1993) and eleven metrics identified from autecological indicator values of Van Dam et al. (1994), were selected as final metrics based on the significance and strength of the correlations with the LDI. The quartile values of 95 th percentile and the corresponding values of 0,3,7,10 for each metric are given in Table 2-19. The fourteen metrics were summed to create the Diatom Index of Wetland Condition (DIWC), with a possible range of value from 0 to 140. One site had a summed DIWC value of zero, and one site scored a perfect 140 (Table 2-20). Reference sites averaged 114.5 points, with a standard deviation of 26.3 points and a median value of 122.5. Impaired sites averaged 42.1 points (+/38.3) and had a median value of 33.0. DIWC scores were correlated with the LDI Score for each site: Spearmans r = 0.79, p < 0.001 (Figure 2-8). However, similar to the metrics that comprised the index, the results appear to be highly variable for any given LDI score. Metric sensitivity appears to increase near LDI scores of 3.2. Mann-Whitney U-test results indicate a significant difference between DIWC scores for impaired and reference sites (Z=5.991, p<0.001). Table 2-19. Quadrisect values and the 95 th percentile data for each proposed biological indicator. Metric 95 th Percentile 0 Scores 3 Scores 7 Scores 10 Scores % Reference Indicators 0.789 <0.0279 0.0279 0.2328 >0.2328 0.5620 >0.5620 % Impaired Indicators 0.934 >0.5512 >0.1094 0.5512 0.0001 0.1094 0 % Sensitive Elevated pH 0.445 0 0.0001 0.0234 >0.0234 0.2000 >0.2000 % Tolerant Elevated pH 0.818 >0.4820 >0.2300 0.4820 0.0571 0.2300 <0.0571 % Sensitive Elevated Salinity 0.840 <0.2361 0.2361 0.4221 >0.4221 0.5889 >0.5889 % Tolerate Elevated Salinity 0.405 >0.1000 >0.035 0.1000 0.0001 0.035 0 % Sensitive Elevated Nitrogen 0.811 <0.1349 0.1349 0.3506 >0.3506 0.5590 >0.5590 % Tolerate Elevated Nitrogen 0.589 >0.1622 >0.0118 0.1622 0.0001 0.0118 0 % Sensitive Low D.O. 0.840 <0.1471 0.1471 0.3274 >0.3274 0.5551 >0.5551 % Tolerate Low D.O. 0.350 >0.1195 >0.0228 0.1195 0.0001 0.0228 0 % Meso& Polysaprobous 0.209 >0.1400 >0.0250 0.1400 0.0001 0.0250 0 % Oligotrophic 0.932 <0.2830 0.2830 0.4582 >0.4582 0.6667 >0.6667 % Eutrophic 0.592 >0.2101 >0.0152 0.2101 0.0001 0.0152 0 % Pollution Tolerant 0.368 >0.1594 >0.0239 0.1594 0.0001 0.0239 0 42 42

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43 Table 2-20. Diatom Index of Wetland Condition scores for sampled sites. Sites DIWC Sites DIWC Audubon 36 IRBlueCypress 53 BearScat 72 IRCanal 41 BigCow 18 IROJ 48 BRSebastian 137 JD6 140 CabPatch 28 KellyPark 91 Caravelle 39 LCork 100 Chuluota 131 LLeeCounty 70 CLBayard 100 LEGo 106 CLCove 16 LESuwan 49 CMWPast 111 MALudy 9 CMWRef 134 MASpray 124 COBurgle 15 McArthur 6 COHole 70 MNElmer 55 Crew 118 MNOcala 140 DEMelon 9 MRPepper 35 Deerfly 105 Myakka 100 Garber 86 OKCara 21 Gbare 20 OKKiss 137 GLDonut 9 OKPast 36 GLPont 3 PacificTom 43 Goethe 106 PallMar 140 GreenSwamp 113 PBCorbett 96 HARare 3 PBEnjay 137 HagueI 3 Penner 140 HagueII 22 POWales 137 HalfMoon 134 POWeowak 134 HEBad 29 RiceCreek 93 HEL2 6 SANorthMya 115 HEOkay 49 SAOscer 127 Highpast 33 SandhillCrane 103 HighRef 87 Savannas 140 HillsRef 83 STCow 0 HuntCamp 137 UNHealthy 13 IFASI 128 Weikiva 140 Immokalee 110

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44 Figure 2-8. Diatom Index of Wetland Condition scores for each site plotted against the disturbance gradient. Discussion Diatom Composition and Environmental Correlates It was anticipated that environmental variables would drive the wetland community composition such that low overlap (as measured by PSI and MRPP) would occur between benthic, epiphytic, and phytoplanktonic diatoms, as reported by Pan and Stevenson (1996) and U.S. EPA (2002e). Benthic diatoms were expected to respond strongly to the nutrient and chemical condition of the wetland sediments (Stevenson 2001). Epiphytic diatoms were expected to respond to nutrients from both the soils and water column, as nutrients taken up by plants from sediments are released and readily absorbed by epiphytic biofilms (Stevenson 2001, p. 121). Phytoplanktonic diatoms were expected to respond most strongly to the nutrients and physical/chemical characteristics of the enveloping waters. However, as found by Van Meter-Kasanof (1973), Moss (1981), de Jonge and van Beusekom (1992), there was substantial overlap for each of the wetland diatom communities, indicating a similar response to forcing functions (i.e., pH, specific conductivity, nutrients). The similarities may also be a result of the spatial location of the sampled diatoms. The benthic community, due to the spatial position at the bottom of the water column, likely integrated not only benthic, but also epiphytic and phytoplanktonic diatoms. This purported ability of benthic diatoms to integrate a longer temporal signature of wetland

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45 conditions vis--vis the epiphytic or phytoplanktonic diatoms is a reflection of their position within the wetland and could be considered an advantage to using diatoms for biological assessment (Stevenson 2001, U.S. EPA 2002e). Benthic diatoms were thus likely composed not only diatoms of the benthos, but also of the rain of dead and sloughed-off diatoms from the phytoplankton and epiphyton communities. Epiphytic diatoms were composed not only of the diatoms equipped to thrive on macrophytes, but also of phytoplanktonic and mobilized benthic diatoms that became entangled in the often thick web of tendrils of soft algae growing from the macrophytes. U.S. EPA (2002e, p. 6) considers wetland epiphytic diatoms a reflection of the last couple of months generally meaning the hydrated period for the wetland, although many of the diatoms may persist during periods of drought. The phytoplankton community was composed of diatoms evolved to move within the water column, as well as organisms mobilized from the sediments and plant matter by wind action or disturbances from vertebrates. The phytoplanktonic diatoms generally reflect the shortest period of wetland conditions, as once they fall from suspension, they become assimilated into the benthos (U.S. EPA 2002e). While high similarities (75%) existed on a global level between diatoms found in benthic, epiphytic, and phytoplanktonic communities, a moderate ~50% within-site similarity was identified (using PSI) for the sampled diatom assemblages. These results may be indicative of temporal variations of within-site species abundances, perhaps a reflection of slower or faster responses of diatoms within a particular community to hydrologic or physical/chemical parameters. Strong correlations were found for soil pH, specific conductivity, and LDI score for the sampled assemblages, and benthic and epiphytic diatoms were also strongly correlated with water TP (see Tables 2-9 to 2-11). It is well established that pH and specific conductivity have a controlling effect on diatom species composition (Lowe 1974, Pan and Stevenson 1996, U.S. EPA 2002e), and that these variables are altered by anthropogenic disturbances such as agro-fertilizer application and hydrologic modifications (Fore and Grafe 2002, U.S. EPA 2002e). Likewise, the link between phosphorus and diatom composition is well established (Lowe 1974, Pan and Stevenson 1996, Stevenson et al. 1999 Barbour et al 1999), and a link would be expected between a general impairment indicator (LDI score), which reflects the physical, chemical, and nutrient alterations to the landscape, and wetland diatom species composition (Carpenter and Waite 2000, OConner et al. 2000, Cuffney et al. 2000, Munn et al. 2002, Fore and Grafe 2002, Fore 2003). Despite the high similarity identified with PSI and MRPP, and similar driving forces identified with NMDS, a much stronger relationship with environmental variables (as measured by Mantel tests) was identified with epiphyton than with benthic or phytoplanktonic diatoms. These results (Mantels r values for each assemblage) do not change by more than 0.01 when species that occur in <2 sites are removed (C. Lane, unpublished data). This suggests that the higher richness found in phytoplanktonic and benthic assemblages do not affect the relationship between a particular assemblage and the measured environmental variables through the addition of ecological noise from rare species (Marchant 2002). These results further support the use of epiphytic diatoms as the selected diatom assemblage for analyses.

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46 Diatom Composition and Wetland Regions The lack of significant differences in the composition of epiphytic diatoms between regions, when simultaneously tested with MRPP, was driven by the lack of significant differences in the composition of impaired sites (see Table 2-12). It is theorized that once a wetland crossed a threshold of impairment (e.g., McCormick and Stevenson 1998), whatever effect physiographic (i.e., mineral or organic soil) or climatic variables may have on the community is muted by the driving energies of the impairment (i.e., alterations to specific conductivity, pH, or phosphorus levels). Thus, there were no significant differences among epiphytic diatoms in impaired sites throughout peninsular Florida, but a significant difference between diatoms found in reference conditions in each region was identified. The environmental driving forces strongly were specific conductivity, soil pH, water color, and TP (C. Lane, unpublished data). Adding latitude and longitude of each site to the second (environmental variables) matrix resulted in the addition of latitude as a strongly correlated variable (C. Lane, unpublished data). These results again distinguish the importance of specific conductivity, pH, and TP as driving variables of diatom community composition, and also suggest that physiographic or climatic variables associated with the North to South axis of peninsular Florida affect the distribution of diatoms located in reference conditions. The addition of water color as a driving variable in diatom communities follows from the negative effect of darker waters on photosynthesis rates, and the necessity of adaptations to such environments. Metric Development Indicator species analysis Indicator species analysis identified 43 taxa with specificity and fidelity to LDI scores of <2.0 and 2.0. Using the abundance of these taxa provided a metric to measure the relationship between the land use around the wetland and the identified sensitive or tolerant taxa within the wetland. Increased sampling would likely affect the composition of the sensitive and tolerant taxa lists as additional taxa would be found that were significantly related to reference or impaired conditions, while some taxa currently listed as sensitive or tolerant would likely be not significantly related to either classification due to increased sampling size clarifying the relationships in the data. The highly variable abundance of reference indicators, when plotted along the LDI, suggests that reference indicators are likewise highly variable in assessing wetland condition, at least until a threshold of LDI scores of approximately 3.2. After that threshold of measured disturbance is reached, the abundance of reference indicators plummets. Impaired indicator abundance appears to react similarly to increasing LDI values, with a similar threshold of approximately 3.4. However, the accuracy and precision of the impaired indicator abundance at LDI values greater than 3.4, appears to be improved vis--vis the abundance of reference indicators at low development intensity values.

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47 Autecological indices The indices of Van Dam et al. (1994) and Bahls (1993) combined autecological values for diatoms of European and the Mountain-west environments, respectively. That the indices developed elsewhere appear to be valid for diatoms of herbaceous depressional wetlands in peninsular Florida is not surprising, considering their use in identifying various disturbance gradients in large rivers of Idaho (Fore and Grafe 2002), streams of the mid-Atlantic states (Fore 2003), Wyoming (Peterson and Porter 2002), and Maine wetlands (U.S. EPA 2002esee case studies). Not only are many of the diatoms cosmopolitan in their worldwide distribution, but they also exhibit fidelity of response to disturbance gradients throughout the world. As in the abundance of indicator taxa, a threshold near 3.2-3.4 appears to dramatically affect the distribution of site scores. For instance, the abundance of diatoms that tolerate elevated pH, salinity, nitrogen, low D.O., and pollution, as well as the eutrophic and meso-polysaprobous all increase markedly in that range, although there are highly variable distributions for any given LDI above a 3.0. This suggests a threshold of tolerance exists up to approximate LDI values of 3.2. Most metrics that decrease with increasing development intensity do so with accuracy and precision (albeit low), especially when compared with metrics that increase with increasing development intensity. A highly variable response is nevertheless evident for those six metrics, although it appears that the highest variability in the data exists near values of 1.0, as well as around LDI values of 3.2. The Diatom Multimetric IndexConclusion and Recommendations The DIWC, which combines species composition and autecological response for diatoms of herbaceous depressional marshes in Florida, was correlated |>0.75| (p<0.001) with increasing land use modification scores. The high number of metrics (14) provided for a wide-range of responses to various possible perturbations from hydrologic alterations to nutrient loading. However, the metric responses, including that of the DIWC, highlighted discrepancies within the distribution of values along the LDI. The highly variable distribution of metrics for any given LDI value was exhibited by all identified metrics. Thresholds appeared to exists at LDI values near 1.0 and 3.3, although these threshold were muted in the DIWC. These results suggest that LDI values of less than 3.2 could most likely be grouped together into a suite of highly variable reference sites little structure in the data (i.e., correlation with the LDI) appeared to be manifested for values of <3.2. Similarly, the rapid increase in most metric values after 3.2 was also highly variable by site. The sites analyzed in the development of this multimetric index were sampled during the late summer. Research on seasonal and annual variation in the distribution of diatoms, and of the variation in the DIWC for diatoms sampled in different years and seasons is currently underway. In addition, the current DIWC requires that the wetland be hydrated for sampling. However, in this study it was unknown how long a given wetland had been hydrated prior to sampling. Thus, although diatoms may respond very quickly to hydration (Stoermer and Smol 1999), sampling response and subsequent analyses may be confounded by temporal variation in hydration. Current research underway (K. Reiss, University of Florida Department of Environmental Engineering Sciences, personal

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48 communication) will determine the utility of benthic diatoms sampled during dry periods to adequately and accurately reflect the condition of the wetland in question. Should the benthic diatoms prove to be year-round indicators of community condition, this multimetric index constructed on epiphytic diatoms should be reassessed. Finally, epiphytic diatoms are generally expected to change in community composition depending on the macrophytes species to which they are attached (Stevenson 2001). It would be well worth examining, in laboratory settings, community variations among epiphytic diatoms when several different wetland macrophytes species common in both impaired and reference conditions are available for colonization.

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CHAPTER 3 MACROPHYTES AS BIOINDICATORS Introduction Wetland macrophytes are well suited for use as reliable biological indicators of the relative condition of Florida freshwater depressional marshes. Defined as plants growing in water or on a substrate that is at least periodically deficient in oxygen as a result of excess water(Cowardin et al. 1979, pg. 40), wetland macrophytes are ubiquitous and identifying features of marshes throughout Florida. Since wetland plants are sessile (save for a few free-floating species), they are unable to actively avoid perturbations through flight mechanisms. Thus, the community composition of marsh macrophytes, reflect[s] the temporal, spatial, chemical, physical, and biological dynamics of a [wetland] system(Fennessy et al. 2001, pg. 3), and changes in wetland macrophyte community composition may be used to indicate both past perturbations and current conditions (Doherty et al. 2000, Adamus et al. 2001, Fennessy et al. 2001). Reliable biological indicators provide information on the condition of a resource relative to reference, or least disturbed conditions, within an ecologically meaningful region (Barbour et al. 1996, Karr and Chu 1999). Wetland macrophytes possess many advantages for use as reliable biological indicators, most notably their prevalence in wetland systems and response to land use changes (Table 3-1). Wetland macrophytes respond to hydrologic, nutrient, and chemical perturbations associated with increased development to wetland landscape matrices (Adamus and Brant 1990, Adamus 1996, Doherty et al. 2000, Fennessy et al. 2001, Adamus et al. 2001). Changes in wetland macrophyte species abundance and composition along nutrient gradients have been noted Bedford et al. 1999). Compositional changes due to chemical loading (i.e., herbicides; McIntyre et al. 1988), hydrologic alterations (Wood and Tanner 1990, Rochow 1994, David 1994, Busch et al. 1998, MaGee et al. 1999) and to destruction of habitat (Blanch and Brock 1994, Winchester et al. 1995, Dobkin et al. 1998, van Oene et al. 1999, Grace and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000) have also been described for wetland macrophytes. Additionally, well-documented collection methods exist for wetland plants (e.g., Brown 1991, Peet et al. 1996, Fennessy et al. 2001), and definitive identification texts abound that permit identification to the species level in most cases (e.g., Godfrey and Wooten 1979, 1981, Wunderlin 1998). Moreover, unlike typical macroinvertebrate and algal indicators, standing water need not be present for the collection of wetland macrophytes, thus increasing the sampling opportunities for wetland assessment. The use of macrophytes as biological indicators is not without disadvantages. There are seasonal differences in species composition and potential lag times between perturbations and responses (Fennessy et al. 2001). While most wetland plants are easily identified with basic field training, some species may lack diagnostic parts during the sampling window or require expert skills to identify. While detractions from using 49

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50 Table 3-1. Advantages and disadvantages of using macrophytes as biological indicators of wetlands condition. Advantages of Macrophyte Biological Indicators Ubiquitous Features of Wetlands Sessile Organisms Established Taxonomy Great Diversity of Species Ecological Tolerances Well-Known Well-developed Sampling Techniques Disadvantages of Macrophyte Indicators Possible lag time between disturbance and response Field Identification Difficult in Certain Seasons Sampling Window May Only Be the Growing Season Some Species Non-responsive to Perturbations Few Published Documentations of Response to Certain Stressors Note: Modified from Cronk and Fennessy (2001). macrophytes exist (see Table 3-1), wetland macrophytes nevertheless provide clear and robust signals of human disturbance (Cronk and Fennessy 2001, p. 373). Recognizing the ability and sensitivity of macrophyte bioindicators to differentiate wetland condition along a gradient of landscape modification, several states have included or are exploring the use of macrophytes in their wetland biological assessment programs (e.g., Ohio: Mack 2001, Montana: Apfelbeck 2000, Minnesota: Gernes and Helgen 1999, Galatowitsch et al. 1999a, North Dakota: Mushet et al. 2002). Additionally, the U.S. Environmental Protection Agencys Biological Assessment of Wetlands Working Group (BAWWG) has supported development of biological assessment criteria, including macrophytes, through funding for state initiatives, workshops, and technical publications (e.g., Doherty et al. 2000, Fennessy et al. 2001, U.S. EPA 2002a). In this chapter, details regarding methods of data analyses and final choices for macrophyte metrics for use in developing biological indicators of wetland condition were given. Analyses of environmental parameters measured (both abiotic and biotic) were also conducted to assess the environmental variables that affected the distribution of macrophyte taxa within wetlands. In addition, metric variation for a given LDI score for the macrophyte metrics was also examined to assess the accuracy and precision of the LDI. Methods Site Selection and Disturbance Gradient Seventy-five isolated depressional marshes (Figure 3-1) were sampled a single timefor macrophyte community composition throughout peninsular Florida in the summers of 1999 (n=35) and 2000 (n=40). Using best scientific judgment, sites were

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51 Figure 3-1. Study site locations and encounter probability for isolated depressional wetlands. Counties shaded darker have a higher density of isolated depressional wetlands <1ha (from U.S. Fish and Wildlife Service 2000). initially stratified into reference (no obvious human modified landscapes within >100m), and impaired (obvious human landscape modification within 100m) categories. Site condition was independently assessed later with the LDI (Brown and Vivas submitted), as noted in the diatom methods section (Chapter 2: Site Selection and Agricultural Development Gradient). Slightly less than half the sites (35) were considered reference sites, generally located in state and federal parks, preserves, and state forests. Wetlands that comprised the remaining 40 sites were located within agricultural landscape matrices and were considered impaired sites (LDI > 2.0). Thirty impaired sites were located in cattle ranches of varying stocking densities, 7 in truck crops (tomatoes, peppers), 2 in citrus groves, and 1 was sampled in a silvicultural forest. Site coordinates and LDI score for each sampled wetland are found in Appendix A. All but five sites were hydrated when sampled.

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52 Field Data Collection Wetland macrophytes were identified and counted in 1m x 5m quadrats along four belt transects. Transects were laid out along each cardinal direction (North, South, East, West) beginning at the wetland edge and extending to the center of the wetland (Figure 3-2). The wetland/upland boundary was determined in the field through plant status (i.e., facultative, obligate, upland) from Tobe et al. (1998) and hydric soil parameters (see U.S. Department of Agriculture 1998). In 1999, the transects continued from the wetland edge until the center was reached or until 15m2 (3 consecutive quadrats) did not change in species composition. (Approximately 2% of the sites had transects not reaching the measured center of the wetland in 1999.) This was changed in 2000 to ensure full characterization of the wetland macrophyte community by collecting data along the entire length of each transect. The presence of living plants was noted within 0.5m along each side of the transect tape for each quadrat from the wetland edge to the center of the wetland. Unknown species were collected, labelled, and pressed for later identification by David Hall of the University of Florida. All collected species were stored in the Howard T. Odum Center for Wetlands herbarium. Figure 3-2. Transect and quadrat locations in a hypothetical depressional wetland.

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53 Drought conditions during 1999 and 2000 field seasons forced the sampling period to be both delayed in its onset and extended in duration to ensure hydration of the sampled wetlands (Table 3-2). Thus, some species encountered lacked the fruiting bodies, flowers, and other parts requisite for identification due to seasonal vagaries in reproduction or growth. All macrophytes found were identified to the lowest level possible, generally species, and entered into the database for further use in metric development. This study focused on taxa identified to species. Table 3-2. Sampling dates for each region. Region Earliest Date 1999 Latest Date 1999 Earliest Date 2000 Latest Date 2000 South Central North August 3 July 23 July 28 November 4 August 17 November 11 August 29 September 9 October 16 October 25 October 26 November 1 Database Development Field data sheets denoting presence of macrophytes within each 1m x 5m quadrat along each of the four transects were transcribed into Microsoft Excel spreadsheets and a Microsoft Access database and error-checked by two people: the person who originally transcribed the data into Microsoft Excel, and another person who reread the original datasheet back to the original transcriber who reviewed the Microsoft Excel output. A master plant list of all plants identified was developed, and ancillary species characteristics from the literature, as well as Coefficient of Conservatism scores (described below), were added to the list. The plant database was linked in such a way that all characteristics could be analyzed by site, transect, or quadrat. Species characteristics Plant species characteristics (listed in Table 3-3) were taken from the literature for use in developing biological indicators. The primary source for these data was Wunderlin (1998), but other sources were also consulted, including Godfrey and Wooten (1979, 1981), Tobe et al. (1998), and the internet-based Atlas of Florida Vascular Plants (Wunderlin and Hansen 2000). Table 3-3. Ancillary data added to the database for each plant species. Family Annual or perennial (biennial plants were incorporated in the annuals) Form: grass, sedge, rush, forbs, vine, fern, tree, shrub, aquatic Deciduous or evergreen Native or exotic Coefficient of Conservatism score

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54 Coefficient of Conservatism Ten expert botanists (Anthony Arcuri, Keith Bradley, Kathy Burks, David Hall, Ashley ONeal, Jim Poppleton, Nina Raymond, Bruce Tatje, John Tobe, and Wendy Zomlefer) were enlisted to assist in identifying species characteristics for use in developing a Coefficient of Conservatism score. The Coefficient of Conservatism (CC) was developed by Wilhelm and Ladd (1988) as part of the Floristic Quality Assessment Index, a method of assessing vegetation in the Chicago area based on expert botanists opinion on the fidelity of a plant species to particular environments. Since its inception, this method has been utilized to assess wetland condition based upon species present in numerous studies (Herman et al. 1997, Fennessey et al. 1998, Mack 2001, Mushet et al. 2002, Cohen et al. submitted). To determine CC scores, the botanists were sent the full list of species encountered during the two sampling seasons (n=397), and were asked to score the plants using the coefficients and definitions given in Table 3-4. The botanists were also asked to weight the confidence of their answers on a 1-3 scale (3 being the most confident). Subsequently, each botanists CC value for each plant was multiplied by each botanists confidence weight for that plant, increasing the proportional representation for extremely confident scores. The score for each plant after confidence weighting was summed and averaged across all botanists, and normalized to a 1-10 scale. See Cohen et al. (submitted) for additional information. Table 3-4. Scoring Criteria for the Coefficient of Conservatism. C of C Description 0 1 3 4 6 7 8 9 10 Alien taxa and those native taxa that are opportunistic invaders or common components of disturbed communities. Widespread taxa that are found in a variety of communities, including disturbed sites. Taxa that display fidelity to a particular community, but tolerant of moderate disturbance to that community. Taxa that are typical of well-established communities that have sustained only minor disturbances. Taxa that exhibit a high degree of fidelity to a narrow set of ecological conditions. Soil and Water Physical-Chemical Sampling and Analysis To relate the distribution of wetland macrophytes to environmental parameters, soil and water physical and chemical parameters were measured at each site as described in Chapter 2 (Methods: Field Data Collection, Sample Preparation and Laboratory Procedures) and Appendix B.

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55 Data Analyses Summary statistics Summary measures of sample richness, Shannon diversity, Simpson diversity, beta, and gamma diversity were calculated for each site and provided information on species distributions vis--vis land use as described in Chapter 2: Data Analyses. Macrophytes-compositional analysis While wetlands throughout peninsular Florida were sampled, the sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions (after Lane 2000, see Figure 3-1). Through examination of data at the regional level, it was expected that variations in species assemblages due to climatic or physiographic differences between sites within a given region would be minimized (Gerritsen et al. 2000, Smogor and Angermeier 2001). To test the significance of the modeled wetland regions on species distribution, a compositional test, the multiple response permutation procedures (MRPP,) available in PCOrd (MjM Software, Gleneden Beach, Oregon, version 4.10) and described in Chapter 2 (Methods: Site Selection and Agricultural Development Gradient), was used. Macrophyte composition and soil and water parameter correlates The following soil variables were arcsine square root transformed to decrease measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Log10 transformations were completed on soil TP, color, specific conductivity, turbidity, ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity among the environmental variables, described as strong correlations between independent variables (Zar 1999), was tested for using the variance inflation factor and tolerance, described in Chapter 2 (Methods: Data Analyses). The non-parametric Mann-Whitney U-test was used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). The relationship between measured environmental values (including LDI score) and species composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS, Kruskal 1974, Mather 1976), both available in PCOrd and described in Chapter 2 (Methods: Data Analyses). A two-dimension NMDS solution was selected for macrophyte taxa as increased dimensionality only marginally improved the fit. Correlations of site scores with environmental parameters, including LDI score and latitude and longitude (decimal degrees), were calculated and a bi-plot of parameters with correlations (Pearsons r 2 0.30) to site scores was constructed. Metric Development Macrophyte metrics were identified from the literature (e.g., Wilhelm and Ladd 1988, Adamus and Brant 1990, Andreas and Lichvar 1995, Adamus 1996, Kantrud and Newton 1996, Gernes and Helgen 1999, Cronk and Fennessy 2001, Mack 2001, Fennessy et al. 2001) or developed from iterative analyses of data response. Metrics were selected

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56 for inclusion in the preliminary Vegetative Index of Wetland Condition (VIWC) if they demonstrated a constant and predictable change with increasing Landscape Development Intensity (LDI) scores as measured by the Spearman correlation coefficient. Final metrics were those with significant (p<0.05) Spearmans correlations |0.50| with the LDI. Metrics were also tested for their ability to discern between the classification of sampled wetlands in impaired (LDI 2.0) and reference (LDI <2.0) landscapes using the nonparametric Mann-Whitney U-test. Additionally, to normalize wetlands of different sizes, metrics that incorporated the enumeration of species (such as the count of exotic species encountered at a site) were changed into abundance values by dividing the sum of the metric by the total number of plants identified to species at a site. All evaluations of potential metrics were conducted with SAS (SAS Institute, Cary N.C., version 8.02). Based on preliminary data analysis and the strength of the metric correlation with the LDI, the macrophyte metrics described below were selected for inclusion in each wetland region. Sensitive and tolerant species Indicator Species Analysis (ISA, Dufrene and Legendre 1997) was utilized to identify species with a significant association with LDI classification of impaired (LDI2.0) or reference conditions (LDI<2.0) as described in Chapter 2 (Metric Development). Exotic species The percent of total species exotic to Florida at a wetland site was calculated by dividing the number of exotic species encountered by the total number of species found at the site. Native or exotic plant status was determined using Tobe et al. (1998), Wunderlin (1998), Godfrey and Wooten (1979, 1981), Langeland and Burks (1998), and Wunderlin and Hansen (various dates 2000). In general, exotic species were those thought to have not been present in Florida before European settlement of North America. The abundance of exotic species was expected to increase with increasing development of the landscape surrounding the wetland (Fennessy et al. 2001). Annual to perennial ratio The ratio of annual to perennial (A:P) species was calculated for each wetland. The trend expected was that as development increased in a wetland landscape matrix, the proportion of weedy, or annual species versus perennial species would increase (Edwards and Weakley 2001). Life-history status (i.e., annual/perennial) was determined from the literature for each species identified, and a ratio was determined for each wetland. Average Coefficient of Conservatism To obtain an average CC score for each wetland sampled, the sum of the confidence weighted CC values for each plant found at the sampled wetland was divided by the total number of plants sampled. The resultant CC score provided an estimate of the

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57 conservatism of the plants encountered. As development increased within the wetland landscape matrix, the CC score for the wetland was expected to decrease, indicating the presence of both plants with more general habitat requirements and exotics. Vegetative Index of Wetland Condition To create a multi-metric index of wetland condition based on metrics that were strongly correlated with the LDI, it was necessary to score the proposed metrics. Scoring allows the disparate metrics (i.e., such as ratios and relative abundance metrics) to be summed to provide a numerical score for the condition of the wetland to compare vis--vis a set of reference wetlands within a given region (Karr and Chu 1997). Scoring methods are described in Chapter 2 (Methods: Constructing the Multimetric Index). Following the metric scoring, the Vegetative Index of Wetland Condition was determined for each wetland sampled by summing the scored metrics. Results Field Data Seventy-five herbaceous depressional wetlands throughout peninsular Florida were sampled in 1999 and 2000. Twenty-three were sampled in the South region, thirty in the Central region, and twenty-two in the North region. Based on the predominant land use around the wetland, twelve of the sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. Three hundred and ninety-seven different taxa from 207 plant genera representing 111 families were identified during the 1999 and 2000 field seasons. Two hundred twenty-six taxa were identified in the South region, 270 taxa were identified in the Central region, and 242 taxa were identified in the North region; many species were found in more than one region. Summary measures of sample richness, Shannon diversity, and Simpson diversity were calculated for each site (Brower et al. 1990). Summary statistics are presented in Table 3-5. Mann-Whitney U-tests indicated no significant difference between reference and impaired sites for richness, Shannon diversity, or Simpson diversity (all tests Z = -0.005, p = 0.996). Two additional indices were also calculated from the macrophyte data: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Beta and gamma diversity were higher in impaired sites than in reference sites (impaired sites average richness: 31.60, beta diversity: 9.81, gamma diversity: 310; reference sites average richness: 31.66, beta diversity: 8.18, gamma diversity: 259). Ancillary Data A histogram of the distribution of CC scores for the species identified is given in Figure 3-3. As the data were normalized, the mean of the distribution is 5.0, while the median value is 5.56, and the standard deviation is 2.57. The plant with the highest conservatism score (10) was Coelorachis tuberculosa. In general, exotic species and invasive native species were given scores of zero. However, several exotic species, such as Xyris jupicai (CC = 3.51), were given higher scores by the botanists, indicating a

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58 Table 3-5. Summary statistics of richness (S), Simpsons diversity index (H) and Shannon diversity index (D) for macrophytes. Site Name S H D` Site Name S H D` ALPaynes 28 3.332 0.9643 IRCanal 22 3.091 0.9545 Audobon 16 2.773 0.9375 IROJ 43 3.761 0.9767 Bear Scat 39 3.664 0.9744 JD6 33 3.497 0.9697 Big Cow 34 3.526 0.9706 Kelly Park 27 3.296 0.963 BRSebastian 24 3.178 0.9583 LCork 48 3.871 0.9792 CabPatch 34 3.526 0.9706 LLeeCounty 58 4.06 0.9828 Caravelle 22 3.091 0.9545 LEGo 41 3.714 0.9756 Chuluota 41 3.714 0.9756 LESuwan 42 3.738 0.9762 CLBayard 20 2.996 0.95 MALudy 54 3.989 0.9815 CLCove 34 3.526 0.9706 MASpray 24 3.178 0.9583 CMWPast 39 3.664 0.9744 McArthur 29 3.367 0.9655 CMWRef 21 3.045 0.9524 MNElmer 45 3.807 0.9778 COBurgle 16 2.773 0.9375 MNErik 38 3.638 0.9737 COHole 25 3.219 0.96 MNOcala 38 3.638 0.9737 Crew 31 3.434 0.9677 MRPepper 46 3.829 0.9783 DEMelon 41 3.714 0.9756 Myakka 35 3.555 0.9714 Deerfly 31 3.434 0.9677 OKCara 47 3.85 0.9787 GarberRanch 22 3.091 0.9545 OKKiss 37 3.611 0.973 GBarE 28 3.332 0.9643 OKPast 28 3.332 0.9643 GLDonut 24 3.178 0.9583 PacificTom 37 3.611 0.973 GLPont 20 2.996 0.95 Pall-Mar 17 2.833 0.9412 Goethe 24 3.178 0.9583 PBCorbett 33 3.497 0.9697 GreenSwamp 34 3.526 0.9706 PBEnjay 43 3.761 0.9767 HaRare 33 3.497 0.9697 Penner 14 2.639 0.9286 HagueI 27 3.296 0.963 POWales 18 2.89 0.9444 HagueII 21 3.045 0.9524 POWeowak 44 3.784 0.9773 Half Moon 37 3.611 0.973 PUPond 19 2.944 0.9474 HEBad 37 3.611 0.973 RiceCreek 16 2.773 0.9375 HEL2 18 2.89 0.9444 SANorthMya 31 3.434 0.9677 HEOKAY 46 3.829 0.9783 SAOscer 38 3.638 0.9737 HighPast 16 2.773 0.9375 SandhillCrane 35 3.555 0.9714 HighRef 23 3.135 0.9565 Savannas 41 3.714 0.9756 HillsRef 43 3.761 0.9767 STCow 40 3.689 0.975 Hunt Camp 26 3.258 0.9615 SUVaca 37 3.611 0.973 IFASI 26 3.258 0.9615 SUWarhol 33 3.497 0.9697 IFASII 27 3.296 0.963 UNHealthy 30 3.401 0.9667 Immokalee 26 3.258 0.9615 Wekiva 15 2.708 0.9333 IRBlueCypress 42 3.738 0.9762

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59 Figure 3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted scores for wetland macrophytes. perceived higher fidelity to a narrower set of ecological conditions. A list of species identified and their corresponding CC scores is given in Appendix D. Compositional Analysis A matrix of the co-occurrence of identified species in the wetland regions of Florida is presented in Table 3-6. The co-occurrence of species found in reference and impaired sites for the three wetland regions are also given in Table 3-6. The South and North regions shared the fewest species, slightly more than half, while approximately 60% of the plants found in the Central region were also found in the North or South regions. The Central region was also most similar to the North and the South regions for both impaired and reference plants. Tests of compositional similarities between wetland regions (Lane 2000) were conducted using MRPP (Table 3-7). Significant differences in compositional similarity among wetland regions were identified for both simultaneous (i.e., South vs. Central vs. North) and iterative tests (i.e., South vs. Central, South vs. North, Central vs. North). When reference sites were compared, significant differences were also identified for both simultaneous and iterative tests. Tests of impaired sites indicated significant differences when simultaneously tested, however, iterative tests found only significant difference between impaired sites of the South and North regions at p<0.05. The iterative tests of impaired sites between all regions were significantly different at p<0.10.

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60 Table 3-6. Co-occurrence matrices of macrophytes by region and impairment condition. Condition Region South Central North All Sites South 100.0 %61.9 %52.3 % (n=75) Central 73.4 %100.0 %66.9 % significant lower in reference conditions at p<0.10. North 56.6 %60.0 %100.0 % Reference South 100.0 %54.4 %47.8 %(n=35) Central 58.1 %100.0 %65.7 % North 43.2 %55.7 %100.0 % Impaired South 100.0 %58.2 %47.9 %(n=40) Central 67.9 %100.0 %55.8 % North 56.2 %56.1 %100.0 % Table 3-7. Simultaneous and iterative tests of community composition among regions. Test Comparison A T p-value Simultaneous Tests: All Sites S vs. C vs. N 0.0211 -6.235 < 0.001 Simultaneous Reference Only S vs. C vs. N 0.0502 -7.198 < 0.001Simultaneous Impaired Only S vs. C vs. N 0.0176 -3.137 0.005 Iterative S vs. C 0.0120 -3.330 0.010Tests: S vs. N 0.0323 -8.066 < 0.001All Sites C vs. N 0.0075 -2.156 0.039 Iterative S vs. C 0.0300 -4.156 0.001Tests: S vs. N 0.0690 -7.492 < 0.001Reference Only C vs. N 0.0204 -2.961 0.010 Iterative S vs. C 0.0094 -1.703 0.060Tests: S vs. N 0.0022 -3.096 0.009Impaired Only C vs. N 0.0110 -1.873 0.050 Note : S = South region, C = Central region, N = North region Community Composition and Environmental Gradients Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in the Appendix B. Significant differences between impaired and reference conditions, as measured by the MannWhitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 3-8). Water color was

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61 Table 3-8. MRPP comparison of the median values of water and soil variables between reference and impaired sites. Water Values Statistic (Z) p-value Color -1.868 0.066 Specific Conductivity -3.919 < 0.001 Turbidity -1.524 0.127 Water pH -4.700 < 0.001 Ammonia -2.707 0.007 Nitrates/Nitrites 0.782 0.437 TKN -2.932 0.003 TP -4.836 < 0.001 Soil Values Statistic (Z) p-value Soil pH -2.894 0.004 %TC -0.616 0.538 %OM -1.105 0.269 %TN -0.924 0.356 %TP -2.719 0.008 Colinearity among variables, which was identified as a VIF>5.0 and a tolerance of <0.20, was recognized for %TC, TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the identified macrophytes and the measured environmental parameters, including LDI score. Results indicated a strong and significant relationship (Mantels r = 0.49, p=0.001). An NMDS ordination was completed to examine the underlying structure of the sites in ordination space and to ascertain the environmental variables driving the composition of sites sampled. Correlations for all measured environmental variables are presented in Table 3-9, and a biplot of site ordination overlaid with vectors representing the environmental variables is presented in Figure 3-4. The stress, or goodness of fit of the ordination was 21.11 and indicated a marginally adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). Likewise, the final instability after 400 iterations was 0.00399, which was higher than the ideal instability (<0.001) but nevertheless a generally acceptable instability value (McCune and Grace 2002). The ordination indicated that 74.5% of the variance in the dataset was captured by the two dimensional ordination (first axis: 42.5%, second axis:33.0%). The ordination scores for each site were linearly correlated (Pearsons r) with the measured environmental values, including LDI, latitude, and longitude. Correlations (Pearsons r2) > 0.30 were found for LDI: 0.66, soil pH 0.57, water TP: 0.48, latitude: 0.39, and specific conductivity: 0.33, indicating their importance in driving the structure of the wetland macrophyte community.

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62 Table 3-9. Correlations of environmental variables and ordination scores. Axis 1 (42.5%) Axis 2 (33.0%) Parameter r2 tau r2 tau Soil pH 0.14 0.26 0.57 0.57 % TN <0.01 0.14 0.16 -0.21 TP (mg/kg) 0.20 0.32 0.05 -0.13 % OM 0.02 0.14 0.22 -0.27 Color (PCU) 0.11 0.21 0.08 -0.17 Spec. Cond. (umhos/cm) 0.33 0.40 0.10 0.23 Turbidity (NTU) 0.07 0.15 0.01 -0.05 Ammonia (mg/L) 0.07 0.24 0.03 -0.07 Nitrate/Nitrite (mg/L) <0.01 -0.05 0.05 -0.20 Water TP (mg/L) 0.48 0.52 <0.01 -<0.01 LDI Score 0.66 0.56 0.11 0.22 Latitude (decimal degrees) 0.01 0.07 0.39 -0.45 Longitude (decimal degrees)0.01 0.04 0.03 -0.14 Metric Development Significant regional differences were identified in species composition, hence initial metric development focused on identifying regionally specific bioindicators with strong correlations with the LDI. It was anticipated that due to the regionally distinct composition of the isolated depressional herbaceous wetlands, the final metrics would likewise vary for each region. However, though the composition of the wetlands varied between regions, the suite of final metrics that had significant correlations with p-values <0.05 and Spearmans correlation coefficients of r >|0.50| with the LDI gradient (% Sensitive, % Tolerant, % Exotic, Average CC, and A:P ratio) did not vary, indicating a common response of wetland systems to increases in land use development. Sensitive and tolerant species Indicator species analysis (ISA) identified 39 taxa as indicative of reference conditions and 26 taxa as indicative of impaired conditions (Tables 3-10 and 3-11, respectively). Thirty-four were identified in the South region (22 reference, 12 impaired), 45 in the Central region (27 reference, 18 impaired), and 8 in the North region (2 reference, 6 impaired). Correlations of the abundance of species indicative of reference conditions (% Sensitive) and impaired conditions (% Tolerant) with the LDI were significant (p<0.001) and >|0.70| for all regions (Table 3-12). There was moderate overlap of indicator species between regions, with 33.9% (22/65) occurring in more than one region.

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63 Figure 3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of original length for clarity. The percent variance explained by each axis is noted on the axis. The length of the vectors represents the strength of the correlation (all >|0.30|) and the angle represents the direction of maximum change. Five variables are shown: soil pH, Cond (specific conductivity), water TP, latitude, and LDI. ISA was also used to identify species with specificity and fidelity to reference and impaired conditions using the peninsular dataset (n=75). While compositional differences existed between regions, it was hypothesized that some taxa would be robust indicators throughout peninsular Florida. It was also hypothesized that increasing the n of the dataset would provide additional power in identifying indicator species. Forty-six species were identified as reference indicator species and 36 were identified as impaired indicators using the peninsular dataset (Tables 3-13 and 3-14, respectively). There was substantial overlap between regional and peninsular indicator species. Three regional impaired indicator species (South Region: Axonopus furcatus, Central Region:

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64 Table 3-10. Regionally derived species indicative of reference conditions. Reference Indicator Species (Sensitive Species) South Central North Amphicarpum muhlenbergianum (50.1, 0.074) Andropogon virginicus (49.9, 0.010) (61.1, 0.019) Aristida purpurascens (38.5, 0.007) Blechnum serrulatum (47.3, 0.026) Cassytha filiformis (27.3, 0.095) Cladium jamaicense (38.4, 0.070) Eriocaulon decangulare (41.8, 0.086) (69.2, <0.001) Eupatorium leptophyllum (36.4, 0.039) Fuirena scirpoidea (62.7, <0.001) Gratiola ramosa (45.5, 0.015) (38.5, 0.011) Hedyotis uniflora (23.1, 0.074) Hypericum brachyphylum (38.5, 0.008) Hypericum fasciculatum (41.8, 0.088) (61.5, <0.001) Ilex glabra (27.3, 0.087) (38.5, 0.009) Ipomoea sagittata (27.3, 0.090) Iva microcephala (27.3, 0.096) Lachnanthes caroliniana (44.5, 0.062) (49.5, 0.084) Ludwigia linifolia (30.8, 0.027) Lycopodium appressum (27.3, 0.087) Lyonia lucida (23.1, 0.071) Oxypolis filiformis (38.4, 0.069) Panicum erectifolium (85.7, <0.001) (48.5, 0.005) Panicum rigidulum (38.4, 0.069) (30.8, 0.026) Panicum spretum (23.1, 0.073) Panicum tenerum (48.5, 0.005) Paspalum monostachyum (27.3, 0.090) Pinus elliottii (54.5, 0.003) (73.6, 0.002) Proserpinaca pectinata (66.7, <0.001) Rhynchospora fascicularis (23.1, 0.070) Rhynchospora filifolia (36.4, 0.037) (30.8, 0.028) Rhynchospora tracyi (50.4, 0.037) (40.9, 0.027) Scleria baldwinii (23.1, 0.077) Serenoa repens (53.8, 0.001) Stillingia aquatica (45.5, 0.015) Syngonanthus flavidulus (33.4, 0.056) Utricularia purpurea (23.1, 0.072) Woodwardia virginica (58.9, 0.007) Xyris elliottii (23.1, 0.068) Xyris jupicai (38.4, 0.066) (38.5, 0.009) Note: Calculated indicator values and the significance of the indicator value for each species, respectively, are given in parentheses.

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65 Table 3-11. Regionally derived species indicative of impaired conditions. Impaired Indicator Species (Tolerant Species) South Central North Alternanthera philoxeroides (36.4, 0.090) Axonopus furcatus (33.3, 0.087) Bacopa monnieri (41.7, 0.036) Centella asiatica (64.3, 0.002) Commelina diffusa (50, 0.014) (41.2, 0.01) Cuphea carthagenensis (50, 0.013) (41.2, 0.010) Cyperus haspan (40.4, 0.036) Cyperus odoratus (41.2, 0.009) Cyperus polystachyos (58.8, 0.001) (45.5, 0.034) Cyperus surinamensis (29.4, 0.050) Diodia virginiana (70.6, <0.001) (46.8, 0.062) Eclipta prostrata (52.9, 0.003) Eupatorium capillifolium (42.2, 0.072) Hydrochloa caroliniensis (33.3, 0.093) Juncus effusus (75.3, <0.001) (54.5, 0.011) Lindernia grandiflora (33.3, 0.090) Ludwigia octovalvis (33.3, 0.092) Ludwigia peruviana (33.3, 0.095) (41.2, 0.010) Panicum repens (41.2, 0.009) Paspalum notatum (41.2, 0.010) Paspalum urvillei (41.2, 0.010) (36.4, 0.086) Phyla nodiflora (42.3, 0.070) (47.1, 0.010) Polygonum hydropiperoides (52.9, 0.088) Polygonum punctatum (47.3, 0.099) (41.2, 0.010) Pontederia cordata (68.7, 0.005) Setaria parviflora (41.7, 0.040) (29.4, 0.050) Note: Calculated indicator values and the significance of the indicator value for each species, respectively, are given in parentheses. Table 3-12. Spearman correlations of the adundance of regional sensitive and tolerance macrophyte species with LDI scores for each site. Region Comparison Spearmans r p-value South % Sensitive Spp. -0.75 < 0.001 % Tolerant Spp. 0.72 < 0.001 Central % Sensitive Spp. -0.77 < 0.001 % Tolerant Spp. 0.78 < 0.001 North % Sensitive Spp. -0.73 < 0.001 % Tolerant Spp. 0.86 < 0.001

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66 Table 3-13. Indicator species of reference conditions derived from the peninsular dataset. Reference Indicator Species (Sensitive Species) Observed Ind. Val.pvalue Reference Indicator Species (Sensitive Species) Observed Ind. Val.p-value Amphicarpum muhlenbergianum 37.5 0.023 Panicum rigidulum 27.1 0.004 Andropogon virginicus 56.2 <0.001 Panicum tenerum 29.3 0.007Aristida purpurascens 22.6 0.034 Paspalum monostachyum 8.6 0.097Brasenia schreberi 11.4 0.043 Paspalum praecox 8.6 0.100Drosera capillaris 11.4 0.042 Pinus elliottii 47.7 <0.001Eriocaulon decangulare 39.3 <0.001 Proserpinaca pectinata 47.6 <0.001Fuirena scirpoidea 39.8 0.007 Rhexia mariana 30.5 0.009Gratiola ramosa 28.6 <0.001 Rhexia nashii 8.6 0.097Hypericum brachyphylum 24.3 0.011 Rhynchospora filifolia 22.9 0.002Hypericum fasciculatum 44.0 <0.001 Rhynchospora rariflora 14.3 0.019Ilex glabra 29.1 <0.001 Rhynchospora tracyi 29.3 0.005Iva microcephala 11.4 0.046 Rhynchospora wrightiana 8.6 0.098Lachnocaulon anceps 8.6 0.094 Scleria baldwinii 12.2 0.089Lachnanthes caroliniana 37.0 0.007 Scleria reticularis 30.4 0.024Lachnocaulon minus 11.4 0.040 Serenoa repens 30.9 0.002Ludwigia linifolia 18.8 0.036 Stillingia aquatica 14.3 0.019Lycopodium appressum 11.4 0.040 Syngonanthus flavidulus 19.9 0.059Nymphaea odorata 19.9 0.089 Utricularia purpurea 12.2 0.094Nyssa biflora 16.0 0.076 Viola lanceolata 8.6 0.099Oxypolis filiformis 22.6 0.029 Woodwardia virginica 38.4 0.002Panicum chamaelonche 12.2 0.094 Xyris elliottii 17.8 0.025Panicum erectifolium 45.3 <0.001 Xyris jupicai 27.1 0.005Panicum hemitomon 52.5 0.027 Xyris smalliana 16.0 0.073 Note : Taxa marked () were not significant indicator species at the regional level. Calculated indicator values and the significance of the indicator value for each species are also presented. Eupatorium capillifolium, and North Region: Polygonum hydropiperoides), all of which have a statewide distribution (Tobe et al. 1998), were not calculated to be peninsularwide indicator species. Nine regional reference indicator species (South Region: Blechnum serrulatum, Cassytha filiformis, Cladium jamaicense, Eupatorium leptophyllum, and Ipomea sagittata, Central Region: Hedyotis uniflora, Lyonia lucida,Panicum spretum, and Rhyncospora fascicularis), all of which have statewide distributions (with the exception of Cassytha filiformis, which is limited to south and central Florida Wunderlin 1998, Tobe et al. 1998), were not significant indicator species using the peninsular dataset. However, 88.5% (23 of 26) of the regional impaired indicator species and 76.9% (30 of 39) of the regional reference indicator species were also indicator species with the peninsular dataset. The additional power from combining the regional data into a peninsular dataset also allowed for an additional 17 species to be identified as indicator species of reference (7 species) or impaired (10 species) conditions (noted in Tables 3-13 and 3-14).

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67 Table 3-14. Indicator species of impaired conditions derived from the peninsular dataset. Impaired Indicator Species (Tolerant Species) Observed Ind. Val.pvalue Impaired Indicator Species (Tolerant Species) Observed Ind. Val. pvalue Alternanthera philoxeroides 20.0 0.007 Kyllinga brevifolia 12.5 0.058 as the number of reference and impaired sites sampled was not equal for the regions (South reference = 11, Central reference = 13, North reference = 11; South impaired = Aster subulatus 27.4 0.002 Lindernia grandiflora 20.0 0.007 Bacopa monnieri 21.7 0.086 Ludwigia octovalvis 24.9 0.005 Carex albolutescens 12.5 0.059 Ludwigia peruviana 35.0 <0.001 Centella asiatica 43.4 0.032 Ludwigia repens 33.4 0.014 Commelina diffusa 39.8 <0.001 Melochia corchorifolia 12.5 0.058 Cuphea carthagenensis 37.3 <0.001 Panicum repens 32.4 0.006 Cynodon dactylon 12.5 0.057 Paspalum acuminatum 20.0 0.015 Cyperus haspan 24.0 0.052 Paspalum notatum 30.0 0.004 Cyperus odoratus 20.0 0.006 Paspalum urvillei 24.9 0.003 Cyperus polystachyos 45.0 <0.001 Phyla nodiflora 37.3 <0.001 Cyperus retrorsus 12.5 0.055 Polygonum punctatum 38.3 <0.001 Cyperus surinamensis 20.0 0.006 Pontederia cordata 43.4 0.057 Diodia virginiana 53.8 <0.001 Sacciolepis striata 26.7 0.080 Eclipta prostrata 30.0 <0.001 Sesbania herbacea 15.0 0.029 Galium uniflorum 12.5 0.060 Setaria parviflora 25.0 <0.001 Hydrochloa caroliniensis 24.0 0.050 Thelypteris interrupta 12.5 0.058 Juncus effusus 52.3 <0.001 Typha latifolia 12.5 0.056 Note : Taxa marked () were not significant indicator species at the regional level. Calculated indicator values and the significance of the indicator value for each species are also presented. Using the peninsular indicator species (n=82 species), the abundance of indicator species for both reference (% Sensitive) and impaired (% Tolerant) conditions was calculated for each site and correlated with the LDI. A plot of the relationship between LDI score and % Sensitive and % Tolerant species are presented in Figures 3-5 and 3-6, respectively. The Spearmans correlation coefficients were significantly and highly correlated with the LDI (% Sensitive r = -0.76, p<0.001; % Tolerant r = 0.75, p<0.001). The abundance of sensitive taxa plotted in Figure 3-5 suggested a relatively accurate and precise distribution, with fair goodness of fit. There was substantial variation in the data for sites with LDI scores of approximately 1.0, but a noticeable and linear decreasing trend with increasing LDI values was evident. Distribution of the % Tolerant data indicated a low correlation between the LDI and the % Tolerant until LDI scores of approximately 3.5. At that point, substantial variation in the dataset was evident, with abundance values ranging from approximately 10% to 75%. The peninsular dataset was utilized to identify the proposed bioassessment metrics. The apparent advantage of utilizing the peninsular dataset lay in the higher number of significant indicator species identified for community condition assessment and the strength and significance of the correlations with the LDI. The combined dataset provided 48 additional indicator species in the South region, 37 additional indicators in the Central region, and 74 additional significant indicators in the North region. However,

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68 Figure 3-5. Abundance of sensitive species along the disturbance gradient. Figure 3-6. Abundance of tolerant species along the disturbance gradient.

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69 12, Central impaired = 17, North reference = 11), Kruskal-Wallis tests were employed to ensure that the median abundance of sensitive and impaired indicators were equal for each region. The Kruskal-Wallis test null hypothesis was equal medians for all groups. Unequal medians would indicate a regional bias in the distribution of indicator species Whitney U-test Z= -5.379, p<0.001). Median values between regions did not differ and likely predispose a reference or impaired site in a particular region to lower assessment values vis--vis reference or impaired sites in the other regions. No significant difference in median values between regions for either % Sensitive or % Tolerant species were identified using the Kruskal-Wallis test (% Sensitive H=0.076, p=0.963, % Tolerant H=1.598, p=0.450). Thus, the abundance of sensitive and tolerant species identified using ISA and the peninsular dataset were selected as metrics. Table 3-15. Exotic taxa encountered and region(s) of occurrence. Exotic Species S C N Exotic Species S C N Aeschynomene indica Alternanthera philoxeroides Alternanthera sessilis Alternanthera tenella Amaranthus blitum Amaranthus spinosus Caperonia palustris Chenopodium ambrosioides Cuphea carthagenensis Cynodon dactylon Cyperus lanceolatus Desmodium triflorum Digitaria bicornis Echinochloa colona Echinochloa crusgalli Eichhornia crassipes Eleusine indica Eragrostis atrovirens Fimbristylis miliacea Gomphrena serrata Hedyotis corymbosa Hymenachne amplexicaulis Ipomoea quamoclit Kyllinga brevifolia Ludwigia peruviana Lygodium microphyllum Macroptilium lathyroides Melaleuca quinquenervia Melochia corchorifolia Mollugo verticillata Murdannia keisak Murdannia nudiflora Panicum maximum Panicum repens Paspalum acuminatum Paspalum notatum Paspalum urvillei Phyllanthus urinaria Polygonum lapathifolium Portulaca amilis Richardia scabra Sacciolepis indica Salvinia minima Schinus terebinthifolius Scleria vaginata Senna occidentalis Solanum viarum Sporobolus indicus Urena lobata Verbena bonariensis Xyris jupicai Percent exotic Fifty-one exotic species were identified throughout peninsular Florida (Table 3-15). Exotics, which included pasture grasses planted for forage, were significantly more abundant in impaired conditions than in reference conditions (peninsular dataset, Mann-

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70 (Kruskal-Wallis H = 0.740, p=0.691), nor were significant differences identified when the abundance of exotic species was compared between regions for both impaired sites (Kruskal-Wallis H=0.247, p=0.884) and reference sites (Kruskal-Wallis H=0.998, p=0.607). The abundance of exotic species was significantly correlated with the LDI in each region (Spearmans r: South = 0.71, p=<0.001; Central = 0.54, p=0.002; North = 0.74, p<0.001). The Spearman correlation coefficient was also calculated for the abundance of exotic species and the LDI using the peninsular data set (Spearmans r = 0.67, p<0.001, Figure 3-7). The abundance of exotic taxa appeared to not be strongly correlated with increases in LDI value until a threshold of approximately 3.5 was reached. Many sites before LDI values of approximately 3.5 appeared to have background values for exotic taxa of less than 10%, suggesting a nearly universal distribution of exotic taxa throughout Florida. Near LDI values of 3.5, however, marked increases in the abundance of exotic taxa suggested a threshold value had been crossed, although substantial variation in the dataset remained. Figure 3-7. Abundance of exotic taxa at each site along the disturbance gradient. Annual to perennial ratio The median annual to perennial ratio was significantly higher in impaired conditions versus reference conditions for the peninsular dataset (Mann-Whitney U-test Z = -5.122, p<0.001). The correlation between the A:P ratio and the LDI was significant

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71 when the peninsular dataset was examined (Spearmans r = 0.65, p< 0.001, Figure 3-8). Spearmans correlation coefficient between the A:P ratio and the LDI was also significant for each region: South r = 0.60, p=0.002; Central r = 0.69, p<0.001; North r = 0.65, p=0.001. The median value for the A:P ratio did not differ between regions (KruskalWallis H = 0.938, p=0.626), nor did median values differ between regions for reference conditions (Kruskal-Wallis H = 2.130, p=0.344) or impaired conditions (Kruskal-Wallis H = 0.114, p=0.945). Variance in the A:P ratio dataset, as well as sensitivity and accuracy appeared to be minimal until a threshold value of approximately 3.2 was passed. At that point, the ratio increased, as did the variance in the data. Figure 3-8. Annual to perennial ratio at each site along the disturbance gradient. Average Coefficient of Conservatism Significant differences in the median CC value between reference and impaired conditions using the peninsular dataset were identified (Mann-Whitney U-test Z = 6.510, p< 0.001). A significant correlation was calculated between the peninsular dataset average CC and the LDI score (Spearmans r = -0.78, p< 0.001, Figure 3-9). Median values between regions were not significantly different (Kruskal-Wallis H = 0.501, p= 0.778). Kruskal-Wallis tests also indicated that the median average CC value did not differ between regions for reference sites (H = 0.501, p= 0.778) or impaired sites (H = 0.140, p= 0.932). Significant (Spearmans r) correlations between the LDI and the average CC were identified for each region (South r = -0.74, p< 0.001; Central r = -0.75, p< 0. 001, North r = -0.76, p< 0.001). The average CC appeared to be sensitive to increases in LDI value once a threshold of approximately 3.0 was passed. Marked

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72 increases in variance within the dataset followed, although in general a trend of decreasing average CC values continued. Figure 3-9. Average Coefficient of Conservatism value for each site along the disturbance gradient. Vegetative Index of Wetland Condition The Vegetative Index of Wetland Condition (VIWC) was calculated for each site by scoring the 95th percentile of each metric based on the peninsula dataset (n=75). The peninsular dataset was utilized as no significant regional effects were found in the distribution of the five metrics between reference and impaired conditions, as previously described. The 95th percentile and the scoring breaks for each metric are given in Table 3-16, and the scores for each site and metric are given in Table 3-17. The scored metrics were summed to calculate the VIWC. The relationship between the LDI and the VIWC for each site is presented in Figure 3-10. The VIWC ranged from 0 (the lowest score Table 3-16. Quadrisect values and 95th percentile for metric scoring. Metric 95th Percentile 0 Scores 3 Scores 7 Scores 10 Scores % Sensitive Spp. 0.5834 < 0.0820 0.0820 0.2308 > 0.2308 0.4474 > 0.4474 % Tolerant Spp. 0.6321 > 0.3723 > 0.1081 0.3723 0.0597 0.1081 < 0.0597 % Exotic Taxa 0.2742 > 0.1198 > 0.0385 0.1198 0.0001 0.0385 0 A:P Ratio 0.3105 > 0.1231 > 0.0625 0.1231 0.0352 0.0625 < 0.0352 Average CC 6.352 < 3.7015 3.7015 5.4085 > 5.4085 5.8874 > 5.8874

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73 Table 3-17. Site scores for each metric and the summed VIWC. Site % Sensitive% Tolerant % Exotic Spp. Average CC A:P Ratio VIWC ALPaynes 7 710107 41 Audobon 3 0000 3Bear Scat 3 7101010 40Big Cow 0 3330 9BRSebastian 10 103107 40CabPatch 3 3337 19Caravelle 3 3337 19Chuluota 7 107107 41CLBayard 7 1010710 44CLCove 0 0000 0CMMPas 7 7101010 44CMWRef 7 3101010 40COBurgle 0 0030 3COHole 3 71037 30Crew 10 77103 37DEMelon 3 0000 3Deerfly 7 10773 34Garber 3 03310 19GbarE 0 0030 3GLDonut 0 3003 6GLPont 0 0000 0Goethe 10 71077 41GreenSwamp 10 1010710 47HaRare 0 0000 0HagueI 0 3000 3HagueII 0 0000 0HalfMoon 7 7101010 44HEBad 0 0000 0HEL2 0 0000 0HEOKAY 7 3373 23HighRef 7 71077 38HighPast 0 0003 3HillsRef 10 710710 44Hunt Camp 10 101077 44IFAS I 3 371010 33IFAS II 7 107107 41Immokalee 10 71077 41IRBlueCypress 3 0333 12IRCanal 0 0000 0IROJ 0 0030 3JD6 10 1071010 47

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74 Table 3-17. Continued. Site % Sensitive% Tolerant% Exotic Spp. Average CC A:P Ratio VIWC Kelly Park 3 31030 19 Lcork 7 7773 31LLeeCounty 7 7333 23LEGo 7 310710 37LESuwan 3 31077 30MALudy 3 0000 3MASpray 7 31037 30McArthur 3 0300 6MNElmer 3 3733 19MNErik 7 7333 23MNOcala 7 710710 41MRPepr 3 3033 Myakka 10 310107 OKCara 3 0030 6OKKiss 10 710107 44OKPast 3 0333 12PacTom 0 0003 3Pall-Mar 5040Penner 10 10101010 50POWales 101040POWeowak 1010107 4710 33 10 737330SANorthMya 107377 31SandhillCrane 3 3330 12Savannas 10 1071010 47STCow 0 0000 0SUVaca 7 1010710 44SUWarhol 0 3000 300 010 12 40 10 10 10 10 10 PBCorbett 10 7 7 10 3 37 PBEnjay 10 10 7 10 3 10 3 7 10 PUPond 10 10 36 RiceCreek 10 3 10 40 SAOscer 7 7 UNHealthy 0 0 0 Wekiva 10 10 10 10 50 possible) to 50 (the highest possible score), with 9 sites scoring 0 and 3 scoring 50. The nine low-scoring sites were all located in cattle pastures with high densities (C. Lane, personal observation) in the South (3 sites), Central (3 sites), and North (3 sites) regions. The three high-scoring sites were also evenly distributed with one in each region: South (on conservation lands owned by the South Florida Water Management District), Central (in a state park), and North (in a national forest). The VIWC was significantly correlated to the LDI score (Spearmans r = -0.75, p< 0.001) and was significantly different between reference and impaired classes (Mann-Whitney U-test Z = 6.496, p< 0.001). No difference between regions was found for the summed VIWC (Kruskal-Wallis H = 0.865,

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75 p= 0.649), nor between regions and impaired sites (Kruskal-Wallis H = 0.438, p= 0.804) or between regions and reference sites (Kruskal-Wallis H = 4.534, p= 0.104). As in the metrics that comprised the VIWC, variance within the dataset appeared to be manifested most strongly at approximate LDI values of 3.5. In addition, higher variance than was expected was also evident at LDI values of approximately 1.0, based on the distribution of the metric values that comprised the VIWC. Figure 3-10. The relationship between the VIWC and the LDI. Discussion Correlations between metrics and LDI scores suggested landscape modification affected that the composition and structure of the wetland flora, although the variance in the dataset was substantial, especially for LDI values near 3.5. Five metrics were correlated >|0.50| with the LDI: abundance of sensitive and tolerant taxa, abundance of exotic taxa, annual to perennial ratio, and average coefficient of conservatism score. The VIWC, which combines the macrophyte metrics into a single value, defined the condition of each wetland such that the lowest scoring wetlands tended to have the highest landscape development intensity scores, while the wetlands with the highest VIWC scores were in areas with lower LDI values. Environmental Gradients and Species Distributions Macrophytes respond strongly to anthropogenic modifications of wetland ecosystems and surrounding landscapes (Doherty et al. 2000, Adamus et al. 2001), including alterations in community composition due to hydrology (van der Valk 1981, David 1996), nutrient loading (Koch and Reddy 1992, Doren et al. 1997, Bedford et al. 1999), physical/chemical alteration (Latham et al. 1994, Adamus et al. 2001),

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76 sedimentation (Waldrop and Brooks 1998), and other factors such as selective herbivory (Reader and Craft 1999), trampling (Blanch and Brock 1994), or modification of fire regime (Bayley and Odum 1976, Winchester et al. 1985, Newman et al. 1998). The wetlands sampled in this study were subjected to a myriad of anthropogenic composition was also correlated with ordination scores. The Florida peninsula, which juts modifications, with the strongest gradient being of increased agricultural land use intensity and associated nutrient loading and chemical modification, along with hydrologic alterations and herbivory/trampling. These vectors of disturbance were manifested by significant differences between the constituents measured (Table 3-8). Five measured constituents or calculated values were of particular importance in driving community structure based on the relationship (Pearsons r2 > 0.30) between the NMDS ordination scores and the LDI, site soil pH, water TP, specific conductivity, and latitude (Table 3-9). Macrophyte composition was most strongly correlated with the LDI score, which is an agglomerative disturbance index capturing landscape modification due to altered hydrology, nutrient loading, and predicted agrochemical application and other disturbances associated with various land uses (Brown and Vivas submitted). As the LDI captures many disturbance vectors, the strength of the relationship between macrophyte distribution and LDI score was not surprising. The ordination results buttress the use of GIS-based independent measures of general impairment, such as the LDI, in identifying modifications to landscapes and predicting wetland community condition (Johnson 1994, Adamus and Bergman 1995, Roth et al. 1996, Miller et al. 1997, Cuffney et al. 2000, 106 Carpenter and Waite 2000, OConner et al. 2000, Munn et al. 2002, Fore and Grafe 2002, Fore 2003). The strength of the relationship between site ordination structure and the LDI also supported the metrics developed with the LDI as the abscissa, or measured disturbance gradient. The ordination scores were also correlated with soil pH, specific conductivity, and water TP. Wetlands are generally low-lying landscape features, which predisposes these ecosystems to down-slope accumulations of nutrients from cattle grazing (Reddy et al. 1998) and crop and citrus agrochemical application and drift (Euliss and Mushet 1999, Anderson and Vondracek 1999). In a south-central Florida study by Graetz and Nair (1995), nutrient augmentation through fertilizers and cattle wastes in pastureland soils augmented background levels, such that approximately 40% of the phosphorous became bioavailable (labile), whereas only 2% was bioavailable in native areas. These massive loading rates may allow nutrients to be moved directly or indirectly into wetland systems from overland or interstitial flow, and can be manifested by drastic alterations in wetland community composition (Craft et al. 1995, Newman et al. 1998, Mitsch and Gosselink 2000). Beyond altering species composition in wetland systems directly down-slope of anthropogenic land uses, sufficient nutrient loading of wetland systems can occur such that wetlands, rather than being nutrient sinks (Flaig and Reddy 1995), may end up as nutrient sources for water bodies farther down-slope including wetlands, streams, and lakes (Agami et al. 1990). Alterations in soil pH, specific conductivity, and available nutrients, among other changes, may be indicative of wetland loading from agrochemical fertilizers and cattle wastes (Fore and Grafe 2002, U.S. EPA 2002e). In addition to the LDI and physical/chemical determinants of community composition from the NMDS ordination, a latitudinal gradient affecting species

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77 into the Gulf of Mexico and Atlantic Ocean, is tempered from climatic extremes by the heat absorbing/desorbing nature of water. This protects many species that have evolved in south Floridas sub-tropical environment. Northern Florida, however, is somewhat exposed to the temperate climate of mainland North America, with many freezing days considered to have optima within the range of environmental conditions often found in and different precipitation patterns than southern Florida (Fernald and Purdum 1998). As suggested by significant compositional differences (Table 3-7) between wetland macrophytes of northern, central, and southern Florida, different species have autecological requirements associated with latitudinal changes. Metric Development The results suggested that while macrophytes responded to increased development intensity, as measured by increased LDI values, substantial variance was evidenced by the five metrics that comprised the VIWC. In addition, the metrics appeared to be marginally sensitive to changes in LDI values until an LDI score of approximately 3.5 was reached. Throughout peninsular Florida, the metrics appeared able to approximate the condition of the sampled wetlands along increases in landscape modification, however, the substantial variance within each of the metric values, especially after LDI values of approximately 3.5, indicated that additional information relating the plant metrics to the landscape metrics was required to more fully understand the relationship between plant metrics and landscape development. The results of the analysis for each of the final metrics are described below. Sensitive and tolerant species It is generally accepted that most organisms have autecological optima, or environmental conditions most suited for the highest possible productivity and/or fitness (Ricklefs 1990, Gaiser et al.1998, Stevenson et al. 1999, U.S. EPA 2002e). These conditions can include adequate water, nutrients, photoperiod, and temperature. A hypothetical gradient (Figure 3-11) is thus likely to exist for each species. As optima exist, there are likewise extremes where conditions are unfavorable for growth, let alone survival, for species not adapted to the environment. Environmental extremes can include altered salinity, pH, hydropatterns, nutrients, physical disturbances, chemical disturbances, anoxia, or photoperiod. In this study, the environmental conditions generally found at reference sites were significantly different in many physical/chemical constituents than those found in impaired sites (Table 3-8). A review of the literature suggests that other constituents of the soil and water, such as metals or pesticides/herbicides, likely differ between reference and impaired conditions (Purvis et al. 1991, Euliss and Mushet 1999, Mitsch and Gosselink 2000). Likewise, though not quantified, pressures associated with browsing and selective grazing were likely significantly different in reference than in impaired conditions. The abiotic and biotic factors listed above could be considered to define the range of environmental conditions acceptable for the plants identified in this study. The LDI was utilized in Indicator Species Analysis as an analog for the acceptable environmental conditions of various species. Species with significant fidelity and specificity to low LDI scores were thus

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78 Figure 3-11. Environmental optima along a hypothetical environmental gradient. reference sites. Those species indicative of higher LDI values were conversely considered to have optima within the range of conditions expressed by impaired sites. It is beyond the scope of this research to explore the autecologies of the sensitive and tolerant plants listed in Tables 3-13 and 3-14 further, but the significance of the relationship suggests proclivities towards particular environmental conditions for those indicator macrophytes. In this study, Indicator Species Analysis was able to discern 82 plants with fidelity and specificity to a particular landscape development condition throughout peninsular Florida. The abundance of these sensitive and tolerant plants was correlated with the LDI (Spearmans r >|0.70|), and not significantly affected by regional vagaries in species composition. However, the highly variable relationship between the abundance of sensitive and tolerant plants and the LDI indicated limitations to conclusions drawn. The abundance of sensitive plants demonstrated high variance throughout the plot along the LDI, although lower values appeared near LDI scores of approximately 3.5. Tolerant plants, which expressed a minimal relationship with the LDI until a threshold of approximately 3.5 was reach, were also highly variable, although not as sensitive to changes in LDI values for the low scores. Percent exotic Increased development has the potential of promoting the spread of exotic species into wetlands where they can alter community composition, patterns, processes, and even functioning (Leibowitz and Brown 1990, Hobbs and Huenneke 1992, Cronk and Fennessy 2001). Disturbance within the wetland itself from activities such as cattle grazing provides a pathway for exotic propagules through cattle feces or by seeds

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79 adhering to the coats of domestic herbivores. The heavy machinery used in typical cropping or citrus operations can also provide a pathway for propagules. The trampling associated with cattle grazing can provide patches of bare ground for colonization of exotic species. Drift of herbicides into wetlands from agricultural practices can alter the plants, by dint of their storage/reproductive structures such as rhizomes, tubers, and corms, are thus better able to pass through the Gleasonian sieve that regulates the composition or fitness of wetland flora and create patches of bare ground, which can subsequently be colonized by exotic species. Drainage of landscapes for development can provide direct conduits to wetlands for exotic species, if those drainages directly link to the wetland (Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). Altering the natural sheet flow pattern through landscape level drainages can also affect the species composition of wetlands by providing drier conditions conducive to colonization by exotic annual species (David 1999). Increased development that affects the landscape surrounding the wetland may also cause a potential increase in exotic propagules entering the wetland system through the increase in the proportion of the perimeter of the wetland that is subjected to seed sources of exotic species. The results, however, suggested that the abundance of exotic taxa was marginally sensitive to increases in land development intensity until a threshold had been crossed, approximately 3.2. Once that threshold had been passed, substantial variance was manifested in the dataset, which suggested additional processes not captured by the LDI were affecting the distribution of exotic taxa throughout peninsular Florida. These processes may be further understood through the collection of additional data (i.e., requesting planting history from land owners) or through additional observations (i.e., the distance from the nearest road to the wetland, or the existence of perches within the site; both would potentially increase the abundance of propagules). Several species found in the wetlands sampled are on the Florida Exotic Pest Plant Councils list of Category I exotics (Eichornia crassipes, Hymenachne amplexicaulis, Lygodium microphyllum, Melaleuca quinquenervia, Panicum repens, Schinus terebinthifolius, and Solanum viarum). Category I exotic species are those considered to alter native plant communities by directly displacing native species, changing the structures or ecological functions within a community, or hybridizing with native species (FLEPPC 2003). Two plants identified were FLEPPC Category II exotic species (Alternanthera philoxeroides and Urena lobata). These plants are increasing in abundance throughout Florida but have not yet affected the natural areas, as have Category I exotics (FLEPPC 2003). It is interesting that not all of the exotic species found appear to possess such damning traits. Richards yellow-eyed grass, Xyris jupicai, native to French Guiana (Wunderlin and Hansen 2000), is one such species. This species was found frequently enough in reference conditions to be considered a sensitive indicator species. Annual to perennial ratio As hydrologic conditions in wetlands are dynamic, many wetland plants have evolved life-history traits to maintain themselves during periods of endogenous environmental perturbations. In an adaptation that enables wetland plants to combine reproductive structures with storage devices, most wetland plants are vegetatively reproducing perennials (Galatowitsch et al. 1999b, Cronk and Fennessy 2001). Perennial

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80 presence and abundance of species within the confines of the wetland system (van der Valk 1981). However, exogenous perturbations that disrupt natural processes, such as hydroperiod alterations, nutrient loading, and trampling, may provide opportunities for the generally faster-growing annual species to out-compete perennial species for nutrients, water, and light. Annual species (often considered weedy species) increase in wetlands undergoing anthropogenic perturbations, while perennial species decline (Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). The results of the annual to perennial ratio metric generally support the conclusions from the literature, as the ratio of annuals to perennials increases with increasing development. However, at low levels of measured disturbance (LDI scores), the results suggested that the A:P ratio was marginally sensitive to change. Only once an LDI threshold of approximately 3.2 was passed were changes evident in A:P ratio. This suggests that wetland processes maintain A:P ratios until development intensity increases sufficiently to alter those processes, for instance through decreased hydroperiod as a result of ditching and draining associated with higher LDI values. Average Coefficient of Conservatism Since its inception by Wilhelm and Ladd (1988) as a method to measure the quality of the vegetation in the Chicago area, the Floristic Quality Assessment Index (FQAI, originally called the Natural Area Index), and the associated Coefficient of Conservatism have found widespread use in a variety of different ecosystems (Southern Ontario Woodlands: Francis et al. 2000; Illinois uplands, flatwoods, and prairies: Taft et al. 1997; North Dakota wetlands: Mushet et al. 2002). Many authors have utilized the FQAI, calculated as the average CC value for the site multiplied by the square root of the total number of species at a site. This inherently rewards systems richer in species and assumes that such a system is more ecologically desirable (Fennessy et al. 1998, Cohen et al. submitted). Like Francis et al. (2000), in this study the average CC score was utilized as a metric. This decreased the influence of species richness on the site score and more accurately reflected the ecological data collected as the average species richness for sites with an LDI score of less than 2.0 (31.70 +/10.80) was not significantly different (Mann-Whitney U-test Z = -0.005, p= 0.990) than those sites scoring greater than 2.0 (31.68 +/9.51). The lack of richer systems in reference wetlands may be a function of the strong hydrological driving forces maintained on the minimally developed landscape. Whereas developed landscapes often drain the wetland area, which can allow species into the wetland proper that would otherwise be excluded due to anoxic soil conditions, the wetlands located in reference landscapes generally have zones where species tolerant of different hydroperiods and anoxia can thrive. Thus the richness found in developed sites may be an artifact of the drainage associated with development. Landscape drainage may have also affected the highly variable distribution of CC values associated with LDI scores of approximately 3.5. As noted, drainage increases the area available for colonization by upland and facultative plants due to decreases in soil anoxia. However, the slope and additional site-specific factors (e.g., the presence of perches, as discussed in the % Exotic metric) may have decreased the opportunity for plants with low CC scores to colonize wetland zones.

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81 Vegetative Index of Wetland Condition The VIWC, developed for isolated depressional herbaceous wetlands in peninsular Florida, combined five biological measurements into a single score to nature and pervasive throughout Florida, the effects were likely evenly distributed in both impaired and reference sites. It was noted, however, that sites in impaired landscapes ascertain the relative condition of a sampled wetland vis--vis a suite of reference wetlands located in low development landscapes (Karr and Chu 1999). While significantly correlated with the disturbance gradient, the VIWC appeared to be highly variable for any given LDI score, especially scores located near LDI values of 1.0 and 3.5. The high variance in each of the metrics, as well as in the final correlation between the LDI and VIWC may have been in locations with a time delay between impairment activity and the manifestation of that impairment in the wetland macrophyte community (i.e., a field, long held fallow, that is now in crop rotation). Conversely, LDI scores, based on landscape values, may not have accurately quantified the condition of a site that was in rotation or grazed that was sampled months or years after such deleterious activities had ceased. While ground-verification occurred, in some cases accurate land use maps or site histories could not be obtained, and best scientific judgment was employed in spatial off-site GIS analysis. While a few outliers appeared to exist in the relationship between the LDI and VIWC, the focus of this analysis was on the utility of macrophytes as indicators of wetland condition. An assumption inherent in this study, as in most analyses utilizing bioindicators, was that should environmental conditions be such that the macrophytic community was characteristic of sites in reference conditions, then the integrity (c.f. PL 92-500, Clean Water Act, (a)) of the site was not suspect. On the other hand, sites with vegetation characteristic of impaired conditions were assumed to be under various degrees of human modification of deterministic, driving variables. In this manner, the VIWC, which directly compares wetland vegetation, may be best employed as an accurate assessment tool for isolated depressional herbaceous wetlands in Florida. Field Data Collection Florida was in the midst of a significant drought during the study period (Lawrimore et al. 2001), which was manifested by decreased hydroperiod, extent, and depth of inundation in many of the sampled wetlands. Many wetlands identified as potential sites were not sampled during the study period due to the lack of standing water originally a prerequisite for inclusion that was slackened as the sampling season waned in 2000. Five of the ephemeral wetlands sampled in this study (all in the North region) were not hydrated during the sampling window, and may not have been hydrated to the point of standing water at any point during the study period. In addition, the hydroperiod may have been significantly decreased in many, if not all, of the wetlands sampled. This may have affected the species composition in both reference and impaired wetlands for instance through the increased abundance of weedy annuals such as Eupatorium capillifolium. The effect of the drought on the macrophytes identified would likely have been most pronounced on the wetland fringe, as macrophytes typically found in more upland conditions may have colonized the non-hydrated wetland fringe and out-competed typical (i.e., obligate or facultative) wetland plants. As the drought was endogenous in

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82 often expressed modified hydrological functioning due to drainage ditches (C. Lane, personal observation) that may have caused a greater response to the effects of the drought. As mentioned, the sampling protocol was modified between sampling years. The slight changes in the sampling protocols between 1999 and 2000 were not expected to have had a noticeable effect on the accurate characterization of the 2% of sampled wetlands without 4 full transects from the wetland edge to the center. No wetland had all 4 transects halted before the center, and the additional information possibly gathered from the extended transects after 15m2 had been sampled without a change in species composition would likely be minimal. Conclusions and Recommendations This chapter of the study quantified the condition of sampled wetlands through an assessment of the structure and composition of the wetland macrophyte community. However, the VIWC, should be seen as a model that must be verified and calibrated to decrease the variability between metric response and the LDI. A recommended calibration for the proposed metrics and the VIWC that is currently underway (C. Lane, unpublished results) includes re-sampling a number of study wetlands to ascertain yearly fluctuations in species assemblages and the subsequent effect on the VIWC. To sample study wetlands twice within a given year but during different seasons would provide the opportunity to examine seasonal effects on the composition and structure of wetlands and the corresponding alterations to the individual metrics and VIWC. Model verification would also increase the value of the proposed VIWC. Florida, by nature of rainfall and topography, is a state rich in wetland resources. Increasing the number of sampled wetlands across all landscape types would increase the power, precision, and accuracy of the individual metrics as well as the multi-metric VIWC. The addition of larger isolated herbaceous wetland systems into the calibration and verification of the VIWC would also permit the expression of the VIWC across wetlands of different scales.

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83 1999, Ludden and Hauer 2000). Macroinvertebrates are well suited for the effective measurement of the spatial and temporal impacts of human-induced disturbances (Table CHAPTER 4 MACROINVERTEBRATES AS BIOINDICATORS Introduction Shallow, isolated depressional wetlands typically support a variety of aquatic, semi-aquatic, and terrestrial invertebrates that are important components of wetland and local terrestrial food webs (Kushlan 1990, Evans 1996, Sharitz and Batzer 1999, Evans et al. 1999, Leslie et al. 1999). Because of the nature of depressional wetlands, invertebrates associated with these ecosystems are regularly subjected to endogenous environmental stresses such as anoxia, wide salinity fluxes, and hydroperiod fluctuations. Invertebrates in depressional wetlands may be further stressed by exogenous (human-induced) factors such as nutrient and organic loading, contaminant toxicity, acidification, salinization, sedimentation, changes in vegetation cover, thermal alteration, dehydration, hydrologic alterations, and habitat fragmentation (Adamus and Brandt 1990, Adamus 1996, Danielson 1998, Doherty et al. 2000). Measured changes in invertebrate community structure and function relative to these exogenic perturbations may be used to assess the ecological condition of the depressional wetland ecosystem through development of a multimetric index of biologic integrity (Adamus 1996, Danielson 1998, Galatowitsch et al. 1999a, Karr and Chu 1999, Kashian and Burton 2000). Multimetric indices utilizing macroinvertebrates have been used in biological monitoring to determine the relative quality of lentic and lotic aquatic ecosystems throughout the country (Hellawell 1986, Plafkin et al. 1989, Cairns and Pratt 1993, Kerans and Karr 1994, Rosenberg and Resh 1996, Karr and Chu 1999). As of 1997, forty-eight states, including Florida, have implemented or have begun developing macroinvertebrate assessment methods for lakes or streams (Karr and Chu 1999). In Florida, the Florida Department of Environmental Protection (FDEP) combined metrics that measure diversity, composition, and functional feeding groups in the development of the Stream Condition Index (SCI) for the evaluation of lotic systems (Barbour et al. 1996). Metrics were likewise identified by the FDEP to assess the biological integrity of lakes in the state (Gerritsen and White 1997, Gerritsen et al. 2000). Macroinvertebrate assemblages in Florida have also been utilized to develop a bio-monitoring program in southern Florida canal systems (Snyder et al. 1998, in Doherty et al. 2000), for evaluating the success of restoration projects (e.g., Merritt et al. 1999) constructed wetlands (e.g., Erwin et al. 1997, Crisman et al. 1997), and for assessing the impact of human-induced disturbances on cypress domes and the Everglades (i.e., Brightman 1984, Leslie et al. 1999, Rader 1999). Multimetric assessments of wetland condition using macroinvertebrates as indicator organisms have been conducted in a growing number of states and agencies (e.g., Yoder and Rankin 1995, Danielson 1998, Burton et al. 1999, Gernes and Helgen

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84 Table 4-1. Advantages and disadvantages of using macroinvertebrates in wetland bioassessment. Advantages Disadvantages identify metrics, or measurable components of the wetland macroinvertebrate Widely distributed in wetlands Easily sampled and generally abundant Some organisms have known response to perturbations Many are sedentary within a single wetland Important components of trophic webs Respond quickly to perturbations Some are long-lived Some are extremely difficult to identify Many short-lived Identification is labor intensive May be sparse in some wetlands or seasonally abundant Hydrated wetlands generally required Poor taxonomic knowledge of some groups Some taxa migrate from other water bodies Sources : Danielson (1998), Doherty et al. (2000), U.S. EPA (2002c) 4-1). Macroinvertebrates are typically abundant in wetlands, easily sampled, and relatively easily identified (Rosenberg and Resh 1993). Additionally, there is ample literature on various sampling methods (Cheal et al. 1993, Adamus 1996), taxonomic keys (i.e., Merrit and Cummins 1996), and macroinvertebrate tolerance values for pollutants in lotic environments (Hilsenhoff 1987, Lenat 1993, Barbour et al. 1996), as well as a growing array of metrics that have responded to the effects of episodic or constant human disturbances on aquatic systems (see Yoder and Rankin 1995, Barbour et al. 1996, Gerritsen and White 1997, Galatowitsch et al. 1999a, Karr and Chu 1999, Gernes and Helgen 1999, Kashian and Burton 2000, Ludden and Hauer 2000, Doherty et al. 2000, U.S. EPA 2002c). While the advantages of macroinvertebrates have dictated their use in biological assessments throughout the country, disadvantages to using them in biological assessments exist (see Table 4-1). Detailed taxonomic keys are necessary to identify most organisms to genus or species levels, and often the keys do not address the diagnostic features of larvae or instars. Sample processing time is large with macroinvertebrates (e.g., sorting, subsampling, enumeration and identification) and some families (e.g., Chironomidae) require mounting specimens on slides for identification. Most wetland macroinvertebrates emerge after the wetland has hydrated, thus requiring adequate rainfall and/or standing water, which typically is seasonal in Florida. The time since the wetland was hydrated will also affect the sampled community composition (e.g., predators typically emerge later than their prey). Additionally, many macroinvertebrate responses to perturbations in the literature are from lotic or lentic systems as data on macroinvertebrate responses to perturbations in wetland systems are sparse, but growing (Danielson 1998, Adamus et al. 2001, U.S. EPA 2002c). In this chapter, results of testing and evaluating community structural and functional measurements for macroinvertebrates (insect and noninsect taxa) of isolated herbaceous depressional wetlands in peninsular Florida are given. The goal was to

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85 community, that showed an empirical and predictable change in value along increases in a landscape-level measure of human disturbance, the Landscape Development Intensity index (Brown and Vivas submitted). Those metrics were selected for use in the creation of the multimetric Macroinvertebrate Index of Wetland Condition, or MIWC. The variation between LDI values and developed metrics was examined to address the sensitivity and precision of macroinvertebrate metrics and the relationship of the metrics to the LDI. Additionally, analyses of environmental parameters measured (both abiotic and biotic) were conducted to assess the environmental variables that affect the distribution of macroinvertebrate taxa within wetlands. Methods Site Selection and Agricultural Development Gradient Seventy isolated depressional marshes were sampled a single time for macroinvertebrate community composition throughout peninsular Florida in the summers of 1999 (n=35) and 2000 (n=35). Site condition was independently assessed using geographic information systems (GIS) and the Landscape Development Intensity index (LDI, Brown and Vivas submitted). Additional information on the sites sampled and the LDI may be found in Chapter 2 (Methods: Site Selection and Agricultural Development Gradient). Macroinvertebrate Collection and Identification Macroinvertebrates were collected using standard U.S. 30-mesh D-frame dip-nets. Twenty sweeps were collected at each site, proportionally divided according to the different vegetation/habitat zones present. Vegetation zones (such as a fringing Panicum spp. zone or a deep water Pontederia sp. zone) were determined from an on-site assessment of dominant wetland plants. A typical marsh had between one and four primary vegetation zones. A single dip-net sweep was one net width and two net lengths covering an area of 0.5m2. The contents of each sweep were deposited into a labeled 3.8L plastic composite jar. When all 20 sweeps were completed, the sample was preserved with buffered formalin at a rate of approximately 10% of the sample volume. The preserved macroinvertebrate samples were stored at the Howard T. Odum Center for Wetlands and delivered to the FDEP for enumeration and identification by FDEP personnel. At FDEP Central Laboratories, the material was sieved and washed following DEP Standard Operating Protocols and placed on a pan with twenty-four numbered cells. Eight random cells were selected (a third of the sample) and placed in another numbered tray. From the second numbered tray a single sub-sample was taken and all organisms enumerated and identified. If fewer than 100 organisms were encountered, a second randomly chosen cell from the second numbered tray was selected and all organisms within that cell enumerated and identified and added to the total of the first count. Identifications by FDEP were made to the lowest taxonomic level possible following FDEP Standard Operating Procedure #IZ-06. Data were error-checked following FDEP protocols and entered into the FDEP database for analysis.

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86 Water and Soil Physical-Chemical Sampling and Analysis To relate the distribution of wetland diatoms to environmental parameters, soil and water physical and chemical parameters were measured at each site as described in Chapter 2 (Methods: Field Data Collection, Sample Preparation and Laboratory Procedures) and Appendix B. Soil variables were transformed to decrease measured skewness and kurtosis in the dataset as described in Chapter 2 (Methods: Data Analyses). Multivariate colinearity among the environmental variables was also examined as described in Chapter 2 (Methods: Data Analyses). In addition, the non-parametric Mann-Whitney U-test was used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). Macroinvertebrate Composition and Environmental Correlates The relationship between measured environmental values (including LDI score) and wetland macroinvertebrate community composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS, Kruskal 1974, Mather 1976) as described in Chapter 2 (Methods: Data Analyses). A three-dimension NMDS solution was selected for macroinvertebrate taxa as increased dimensionality only marginally improved the fit. Correlations of site scores with environmental parameters, including LDI score and latitude and longitude (decimal degrees), were calculated and a bi-plot of parameters with Pearsons correlations (r2 0.30) to site scores was constructed. Macroinvertebrate Compositional Analyses Summary statistics Summary measures of sample richness, Shannon diversity, Simpson diversity, beta, and gamma diversity were calculated for each site and provided information on species distributions vis--vis land use as described in Chapter 2: Data Analyses. Regional composition of macroinvertebrates As isolated depressional marshes are not uniformly distributed throughout Florida, the sites were likewise generally located in counties with the necessary hydrology and geomorphic setting (Lane 2000, see Figure 2-1). The sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions after Lane (2000). Two compositional tests, the multiple response permutation procedures (MRPP) available in PCOrd and the Percent Similarity Index (PSI, Wolda 1981), were used to identify the ecological significance of the modeled wetland regions for macroinvertebrate distribution and are described further in Chapter 2 (Methods: Data Analyses).

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87 Macroinvertebrate Metric Development Metrics based on richness, taxonomic composition, and structural/feeding guilds were identified from literature sources and iterative tests of the dataset (e.g., Barbour et Sources : 1=Barbour et al. (1996); 2=Barbour et al. (1999); 3=Gernes and Helgen (1999); 4=Fore et al. (1996) al. 1996, Gerritsen and White 1997, Burton et al. 1999, U.S. EPA 2002c). Metrics were tested for the strength of Spearmans coefficient of correlation (Spearmans r) with the LDI. Final metrics were selected as those with significant (p<0.05) correlations and Spearman correlation coefficients with the LDI of at least |0.30|. All evaluations of potential metrics were conducted with SAS (SAS Institute, Cary N.C., version 8.02). Categorical metrics Categorical metrics were based on the relative abundance of a specific taxonomic or functional group. The categorical metrics tested provided information on the composition and trophic relationships of the assemblages of macroinvertebrates along the LDI gradient and between development classes. Categorical metrics tested were initially based on studies of Florida macroinvertebrates by Barbour et al. (1996) and Gerritsen and White (1997). As these authors examined macroinvertebrates within lentic and lotic environments, additional categorical metrics focusing on macroinvertebrates common in wetland environments were tested for their correlation with the LDI. Composition measures (Table 4-2) provide information regarding the relative contribution of a population to the community structure of the wetland system (Barbour et al. 1996, Barbour et al. 1999). To compensate for species rich or species poor sites where richness may not be a reflection of the condition of the wetland (King and Richardson 2002), relative rather than absolute values were used for this measurement. In general, wetland systems without landscape modification will remain relatively consistent in proportional representation vis--vis other unperturbed wetlands, although individual abundance may vary in magnitude (Barbour et al. 1999). Variations in the Table 4-2. Compositional metrics, definition, and expected response. Composition Metrics Definition ResponseSource Dominant taxon (%) Abundance of the single most abundant taxon Increase 1 % Diptera % of dipterans Increase 1 % Coleoptera % of beetles Decrease 1 % Odonata % of dragonflies and damselflies Variable 1 % Ephemeroptera % of mayflies Decrease 1 % Oligochaeta % of aquatic worms Increase 4 % Hemiptera % of true bugs Variable 3 % Gastropoda % of snails Decrease 1 % Decapoda % of individuals classed as crustaceans Decrease 2 % Tricoptera % of caddis flies Decrease 1 % Trombidiformes % of mites ? % Amphipoda % of amphipods Decrease 1 Florida Index Weighted sum of intolerant taxa, which are classed as Decrease 1 1 (least tolerant) or 2 (intolerant).

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88 representational proportion of taxonomic groups may indicate the encroachment of exogenous perturbations (Barbour et al. 1999). In addition to the measures listed in Table 4-2, compositional measures of each order, family, and genus were examined along the disturbance gradient and within each development classification for each site. Trophic categorical measures provide information on trophic relations, production, and feeding strategies (Resh and Jackson 1993, Barbour et al. 1999). A list of trophic measures examined, and the expected response to exogenous perturbations are given in Table 4-3. As in compositional measures, the trophic relationships in wetland systems with low LDI scores are expected to remain relatively stable vis--vis other wetlands in reference landscapes (Barbour et al. 1999). Increased landscape modification to the system was expected to alter the relative proportions of different trophic classes. Table 4-3. Trophic metrics, definition, and expected response. Trophic Metrics Definition ResponseSource Predator % % of the predator functional feeding group Variable 4 Shredder (macr) (fw) % % of the plant shredders functional feeding group Decrease 2 Scraper (peri) (fw) % % of the periphyton scrapers functional feeding group Decrease 2 Col-fltr/susp fdr % % collector-filterers/suspended feeders functional group Variable 1 Plant piercer % % of the macrophyte piercing functional feeding group Decrease 1 Sub col-gthr/dep fdr % % collector-gatherers/deposit feeders functional group Variable 1 Epi col-gthr/dep fdr % % collector-gatherers/deposit feeders functional group Variable 1 Scavenger (animals) % % of macrofauna that feed on dead animals ? Browser-grazer % % of macrobenthos that browse/graze upon periphyton Decrease 3 Parasite % % of the parasite functional feeding group ? 2 Sources : 1=Barbour et al. (1996); 2=Gerritsen and White (1997); 3=Barbour et al. (1999); 4=Kerans and Karr (1994) Ancillary data Ancillary data for categorical analyses described above were obtained from the literature and the United States Department of Agricultures Integrated Taxonomic Information System on-line database (United States Department of Agriculture 2003). The feeding strategy or trophic position of each organism was determined through literature reviews, particularly the text by Merritt and Cummins (1996) on aquatic invertebrates. Sensitive and tolerant species Indicator Species Analysis (ISA, Dufrene and Legendre 1997) was utilized to identify macroinvertebrate taxa having significant association with LDI classification of impaired (LDI2.0) or reference conditions (LDI<2.0). ISA is described in Chapter 2 (Methods: Metric Development). The abundance of species with significant specificity and fidelity to reference or impaired conditions was assessed for each site and correlated (Spearmans r) with the LDI.

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89 Macroinvertebrate Index of Wetland Condition To create a multimetric index of wetland condition using macroinvertebrates, it was necessary to score the proposed metrics. The scoring was completed by taking the th while South and North regions only shared 56%. Central and North regions were 64% similar. MRPP results using the full dataset were equivocal as abundance measures and quartile of the 95 percentile of the measured results for each metric. Doing this decreases the influence of outliers on the distribution of metric scores (Mack 2001). For metrics decreasing with increasing LDI scores, the lowest quartile was given a score of 0, the second quartile 3, the third quartile 7, and the highest quartile 10. Score values were switched for metrics that decreased with increasing LDI scores. A hypothetical example of this scoring method is presented in Figure 2-2. The Macroinvertebrate Index of Wetland Condition was determined for each wetland by summing the scores of the metrics. Results Wetland Macroinvertebrate Composition Seventy herbaceous depressional wetlands throughout peninsular Florida with standing water were sampled in 1999 and 2000 (see Figure 2-1). Twenty-three were sampled in the South region, thirty in the Central region, and seventeen in the North region. Based on the dominant land use around the wetland, twelve of the sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. The organisms identified in the samples from the studied wetlands represent 24 orders, 81 families, 182 different genera, and 120 different species. Of the organisms sampled and enumerated, 82% were identified to at least the genus level, but identification to the species level was possible for only 48% of the organisms due to lack of diagnostic features. While each site averaged 23.9 (+/5.7) taxa identified at least to genus, on average only 10.4 taxa (+/3.7) were identified to species. Analyses to develop indicators of wetland condition using macroinvertebrates and all subsequent analyses were therefore completed at the genus level. Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity using the genus-level data were calculated for each site (Table 4-4). Mann-Whitney U-tests indicated no significant difference between reference and impaired sites for richness, evenness, Shannon diversity, or Simpson diversity (Table 4-5). No significant differences were found between wetland regions (e.g., South, Central, North) for summary metrics (see Table 4-5). Two additional indices were also calculated from the macroinvertebrate data and compared between wetland condition classes: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Both were higher in reference sites than in impaired sites (reference sites average richness: 20.82, beta diversity: 7.06, gamma diversity: 147; impaired sites average richness: 21.03, beta diversity: 6.56, gamma diversity: 138). Macroinvertebrate compositional similarities between wetland regions (sensu Lane 2000) were made using PSI and MRPP. In general, the South region and North region were most dissimilar, but the differences were slight. Comparisons using PSI indicated that South and Central regions shared 71% of the macroinvertebrate genera,

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90 Table 4-4 Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for macroinvertebrates. Name S E H D` Name S E H D` Audubon 8 0.602 1.2530.5789 Immokalee 15 0.761 2.060 0.8198 BearScat 22 0.892 2.7570.9106 IRBlueCypress 26 0.689 2.246 0.7960 BigCow 25 0.794 2.5570.8695 IRCanal 22 0.685 2.117 0.8146 BRSebastian 26 0.923 3.0060.9383 IROJ 29 0.892 3.003 0.9365 CabPatch 21 0.802 2.4430.8704 JD6 11 0.907 2.175 0.8685 Caravelle 23 0.758 2.3770.8446 KellyPark 16 0.783 2.170 0.8219 Chuluota 28 0.759 2.5280.8702 LCork 21 0.656 1.996 0.7086 CLBayard 10 0.727 1.6750.7653 LEGo 16 0.722 2.003 0.8031 CLCove 11 0.467 1.1210.4518 LESuwan 22 0.814 2.518 0.8812 CMWPast 27 0.903 2.9750.9351 LLeeCounty 30 0.879 2.989 0.9321 CMWRef 29 0.828 2.7900.8989 MALudy 20 0.781 2.339 0.8697 COBurgle 25 0.730 2.3500.8384 MASpray 20 0.776 2.326 0.8475 COHole 24 0.803 2.5510.8651 McArthur 17 0.646 1.829 0.6840 Crew 21 0.773 2.3530.8479 MNElmer 30 0.905 3.077 0.9354 Deerfly 21 0.832 2.5320.8843 MNOcala 22 0.842 2.601 0.8832 DEMelon 14 0.798 2.1070.8269 MRPepper 19 0.790 2.326 0.8498 Garber 20 0.875 2.6200.9023 Myakka 18 0.688 1.988 0.7861 GbarE 27 0.782 2.5780.8747 OKCara 18 0.736 2.128 0.8230 GLDonut 18 0.709 2.0500.7880 OKKISS 18 0.736 2.128 0.8277 GLPont 23 0.790 2.4780.8615 OKPast 25 0.773 2.487 0.8582 Goethe 23 0.631 1.9790.7073 PacificTom 27 0.784 2.583 0.8568 GreenSwamp 24 0.870 2.7640.9147 PallMar 21 0.777 2.367 0.8256 HagueI 20 0.721 2.1610.7877 PBCorbett 23 0.748 2.344 0.8296 HagueII 12 0.760 1.8880.8100 PBEnjay 16 0.885 2.455 0.8953 HalfMoon 20 0.866 2.5930.8974 Penner 17 0.725 2.053 0.7967 HARare 25 0.818 2.6320.8915 POWales 25 0.814 2.621 0.8831 HEBad 25 0.756 2.4350.8637 POWeowak 27 0.701 2.311 0.7625 HEL2 18 0.506 1.4640.6243 RiceCreek 18 0.860 2.485 0.8930 HEOkay 14 0.552 1.4580.5600 SandhillCrane 30 0.782 2.658 0.8710 HighPast 25 0.849 2.7330.9209 SANorthMya 24 0.705 2.241 0.7867 HighRef 19 0.838 2.4670.8674 SAOscer 22 0.865 2.673 0.9067 HillsRef 18 0.887 2.5640.9020 Savannas 15 0.793 2.146 0.8178 HuntCamp 31 0.728 2.5000.8720 STCow 17 0.684 1.939 0.7770 IFASI 21 0.483 1.4710.5149 UNHealthy 16 0.735 2.038 0.8350 IFASII 19 0.785 2.3110.8541 Weikiva 15 0.873 2.365 0.8864

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91 Table 4-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes and between regional datasets. S E H (Shannon D (Simpsons there were no significant differences between the composition of impaired sites when (Richness) (Evenness) Diversity) Diversity) Peninsular Dataset Impaired vs. Reference Z-statistic (p-value) -0.301 (0.764) 1.418 (0.156) 0.847 (0.398) 0.971 (0.332) Regional Dataset Regional Comparison Z-statistic (p-value) 1.998 (0.368) 2.111 (0.348) 2.901 (0.235) 1.913 (0.384) presence measures differed in interpretation. Global tests (South vs. Central vs. North) of genera abundance data indicated a significant compositional difference between wetland regions (A = 0.009, T = -2.41, p= 0.019). However, global test using genus presence, which is less subjected to temporal variation in data structure than abundance measures (McCune and Grace 2002), did not indicate a significant difference between wetland regions at p<0.05 (A = 0.006, T = 1.674, p=0.060). Thus, while the abundance of macroinvertebrate genera differed between regions, the genera that comprised the macroinvertebrates assemblages identified did not. Iterative tests of both abundance and presence data indicated significant compositional differences between the South and North regions (Table 4-6), suggesting that SouthNorth compositional variations were likely driving the differences identified in the global abundance MRPP tests. Table 4-6. MRPP analyses of the macroinvertebrate compositional similarity between South, Central, and North wetland regions. Test A T p-value Abundance S vs. C 0.003 -0.787 0.195 Iterative S vs. N 0.017 -3.622 0.004 Tests C vs. N 0.004 -1.017 0.015 Presence S vs. C -0.001 0.155 0.502 Iterative S vs. N 0.015 -2.974 0.010 Tests C vs. N 0.004 -1.001 0.155 Note : Abbreviations are S (South Region), C (Central Region), N (North Region). Iterative tests exclude one group (of three) during the MRPP procedure. Simultaneous and iterative MRPP tests were also conducted using only the impaired (n = 37) or reference (n = 33) sites data. The composition of reference sites was significantly different across regions when simultaneously tested (Table 4-7) with both abundance and presence data, and significant between all regions except Central and North when both abundance and presence data were iteratively tested. In stark contrast,

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92 either simultaneously or iteratively tested using either abundance or presence data (Table 4-8). Thus, while differences in the composition of reference sites were found through peninsular Florida, the composition of impaired sites was generally static. Table 4-7. MRPP analyses of the macroinvertebrate compositional similarity for reference sites between South, Central, and North wetland regions. Test A T p-value Abundance Global Test S vs. C vs. N 0.016 -2.171 0.028 Presence Global Test S vs. C vs. N 0.0177 -2.375 0.017 Abundance S vs. C 0.0192 -2.478 0.019 Iterative S vs. N 0.0231 -2.693 0.013 Tests C vs. N -0.0049 0.574 0.683 Presence S vs. C 0.0180 -2.671 0.022 Iterative S vs. N 0.0260 -2.816 0.011 Tests C vs. N -0.0030 0.041 0.636 Note: Abbreviations are S (South Region), C (Central Region), N (North Region). Global tests refer to simultaneous multivariate tests of the pooled macroinvertebrates from all three wetland regions. Iterative tests exclude one group (of three) during the MRPP procedure. Community Composition and Environmental Gradients Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in the Appendix B. Significant differences between impaired and reference conditions, as measured by the Mann-Whitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 4-9). Water color was significant lower in reference conditions at p<0.10. Colinearity among variables, which was identified as a VIF>5.0 and a tolerance of <0.20, was recognized for %TC, TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the identified macroinvertebrates and the measured environmental parameters, including LDI score. Results indicated a moderate and significant relationship (Mantels r =0.35, p=0.001), suggesting that the genus-level composition of peninsular herbaceous marshes was determined by the measured environmental driving factors.

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93 Table 4-8. MRPP analyses of the macroinvertebrate compositional similarity for impaired sites between South, Central, and North wetland regions. Test A T p-value Abundance Global Test S vs. C vs. N 0.0005 -0.064 0.431 Presence Global Test S vs. C vs. N 0.0029 -0.410 0.319 Abundance S vs. C -0.0037 0.583 0.687 Iterative S vs. N 0.0044 -0.430 0.290 Tests C vs. N 0.0031 -0.434 0.293 Presence S vs. C -0.0059 0.946 0.831 Iterative S vs. N 0.0122 -1.134 0.130 Tests C vs. N 0.0064 -0.910 0.178 Note : Abbreviations are S (South Region), C (Central Region), N (North Region). Global tests refer to simultaneous multivariate tests of the pooled macroinvertebrates from all three wetland regions. Iterative tests exclude one group (of three) during the MRPP procedure. Table 4-9. Comparison of the medians of water and soil variables between reference and impaired conditions with the Mann-Whitney U-test. Water Values Statistic (Z) p-value Color -1.868 0.062 Specific Conductivity -3.919 <0.001 Turbidity -1.524 0.127 Water pH -4.677 <0.001 Ammonia -2.690 0.007 Nitrates/Nitrites 0.771 0.441 TKN -2.932 0.003 TP -4.836 <0.001 Soil Values Statistic (Z) p-value Soil pH -3.036 0.002 %TC -0.818 0.414 %OM -1.253 0.210 %TN -1.147 0.251 %TP -2.771 0.006

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94 An NMDS ordination was completed to examine the underlying structure of the sites in ordination space and to ascertain the environmental variables driving the composition of the sites sampled. Correlations for all measured variables are presented in Table 4-10, and a biplot of site ordination overlaid with vectors representing the environmental variables is presented in Figure 4-1. The stress, or goodness of fit of the ordination was 19.32 and indicated an adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). Approximately sixty-eight percent of the variance in the dataset was captured by the three-dimensional NMDS ordination (first axis: 12.9%, second axis: 25.3%, third axis: 30.3%). In NMDS, unlike other ordination methods (e.g., principal components analysis, detrended correspondence analysis), axes are not necessarily ordered based on their importance. The third axis contained the most data in the NMDS ordination. As the second and third axes accounted for most of the variance in the dataset, the plot in Figure 4-1 is of sites along these two axes. The ordination scores for each site were linearly correlated (Pearsons r) with the measured environmental values, including LDI, latitude, and longitude. Correlations (Pearsons r2) > 0.30 were found for LDI, specific conductivity, soil pH, water TP, and color, suggesting their importance in driving the structure of the wetland macroinvertebrate community. Table 4-10. Correlations of environmental variables and ordination scores for macroinvertebrates. Axis 1 (12.9%) Axis 2 (25.3%) Axis 3 (30.3%) Parameter r2 tau r2 tau r2 tau LDI Score 0.12 -0.24 0.06 -0.18 0.42 0.41 Soil pH 0.34 -0.39 0.11 0.21 0.19 0.36 % TN <0.01 0.04 0.06 -0.22 <0.01 0.01 TP (mg/kg) 0.03 -0.15 0.09 -0.26 0.03 0.11 % OM 0.02 0.02 0.11 -0.26 <0.01 -0.03 Color (PCU) <0.01 -0.03 0.30 -0.33 0.03 0.10 Spec. Cond. (umhos/cm) 0.30 -0.37 0.02 -0.14 0.36 0.45 Turbidity (NTU) 0.01 -0.03 0.10 -0.11 0.09 0.18 Ammonia (mg/L) <0.01 -0.10 0.07 -0.17 0.08 0.31 Nitrate/Nitrite (mg/L) 0.01 <0.01 0.01 -0.12 <0.01 0.04 Water TP (mg/L) 0.07 -0.19 0.25 -0.38 0.33 0.43 Longitude <0.01 <0.01 0.13 -0.24 <0.01 -0.07 Latitude 0.03 0.10 0.20 -0.32 0.01 -0.08 Metric Development Compositional analyses between wetland regions equivocated on the ecological significance of the modeled wetland regions (Lane 2000) to macroinvertebrate distribution in isolated depressional marshes. Initial metric development utilized regional data sets however, the small n of the regional data and the low to moderate correlation of macroinvertebrates to the disturbance gradient (C. Lane unpublished research, see also

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95 Figure 4-1. Biplot of macroinvertebrate NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of their original length for clarity. The length of the vectors represents the strength of the Pearsons correlation (all r2 >0.30) and the angle represents the direction of maximum change. Four variables are shown: LDI (Landscape Development Intensity index), wTP (water total phosphorus), Spec (specific conductivity), and color. Soil pH was strongly correlated with the first axis, not shown. Tangen et al. 2003) limited development of regionally significant biological indicators of wetland condition. Perhaps due to the greater power of analysis, responsive patterns in the structure and composition of macroinvertebrate communities along the landscape modification gradient were discerned when the combined peninsular dataset (n=70) was examined. Thus, metrics to assess the condition of Floridas isolated herbaceous wetlands were identified utilizing the peninsular data set. In an effort to discern potential macroinvertebrate metrics, more than 60 categorical and compositional metrics were examined for the strength of the correlation

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96 with the LDI. Five metrics were developed that were selected based on the strength of their correlations with the LDI. These metrics are described below: % Sensitive Taxa, % Tolerant Taxa, % Predators, % Odonata, and % Orthocladiinae. Sensitive and tolerant taxa Indicator species analysis (calculated using genus-level data) identified twenty-seven genera with specificity and fidelity to reference or impaired conditions. Fourteen genera were significantly associated with reference conditions (Table 4-11), and thirteen genera were significantly associated with impaired conditions (Table 4-12). The taxa, calculated indicator species value, and p-value of the Monte Carlo test are also given in Tables 4-11 and 4-12. Once the sensitive and tolerant taxa were identified, a metric was developed based on the abundance of the indicator taxa. The relationship between the abundance of sensitive and tolerant genera, respectively, and the LDI is presented in Figures 4-2 and 4-3. The abundance of sensitive and tolerant genera were correlated with the LDI: % Sensitive Spearmans r = -0.65, p< 0.001; % Tolerant Genera Spearmans r = 0.71, p< 0.001. The distribution of the abundance of sensitive taxa appeared to be highly variable for any given LDI value, although a decreasing trend with increasing LDI scores was evident. The abundance of tolerant taxa did not appear to correlate strongly with the LDI until a threshold of approximately 3.2 was reached. The abundance of tolerant taxa was also highly variable, although this was only evidenced after LDI values of 3.2 were obtained. Table 4-11. Statewide indicators of reference conditions as determined from Indicator Species Analysis. Indicator Genera (LDI <2.0) Observed Ind. Value p-value Ablabesmyia 48.9 <0.001 Chaoborus 54.1 0.004 Clinotanypus 12.1 0.042 Corethrella 9.1 0.099 Hydroporus 9.1 0.097 Ischnura 16.0 0.088 Labrundinia 50.2 <0.001 Larsia 48.9 0.014 Lestes 12.1 0.046 Limnochares 9.1 0.097 Orthotrichia 9.1 0.097 Piona 12.1 0.045 Procladius 24.9 0.005 Sminthurinus 9.1 0.098

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97 Table 4-12. Statewide indicators of impaired conditions as determined from Indicator Species Analysis. Indicator Genera (LDI 2.0) Observed Ind. Value p-value Atrichopogon 26.5 0.041 Beardius 27.7 0.071 Enochrus 25.4 0.060 Goeldichironomus 70.7 <0.001 Haliplus 13.5 0.055 Mansonia 21.6 0.006 Micromenetus 23.1 0.025 Monopelopia 62.5 <0.001 Odontomyia 27.7 0.004 Pachydrus 21.1 0.028 Physella 20.9 0.076 Ranatra 16.2 0.025 Zavreliella 16.3 0.079 Figure 4-2. Abundance of sensitive taxa plotted against the LDI.

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98 Figure 4-3. Abundance of tolerant taxa plotted against the LDI. Percent predators The abundance of organisms classified in the predator functional feeding group was expected to decrease with increasing LDI scores (U.S. EPA 2002c). As demonstrated in Figure 4-4, these results support that hypothesis, as the abundance of predators decreased significantly (Spearmans r = -0.32, p= 0.007) along the increasing LDI gradient. Additionally, predators were significantly more abundant in reference conditions than in impaired conditions (Mann-Whitney U-test Z = 2.900, p= 0.004). However, the data were highly variable with any given LDI value, indicating marginal precision and accuracy, despite the significant correlation. Percent Odonata The abundance of members of the order Odonata (dragonflies and damselflies; class Insecta) was identified as an indicator of wetland condition in isolated depressional wetlands across peninsular Florida. With increasing LDI scores, the abundance of odonates decreased. A plot of the relationship between the abundance of odonates and the LDI is presented in Figure 4-5. Results of the Mann-Whitney U-test indicated a significant difference in Odonata abundance between reference and impaired wetlands (Z = 2.334, p= 0.020). The metric was significantly but moderately correlated (Spearmans r = -0.33, p= 0.005) with the disturbance gradient. The weak relationship between the LDI and the abundance of Odonata was also evidenced by highly variable values along the LDI gradient.

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99 Figure 4-4. Predator abundance plotted against the LDI. Figure 4-5. Odonata abundance plotted against the LDI Percent Orthocladiinae The abundance of the Orthocladinae tribe (midges, class Insecta, Chironomidae family) was correlated with disturbance gradient. Increases in LDI scores were generally reflected by increased abundance of Orthocladiinae midges (Figure 4-6), although the variance in the data was very high for any given LDI score. Orthocladinae were

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100 Figure 4-6. The abundance of Orthocladiinae plotted against the LDI. significantly more abundant at impaired than reference sites (Mann-Whitney U-test Z = 3.100, p = 0.002). The abundance of Orthocladiiae midges was moderately but significantly correlated with the LDI (Spearmans r = 0.33, p= 0.006). Macroinvertebrate Index of Wetland Condition The five final metrics were scaled, scored, and summed to create the Macroinvertebrate Index of Wetland Condition (MIWC). The 95th percentile and the quartile scores for each of the five metrics are presented in Table 4-13. The relationship between the MIWC and the LDI is presented in Figure 4-7. Scores for the MIWC range from 0 (three sites) to 50 (one site) (Table 4-14). Two of the three low-scoring sites were located in cattle pastures, while the third was surrounded by a watermelon farm. The highest scoring site was located in Ocala National Forest. The MIWC was correlated with the LDI: (Spearmans r = 0.79, p< 0.001). Data distribution was highly variable, although a decreasing linear trend was apparent. A Mann-Whitney U-test of the difference in median MIWC scores between reference and impaired sites indicated a highly significant difference (Z = 5.331, p< 0.001). Table 4-13. Quadrisect values and the 95th percentile data for each proposed biological indicator. Metric 95th Percentile0 Scores 3 Scores 7 Scores 10 Scores % Sensitive Genera 28.31 < 1.27 1.27 5.28 > 5.28 13.06 > 13.06 % Tolerant Genera 46.00 > 12.58 > 3.45 12.58 0.85 3.45 < 0.85 % Predators 59.74 < 17.85 17.85 25.78 > 25.78 37.98 > 37.98 % Odonata 13.15 < 0.81 0.81 2.25 > 2.25 5.02 > 5.02 % Orthocladiinae 44.52 > 22.40 > 15.06 22.407.95 15.06 < 7.95

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101 Figure 4-7. The Macroinvertebrate Index of Wetland Condition plotted against the LDI. Discussion Increases in land use intensity directly surrounding the study wetlands were manifested within the wetland through alterations in the composition of the macroinvertebrate community when compared with systems in reference, or low development intensity landscapes. Five metrics were discerned that permitted a measurement of the effect of increased landscape development on the macroinvertebrate community: the abundance of sensitive and tolerant genera, predators, odonates, and Orthocladiinae. The results of this study suggest that macroinvertebrate metrics, both compositional and categorical, were able to discern the relative condition of isolated depressional wetlands throughout peninsular Florida. Likewise, strong correlations between the LDI and the Macroinvertebrate Index of Wetland Condition, which synthesizes scores of each metric, supports macroinvertebrates indicators of freshwater wetland condition, although the relationships were not highly sensitive or precise. Environmental Correlates and Macroinvertebrate Composition A premise behind the biological assessment of aquatic systems is the intimate relationship of organisms and the environment. Both exogenous and endogenous alterations to the environment, if sufficiently intense (or if synergistic relationships are sufficiently intense), are manifested in the community characteristics of various assemblages (Karr and Chu 1997). Allan and Johnson (1997) and Hynes (1975) theorized that aquatic communities (i.e., riverine and lacustrine systems) respond to environmental

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102 Table 4-14. Macroinvertebrate Index of Community Condition scores for sampled sites. Sites MIWCSites MIWC Audubon 0 Immokalee 17 BearScat 23 IRBlueCypress 16 variables such as water TP, soil pH, color, and specific conductivity affected community BigCow 3 IRCanal 3 BRSebastian 41 IROJ 29 CabPatch 9 JD6 26 Caravelle 33 KellyPark 6 Chuluota 37 LCork 20 CLBayard 40 LLeeCounty 36 CLCove 14 LEGo 31 CMWPast 27 LESuwan 43 CMWRef 27 MALudy 10 COBurgle 16 MASpray 34 COHole 22 McArthur 27 Crew 27 MNElmer 33 DEMelon 40 MNOcala 50 Deerfly 0 MRPepper 3 Garber 23 Myakka 34 GBarE 9 OKCara 16 GLDonut 10 OKKiss 47 GLPont 30 OKPast 20 Goethe 41 PacificTom 24 GreenSwamp 43 PallMar 27 HARare 10 PBCorbett 34 HagueI 3 PBEnjay 37 HagueII 7 Penner 43 HalfMoon 40 POWales 47 HEBad 16 POWeowak 47 HEL2 0 RiceCreek 37 HEOkay 20 SANorthMya 34 Highpast 33 SAOscer 20 HighRef 47 SandhillCrane 27 HillsRef 44 Savannas 43 HuntCamp 27 STCow 10 IFASI 13 UNHealthy 7 IFASII 20 Weikiva 40 stimuli that operate at various spatial and temporal scales. In this study, the ordination of macroinvertebrate genera abundance data identified LDI score, specific conductivity, soil pH, water TP, and water color as significant variables determining macroinvertebrate community composition (see Table 4-10). Temporal and spatial changes in landscape-scale development intensity, as well as daily, weekly, and seasonal changes in localized

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103 composition. Thus, the results of this study suggested that the notions proffered by Allen and Johnson (1997) and Hynes (1975) can also be applied to wetland systems. As macroinvertebrates are responsive to a suite of anthropogenic alterations (this study; Adamus and Brant 1990, Adamus 1996, Danielson 1998, Anderson and be hypothesized, however, that increasing the opaqueness of the water may affect diatom Vondracek 1999, Euliss and Mushet 1999, Adamus et al. 2001, but see also Tangen et al. 2003), it is not surprising that a significant relationship with a general impairment indicator was identified. The use of a general, independent disturbance gradient to measure anthropogenic disturbance has enjoyed recent successes in biological assessment (Carpenter and Waite 2000, Cuffney et al. 2000, OConner et al. 2000, Munn et al. 2002, Fore and Grafe 2003). Landscape-scale assessment methods, such as the LDI, are generally adept at indirectly or directly capturing alterations not easily quantified such as hydrologic modification through ditching, draining, and berm building, changes due to landscape variables such as fire frequency and intensity, and modifications to physical, chemical, and nutrient loading rates as landscapes change. However, including smaller-scale (temporal and spatial) measurements such as soil and water chemistry are integral to understanding particular deterministic variables affecting aquatic communities and may assist in explaining high variance for given LDI values. As noted, in addition to LDI value, this study determined specific conductivity, (soil) pH, water TP, and water color to be important structuring components of macroinvertebrate communities in isolated herbaceous depressional marshes of peninsular Florida. Elevated conductivity measures can generally affect aquatic organisms through osmotic regulatory alterations (Stevenson et al. 1999, Spieles and Mitsch 2000). Specific conductivity measures play an important part in macroinvertebrate community composition (Ormerod and Edwards 1987, Growns et al. 1992, Tate and Heiny 1995, Spieles and Mitsch 2000, Carlisle et al. 2003). Studies by Malmqvist and Maki (1994) and Evans et al. (1999) have indicated the responsiveness of aquatic macroinvertebrates to alterations in pH. Danielson (1998), Doherty et al. (2000), and Adamus et al. (2001), reviewing macroinvertebrates as biological indicators, noted their utility in identifying pH-modified wetland systems. It is well established that as a result of both the gradual translocation of materials available for cation exchange (Evans et al. 1999) and the extended anoxic conditions in inundated soils, wetlands in pine flatwoods are generally low pH systems characterized by organisms evolved to tolerate acidic conditions (Kushlan 1990, Evans et al. 1999). Conversely, elevated pH values are often found in agricultural settings due to application of agrochemicals composed of basic compounds, which can alter the pH of receiving water bodies and hence species composition (Fore and Grafe 2002). Macroinvertebrate communities respond to alterations in phosphorous concentrations (Brightman 1984, Adamus and Brandt 1990, Malmqvist and Maki 1994, Tate and Heiny 1995, Adamus 1996, Danielson 1998, Doherty et al. 2000). Nutrients, such as TP, can increase productivity but also increase community respiration and thus affect dissolved oxygen levels and physical/chemical characteristics of the water body with subsequent effects on wetland communities (Dierberg and Brezonik 1984). Few studies have implicated water color as directly affecting macroinvertebrate community composition (Malmqvist and Maki 1994, but see Crisman et al. 1998). It can

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104 productivity through decreases in the available light for photosynthetic processes. Possible decreases in macroinvertebrate assemblages consuming epiphytic and benthic algae (i.e., scrappers) could be expected, with potential interactions throughout the macroinvertebrate food web. In addition, increases in water color may affect visual predatory macroinvertebrates by decreasing the visibility of prey. Regional Data Analyses Data were initially analyzed at the regional level to account for differences between the macroinvertebrate composition of peninsular Florida wetlands that could be attributed to latitudinal, geophysical, or climatological vagaries. However, while significant differences were found between regions using the abundance dataset, no significant differences were identified using presence-absence data. While both presence and abundance may differ temporally, abundance data are much more dynamic and may be more a reflection of sampling period than of landscape characteristics affecting wetland communities. The lack of significant correlations between NMDS ordination scores and latitude and longitude (as analogs for wetland regions see Lane 2000) similarly decreased the importance of regions for macroinvertebrate analyses in herbaceous wetlands. In addition, the increased power of analyses using a larger dataset (i.e., not incorporating the modeled wetland regions) made for stronger, more significant relationships between site composition and landscape characteristics. It was therefore determined that regionally unique metrics were not necessary, and the final metrics described in this chapter were developed utilizing the peninsular dataset (n=70). However, additional sampling and analyses within each wetland region may provide fruitful information germane to regionally unique macroinvertebrate metrics, and the development of additional metrics for macroinvertebrates may utilize regions as reports developed for stream and lake biological assessment in Florida (Barbour et al. 1996, Gerritsen et al. 2000) have concluded. Final Metrics Five final metrics were significantly correlated with increasing LDI scores: the abundance of sensitive and tolerant taxa, the abundance of predators, the abundance of Odonata, and the abundance of Orthocladiinae. Final metric correlations with the LDI were significant (p< 0.05) and Spearmans correlation coefficients were greater than |0.30|. While significant trends in the dataset were identified, lower correlation coefficients were obtained than anticipated and reflected the lack of sensitivity and precision inherent within the data that comprised the MIWC. The variance within each metric was large for any given LDI value, and only general trends were evidenced in the relationship between the LDI and the metrics. However, information germane to the development of biological indicators was nevertheless obtained, as suggested by the significance of the correlation between the LDI and the summed MIWC. The five final metrics are discussed below.

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105 Sensitive and tolerant genera To be able to statistically evaluate the specificity and fidelity of taxa to a particular class through a Monte Carlo randomization algorithm is an alluring LDI scores, as occurred in this study, due to similar reasons described above (see Categorical Metrics Predators). However, the relationship between the LDI and the characteristic of Indicator Species Analysis (ISA). Indeed, the use of ISA in ecological literature is increasing (McCune and Grace 2002), although a recent report suggested that ISA was conservative in dealing with rare taxa (Chytry et al. 2002). Nevertheless, use of ISA in this analysis allowed for the identification of twenty-seven taxa indicative of reference or impaired conditions. However, the distribution of the data indicated that neither the abundance of sensitive taxa or tolerant taxa were particularly precise or accurate indicators of LDI values due to the highly variable nature of the relationship between the LDI and the metrics. A general trend, although highly variable, was evidenced by the abundance of sensitive taxa, while tolerant taxa did not appear to reflect greater than background values until LDI scores of approximately 3.3. The high variance in these metrics may be a result of the taxonomic level in the analyses. Additional analyses to develop optima (i.e., U.S. EPA 2002e) for indicator species, or to further determine which environmental factors were most responsible for the distribution of the indicator taxa are suggested by these results and would assist in determining the ecological significance of the indicator taxa and the relationship of metrics to the LDI gradient. Categorical metricspredators A general decline was apparent in the abundance of predators identified within each sample with increasing LDI value, indicating the increasing importance of generalists and lower-structured food webs. However, the variance within the dataset was very large regardless of LDI value. This may be explained by several factors acting independently or in concert. For instance, Chovanec and Raab (1997) found that a physical disturbance in wetlands (such as vegetation removal by ruminates and subsequent lack of perches) affected the abundance of predators. Altered timing, depth, and duration of water, which often occurs on managed landscapes, affected development of various instars of predatory macroinvertebrates (Anderson and Vondracek 1999). Agrochemical applications within a wetland watershed altered the trophic structure (i.e., increase the abundance of generalists) of wetlands in North Dakata (Euliss and Mushet 1999). A decrease in wetland water clarity from the constant re-suspension of flocculent materials in areas of high cattle densities (Newcombe and MacDonald 1991) negatively affected the abundance of predatory macroinvertebrates due to decreased success from visual predators. Categorical metricsOdonates Larval odonates comprise an important part of many aquatic system food webs, including fish, amphibians, birds, and other organisms (Merrit and Cummins 1996). As predators, members of the order Odonata would be expected to decrease with increasing

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106 abundance of Odonates was highly variable for any given LDI value, decreasing the information content of the relationship, as well as the sensitivity and accuracy. Odonates tend to equivocate on their response to disturbances, which may explain some of the variance in the dataset. Odonates are tolerant to many disturbances such as altered pH, assessment at a fine scale. It may be important in future analyses to target the Chironomidae and thus decrease the laboratory sampling time spent on other families, or and low to moderate nutrient loading (Chovanec and Raab 1997), which would tend to decrease their utility as biological indicators. However, they have been identified as indicators of, the ecological integrity of ecosystem structures, the ecological quality of the land-water interface, and the connectivity of aquatic ecosystems to other landscape units (Chovanec and Raab 1997, p. 383). These abilities may be due in part to the long life cycle of odonates, as they would be expected to integrate long term and short, episodic perturbations to the wetland. Conrad et al. (1999) also reported the importance of landscape-level connectivity and structure to odonate population dynamics. Often, marsh systems are drained and filled in the course of agricultural operationsdecreasing the abundance of these systems on a landscape scale when compared to marsh systems located in reference landscapes (Pearlstine et al. 1997). Categorical metricsOrthocladiinae That midges (Diptera: Chironomidae) comprise a metric for the assessment of wetland condition was not surprising, given that they are often the most numerous insects present in freshwater environments (Cranston 1995, Coffman and Ferrington 1996). Midges have been so abundant in the benthos of both lentic and lotic aquatic systems as to be used in classifying streams and lakes (Lindegaard 1995), and were used as some of the earliest indicator organisms of anthropogenic eutrophication as the Chironomidae family contains genera extremely sensitive to disturbances (such as nutrient enrichment, Rosenberg and Resh 1993). The Chironomidae also contain genera that are extremely tolerant of such conditions, which implies identification to at least sub-family, as suggested by Lindegaard (1995). The majority of biological assessment research on midges (and macroinvertebrates in general) has been conducted for assessment of streams and lakes, and not wetlands (Rosenberg and Resh 1993, but see Driver 1977, Delettre 1989, Streever et al. 1995, Leeper and Taylor 1998, Gernes and Helgen 1999, Kashian and Burton 2000, King and Richardson 2002, U.S. EPA 2002c). Thus, many of the tolerance values or responses to disturbance present in the literature for cosmopolitan midges of those habitats (i.e., Beck 1954, Lenat 1993) may not be viable for the assessment of wetland environments due to the different driving forces acting on them. Despite apparent benefits in the assessment of herbaceous wetland systems, use of the Chironomidae in biotic assessment should include caveats: first, many chironomids may only be identified to species after being mounted on microscope slides and examined under high-magnification, with complimentary increases in sample processing time and cost. To wit, the time spent in-lab washing, sorting, subsampling, and identifying 100 to 150 organisms, including the Chironomidae, averaged over 20 hours per site (R. Frydenborg, FDEP, personal communication). Second, the variance within the dataset indicated that the relationship between the LDI and the Chironomidae was highly variable for any given LDI score, which would decrease their relative utility in wetland

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107 to examine larval Chironomidae further for developmental abnormalities as deformations have been correlated to exogenous perturbations (Johnson et al. 1993). Macroinvertebrate Index of Wetland Condition sampled in late summer to early fall. Most sites identified in spring were dry, yet all sites studied (for macroinvertebrate analyses) were hydrated when sampled. However, no The macroinvertebrate metrics were significantly correlated with the LDI, although the data were generally neither sensitive nor precise at that scale, as reflected by high variance for any given LDI value. While many agencies and researchers have touted use of macroinvertebrates to assess stream and lake systems (Barbour et al. 1996, Gerritsen and White 1997), as well as wetland systems (U.S. EPA 2002c), recent literature has indicated that the macroinvertebrate community may not be particularly responsive to agricultural perturbations (Tangen et al. 2003). These results support the use of macroinvertebrates as biological indicators of wetland condition in agricultural settings at the scale provided, but also suggest exploration of macroinvertebrate composition and structure along additional scales to increase the strength of the relationship. Field Sampling and Macroinvertebrate Identification Field sampling The very nature of wetlands predisposes macroinvertebrates to wide fluctuations in hydrology, as well as associated fluctuations in temperature, salinity, and dissolved oxygen levels (Sharitz and Batzer 1999, Leslie et al. 1999, Evans et al. 1999). Florida is generally wettest during summer and driest during late winter and early spring (Chen and Gerber 1990). However, an expansive drought subjected many peninsular Florida wetlands to depressed or non-existent hydroperiods during the sample period of 1999 and 2000 (Lawrimore et al. 2001). As such, the study wetlands were sampled late in the summer growing season to ensure that the wetlands were sufficiently hydrated (mean sampling date in 1999 was September 5, and September 29 in 2000). This late sampling date, and the range in dates for each region and year (Table 3-2), may have had ramifications on the observed macroinvertebrates, since the late summer to fall sampling window may have excluded some species that complete their life cycle early in the growing season (Anderson and Vondracek 1999). Additionally, the range in sampling dates from July and August to early November could affect the results, and thus comparative site scoring as some sites might have been sampled early in the summer while others in the same region were sampled in the fall, yet they were compared in the analyses to each other. In essence, some organisms might have been collected early in the season but were not found later in the season not as a function of the land use around the wetland but as a function of the date sampled. Thus, the presence or abundance of an organism at a site may be related to the sampling date instead of the character of the landscape surrounding the wetland. Sites were selected for inclusion based on the providence of supportive landowners and managers and the prevalent land use around each wetland. The sites sampled were generally identified in early spring to mid summer, and subsequently

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108 gauges were placed on-site to discern the time span between wetland hydration and the sampling date. Some sites sampled may have only recently been hydrated and thus may have supported only a paltry abundance of organisms or a particular composition not due to landscape factors but due to the short window of opportunity for emergence for many fixed count results in substantial information loss in analyses of stream biota. In a study of wetlands of the Everglades, King and Richardson (2002) found that fixed counts of macroinvertebrates (Wiggins et al. 1980, Wallace and Anderson 1996). Many authors have noted seasonal differences in the emergence of macroinvertebrates (Anderson and Vondracek 1999, Stewart and Loar 1994, Wallace and Anderson 1996) and the existence of delay between hydration and emergence of macroinvertebrates (Sharitz and Batzer 1999, Wallace and Anderson 1996, Battle and Golladay 2001, Euliss and Mushet 1999). Current research (C. Lane, unpublished research), including resampling studied wetlands across years and various seasons, may assist in understanding these relationships and their effect on biological assessment. Macroinvertebrate identification and enumeration Taxonomic resolution. Macroinvertebrates were identified to the lowest possible taxon, with 82% being identified to genus. Incomplete specimens, early instars, or lack of diagnostic features hampered identification to species level. With only 48% of the organisms encountered identified to species, a substantial amount of information was lost from the inability to identify the organism to a lower phylogenic level. For instance, Bailey et al. (2001) reported that there was substantial variation in the response of organisms at the family, genus, and species level to perturbations. Resh and Unzicker (1975) reported that assessment analyses conducted at the species level differed from results obtained when the data were analyzed at the genus level. In the only analysis of taxonomic resolution in wetland macroinvertebrate data to date, King and Richardson (2002) found that metrics consisting of family-level indicators were inferior in their environmental relationship to genus and species level indicators. However, multivariate analyses completed by Bowman and Bailey (1998) and Furse et al. (1984) indicated that the difference between lentic study sites in ordinate space was very similar between genus and order levels, indicating that they both reflect similar site information. Many state wetland bioassessment programs incorporate analyses at the family level (Montana, Ohio, Minnesota, cited in U.S. EPA 2002c) or order level (Maine, Minnesota, Montana, Ohio, cited in U.S. EPA 2002c). Often, these programs are trying to categorize aquatic systems as impaired or unimpaired, or as good, fair, or poor, and not attempting to delve into the specific impairments. Using a coarse taxonomic resolution appears to permit such statements but may prevent elucidation of a more detailed assessment regarding the types of perturbations affecting a target aquatic system (Bailey et al. 2001). Fixed count methodology. The Florida Department of Environmental Protection mandates fixed counts of approximately 100 organisms for both the Stream Condition Index (Barbour et al. 1996) and Lake Condition Index (Gerritsen et al. 2000). The organisms colleted in this study were identified by the FDEP Central Lab utilizing the same 100-count protocols as these indices. There has been substantial dialogue in the literature regarding the efficacy of fixed-count subsampling to 100 organisms in rapid assessment programs. Doberstein et al. (2000) agreed with Courtemanch (1996), Sovell and Vondracek (1999), and Karr and Chu (1999) that subsampling using a 100-organism

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109 200 did substantially better at determining impairment than counts of 100 organisms, but increases above 200 organisms resulted in no change in impairment detection ability. Doberstein et al. (2000) also commented that counting 100 organisms introduces within-site variability with subsampling replicates, and that the variance decreases with window expanded to both increase the power of the analyses and to expand the applicability of the results. As these metrics were developed with genus-level data, increasing subsample size. The results of this study suggest that fixed count sampling to approximately 100 organisms provides adequate information to characterize the fauna and to discern the relative quality of the sampled isolated depressional herbaceous wetlands. As the metrics proposed are abundance metrics, they are less affected by the increases in sampling effort due to expected isometric responses (Barbour and Gerritsen 1996). However, the sites sampled in this study were generally polarized along the disturbance gradient. Classification into two (or three) groups (such as good, fair, or poor) is generally reliable under such circumstances (Karr and Chu 1999, but see Doberstein et al. 2000, King and Richardson 2002). It may be more difficult to discern differences in mid-quality wetland assessments using fixed counts of 100 organisms (Doberstein et al. 2000), and more organisms or additional search methods (i.e., select for large, rare macroinvertebrates) may be warranted under such circumstances (Barbour et al. 1999). Another criticism of fixed-count subsampling is that rare species are often overlooked (Sovell and Vondracek 1999, Cao et al. 2001, Bailey et al. 2001). This study did not analyze species-level information, which decreases the likelihood of rare taxa. Including species-level information may provide additional data from which metrics may be identified, however, additional costs and time are involved. The relationship between rare species and wetland characterization warrants additional attention. Conclusions and Recommendations Five attributes of macroinvertebrate community composition or structure were identified for use as biological indicators. The summed value of these five metrics, creating the Macroinvertebrate Index of Wetland Condition (MIWC), was correlated with the LDI gradient >0.75, although the precision and sensitivity of the metrics that comprise the MIWC was generally low. The macroinvertebrate composition of isolated systems in Florida was driven by variation in Landscape Development Intensity, soil pH, specific conductivity, and water TP. Specific actions to decrease the influence of these deterministic environmental variables in isolated wetland systems may result in wetland systems with community structure and function more similar to reference sites. Additional information on the relationship of the macroinvertebrate community along a disturbance gradient may be gleaned from a more detailed taxonomic examination of the composite samples. Stronger correlations, including the development of optima may be ascertained from species-level studies, although generalizations could be made using genus-level (or perhaps higher, e.g., Hilsenhoff 1988). However, as previously mentioned, laboratory identification to species of certain families of macroinvertebrates can be laborious and difficult. Also, as diagnostic features may be temporally available, or development seasonally dependent, species identification may be fortuitous at best. It is suggested, therefore, that additional sites be sampled and the temporal study

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110 increasing the sample size will necessarily increase the power of the analyses and also decrease variation in the data due to the relatively coarse level of identification. For instance, some taxa have species that are sensitive to, and species that are tolerant of, measured changes such as decreased dissolved oxygen (Barbour et al. 1999). Increasing sample size may assist in further elucidating trends between environmental variables of interest and macroinvertebrate community response. In addition, increasing sample size will likewise increase the likelihood of improved taxonomic resolution as laboratories become more familiar with taxa of isolated depressional wetlands and increase their reference collections. Increase in sample size may also permit the development of additional metrics or the exploration of different disturbances (e.g., urban systems). Finally, as wetland macroinvertebrate community composition was also related to environmental gradients (such as TP, specific conductivity, pH, etc.), additional laboratory studies of the relationship between particular gradients (i.e., increases in pH) may be fruitful. Controlling for particular effects may further the knowledge of the response of wetland macroinvertebrates to anthropogenic disturbances and assist in identifying optima and other discursive and useful information on wetland macroinvertebrates autecology.

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CHAPTER 5 SUMMARY AND SYNTHESIS Metric Summary A Wetland Condition Index (WCI) of twenty-four metrics was developed from the three assemblages sampled from isolated depressional herbaceous wetlands located throughout peninsular Florida: fourteen algal metrics, five macrophyte metrics, and five macroinvertebrate metrics. The metrics identified were comprised of compositional, trophic, and autecological attributes that varied with respect to changes in the development intensity within a 100m buffer immediately surrounding the study wetlands. Correlations between the three indices (Diatom Index of Wetland Condition, Vegetative Index of Wetland Condition, and Macroinvertebrate Index of Wetland Condition) and the measured Landscape Development Intensity index (LDI) were each greater than |0.65| and were highly significant (p<0.001), although also highly variable. Landscape Assessment and Index Development An assumption inherent in this study is the direct relationship between the land use within the wetland basin and the composition and function of the wetland itself. This assumption was predicated on the use of landscape-scale characteristics obtained from the literature to quantify the level of disturbance within a system (Cuffney et al. 2000, Galatowitsch et al. 1999a). Landscape-scale measurements of human disturbance, such as the Landscape Development Intensity index (LDI), provided an independent assessment of possible deleterious inputs (e.g., phosphorous loading from agricultural operations) and alterations to the proper functioning of the wetland (e.g., changes in fire or hydrologic regime due to land use change). Landscape-scale measurements, when coupled with GIS analyses, also provided repeatable measurements when compared with subjective on-site procedures (e.g., Wetland Rapid Assessment Procedure, Miller and Gunsalus 1997). The scale of the disturbance assessment may have had ramifications on the correlation coefficient of the measured ecological condition of the wetland sampled. For instance, the LDI does not incorporate slope, elevation, or direction of flow into the assessment. Thus, a system with a potentially disruptive land use (e.g., a dairy farm) within the 100m buffer but down hill would have the same score as a site with a dairy farm within the 100m buffer but uphill despite the obvious advantages to being located uphill of such a potential perturbation. This landscape assessment artifact may be reflected in the high variance, low precision, and low sensitivity of the metric values for any given LDI score (i.e., Figure 2-6). Improvements to the LDI, such as incorporating the existence of buffers to flow (i.e., berms) or access (i.e., Serenoa repens) may improve the relationship between organismal response and landscape perturbation. 111

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112 The Landscape Development Intensity index, as an agglomerative measure, incorporates and assigns disturbance coefficients to multiple land uses based on non-renewable fuel use (Brown and Vivas submitted). However, ecological responses to increases in non-renewable fuel use may not follow the rank order inherent within the LDI. For instance, agricultural practices generally use less non-renewable fuel per hectare than single family residential land use (Table 1-1). The pesticides and fertilizers used in agricultural practices, however, have a direct effect on the composition and functioning of wetland systems (Euliss and Mushet 1999). Single family residential land use may use pesticides and fertilizers, but likely at a much lower per hectare dosage in other words the direct effect on ecosystems may not be as intense. Thus higher LDI scores may not be directly analogous to increased stressors on wetland assemblages. This may led to highly variable responses from metrics for any given LDI score (e.g., Figure 2-6). The LDI was developed as an agglomerative index of energy intensity, but based on the highly variable metric response in these analyses, it appears that additional information germane to development intensity might improve the relationship between the biological data and the landscape data. For instance, improvements to the development index could come from separating out the effect of altered hydrology from other values due to its relative importance to wetlands (Mitsch and Gosselink 2000). In the current LDI, hydrological alterations are impossible to identify due to the methodology inherent within the LDI (Brown and Vivas submitted). With two exceptions (mean Coefficient of Conservatism and Annual to Perennial ratio), metrics identified in this analysis are based on the abundance of various compositional, functional, or trophic assemblages. Data are constrained (Aitchison 1986) due to the abundance values necessarily ranging from 0% 100%. The use of constrained data in developing the three indices of wetland condition may be implicated in the highly variable empirical scores for metrics along increasing LDI values. Membership in one group (e.g., % Orthocladiinae) may be inversely related to membership in another group (e.g., % Tolerant). For instance, a high abundance of Orthocladiinae in any given sample necessitates a lower abundance of tolerant organisms, as the non-Orthocladiinae portion of the sample would be small (i.e., 100% Orthocladiinae % = remaining sample for categorizing). Thus, some metric values may be lower than anticipated for any given LDI score not as a function of the surrounding land use but due to the effects of constrained data. In summary, as a general, landscape level development intensity index, the LDI was significantly correlated with each of the metric developed, although the results were highly variable. However, the LDI remains a useful relative indicator of wetland condition despite the relatively low resolution as conclusions may be drawn regarding the expected landscape relationship to down-slope wetlands. In addition, the LDI, compared to field work, provides a relatively simple assessment for a minor expenditure of effort and money. In addition, the use and acceptability of GIS in landscape assessment is increasing as the number of available coverages and GIS applications continues to increase (Cuffney et al. 2000).

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113 Environmental Variables Driving Wetland Composition Across Assemblages Soil and water samples from wetlands in reference and developed landscapes were shown to be significantly different for the following non-collinear environmental anoxia, such as the release of bound phosphorous from the soil, could further alter community composition. variables: soil pH, soil TP, specific conductivity, ammonia, and water TP. Dimension-reducing ordination with non-metric multidimensional scaling (NMDS) and subsequent correlations of environmental variables with ordination scores indicated that for algal, macrophyte, and macroinvertebrate assemblages, LDI score, soil pH, specific conductivity, and water TP were important components driving wetland composition. Latitude and water color were also correlated with ordination scores for macrophytes and macroinvertebrates, respectively. While the relationship of each assemblage with the four (or five, in the case of macrophytes and macroinvertebrates) environmental variables was discussed, the strong correlation of the composition of these three very different assemblages with the variables LDI, soil pH, specific conductivity, and water TP warrants additional attention. The four driving environmental variables were measures that acted on various scales. LDI was a coarse measurement of human landscape modification. Specific conductivity and water TP were finer-scale measurements that typically emanated from the interaction of precipitation and constituent mobilization and runoff into the wetland system. These two variables may also have been modified by human landscape alterations such that irrigation, rather than natural rainfall, may have played a role in either mobilizing the constituents to the wetland or in increasing the specific conductivity of the receiving water body (Fore and Grafe 2002). Soil pH, another environmental variable operating on a finer scale, would be expected to be less reactive to landscape modifications since direct pH loading generally does not occur. However, agrochemicals are typically more basic, thus runoff and transportation of agrochemicals into receiving water bodies such as wetlands may affect not only the nutrient levels in the receiving waters, but also the pH of the system (Fore and Grafe 2002). Since the LDI was a general landscape modification measurement, it was expected that wetland species composition would be correlated with changes in the LDI across each assemblage. The results suggested that the LDI was able to couple the disparate effects of human landscape modification, such as altered hydrology (strongly affecting diatoms and macroinvertebrates) or trampling/selective herbivory (strongly affecting macrophytes), into a single value, which was assumed to be manifested by changes in assemblage composition. Phosphorous in the system would be expected to increase metabolic rates throughout the aquatic system. Thus, diatoms and macrophytes would increase production due to increased availability of a typically limiting nutrient, and macroinvertebrates would likewise increase in abundance as additional resources would be made available from plant production and subsequent decay. Increases in nutrient levels, however, can have deleterious impacts on wetland systems that can cascade through the various assemblages. For instance, increased nutrient loading can affect dissolved oxygen levels with the water body as chemical and biological oxygen demand may surpass available oxygen levels. This would drastically affect the three assemblages sampled (as well as most other organisms within the system). Chemical reactions to

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114 Specific conductivity and soil pH directly affect diatom community composition, generally through decreases in bio-available constituents (Pan and Stevenson 1996, U.S. EPA 2002e). Compositional changes related to either variable were generally less pronounced for macroinvertebrates (Spieles and Mitsch 2000) and macrophytes (Adamus integrity of wetland systems, methods to assess the relative condition of these systems et al. 2001). As diatoms are an important component of macroinvertebrate food webs, alterations to the macroinvertebrate food base may be manifested through compositional changes of the macroinvertebrate assemblage. Macrophytes are affected minimally by alterations in specific conductivity and pH (Danielson 1998, Adamus et al. 2001), although changes in these constituents may often indicate increased nutrient loading or groundwater irrigation (and associated landscape changes). Environmental Variables and Management Concerns Four environmental variables (LDI, soil pH, specific conductivity, and water TP) were strongly correlated with the community composition of diatoms, macrophytes, and macroinvertebrates of isolated herbaceous depressional wetlands of peninsular Florida. As the assemblages sampled represent primary, secondary, and tertiary trophic classes, structural components of the wetland itself, and a portion of the landscape food web (i.e., food source for passerines and wading birds, reptiles and amphibians, small mammals, etc.), changes in wetland management to decrease the effect of the controlling environmental variables would be advantageous to meeting the goals of the Clean Water Act. To ameliorate the impact of human landscape modification on wetland systems, it is hypothesized that creating buffer zones around wetlands would improve the community composition (i.e., the system would become more similar to wetlands in reference conditions) and improve biotic integrity. Buffer zones emanating from the wetland/upland boundary would likely improve wetland water quality through particle retention and nutrient uptake by upland/facultative plants of the buffer zone. Preventing domestic herbivores from grazing in the wetland through fencing or shrubbery (e.g., Serenoa repenssaw palmetto) would decrease damage from selective herbivory, as well as decrease nutrient loading from cattle wastes. Specific conductivity may decrease as a result of constituent uptake by buffer vegetation and immobilization of micro-constituents of the overland or subsurface flow. Soil pH in the wetland, considered a function of agrochemical loading, may also decrease as a result of wetland buffers as agrochemicals of the overland flow could be assimilated by buffer vegetation, and agrochemicals adsorbed onto soil particles would be sequestered in buffer vegetation. Conclusions and Recommendations Isolated, depressional wetlands provide many functions to the landscape and to the State of Florida. However, their spatial location, generally smaller size, and irregular or patchy distribution on the landscape have contributed to their filling or destruction such that they have been greatly reduced in number (Kirkman et al. 1999). Those that remain, if in developed landscapes, often have decreased functionality and integrity (sensu Karr 1981) due to anthropogenic inputs or landscape activities. To attempt to meet the goals of the Clean Water Act, which include maintaining the chemical, physical, and biological

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115 had to be developed. Once the relative condition was known, efforts to restore wetland systems could be undertaken. In this study, methods were developed to assess the relative condition of isolated herbaceous wetland systems in peninsular Florida using endemic wetland flora and fauna. Seventy-five isolated wetlands were sampled throughout peninsular Florida, and twenty-four metrics were developed from the algal, macrophyte, and macroinvertebrate assemblages identified. Individual metrics were summed for each of the assemblages and three indices developed for the Wetland Condition Index: the Diatom Index of Wetland Condition, the Macrophyte Index of Wetland Condition, and the Macroinvertebrate Index of Wetland Condition. Correlations of these three indices with the Landscape Development Intensity index, an independent, GIS analysis of human landscape modification were significant and >|0.65| (Spearmans r). In addition to developing biometrics for the three assemblages, environmental variables responsible for algal, macrophyte, and macroinvertebrate community composition were discerned. The parameters responsible, identified through site ordination, were of both coarse (LDI scores, and latitude for macrophytes) and finer scales (soil pH, water TP, and specific conductivity, as well as water color for macroinvertebrates). Efforts to decrease the impact of these inputs on wetland community composition through the development of wetland buffers were proffered. Due to the highly variable response of the twenty-four metrics identified vis--vis the LDI, efforts to improve the goodness of fit between the LDI and the biological data are warranted. Significant correlations were identified, however improvements in the correlation may be obtained through modifying the LDI (e.g., revising calculations) or changing the scale of the landscape analyses to include hydrologic alterations (currently not an itemized perturbation). An additional method to improve the fit of the data would through multiple regression analyses of sampled data and land use (before combined into the LDI). Recommendations for future work following these analyses are of two veins: validation (expanding the current n to compare and contrast how additional sites relate to the sites used to develop these indices) and calibration (amending the metrics developed from these analyses based on the results of the validation and the larger n), and expansion. Revisiting sites, increasing the dataset through the addition of new sites, and reevaluating the metrics developed based on the additional sampling effort are the hallmarks of a thorough validation and calibration program. An n of 75, while statistically satisfying, should be increased to capture the breadth and depth of the wetland systems of peninsular Florida more thoroughly. An expansion of this research into other impairments and marshes of varying size and location (i.e., the Florida panhandle) is also recommended. Impairments of different intensity, such as industrial or urban development, may be manifested by markedly different attributes in isolated wetlands located in those landscape matrices. Finally, including additional assemblages, such as reptiles/amphibians, soil microbes, or birds, could increase the information obtained from the wetland systems and perhaps permit a deeper understanding of the relationship between stressors, sources of stress, and the manifestation of exogenous perturbations on the flora and fauna, and ultimately the integrity itself, of isolated depressional wetlands throughout Florida.

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116 APPENDIX A SITE DESCRIPTIONS Seventy-five sites were sampled throughout peninsular Florida. Access to many sites was obtained through cooperation with landowners and was often contingent on site anonymity. Coordinates for sites sampled, exclusive of the anonymous sites, are given below (Table A-1), as are Landscape Development Intensity (LDI) scores. Additional information on LDI scores may be found in Brown and Vivas (submitted). Table A-1. Site coordinates and LDI score. Site LDI Latitude Longitude Site LDILatitude Longitude ALPaynes 1.38 29.60210 -82.23563HARare 3.58n/a n/a Audobon 3.54 28.11827 -82.11629HEBad 3.4926.30340 -81.24560 Bear Scat 1.18 26.18502 -81.25442HEL2 3.43n/a n/a Big Cow 3.58 26.23075 -81.26520HEOkay 1.0526.59035 -81.32581 BRSebastian 1.09 27.83263 -80.58833HighPast 3.7127.42338 -81.56088 CabPatch 3.54 29.43420 -81.34030HighRef 1 27.48100 -81.55022 Caravelle 3.54 29.51767 -81.72119HillsRef 1.2328.14610 -82.23110 Chuluota 1.00 28.61731 -81.05781Hunt Camp 1 29.32275 -81.74680 CLBayard 1.07 29.96117 -81.61504IFASI 2.2529.72395 -82.40680 CLCove 3.54 29.95187 -81.66341IFASII 1.8429.72678 -82.40619 CMWPast 2.14 26.85486 -81.78479Immokalee 2.6 26.46316 -81.44605 CMWRef 1.62 26.94567 -81.84494IRBlueCypress3.58n/a n/a COBurgle 3.36 n/a n/a IRCanal 3.59n/a n/a COHole 1.11 26.02437 -81.26467IROJ 3.68n/a n/a CREW 1.78 26.48973 -81.53834JD6 1.2427.00147 -80.14629 Deerfly 2.39 29.17017 -81.62333Kelly Park 3.6528.79637 -81.43891 DEMelon 4.20 n/a n/a LCork 1 26.47915 -81.54871 GarberRanch 2.75 27.21615 -82.15127Lego 1 29.13782 -82.63217 GBarE 3.38 n/a n/a LESuwan 2.1229.31693 -83.04337 GLDonut 3.59 n/a n/a LLeecounty 1.0226.70824 -81.65356 GLPont 3.29 n/a n/a MALudy 3.5 n/a n/a Goethe 1.52 29.16072 -82.59969MASpray 3.8 n/a n/a GreenSwamp 1.60 28.35458 -82.01761McArthur 3.7527.16536 -81.19631 HagueI 4.12 29.78267 -82.41186MNElmer 3.13n/a n/a HagueII 5.63 29.78350 -82.41133MNErik* 3.06n/a n/a Half Moon 1.99 28.91872 -82.25719MNOcala 1.5829.10181 -81.89731

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117 Table A-1. Continued. Site LDI Latitude Longitude Site LDILatitude Longitude MRPepper 4.54 n/a n/a PUPond* 1.4229.71649 -81.96575 Myakka 1.25 27.23684 -82.33043RiceCreek 1.8829.68086 -81.74208 OKCara 4.79 n/a n/a Sandhillcrane 3.1026.86677 -80.21878 OKKiss 1.20 27.55004 -81.00910SANorthmya 1.2027.27050 -82.25933 OKPast 3.58 27.59890 -81.03172SAOscer 1.1227.19536 -82.45383 PacificTom 4.54 26.52025 -81.67369Savannas 1.1327.30214 -80.27348 PallMar 1.00 26.94969 -80.31057STCow 3.94n/a n/a PBCorbett 1.13 26.94206 -80.36113SUVaca* 3.1728.91047 -82.25994 PBEnjay 1.00 26.95468 -80.18508SUWarhol* 3.66n/a n/a Penner 1.27 29.49614 -81.82489UNHealthy 3.9 30.04499 -82.17451 POWales 1.26 27.66359 -81.42379Weikiva 1.0028.73703 -81.48396 POWeowak 1.53 27.77768 -81.44651 Note: Latitude and longitude positions marked with n/a were accessed through agreements with anonymous landowners.

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118 of the lowest detectable level. APPENDIX B SOIL AND WATER SAMPLING METHODS AND RESULTS To relate the distribution of sampled communities to environmental parameters, soil and water physical and chemical constituents were measured (Tables B-1 and B-2, respectively). Soil chemistry samples were obtained at each site and the following parameters determined in the lab: total phosphorous (soil TP, mg/kg), percent total nitrogen (%TN), percent total carbon (%TC), percent organic matter (%OM), and pH. For soil samples the study wetland was separated in to dominant vegetation zones and four soil cores were proportionally distributed within the dominant vegetation zones (e.g., if 75% of the wetland was Panicum hemitomon and 25% Pontederia cordata, 3 samples would be taken in the Panicum zone and 1 sample in the Pontederia zone). The cores were taken with an approximately 8cm inner-diameter beveled PVC pipe. At each sample location, the duff layer was removed and the PVC pipe outline traced with a 15cm knife to reduce sample compaction. The PVC pipe was pounded into the wetland soil to an approximate depth of 10cm and extracted using a trowel. The surficial water was gently poured from the top, and the 10cm sample extruded. Samples from the same zone were mixed and a composite sample of approximately one liter scooped into a labeled container. All samples were placed on ice in the field and stored in a laboratory refrigerator until analyzed by the University of Florida Soil Science Department. In the lab, pH readings were taken and subsamples were dried to a constant weight and finely ground (<0.2 mm). Percent C and N were obtained from the ground samples utilizing a Carlo-Erba NA-1500 CNS Analyzer (Haak-Buchler Instruments, Saddlebrook, NJ). Total P analysis was performed by ashing additional subsamples at 550oC for 4 hours, dissolving the dried sample in 6M HCl (Anderson 1976), and analyzing the digestate for P following U.S. EPA method 365.4 (U.S. EPA 1983). Percent organic matter was obtained during the analysis of the total P. For subsequent site-specific analyses, a weighted average for each soil constituent was obtained by utilizing the percent extent of each wetland vegetation zone sampled. Samples for analysis of water chemistry parameters were collected at each site. Water samples for nutrient analysis were taken from the center of the wetland at an approximate depth of 10cm with a 0.5L pre-rinsed Polypropylene bottle and preserved with 2mL 1:1 H2SO4. The same method was used for chemical analysis (color, specific conductivity, turbidity, and pH) samples, with the exception that no preservative was added. Both bottles were placed on ice and delivered overnight to the FDEP Central Laboratories for processing. The following parameters were measured by FDEP following FDEP protocols (SOP #TA-06.04-5): color (PCU), specific conductivity (umhos/cm), turbidity (NTU), pH, ammonia (mg/L), nitrate/nitrite (mg/L), total Kjeldahl Nitrogen (TKN, mg/L), and total Phosphorus (water TP, mg/L). In the event that the constituent measured was below detection levels, the value entered for analysis was half

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119 Table B-1. Soil characteristics measured at each study site. Sites pH % TC % OM % TN TP (mg/kg) ALPaynes 3.82 42.73 3.00 787.40 83.91 Audubon 4.25 9.11 16.48 0.72 659.83 BearScat 7.12 5.75 10.76 0.53 81.16 BigCow 6.87 4.09 6.35 0.39 67.82 BRSebastian 4.12 9.71 19.58 0.50 99.78 CabPatch 5.66 7.46 15.71 0.52 321.64 Caravelle 4.75 11.98 24.32 0.64 251.89 Chuluota 3.90 19.34 36.63 1.17 223.45 CLBayard 3.65 19.07 34.94 0.88 16.36 CLCove 5.52 10.66 22.87 0.78 591.44 CMWPast 5.91 1.93 4.53 0.12 46.94 CMWRef 5.33 2.10 3.97 0.12 53.65 COBurgle 6.29 17.95 29.32 1.38 6.48 COHole 7.35 11.90 14.66 0.72 137.28 Crew 5.28 3.91 9.75 0.24 59.30 DEMelon 5.66 6.47 11.67 0.46 202.29 Deerfly 4.79 46.55 83.95 2.68 340.87 Garber 5.13 16.52 31.34 0.94 394.21 GBarE 3.98 48.07 3.19 371.79 91.88 GLDonut 4.90 9.43 19.39 0.68 73.36 GLPont 5.22 17.01 33.33 1.14 292.14 Goethe 4.09 14.42 26.73 0.88 200.91 GreenSwamp 4.60 13.83 25.09 0.87 372.60 HaRare 6.18 11.43 20.66 0.79 144.37 HagueI 5.51 7.22 98.80 0.49 969.13 HagueII 6.28 3.47 7.46 0.23 803.59 HalfMoon 4.11 15.91 29.18 1.07 95.75 HEBad 6.42 10.53 17.63 0.82 470.63 HEL2 6.53 22.57 49.44 1.81 418.91 HEOkay 5.10 21.02 5.03 1.43 37.16 Highpast 5.01 3.31 6.13 0.23 105.21 HighRef 4.26 8.81 18.83 0.56 325.15 HillsRef 5.13 10.21 20.73 0.57 185.93 HuntCamp 4.55 34.83 57.02 2.53 271.52 IFASI 4.39 49.08 96.15 3.42 649.48 IFASII 4.60 37.62 72.61 2.75 1011.63 Immokalee 4.47 8.53 14.94 0.50 145.91 IRBlueCypress 5.67 17.56 22.43 1.34 322.85

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120 Table B-1. Continued. Sites pH % TC % OM % TN TP (mg/kg) IRCanal 5.9515.6329.151.03521.02 IROJ 6.098.4615.850.68317.99JD6 4.923.057.770.1825.93KellyPark 3.9149.4589.953.33460.89LCork 6.350.774.350.0653.64LLeeCounty 5.307.5512.540.57138.68LEGo 4.239.8711.030.67110.37LESuwan 5.026.7311.170.4177.94MALudy 5.535.429.180.34209.99MASpray 4.1525.7211.581.4145.99McArthur 4.7116.1028.671.07300.08MNElmer 4.2326.5954.121.37790.86MNErik 3.9848.073.19371.7991.88MNOcala 4.5211.8622.510.81166.61MRPepper 4.8348.0293.752.72492.98Myakka 4.567.6213.150.4242.16OKCara 5.764.187.690.3058.68OKKiss 4.853.109.210.1977.80OKPast 6.102.465.770.1767.25PacificTom 5.980.984.830.0632.54PallMar 5.506.3711.360.3740.47PBCorbett 5.825.4213.240.25262.93PBEnjay 4.782.815.370.2042.87Penner 4.758.309.880.4691.55POWales 4.225.027.960.3273.44POWeowak 5.0611.7321.320.87312.90PUPond 3.8242.733.00787.4083.91RiceCreek 4.3114.1227.890.84478.98SANorthMya 4.883.534.340.2653.16SAOscer 4.893.314.940.2955.46SandhillCrane 4.803.058.670.2061.06Savannas 4.667.3313.080.3742.67STCow 5.5513.7725.171.01393.92SUVaca 3.9848.073.19371.7991.88SUWarhol 3.9848.073.19371.7991.88UNHealthy 6.633.148.740.21261.10Weikiva 3.3845.0285.242.16518.94 Note: Average values of impaired site soil parameters were given to site GBarE as access for soil sampling was not available.

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121 APPENDIX C DIATOM AUTECOLOGICAL VALUES Autecological values (Bahls 1993, Van Dam et al. 1994) for the epiphytic diatoms are given below. For metric development, the values were recoded as given in Table 2-19. Table C-1. Diatom Autecological Values. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Achnanthes exilis 5 2 1 1 1 2 3 Achnanthes hungarica 4 2 2 4 3 6 3 Achnanthes minutissima 3 2 2 1 2 7 3 Achnanthes minutissima scotica 3 2 Amphora veneta 5 3 2 3 4 5 2 Anomoeneis serians 1 1 1 2 1 1 Anomoeneis vitrea 4 2 1 2 1 2 Asterionella formosa 4 2 2 2 2 4 3 Aulacoseira alpigena 2 1 1 1 1 1 3 Aulacoseira crenulata 3 1 1 1 1 1 Aulacoseira granulata 4 2 2 3 2 5 3 Caloneis bacillum 4 2 1 2 2 4 2 Cocconeis placentula lineata 4 2 2 3 2 5 3 Cyclotella meneghiniana 4 3 3 5 4 5 2 Cyclotella pseudostelligera 3 2 2 3 3 5 2 Cymbella cesatii 3 1 1 1 1 1 3 Cymbella gracilis 2 1 1 1 1 2 3 Cymbella microcephala 4 2 1 1 1 4 2 Cymbella minuta 3 2 2 Diploneis parma Eunotia bilunaris 6 2 2 2 2 7 Eunotia bilunaris mucophila 2 2 2 2 1 2 Eunotia circumborealis 1 Eunotia faba 2 1 1 1 1 2 Eunotia fallax 2 1 1 1 1 1 Eunotia flexuosa 2 1 1 1 1 2 3 Eunotia formica 2 2 1 1 1 3 Eunotia glacialis 2 1 1 1 1 2 3 Eunotia implicata 2 1 Eunotia incisa 2 1 1 1 1 1 3

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122 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Eunotia monodon 2 1 1 1 1 1 3 Eunotia monodon bidens 2 1 1 1 1 1 Eunotia naegelii 2 1 1 1 1 1 Eunotia paludosa 1 1 1 1 1 1 Eunotia paludosa trinacria 1 1 1 1 1 1 Eunotia pectinalis 2 1 2 1 2 3 3 Eunotia pectinalis undulata 2 1 2 1 2 1 3 Eunotia pirla Eunotia praerupta 2 1 1 1 1 2 3 Eunotia rhomboidea 2 1 1 1 1 1 Eunotia soleirolii 3 1 2 1 2 1 Eunotia veneris 2 1 1 1 1 2 Fragilaria vaucheriae 4 2 2 3 3 5 2 Frustulia rhomboides 2 1 1 1 1 1 3 Frustulia rhomboides amphipleuroides2 1 1 1 1 1 3 Frustulia rhomboides crassinerva 2 1 1 1 1 1 Frustulia rhomboides saxonica 1 1 1 1 1 1 3 Gomphonema affine 4 2 1 1 2 3 3 Gomphonema angustatum 2 Gomphonema augur turris Gomphonema clavatum 3 1 1 1 1 4 2 Gomphonema gracile 3 2 1 1 1 3 2 Gomphonema parvulum 3 2 3 4 4 5 1 Gomphonema pseudotenellum Hantzschia amphioxys 3 2 2 2 3 7 2 Mastogloia smithii 4 4 2 2 Navicula accommoda 4 2 4 5 5 6 Navicula arvensis 4 2 3 4 4 5 2 Navicula bicephala 3 Navicula clementis 4 3 2 1 2 4 2 Navicula cohnii 4 3 2 1 2 5 2 Navicula confervacea 3 3 3 3 3 5 2 Navicula cryptocephala 3 2 2 3 3 7 3 Navicula cryptotenella 4 2 2 7 2 Navicula detenta 3 Navicula erifuga 4 3 5 2 Navicula evanida 3 2 1 1 1 3 Navicula festiva 1 1 1 1 1 1 2 Navicula hambergi 2 1 Navicula kotschyi 4 2 1 1 2 Navicula kriegerii Navicula laevissima 3 1 1 1 1 3 3 Navicula mediocris 2 1 1 1 1 1 Navicula minima 4 2 3 4 4 5 1 Navicula molestiformis 4 2 3 4 4 5 1

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123 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Navicula mutica 3 3 2 1 3 5 2 Navicula notha 2 1 1 1 1 2 2 Navicula pseudoventralis 4 2 1 1 1 2 2 Navicula pupula 3 2 2 3 3 4 2 Navicula pupula elliptica 4 2 4 2 Navicula pupula mutata 3 2 2 2 2 Navicula pupula rectangularis 3 2 2 3 3 4 2 Navicula pygmaea 5 3 3 3 3 5 2 Navicula radiosa 3 2 2 2 2 4 3 Navicula schadei 3 2 1 1 1 3 Navicula seminulum 3 2 3 4 4 5 1 Navicula subtilissima 1 1 1 1 1 1 2 Navicula tenelloides 4 2 1 1 1 5 1 Navicula trivialis 4 3 2 3 3 5 2 Navicula viridula rostellata 4 2 2 2 2 5 2 Neidium alpinum 2 1 1 1 3 Neidium bisulcatum 3 1 1 1 1 1 Neidium hercynicum 2 2 3 Neidium javanicum Nitzschia acidoclinata 3 1 1 1 2 3 3 Nitzschia agnita 4 1 Nitzschia amphibia 4 2 3 3 3 5 2 Nitzschia brevissima 3 3 3 2 5 2 Nitzschia capitellata 4 4 5 6 2 Nitzschia debilis 4 2 2 1 3 Nitzschia dissipata 4 2 2 2 2 4 3 Nitzschia frustulum 4 3 4 3 2 5 2 Nitzschia gracilis 3 1 2 2 3 2 Nitzschia intermedia 3 2 2 5 3 Nitzschia microcephala 4 2 4 3 3 5 1 Nitzschia nana 3 2 1 2 3 Nitzschia palea 3 2 4 4 5 6 1 Nitzschia palea debilis 3 1 1 1 Nitzschia palea tenuirostris 3 2 1 Nitzschia paleaformis 1 2 2 2 2 7 Nitzschia perminuta 4 2 1 1 1 2 3 Nitzschia pura 2 1 2 Nitzschia pusilla 3 2 2 2 2 7 1 Nitzschia solita 3 5 Nitzschia subacicularis 4 2 1 1 2 7 2 Nitzschia terrestris 3 2 1 Pinnularia braunii 1 1 1 1 Pinnularia gibba 3 2 2 3 3 7 3 Pinnularia gibba mesogongyla 3 1 Pinnularia interrupta 3 1 1 1 1 2

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124 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Pinnularia maior 3 2 2 2 2 4 3 Pinnularia microstauron 3 2 2 3 2 7 2 Pinnularia obscura 3 2 1 1 1 3 Pinnularia subcapitata 2 2 2 3 2 2 3 Pinnularia subrostrata 3 Pinnularia viridis 3 2 2 3 2 7 3 Rhopalodia gibberula 3 Stauroneis anceps 3 2 2 2 2 4 3 Stauroneis kriegeri 3 2 2 2 2 4 3 Stauroneis phoenicenteron 3 2 2 3 2 4 2 Stauroneis thermicola 3 2 2 1 2 7 3 Stenopterobia curvula 2 1 1 1 1 1 Stenopterobia delicatissima 2 1 1 1 1 1 Synedra tenera 2 1 1 1 1 2 3 Note: Abbreviations are as follows: Salin. (Salinity); Nitro (Nitrogen); D.O. (Dissolved Oxygen); Sapro. (Saprobity); Troph. (Trophic); Poll. (Pollution Tolerance).

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125 APPENDIX D COEFFICIENT OF CONSERVATISM Each macrophyte taxon identified was given a Coefficient of Conservatism (CC) score (Wilhelm and Ladd 1988) as detailed in Cohen et al. (submitted). The table below provides a list of the average confidence-weighted Coefficient of Conservatism for each species identified. Table D-1. Coefficient of Conservatism scores for sampled macrophytes. Site Name CC Site Name CC Acalypha gracilens 3.29 Axonopus furcatus 2.12 Acer rubrum 4.65 Azolla caroliniana 1.81 Aeschynomene indica 0.49 Baccharis glomeruliflora 6.12 Agalinis filifolia 6.69 Baccharis halimifolia 2.53 Agalinis linifolia 7.04 Bacopa caroliniana 5.31 Agalinis obtusifolia 6.50 Bacopa inominata 7.48 Alternanthera philoxeroides 0.00 Bacopa monnieri 4.49 Alternanthera sessilis 0.11 Bidens laevis 7.19 Alternanthera tenella 0.00 Bidens mitis 6.31 Amaranthus blitum 0.00 Bigelowia nudata 7.59 Amaranthus spinosus 0.04 Blechnum serrulatum 7.15 Ambrosia artemisiifolia 0.95 Boehmeria cylindrica 5.91 Ammannia latifolia 4.55 Boltonia diffusa 4.96 Ampelopsis arborea 3.25 Brasenia schreberi 8.79 Amphicarpum muhlenbergianum 5.70 Burmannia capitata 8.13 Andropogon glomeratus 3.90 Canna flaccida 6.75 Andropogon virginicus 3.44 Caperonia castaneifolia 4.94 Aristida affinis 8.23 Caperonia palustris 0.52 Aristida lanosa 8.73 Cardamine pensylvanica 4.42 Aristida palustris 8.84 Carex alata 4.27 Aristida patula 4.85 Carex albolutescens 3.47 Aristida purpurascens 5.58 Carex fissa 3.90 Aristida stricta 8.67 Carex stipata 4.46 Asclepias lanceolata 6.73 Carex verrucosa 7.97 Aster dumosus 2.53 Carphephorus odoratissimus 6.93 Aster elliottii 6.76 Cassytha filiformis 3.34 Aster subulatus 5.74 Celtis laevigata 5.08 Axonopus affinis 1.89 Centella asiatica 1.92

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126 Table D-1. Continued. Site Name CC Site Name CC Cephalanthus occidentalis 7.27 Eclipta prostrata 3.21 Echinochloa walteri 3.36 Helianthus floridanus 5.85 Chenopodium album 0.78 Eichhornia crassipes 0.00 Chenopodium ambrosioides 0.59 Eleocharis atropurpurea 5.69 Chrysobalanus icaco 5.63 Eleocharis baldwinii 2.82 Cirsium nuttallii 3.08 Eleocharis cellulosa 7.80 Cladium jamaicense 9.04 Eleocharis elongata 6.97 Coelorachis rugosa 8.91 Eleocharis equisetoides 9.10 Coelorachis tuberculosa 10.00 Eleocharis interstincta 7.80 Commelina diffusa 2.02 Eleocharis microcarpa 5.78 Conoclinium coelestinum 4.37 Eleocharis vivipara 3.81 Conyza canadensis 1.01 Elephantopus elatus 2.72 Crinum americanum 8.67 Eleusine indica 0.00 Cuphea carthagenensis 1.92 Eragrostis atrovirens 1.58 Cynodon dactylon 0.29 Eragrostis elliottii 4.14 Cyperus articulatus 6.64 Eragrostis spectabilis 3.44 Cyperus compressus 2.74 Erechtites hieracifolia 1.37 Cyperus croceus 1.30 Erianthus giganteus 6.34 Cyperus distinctus 5.00 Erigeron quercifolius 3.31 Cyperus haspan 5.68 Eriocaulon compressum 7.50 Cyperus lanceolatus 2.04 Eriocaulon decangulare 7.50 Cyperus odoratus 4.25 Eupatorium capillifolium 0.83 Cyperus polystachyos 1.56 Eupatorium compositifolium 2.72 Cyperus retrorsus 1.79 Eupatorium leptophyllum 4.94 Cyperus strigosus 4.49 Eupatorium mohrii 6.87 Cyperus surinamensis 2.03 Eupatorium perfoliatum 5.85 Cyperus virens 5.70 Euthamia carolinana 3.25 Decodon verticillatus 7.80 Ficus aurea 3.38 Desmodium triflorum 0.43 Fimbristylis dichotoma 3.55 Dichromena colorata 6.18 Fimbristylis miliacea 1.95 Dichromena latifolia 6.62 Fuirena breviseta 7.60 Digitaria bicornis 0.00 Fuirena pumila 5.92 Digitaria ciliaris 1.30 Fuirena scirpoidea 6.50 Digitaria serotina 1.39 Galactia elliottii 5.54 Diodia virginiana 4.96 Galium pilosum 4.77 Diospyros virginiana 5.76 Galium uniflorum 5.80 Drosera brevifolia 8.21 Gaylussacia dumosa 5.44 Drosera capillaris 7.09 Gomphrena serrata 0.87 Drosera intermedia 8.23 Gordonia lasianthus 9.03 Drymaria cordata 2.72 Gratiola pilosa 6.63 Dulichium arundinaceum 7.31 Gratiola ramosa 6.87 Echinochloa colona 0.24 Habenaria repens 4.58 Echinochloa crusgalli 0.22 Hedyotis corymbosa 2.31 Echinochloa muricata 6.01 Hedyotis uniflora 4.04

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127 Table D-1. Continued. Site Name CC Site Name CC Hibiscus grandiflorus 6.86 Ludwigia alata 5.85 Hydrochloa caroliniensis 4.79 Ludwigia alternifolia 6.24 Hydrocotyle umbellata 1.92 Ludwigia arcuata 5.32 Hydrolea corymbosa 5.85 Ludwigia decurrens 6.76 Hymenachne amplexicaulis 0.00 Ludwigia lanceolata 6.15 Hypericum brachyphylum 7.55 Ludwigia linearis 5.72 Hypericum cistifolium 6.32 Ludwigia linifolia 7.04 Hypericum fasciculatum 7.27 Ludwigia maritima 5.85 Hypericum hypericoides 5.44 Ludwigia microcarpa 4.81 Hypericum mutilum 4.04 Ludwigia octovalvis 4.09 Hypericum myrtifolium 6.56 Ludwigia palustris 4.77 Hyptis alata 4.58 Ludwigia peruviana 0.62 Ilex cassine 7.66 Ludwigia repens 5.20 Ilex glabra 5.85 Ludwigia suffruticosa 6.23 Ipomoea quamoclit 0.26 Ludwigia virgata 6.73 Ipomoea sagittata 6.42 Lycopodiella alopecuroides 7.61 Iris hexagona 6.97 Lycopodium appressum 8.01 Itea virginica 7.09 Lycopus rubellus 6.75 Iva microcephala 4.68 Lygodium microphyllum 0.78 Juncus coriaceus 8.51 Lyonia ferruginea 8.39 Juncus effusus 3.25 Lyonia lucida 7.06 Juncus marginatus 3.65 Lythrum alatum 3.55 Juncus megacephalus 5.70 Macroptilium lathyroides 0.41 Juncus polycephalus 4.96 Magnolia virginiana 9.44 Juncus repens 6.91 Mayaca fluviatilis 8.45 Juncus scirpoides 4.33 Melaleuca quinquenervia 0.00 Justicia angusta 8.56 Melochia corchorifolia 2.24 Justicia ovata 8.88 Melothria pendula 3.31 Kosteletzkya virginica 7.49 Micranthemum umbrosum 5.66 Kyllinga brevifolia 1.42 Micromeria brownei 6.34 Kyllinga pumila 5.53 Mikania scandens 1.95 Lachnanthes caroliniana 3.76 Mollugo verticillata 1.30 Lachnocaulon anceps 7.15 Murdannia keisak 2.34 Lachnocaulon beyrichianum 9.18 Murdannia nudiflora 1.42 Lachnocaulon minus 7.97 Myrica cerifera 3.82 Lechea cernua 8.67 Myriophyllum laxum 5.85 Leersia hexandra 5.61 Nuphar luteum 6.09 Lemna minor 3.77 Nymphaea odorata 7.18 Leucothoe racemosa 9.44 Nymphoides aquatica 6.09 Limnobium spongia 4.79 Nyssa biflora 9.04 Lindernia grandiflora 3.60 Osmunda cinnamomea 6.44 Liquidambar styraciflua 5.56 Osmunda regalis 8.04 Lobelia glandulosa 6.03 Oxypolis filiformis 8.69 Lobelia paludosa 8.08 Panicum abscissum 9.22

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128 Table D-1. Continued. Site Name CC Site Name CC Panicum aciculare 6.01 Polygonum hydropiperoides 4.02 Panicum chamaelonche 7.69 Polygonum lapathifolium 1.95 Panicum ciliatum 7.15 Polygonum punctatum 4.02 Panicum commutatum 7.57 Polypremum procumbens 1.71 Panicum dichotomiflorum 4.96 Pontederia cordata 5.38 Panicum dichotomum 5.61 Portulaca amilis 0.87 Panicum ensifolium 6.50 Proserpinaca palustris 5.85 Panicum erectifolium 7.39 Proserpinaca pectinata 5.50 Panicum hemitomon 5.82 Pteridium aquilinum 3.90 Panicum hians 6.63 Quercus laurifolia 5.14 Panicum maximum 0.78 Quercus nigra 4.14 Panicum repens 0.41 Quercus virginiana 4.85 Panicum rigidulum 5.47 Rhexia cubensis 7.22 Panicum spretum 6.63 Rhexia mariana 5.50 Panicum tenerum 8.67 Rhexia nashii 7.80 Panicum tenue 5.85 Rhexia nuttallii 7.93 Panicum verrucosum 6.83 Rhexia petiolata 7.90 Parthenocissus quinquefolia 3.43 Rhus copallinum 3.65 Paspalum acuminatum 1.06 Rhynchospora cephalantha 6.19 Paspalum conjugatum 3.84 Rhynchospora debilis 7.80 Paspalum distichum 5.54 Rhynchospora divergens 5.53 Paspalum laeve 5.79 Rhynchospora fascicularis 5.92 Paspalum monostachyum 9.80 Rhynchospora fernaldii 4.77 Paspalum notatum 0.14 Rhynchospora filifolia 8.13 Paspalum praecox 6.50 Rhynchospora inundata 7.25 Paspalum repens 6.69 Rhynchospora microcarpa 5.29 Paspalum setaceum 3.44 Rhynchospora microcephala 6.50 Paspalum urvillei 0.00 Rhynchospora nitens 5.20 Persea borbonia 8.02 Rhynchospora perplexa 5.20 Persea palustris 8.31 Rhynchospora pusilla 7.54 Phyla nodiflora 1.92 Rhynchospora rariflora 8.63 Phyllanthus urinaria 0.22 Rhynchospora tracyi 9.03 Phytolacca americana 2.09 Rhynchospora wrightiana 7.80 Pinus elliottii 4.21 Ricciocarpus natans 4.55 Pinus palustris 4.77 Richardia scabra 0.00 Pinus taeda 5.34 Rosa palustris 6.01 Pluchea foetida 6.65 Rubus argutus 3.56 Pluchea longifolia 5.85 Rubus cuneifolius 3.90 Pluchea odorata 4.96 Rubus trivialis 2.60 Pluchea rosea 5.45 Sabatia grandiflora 7.09 Polygala cymosa 7.67 Sacciolepis indica 0.92 Polygala rugelii 8.17 Sacciolepis striata 5.35 Polygonum densiflorum 5.32 Sagittaria graminea 5.53 Polygonum hirsutum 8.17 Sagittaria lancifolia 4.96

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129 Table D-1. Continued. Site Name CC Site Name CC Sagittaria latifolia 6.50 Syngonanthus flavidulus 6.93 Salix caroliniana 2.95 Taxodium ascendens 7.21 Salvinia minima 2.03 Taxodium distichum 7.21 Sambucus canadensis 1.48 Teucrium canadense 6.44 Sarcostemma clausum 3.81 Thalia geniculata 7.12 Saururus cernuus 7.33 Thelypteris interrupta 6.74 Schinus terebinthifolius 0.00 Toxicodendron radicans 1.44 Schizachyrium scoparium 5.44 Triadenum virginicum 8.16 Schoenolirion albiflorum 9.10 Triadenum walteri 7.92 Scleria baldwinii 8.67 Tripsacum dactyloides 6.03 Scleria georgiana 8.78 Typha domingensis 0.59 Scleria reticularis 6.79 Typha latifolia 1.60 Scleria triglomerata 6.74 Ulmus americana 7.68 Scleria vaginata 0.00 Urena lobata 0.00 Scoparia dulcis 2.36 Utricularia cornuta 7.46 Senna occidentalis 0.00 Utricularia foliosa 6.44 Serenoa repens 7.03 Utricularia purpurea 6.50 Sesbania herbacea 1.49 Utricularia radiata 6.01 Sesbania vesicaria 1.44 Utricularia subulata 7.23 Setaria parviflora 3.40 Vaccinium corymbosum 5.63 Sida rhombifolia 1.65 Vaccinium darrowii 7.15 Smilax auriculata 3.96 Verbena bonariensis 0.56 Smilax bona-nox 3.78 Viola lanceolata 5.32 Smilax pumila 6.01 Viola primulifolia 6.11 Solanum americanum 1.16 Vitis rotundifolia 1.18 Solanum carolinense 2.13 Woodwardia areolata 7.68 Solanum viarum 0.00 Woodwardia virginica 6.50 Solidago fistulosa 4.49 Xyris ambigua 6.43 Solidago latissimifolia 7.51 Xyris baldwiniana 6.97 Solidago stricta 5.49 Xyris brevifolia 7.20 Solidago tortifolia 6.96 Xyris caroliniana 6.14 Sorghastrum secundum 7.73 Xyris difformis 7.50 Spartina bakeri 5.98 Xyris elliottii 6.69 Spermacoce assurgens 3.09 Xyris fimbriata 7.08 Spirodela polyrhiza 2.95 Xyris flabelliformis 7.43 Sporobolus domingensis 2.47 Xyris jupicai 3.51 Sporobolus indicus 0.99 Xyris platylepis 5.32 Stillingia aquatica 8.32 Xyris smalliana 7.80 Stillingia sylvatica 7.30

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130 ecoregions in the prairie pothole region. Wetlands 19(3): 648-664. LIST OF REFERENCES Adamus, C. and M. J. Bergman. 1995. Estimating non-point source pollution loads with a GIS screening model. Water Resources Bulletin 31(4): 647-655. Adamus, P. R. 1996. Bioindicators for Assessing Ecological Integrity of Prairie Wetlands, EPA/600/R-96/082. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, Corvallis, OR. Adamus, P. R and K. Brant. 1990. Impacts on Quality of Inland Wetlands of the United States: A Survey of Indicators, Techniques, and Applications of Community Level Bio-monitoring Data, EPA/600/3-90/073. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. Adamus, P.R., T. Danielson, and A. Gonyaw. 2001. Indicators for Monitoring Biological Integrity of Inland, Freshwater Wetlands: A Survey of North American Technical Literature (1990-2000). EPA843-R-01. U.S. Environmental Protection Agency, Office of Water, Wetlands Division. Washington, DC. Adamus, P.R., L. T. Stockwell, Jr. Ellis J. Clairain, Michael E. Rozas Lawrence P. Morrow, and R. Daniel Smith. 1991. Wetland Evaluation Technique. WRP-DE-2. U.S. Army Corp of Engineers. Washington, DC. Agami, M., K. R. Reddy, D. A. Graetz, L. J. Scinto, P. R. F. Barrett, M. P. Greaves, K. J. Murphy, A. H. Pieterse, P. M. Wade, and M. Walsten. 1990. Phosphorus and nitrogen storage/release capacity of aquatic macrophytes in two wetland stream systems of the Taylor Creek/Nubbins Slough and Kissimmee River basin, Florida. 8th International Symposium on Aquatic Weeds. Swedish University of Agricultural Sciences, Uppsala, Sweden, August 13-17 1990. European Weed Research Society. Wageningen, Netherlands. Allan, J. D. and L. B. Johnson. 1997. Catchment-scale analysis of aquatic ecosystems. Freshwater Biology 37: 107-111. American Public Health Association (APHA). 1995. Standard Methods for the Examination of Water and Wastewater. American Public Health Association. Washington, D.C Anderson, D. J. and B. Vondracek. 1999. Insects as indicators of land use in three

PAGE 147

131 Anderson, J. M. 1976. An ignition method for determination of total phosphorus in lake sediments. Water Research 10: 329-331. Andreas, B. K. and R. Lichvar. 1995. A Floristic Assessment System in Northern Ohio. WRP-DE-8. U.S. Army Corps of Engineers. Washington, DC. Apfelbeck, R. 2000. Developing Preliminary Bioassessment Protocols for Montana Wetlands, State of Montana Department of Environmental Quality. Helena, MT. Atchison, J. 1986. The Statistical Analysis of Compositional Data. Chapman and Hall. London. Babbitt, K. J. and G. W. Tanner. 2000. Use of temporary wetlands by anurans in a hydrologically modified landscape. Wetlands 20(2): 313-322. Bahls, L. L. 1993. Periphyton Bioassessment Methods of Montana Streams. Water Quality Bureau, Department of Health and Environmental Sciences. Helena, MT: Bailey, R. C. R. H. Norris and T. B. Reynoldson. 2001. Taxonomic resolution of benthic macroinvertebrate communities in bioassessments. Journal of the North American Benthological Society 20(2): 280-286. Barbour, M. T., J. Gerritsen, G. E. Griffith, R. Frydenborg, E. McCarron, J. S. White, and M. L. Bastian. 1996. A framework for biological criteria for Florida streams using benthic macroinvertebrates. Journal of the North American Benthological Society 15(2): 185-211. Barbour, M. T., J. Gerritsen, B. D. Snyder, and J. B. Stribling. 1999. Rapid Bioassessment Protocols For Use in Streams and Wadeable Rivers. 2nd ed.. EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water. Washington, DC. Battle, J. and S. W. Golladay. 2001. Water quality and macroinvertebrate assemblages in three types of seasonally inundated limesink Journal of Freshwater Ecology 16(2): 189-207. Bayley, S., and H. T. Odum. 1976. Simulation of Interrelations of the Everglades' Marsh, Peat, Fire, Water, and Phosphorus. Ecological Modeling 2: 169-188. Beck, W. M. 1954. Studies in Stream Pollution Biology I. A Simplified Ecological Classification of Organisms. Quarterly Journal of the Florida Academy of Scientists 17(4): 211-227. Bedford, B. L. 1999. Cumulative effects on wetland landscapes: links to wetland restoration in the United States and southern Canada. Wetlands 19(4): 775-788.

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132 Bedford, B. L., M. R. Walbridge, and A. Aldous. 1999. Patterns in nutrient availability and plant diversity of temperate North American wetlands. Ecology 80(7): 2151-2169. Blanch, S. J. and M. A. Brock. 1994. Effects of grazing and depth on two wetland plant species. Australian Journal of Marine and Freshwater Research 45: 1387-1394. Bowman, M. F. and R. C. Bailey. 1998. Does taxonomic resolution affect the multivariate description of the structure of freshwater benthic macroinvertebrate communities? Canadian Journal of Fisheries and Aquatic Sciences 54: 1802-1807. Brightman, R. S. 1984. Benthic macroinvertebrate response to secondarily treated wastewater in north-central Florida cypress domes. Pp. 186-197 in Cypress Swamps. Edited by K. C. Ewel and H. T. Odum. University Press of Florida. Gainesville, FL. Brinson, M. M., and R. Reinhardt. 1996. The role of reference wetlands in functional assessment and mitigation. Ecological Applications 6(1): 69-76. Brower, J. E., J. H. Zar, and C. N. von Ende. 1990. Field and Laboratory Methods for General Ecology. W.C. Brown Publishers. New York, New York. Brown, M. T. 1991. Evaluating Created Wetlands Through Comparisons With Natural Wetlands. Environmental Research Laboratory. EPA/600/3-91/058. US Environmental Protection Agency, Corvallis, OR. Brown, M. T. and M. B. Vivas. submitted. A Landscape Development Intensity Index. Environmental Monitoring and Assessment. Ecological Monitoring and Assessment. Burton, T. M., D. G. Uzarski, J. P. Gathman, J. A. Genet, B. E. Keas, and C. A. Stricker. 1999. Development of a preliminary invertebrate index of biotic integrity for Lake Huron coastal wetlands. Wetlands 19(4): 869-882. Busch, D. E., W. F. Loftus, O. L. Bass. 1998. Long term hydrologic effects on marsh plant community structure in the southern Everglades. Wetlands 18(2): 230-241. Cairns, J. and J. R. Pratt. 1993. A History of Biological Monitoring Using Benthic Macroinvertebrates. Pp. 10-27 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. New York, New York. Cao, Y., D. P. Larsen, and R. S. J. Thorne. 2001. Rare species in multivariate analysis for bioassessment: some consideration. Journal of the North American Benthological Society 20(1): 144-153.

PAGE 149

133 Carlisle, D. M., P. M. Stewart, and J. T. Butcher. 2003. Macroinvertebrate assemblages associated with patterns in land use and water quality. Pp. 271-285 in Biological Response Signatures: Indicator Patterns Using Aquatic Communities. Edited by T.P. Simon. CRC Press. Boca Raton, Florida. Carpenter, K. D. and I. R. Waite. 2000. Relations of Habitat-Specific Algal Assemblages to Land Use and Water Chemistry in the Willamette Basin, Oregon. Environmental Monitoring and Assessment 64: 247-257. Charles, D., F. Aker, and N.A. Roberts. 1996. Diatom Periphyton in Montana Lakes and Wetlands: Ecology and Potential as Bioassessment Indicators. Patrick Center of Environmental Research, Environmental Research Division. The Academy of Natural Sciences. Philadelphia, PA. Cheal, F. J., A. Davis, J. E. Growns, J. S. Bradley, and F. H. Whittles. 1993. The influence of sampling method on the classification of wetland macroinvertebrate communities. Hydrobiologia 257(1): 47-56. Chen, E. and J. F. Gerber. 1990. Climate. Pp. 11-35 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Chovanec, A. and R. Raab. 1997. Dragronflies (Insecta, Odonata) and the Ecological Status of Newly Created Wetlands Examples for Long-term Bioindication Programmes. Limnologica 27(3-4): 381-392. Chytry, M., L. Tichy, J. Holt, and Z. Botta-Dukat. 2002. Determination of diagnostic species with statistical fidelity measures. Journal of Vegetation Science 13: 79-90. Clarke, K. R. 1993. Non-parametric multivariate analyses of changes in community structure. Australian Journal of Ecology 18: 117-143. Coffman, W. P. and L. C. Ferrington, Jr. 1996. Chironomidae. Pp. 635-754 in An Introduction to the Aquatic Insects of North America. 3rd ed.. Edited by R. W. Cummins and K. W. Merritt. Kendall/Hunt Publishers. Dubuque, IO. Cohen, M. J., S. Carstenn, and C. R. Lane. submitted. Floristic quality assessment of depressional marshes in Florida along an agricultural disturbance gradient. Ecological Applications. Conrad, K. F., K. H. Wilson, I. F. Harvey, C. J. Thomas, and T. N. Sherratt. 1999. Dispersal characteristics of seven odonate species in an agricultural landscape. Ecography 22: 524-531. Courtemanch, D. L. 1996. Commentary on the subsamlping procedures used for rapid bioassessments. Journal of the North American Benthological Society of America 15(3): 381-385.

PAGE 150

134 Cowardin, L. M., V. Carter, F. C. Goulet, and E. T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service. Washington DC. Restoration Ecology 7: 497-510. Craft, C. B., J. Vymazal, and C. J. Richardson. 1995. Response of Everglades plant communities to nitrogen and phosphorus additions. Wetlands 15(3): 258-271. Cranston, P. S. 1995. Introduction. Pp. 1-7 in The Chironomidae: Biology and Ecology of Non-Biting Insects. Edited by P.D. Armitage, P. S. Cranston, and L. C. V. Pinder. Chapman and Hall. Englewood Cliffs, NJ. Crisman, T.C., L.J. Chapman, C.A. Chapman. 1998. Predictors of Seasonal Oxygen Levels in Small Florida Lakes: The Importance of Color. Hydrobiologia 386(1-3): 149-155. Crisman, T. C., W. J. Streever, and D. L. Evans. 1997. An Evaluation of Plant Community Structure, Fish and Benthic Meioand Macrofauna as Success Criteria for Reclaimed Wetlands. Center for Wetlands Report 03-086-135. Center for Wetlands, University of Florida, Gainesville, FL. Cronk, J. K. and M. S. Fennessy. 2001. Wetland Plants: Biology and Ecology. Lewis Publishers. Boca Raton, FL. Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 2000. Responses of physical, chemical, and biological indicators of water quality to a gradient of agricultural land use in the Yakima River basin, Washington. Environmental Monitoring and Assessment 64: 259-270. Dahl, T. E. 1990. Wetlands Losses in the United States, 1780's to 1980's. Washington DC: U.S. Fish and Wildlife Service Report to Congress. Danielson, Thomas J. 1998. Indicators for Monitoring and Assessing Biological Integrity of Inland Freshwater Wetlands, Wetlands Division Office of Water. EPA843-R-98-002. United States Environmental Protection Agency, Washington, DC. Daoust R. J, and D. L. Childers. 1999. Controls on emergent macrophyte composition, abundance, and productivity in freshwater everglades wetland communities. Wetlands 19(1) 1:262-275. David, P G. 1996. Changes in plant communities relative to hydrologic conditions in the Florida Everglades. Wetlands 16(1): 15-23. David, P. G. 1994. The effects of regulating Lake Okeechobee water levels on flora and fauna. Lake and Reservoir Management. 9(2): 67-75. 1999. Response of Exotics to restored hydroperiod at Dupuis Reserve, Florida.

PAGE 151

135 Davis, S. M. and J. C. Ogden. 1994. Everglades. St. Lucie Press. Delray Beach, FL. de Jonge, V. N. and J. E. E. van Beusekom. 1992. Contribution of resuspended microphytobenthos to total phytoplankton in the Ems estuary and its possible role communities of temporary wetlands in the Prairie Pothole region of North Dakota, USA. Wetlands 19(3): 578-583. for grazers. Netherlands Journal of Sea Research 30: 91-105. Delettre, Y. R. 1989. Effects of the duration and intensity of drought on abundance and phrenology of adult Chironomidae (Diptera) in a shallow temporary pool. Archiv Fur Hydrobiologie 114: 383-399. Dierberg, F. E. and P. L. Brezonik. 1984. The effect of wastewater on the surface water and groundwater quality of cypress domes. Pp. 83-101 in Cypress Domes. Edited by K. C. Ewel and H. T. Odum. University Presses of Florida. Gainesville, FL. Doberstein, C. P., J. R. Karr, and L. L. Conquest. 2000. The effect of fixed-count subsampling on macroinvertebrate biomonitoring in small streams. Freshwater Biology 44: 355-371. Dobkin, D. S., A. C. Rich, and W. H. Pyle. 1998. Habitat and avifaunal recovery from livestock grazing in a riparian system of the Northwestern Great Basin. Conservation Biology 12(1): 209-221. Doherty, S., M. Cohen, C. Lane, L. Line, and J. Surdick. 2000. Biological Criteria for Inland Freshwater Wetlands in Florida: A Review of Technical and Scientific Literature (1990-1999). Report to the U.S. Environmental Protection Agency. Center for Wetlands, University of Florida, Gainesville, FL. Doren, R. F., T. V. Armentano, L. D. Whiteaker, and R. D. Jones. 1997. Marsh Vegetation Patterns and Soil Phosphorus Gradients in The everglades Ecosystem. Aquatic Botany 56(2): 145-163. Driver, E. A. 1977. Chironomid communities in small prairie ponds: some characteristics and controls. Freshwater Biology 7: 121-133. Dufrene, M. and P. Legendre. 1997. Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecological Monographs 67: 345-366. Edwards, A. L. and A. S. Weakley. 2001. Population Biology and Management of Rare Plants in Depression Wetlands of the Southeastern Coastal Plain, USA. Natural Areas Journal 21(1): 12-35. Erwin, K. L., S. J. Doherty, M. T. Brown, and G. R. Best. 1997. Evaluation of Constructed Wetlands on Phosphate Mined Lands in Florida. Center for Wetlands, University of Florida. Gainesville, FL. Euliss, N. H. and D. M. Mushet. 1999. Influence of agriculture on aquatic invertebrate

PAGE 152

136 Evans, D. L. 1996. Aquatic Macroinvertebrate Communities of Constructed and Natural Marshes in Central Florida. Ph.D. Dissertation, University of Florida. Gainesville, FL. floristic quality in southern Ontario woodlands. Natural Areas Journal 20: 66-77. Evans, D. L. W. J. Streever and T. L. Crisman. 1999. Natural Flatwoods Marshes and Created Freshwater Marshes of Florida: Factors Influencing Aquatic Invertebrate Distribution and Comparisons between Natural and Created Marsh Communities. Pp. 81-104 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. P. Batzer, R. B. Rader, and S. A. Wissinger. John Wiley and Sons. New Yokr, NY. Ewel, J. J. 1990. Introduction. Pp. 3-10 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Fennessy, S., M.Gernes, J. Mack, D. H. Waldrop. 2001. Methods for Evaluating Wetland Condition: Using Vegetation to Assess Environmental Conditions in Wetlands, EPA 822-R-01-007j. U.S. Environmental Protection Agency, Office of Water, Washington, DC. Fennessy, S., R. Geho, B. Elifritz and R. Lopez. 1998. Testing the Floristic Quality Assessment Index as an Indicator of Riparian Wetland Disturbance. Ohio EPA Wetlands Unit of Division of Surface Water. Columbus, OH. Fernald, E. A. and E. D. Purdum. 1998. Water Resources Atlas of Florida. Florida State University Institute of Science and Public Affairs. Tallahassee, FL. Flaig E. G., and K. R. Reddy. 1995. Fate of phosphorus in the Lake Okeechobee watershed, Florida, USA: Overview and recommendations. Ecological Engineering, 5(2-3): 127-142. Florida Exotic Plant Pest Council (FLEPPC). 2003. List of Florida's Invasive Species. Web page. Available at www.fleppc.org/01list.htm. Fore, L. S. 2003. Response of diatom assemblages to human disturbance: development and testing of a multimetric index for the mid-Atlantic region (USA). Pp. 445-471 in Biological Response Signatures: Indicator Patterns Using Aquatic Communities. Edited by T. P. Simon. CRC Press. Boca Raton, FL. Fore, L. S and C. Grafe. 2002. Using diatoms to assess the biological condition of large rivers in Idaho (U.S.A.). Freshwater Biology 47: 2015-2037. Fore, L. S., J. R. Karr, and R. W. Wisseman. 1996. Assessing invertebrate responses to human activities: evaluating alternative approaches. Journal of the North American Benthological Society 15(2): 212-231. Francis, C. M., M. J. W. Austen,. J. M. Bowles, and W. B. Draper. 2000. Assessing

PAGE 153

137 Freeland, J. A., J. L. Richardson, and L. A. Foss. 1999. Soil indicators of agricultural impacts on Northern Prairie wetlands: Cottonwood Lake research area, North Dakota, USA. Wetlands 19(1): 56-64. Furse, M. T., D. Moss, J. F. Wright, and P. D. Armitage. 1984. The influence of seasonal and taxonomic factors on the ordination and classification of running-water sites in Great Britain and on the prediction of their macro-invertebrate communities. Freshwater Biology 14: 257-280. Gaiser, E. E., T. E. Philippi, and B. E. Taylor. 1998. Distribution of diatoms among intermittent ponds on the Atlantic Coastal Plain: development of a model to predict drought periodicity from surface-sediment assemblages. Journal of Paleolimnology 20: 71-90. Galatowitsch, S. M., D. C. Whited, and J. R. Tester. 1999a. Development of community metrics to evaluate recovery of Minnesota wetlands. Journal of Aquatic Ecosystem Stress and Recovery 6: 217-234. Galatowitsch, S. M., N. O. Anderson, and P. D. Ascher. 1999b. Invasiveness in Wetland Plants in Temperate North America. Wetlands 19(4): 733-755. Gernes, M. C., and J. C. Helgen. 1999. Indexes of Biotic Integrity (IBI) for Wetlands: Vegetation and Invertebrate IBI's, Report CD995525-01. Minnesota Pollution Control Agency. St. Paul, MN. Gerritsen, J., M. T. Barbour and K. King. 2000. Apples, oranges, and ecoregions: on determining patern in aquatic assemblages. Journal of the North American Benthological Society 19(3): 487-496. Gerritsen, J. and J. White. 1997. Development of a Biological Index for Florida Lakes Tetra Tech, Inc., Owings Mills, MD. Godfrey, R. K. and J. W. Wooten. 1979. Aquatic and Wetland Plants of Southeastern United States: Monocotyledons. University of Georgia Press. Athens, GA. Godfrey, R. K. and J. W. Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States: Dicotyledons. University of Georgia Press. Athens, GA. Goldsborough, G. and G. G. C. Robinson. 1996. Pattern in Wetlands. Pp. 77-117 in Algal Ecology. Editors M. L. Bothwell and R. L. Lowe. Academic Press. San Diega, CA. Grace, J. B. and H. Jutila. 1999. The relationship between species density and community biomass in grazed and ungrazed coastal meadows. Oikos 85: 398-408. Graetz, D. A. and V. D. Nair. 1995. Fate of phosphorus in Florida Spodosols contaminated with cattle manure. Ecological Engineering: 5: 163-181.

PAGE 154

138 Growns, J. E., J. A. Davis, F. Cheal, L. G. Schmidt, R. S. Rosich, and S. J. Bradley. 1992. Multivariate pattern analysis of wetland invertebrate communities and environmental variables in Western Australia. Australian Journal of Ecology 17: 275-288. 5: 177-191. Gunderson, L. H. and L. Pritchard. 2002. Resilience and the Behavior of Large-Scale Systems. Island Press.Washington, DC. Hasle, G. R. and G. A. Fryxell. 1970. Diatoms: cleaning and mounting for light and electron microscopy. Transactions of the American Microscopy Society 89: 466-474. Hellawell, J. M. 1986. Biological Indicators of Freshwater Pollution and Environmental Management. Elsevier. London. Herman, K. D., A. A. Reznicek, L. A. Masters, G. S. Wilhelm, M. R. Penskar, and W. W. Brodowicz. 1997. Floristic Quality Assessment: Development and Application in the State of Michigan (USA). Natural Area Journal 17: 265-279. Hilsenhoff, W. L. 1988. Rapid field assessment of organic pollution with a family-level biotic index. Journal of American Benthological Society 7(1): 65-68. Hobbs, R. J. and L. F. Huenneke. 1992. Disturbance, Diversity, and Invasion: Implications for Conservation. Conservation Biology 6(3): 324-37. Hunsaker, C. T. and D. E. Carpenter. 1990. Ecological Indicators for the Environmental Monitoring and Assessment Program, EPA 600/3-90/060. U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC. Hynes, H. B. N. 1975. The stream and its valley. Verh.Interna.Verein.Limnol 19: 1-15. Johnson, R. K., T. Wiederholm and D. M. Rosenber. 1993. Freshwater Biomonitoring Using Individual Organisms, Populations, and Species Assemblages of Benthic Macroinvertebrates. Pp. 40-158 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. Englewood Cliffs, NJ. Johnston, C A. 1994. Cumulative impacts to wetlands. Wetlands 14(1): 49-55. Kalmbacher, R. S., K. R. Long, M. K. Johnson, and F. G. Martin. 1984. Botanical composition of diets of cattle grazing South Florida rangeland. Journal of Range Management 37(4): 334-340. Kantrud, H. A. and W. E. Newton. 1996. A test of vegetation related indicators of wetland quality in the prairie pothole region. Journal of Aquatic Ecosystem Health

PAGE 155

139 Karr, J. R. 1981. Assessment of biotic integrity using fish communities. Fisheries 6(6): 21-27. 1993. Defining and assessing ecological integrity: beyond water quality. Environmental Toxicology and Chemistry 12: 1521-1531. 1995. Protecting Aquatic Ecosystems: Clean Water is Not Enough. Pp. 7-15 in Biological Assessment and Criteria: Tools for Water Resource Planning and Decision Making. Edited by W. S. Davis and T. P. Simon. CRC Press. Boca Raton, FL. Karr, J. R., and E. W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively, EPA 235-R97-001. U.S. Environmental Protection Agency. Washington, DC. 1999. Restoring Life in Running Waters. Island Press. Washington, DC. Karr, J. R. and D. R. Dudley. 1981. Ecological perspective on water quality goals. Environmental Management 5: 55-68. Kashian, D. R. and T. M. Burton. 2000. A Comparison of Macroinvertebrates of Two Great Lakes Coastal Wetlands: Testing Potential Metrics for an Index of Ecological Integrity. Journal of Great Lakes Research 26(4): 460-481. Kautz, R. S. 1993. Trends in Florida wildlife habitat 1936-1987. Florida Scientist 56: 7-24. Kerans, B. L., and J. R. Karr. 1994. A benthic index of biotic integrity (B-IBI) for rivers of the Tennessee valley. Ecological Applications 4(4): 768-785. King, R. S. and C. J. Richardson. 2002. Evaluating subsampling approaches and macroinvertebrate taxonomic resolution for wetland bioassessment. Journal of the North American Benthological Society 21(1): 150-171. Kirkman, L. K., M. B. Drew, L. T. West, and E. R. Blood. 1998. Ecotone characterization between upland longleaf pine/wiregrass stands and seasonally ponded isolated wetlands. Wetlands 18(3): 346-364. Kirkman, L. K., P. C. Goebel, L. West, M. B. Drew, and B. J. Palik. 2000. Depressional wetland vegetation types: a question of plant community development. Wetlands 20(2): 373-385. Kirkman, L. K., R. F. Lide, G. Wein, and R. R. Sharitz. 1996. Vegetation changes and land-use legacies of depression wetlands of the western Coastal Plain of South Carolina: 1951-1992. Wetlands 16(4): 564-576.

PAGE 156

140 Koch, M. S. and K. R. Reddy. 1992. Distribution of soil and plant nutrients along a trophic gradient in Florida Everglades. Soil Science Society of America Journal 56(5): 1492-1499. tolerance values, with criteria for assigning water-quality ratings. Journal of the North America Benthological Society 12(3): 279-290. Kolozsvary, M. B. and R. K. Swihart. 1999. Habitat fragmentation and the distribution of amphibians: patch and landscape correlates in farmland. Canadian Journal of Zoology 77: 1288-1299. Kruskal, J. B. 1964. Nonmetric multidimensional scaling: a numerical method. Psychometrika 29: 115-129. Kushlan, J. A. 1990. Freshwater Marshes. Pp. 323-363 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Lane, C. R. 2000. Proposed Ecological Regions for Freshwater Wetlands of Florida. M.S. Thesis, University of Florida. Gainesville, FL. Lange-Bertalot, H. 1979. Pollution tolerance of diatoms as a criterion for water quality estimation. Nova Hedwigia 54: 285-304. Langeland, K. A. and K. C. Burks. 1998. Identification and Biology of Non-native Plants in Florida's Natural Areas. University of Florida Press. Gainesville, FL. Latham, P. J., L. G. Pearlstine, and W. M. Kitchens. 1994. Species association changes across a gradient of freshwater, oligohaline, and mesohaline tidal marshes along the lower Savannah River. Wetlands 14(3): 174-183. Lawrimore, J. H., M. S. Halpert, G. D. Bell, M. J. Menne, B. Lyon, R. C. Schnell, K. L. Gleason, D. R. Easterling, W. Thiaw, W. J. Wright, R. R. Heim, D. A. Robinson, and L. Alexander. 2001. Climate Assessment for 2000. Bulletin of the American Meteorological Society 82(6): 51-106. Leeper, D. A. and B. E. Taylor. 1998. Insect emergence from a South Carolina (USA) temporary wetland pond, with emphasis on the Chironomidae (Diptera). Journal of the North American Benthological Soicety 17(1): 54-72. Leibowitz, N. C. and M. T. Brown. 1990. Indicator Strategy for Wetlands. Pp. 5.1 5.15 in Environmental Monitoring and Assessment Program Ecological Indicators. Edited by C.T. Hunsaker and D. E. Carpenter. EPA/600/3-90/060. U.S. Environmental Protection Agency Office of Research and Development, Washington, DC. Leland, H. V. and S. D. Porter. 2000. Distribution of benthic algae in the upper Illinois River basin in relation to geology and land use. Freshwater Biology 44: 279-301. Lenat, D. R. 1993. A biotic index for the southeastern United States: derivation and list of

PAGE 157

141 Lesica, P., B. McCune, S. Cooper, and W. S. Hong. 1991. Differences in lichen and bryophyte communities between old-growth and managed second-growth forests. Canadian Journal of Botany 69: 1745-1755. Leslie, A. J., J. P. Prenger, and T. L. Crisman. 1999. Cypress Domes in North Florida: Invertebrate Ecology and Response to Human Disturbance. Pp. 105-119 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. P. Batzer, R. B. Rader, and S. A. Wissinger. John Wiley and Sons. London. Long, K. R., R. S. Kalmbacher, and F. G. Martin. 1986. Diet quality of steers grazing three range sites in south Florida. Journal of Range Management 39(5): 389-392. Lowe, R. L. 1974. Environmental requirements and pollution tolerance of freshwater diatoms. U.S. Environmental Protection Agency, National Environmental Research Center, Office of Research and Development. EPA-670/4-74-005. Cincinnati, OH. Ludden, V. E. and F. R. Hauer. 2000. The Effects of Natural Variability on the Use of Macroinvertebrates as Bioindicators of Disturbance in Intermontane Depressional Wetlands in Northwestern Montana, USA. Flathead Lake Biological Station: University of Montana., Bozeman, MT. Mack, J. 2001. Vegetation Index of Biologic Integrity (VIBI) for Wetlands: Ecoregional, Hydrogeomorphic, and Plant Community Comparisons with Preliminary Wetland Aquatic Life Use Designations, Ohio Environmental Protection Agency, Wetland Ecology Division, Columbus, OH. MaGee, T. K., T. L. Ernst, M. E. Kentula, and K. A. Dwire. 1999. Floristic comparison of freshwater wetlands in an urbanizing environment. Wetlands 19(3): 517-534. Malmqvist, B. and M. Maki. 1994. Benthic macroinvertebrate assemblages in north Swedish streams: environmental relationships. Ecography 17: 9-16. Mantel, N. 1967. The detection of disease clustering and generalized regression approach. Cancer Research 27: 209-220. Marchant, R. 2002. Do rare species have any place in multivariate analysis for bioassessment? Journal of the North American Benthological Society 21(2): 311-313. Martin, D. B. and W. A. Hartman. 1987. The effect of cultivation on sediment composition and deposition in prairie pothole wetlands. Water, Air, and Soil Pollution 34: 45-53. Mather, P. M. 1976. Computational Methods of Multivariate Analysis in Physical Geography. J. Wiley and Sons. London.

PAGE 158

142 Mathews, W. J., R. C. Cashner, and F. P. Gelwick. 1988. Stability and Persistence of Fish Faunas and Assemblages in Three Midwestern Streams. Copeia 4: 945-955. Maul, J. D. and C. M. Cooper. 2000. Water quality of seasonally flooded agricultural Approach. Springer-Verlag. New York, NY. fields in Mississippi, USA. Agriculture, Ecosystems, and Environment 81: 171-178. McCarron, E. and R. Frydenborg. 1997. The Florida Bioassessment Program: an Agent of Change. Human and Ecological Risk Assessment 3(6): 967-977. McCormick, P. V. and J. Cairns Jr. 1997. Algal indicators of aquatic ecosystem condition and change. Pp. 178-207 in Plants for Environmental Studies. Edited by W. Wang J. W. Gorsuch and J. S. Hughes. CRC Lewis. Boca Raton, FL. McCormick, P. V., M. J. Chimney, and D. R. Swift. 1997. Diel oxygen profiles and water column community metabolism in the Florida Everglades, U.S.A. Archiv Fur Hydrobiologie. Stuttgart. 140(1): 117-129. Mccormick, P. V., and R. J. Stevenson. 1998. Periphyton as a Tool for Ecological Assessment and Management in the Florida Everglades. Journal of Phycology 34(5): 726-733. McCune, B. and J. B. Grace. 2002. Analysis of Ecological Communities. MjM Software Design. Gleneden Beach, OR. McCune, B., J. Hutchinson, and S. Berryman. 2002. Concentration of rare epiphytic lichens along large streams in a mountainous watershed in Oregon, U.S.A. The Bryologist 105(3): 439-450. McIntyre, S., P. Y. Ladiges, G. Adams. 1988. Plant species-richness and invasion by exotics in relation to disturbance of wetland communities on the Riverine Plain, NSW. Australian Journal of Ecology 13: 361-373. Merritt, G. D., B. Dickes and J. S. White. 1999. Biological Assessment of Small Streams in the Coast Range Ecoregion and the Yakima River Basin. Report No. 99-302. Washington State Department of Ecology, Environmental Investigations and Laboratory Services Program, Olympia, WA. Merritt, R. W. and K. W. Cummins. 1996. An Introduction to the Aquatic Insects of North America. Kendall/Hunt. Dubusque, IO. Mielke, P. W. 1984. Meteorological applications of permutation techniques based on distance functions. Pp. 813-830 in Handbook of Statistics. vol. 4 Edited by P.R. Krishnaiah and P.K. Sens. Elsevier Science Publisher. London. Mielke, P. W. and K. J. Berry. 2000. Permutation Methods: a Distance Function

PAGE 159

143 Miller, J. N., R. P. Brooks, and M. J. Croonquist. 1997. Effects of landscape patterns on biotic communities. Landscape Ecology 12: 137-153. Miller, R. E. and B. E. Gunsalus. 1997. Wetland Rapid Assessment Procedure (WRAP). South Florida Water Management District. West Palm Beach, FL. Mitsch, W. J. and J. G Gosselink. 2000. Wetlands. John Wiley and Sons. New York, NY. Moss, B. 1981. The composition and ecology of periphyton communities in freshwaters. II. Inter-relationships between water chemistry, phytoplankton populations, and periphyton populations in a shallow lake and associated experimental resevoir. British Phycology Journal 16: 59-76. Moss, B. 1992. Uses, Abuses, and Management of Lakes and Rivers. Hydrobiologia 243: 31-45. Munn, M. D., R. W. Black, and S. J. Gruber. 2002. Response of benthic algae to environmental gradients in an agriculturally dominated landscape. Journal of the North America Benthological Society 21(2): 221-237. Mushet, D. M., N. H. Euliss, and T. L. Shaffer. 2002. Floristic quality assessment of one natural and three restored wetland complexes in North Dakota, USA. Wetlands 22(1): 126-138. Newcombe, C. P. and D. D. MacDonald. 1991. Effects of suspended sediments on aquatic ecosystems. North American Journal of Fisheries Management 11: 72-82. Newman, S., J. Schuette, J. B. Grace, K. Rutchey, T. Fontaine, K. R. Reddy, and M. Pietrucha. 1998. Factors influencing cattail abundance in the northern Everglades. Aquatic Botany 60(3): 265-280. O'Conner, R. J., T. E. Walls, and R. M. Hughes. 2000. Using multiple taxonomic groups to index the ecological condition of lakes. Environmental Monitoring and Assessment 61: 207-228. Odum, H.T. 1995. Environmental Accounting. J. Wiley and Sons. New York, NY. Ormerod, S. J. and R. W. Edwards. 1987. The ordination and classification of macroinvertbrate assemblages in the catchments of the River Wye in relation to environmental factors. Freshwater Biology 17: 533-546. Pan, Y., and R. J. Stevenson. 1996. Gradient Analysis of Diatom Assemblages in Western Kentucky Wetlands. Journal of Phycology 32: 222-232. Pearlstine, L. G, L. A. Brandt, F. J. Mazzotti, and W. M. Kitchens. 1997. Fragmentation of pine flatwood and marsh communities converted for ranching and citrus. Landscape and Urban Planning 38(3-4): 159-169.

PAGE 160

144 Peet, R. K., T. R. Wentworth, R. Duncan, and P. S. White. 1996. The North Carolina Vegetation Survey Protocol: A Flexible, Multipurpose Method for Recording Vegetation Composition and Structure. Department of Biology, University of North Carolina at Chapel Hill. Chapel Hill, NC. Peterson, G., C. R. Allen, and C. S. Holling. 1998. Ecological Resilience, Biodiversity, and Scale. Ecosystems 1: 6-18. Peterson, D. and S. Porter. 2002. Biological and chemical indicators of eutrophication in the Yellowstone River and major tributaries during August 2000. National Monitoring Conference Proceedings. National Water Quality Monitoring Council (web document: wy.water.usgs.gov/YELL/nwqmc/nwqmc.pdf). Plafkin, J. L., M. T. Barbour, K. D. Porter, S. K. Gross, and R. M Hughes. 1989. Rapid Bioassessment Protocols for Use in Streams and Rivers: Benthic Macroinvertebrates and Fish. EPA 440-4-89-001. U.S. Environmental Protection Agency, Office of Water Regulations and Standards, Washington, DC. Purvis, A. R., L. Kellogg, and W. G. Boggess. 1991. Agriculture and Water Quality in the Southeastern Coastal Plains: A Descriptive Analysis. Staff Paper #91-38. Food and Resource Economics Department, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL. Rader, R. B. 1999. The Florida Everglades: Natural variability, invertebrate diversity, and foodweb stability. Pp. 25-54 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. P. Batzer, R. B. Rader, and S. A. Wissinger. John Wiley and Sons. New York, NY. Rader, R. B., and C. J. Richardson. 1992. The effects of nutrient enrichment on algae on macroinvertebrates in the Everglades: A review. Wetlands 12(2): 121-135. Raschke, R. L. 1993. Diatom (Bacillariophyta) community response to phosphorus in the Everglades National Park, USA. Phycologia 32(1): 48-58. Reader, J. and C. Craft. 1999. Comparison of wetland structure and function on grazed and ungrazed salt marshes. Journal of the Elisha Mitchell Scientific Society 115(4): 236-249. Reddy, K. R., E. G. Flaig, and D. A. Graetz. 1996. Phosphorus storage capacity of uplands, wetlands and streams of the Lake Okeechobee Watershed, Florida. Agriculture Ecosystems & Environment 59(3): 203-216. Reddy, K. R., G. A. O. Connor, and P. M. Gale. 1998. Phosphorus sorption capacities of wetland soils and stream sediments impacted by dairy effluent. Journal of Environmental Quality 27(2): 438-447.

PAGE 161

145 Reed, P. B. 1986. Wetland Plants of Florida and the Southeast Region, Fish and Wildlife Service. WELUT-86/W12.09. U.S. Department of the Interior, U.S. Fish and Wildlife Service. Washington, DC. Journal of Wildlife Management 64(3): 615-631. Reed, P. B. 1997. Revision of the National List of Plant Species that Occur in Wetlands. U.S. Department of the Interior, U.S. Fish and Wildlife Service. Washington, DC. Resh, V. H. and J. K. Jackson. 1993. Rapid assessment approaches in benthic macroinvertebrate biomonitoring studies. Pp. 195-233 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. New York, NY. Resh, V. H. and T. D. Unzicker. 1975. Water quality monitoring and aquatic organisms: the importance of species identification. Journal of the Water Pollution Control Federation 47: 9-19. Reynoldson, T. B., R. H. Norris, V. H. Resh, K. E. Day, and D. M. Rosenberg. 1997. The reference condition: a comparison of multimetric and multivariate approaches to assess water-quality impairment using benthic macroinvertebrates. Journal of the North American Benthological Association 16(4): 833-852. Ricklefs, R. E. 1990. Ecology. 3rd ed. W.H. Freeman and Company. New York, NY. Rochow, T. F. 1994. The Effects of Water table Level Changes in the Northern Tampa Bay Region, Southwest Florida Water Management District, Brooksville, FL. Rosenberg, D. M. and V. H. Resh. 1993. Introduction to freshwater biomonitoring and benthic macroinvertebrates. Pp. 1-9 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. New York, NY. 1996. The use of aquatic insects in biomonitoring. Pp. 87-97 in An Introduction to the Aquatic Insects of North America. Edited by R. W. Merritt and K. W. Cummins. Kendall-Hunt. Dubuque, IO. Roth, N. E., J. D. Allan, and D. L. Erickson. 1996. Landscape influences on stream biotic integrity assessed at multiple spatial scales. Landscape Ecology 11(3): 141-156. Rushton, B., and D. Carr. 1993. Isolated wetland used for stormwater treatment. Pp. 105-108 in Water Management in the 1990s. American Society of Civil Engineers. New York, NY. SAS Institute, Inc. (SAS) 1990. SAS User's Guide, version 6, fourth edition. SAS Institute, Inc. Cary, NC. Semlitsch, R. D. 2000. Principles for management of aquatic-breeding amphibians.

PAGE 162

146 Sharitz, R. and D. Batzer. 1999. An introduction to freshwater wetlands in North America and their invertebrates. Pp. 1-22 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. Batzer, R. Rader and S. Wissinger. John Wiley and Sons, Inc. New York, NY. (Diptera) and vegetation in a created wetland and implications for sampling. Wetlands 15(3): 285-289. Shutler, D., A. Mullie, and R. G. Clark. 2000. Bird communities of prairie uplands and wetlands in relation to farming practices in Saskatchewan. Conservation Biology 14(5): 1441-1451. Smogor, R. A. and P. L. Angermeier. 2001. Determining a Regional Framework for Assessing Biotic Integrity of Virginia Streams. Transactions of The American Fisheries Society 130: 18-35. Snyder, B.D., M.T. Barbour, and E.W. Leppo. 1998. Development of a watershed-based approach for biomonitoring of fresh surface waters in southern Floirda canal systems. Metro-Dade Enviromental Resources Management. Miami, FL. Sovell, L. A. and B. Vondracek. 1999. Evaluation of the fixed-count method for Rapid Bioassessment Protocol III with benthic macroinvertebrate metrics. Journal of the North America Benthological Society 18(3): 420-426. Spieles, D. J. and W. M. Mitsch. 2000. Macroinvertebrate community structure in highand low-nutrient constructed wetlands. Wetlands 20(4): 716-729. Stevenson, R. J. 2001. Using algae to assess wetlands with multivariate statistics, multimetric indices, and an ecological risk assessment framework. Pp. 113-140 in Bioassessment and Management of North American Freshwater Wetlands. Edited by D. P. Batzer, R.B. Rader, and S. A. Wissinger. John Wiley and Sons. New York, NY. Stevenson, R.J., M. Bothwell, R.L. Lowe. 1996. Algal Ecology, Freshwater Benthic Ecosystems. Academic Press. San Diego, CA. Stevenson, R. J., P. R. Sweets, Y. Pan, and R. E. Schultz. 1999. Algal community patterns in wetlands and their use as indicators of ecological conditions. Pp. 517-527 in Proceedings of INTECOL's Vth International Wetland Conference. Edited by A. J. McComb and J. A. Davis. Gleneagles Press. New York, NY. Stewart, A. J. and J. M. Loar. 1994. Spatial and Temporal Variation in Biomonitoring Data. Pp. 91-124 in Biological Monitoring of Aquatic Systems. Edited by S. L. Loeb and A. Spacie. CRC Press, Inc. Boca Raton, FL. Stoermer, E. and J. Smol. 1999. The diatoms: applications for the environmental and earth sciences. Cambridge University Press. New York, NY. Streever, W. J., D. L. Evans, C. M. Keenan, and T. L. Crisman. 1995. Chironomidae

PAGE 163

147 Taft, J. B., G. S. Wilhelm, D. M. Ladd, and L. A. Masters. 1997. Floristic Quality Assessment for Vegetation in Illinois, a Method for Assessing Vegetation Integrity. Erigenia 15: 3-25. Tangen, B. A., M. G. Butler, and M. J. Ell. 2003. Weak correspondence between macroinvertebrate assemblages and land use in Prairie Pothole region wetlands, USA. Wetlands 22(4): 104-115. Tanner, G.W., L.D. Sandoval, and F.G. Martin. 1984. Cattle behavior on a South Florida range. Journal of Range Management 37(3): 248-251. Tate, C. M. and J. S. Heiny. 1995. The ordination of benthic invertebrate communities in the South Platte River Basin in relation to environmental factors. Freshwater Biology 33: 439-454. ter Braak, C. J. F. 1987. The analysis of vegetation-environmental relationships by canonical correspondence analysis. Vegetatio 69: 69-77. Tilley. D.R. and M.T. Brown. 1998. Wetland networks for stormwater management in subtropical urban watersheds. Ecological Engineering 10: 131-158. Tobe, J. D., K. C. Burks, R. W. Cantrell, M. A. Garland, M. E. Sweeley, D. W. Hall, P. Wallace, G. Anglin, G. Nelson, J. R. Cooper, D. Bickner, K. Gilbert, N. Aymond, K. Greenwood, and N. Raymond. 1998. Florida Wetland Plants An Identification Manual. Florida Department of Environmental Protection. Tallahassee, FL. U.S. Department of Agriculture. 1998. Field indicators of Hydric Soils in the United States. U.S.D.A. Natural Resources Conservation Service, Fort Worth, TX. U.S. Department of Agriculture. (2003) Integrated Taxonomic Information System (IT IS). Web page. Available at www.itis.usda.gov. U.S. Environmental Protection Agency (U.S. EPA). 1990. Feasibility Report on Environmental Indicators for Surface Water Programs. Office of Water Regulations and Standards and Office of Policy, Planning and Evaluation. Washington, DC. 1983. Methods for Chemical Analysis of Water and Wastes. EPA 600/4-79-020. U.S. E.P.A. Office of Research and Development. Washington, DC. 2002a. Methods for Evaluating Wetland Condition: Introduction to Biological Assessment. EPA-822-R-02-014. Office of Water, U.S. Environmental Protection Agency. Washington, DC. 2002b. Methods for Evaluating Wetland Condition: Biological Assessment Models for Birds. EPA-822-R-02-023. Office of Water, U.S. Environmental Protection Agency. Washington, DC.

PAGE 164

148 2002c. Methods for Evaluating Wetland Condition: Developing and Invertebrate Index of Biological Integrity for Wetlands. EPA-822-R-02-019. Office of Water, U.S. Environmental Protection Agency. Washington, DC. 2002d. Methods for Evaluating Wetland Condition: Using Amphibians in Bioassessment of Wetlands. EPA-822-R-02-022. Office of Water, U.S. Environmental Protection Agency. Washington, DC. 2002e. Methods for Evaluating Wetland Condition: Using Algae to Assess Environmental Conditions in Wetlands. EPA-822-R-02-021. Office of Water, U.S. Environmental Protection Agency. Washington, DC. U.S. Fish and Wildlife Service. 2000. National Wetlands Inventory. Web page. Available at www.nwi.fws.gov. U.S. General Accounting Office (U.S. GAO). 1988. Environmental Protection Agency: Protecting Human Health and the Environment Through Improved Management. GAO/RECD-88-101. U.S. GAO: Washington, D.C. Van Dam, H., A. Mertens, and J. Sinkeldam. 1994. A coded checklist and ecological indicator values of freshwater diatoms from The Netherlands. Netherlands Journal of Aquatic Ecology 28: 117-133. van der Valk, A. G. 1981. Succession in wetlands: a Gleasonian approach. Ecology 62: 688-696. Van Meter Kasanof, N. 1973. Ecology of the microalgae of the Florida Everglades. Part 1. Environment and some aspects of freshwater periphyton. Nova Hedwigia 24: 619-664. van Oene, H., E. J. Mieleke van Deursen, and F. Berendse. 1999. Plant-herbivore interaction and its consequence for succession in wetland ecosystems: a modeling approach. Ecosystems 2: 122-138. Vulink, J. T., H. J. Drost, and L. Jans. 2000. The influence of different grazing regimes on Phragmitesand shrub vegetation in the well-drained zone of a eutrophic wetland. Applied Vegetation Science 3: 73-80. Waichler, W. S., R. F. Miller, and P. S. Doescher. 2001. Community characteristics of old-growth western juniper woodlands. Journal of Range Management 54: 518-527. Wallace, J. B. and N. H. Anderson. 1996. Habitat, Life History, and Behavioral Adaptations of Aquatic Insects. Pp. 41-74 in An Introduction to the Aquatic Insects of North America. 3rd ed.. Edited by. R.W. Merritt and K.W. Cummins. Kendall/Hunt Publishing. Dubuque, IO.

PAGE 165

149 Wardrop, D. H. and R. P. Brooks. 1998. The Occurrence and Impact of Sedimentation in Central Pennsylvania Wetlands. Environmental Monitoring and Assessment 51: 119-130. Whitmore, T. J. 1989. Florida diatom assemblages as indicators of trophic state and pH. Limnology and Oceanography 34(5): 882-95. Whittaker, R. H. 1972. Evolution and measurement of species diversity. Taxon 18: 213-251. Wiggins, G. B. R. J. Mackay and I. M. Smith. 1980. Evolutionary and ecological strategies of animals in annual temporary pools. Arch.Hydrobiol./Suppl. 58: 97-206. Wilhelm, G. and D. Ladd. 1988. Natural Area Assessment in the Chicago Region. Transactions of the 53rd North American Wildlife and Natural Resource Conference, 361-375. Chicago, IL. Winchester, B. H., J. S. Bays, J. C. Higman, and R. L. Knight. 1985. Physiography and vegetation zonation of shallow emergent marshes in southwestern Florida. Wetlands 5: 99-118. Winter, J. G. and H. C. Duthie. 2000. Epilithic diatoms as indicators of stream total N and total P concentration. Journal of the North American Benthological Society 19(1): 32-49. Wolda, H. 1981. Similarity Indices, Sample Size, and Diversity. Oecologia 50: 296-302. Wood, J. M., and G. W. Tanner. 1990. Graminoid community composition and structure within four Everglades management areas. Wetlands 10(2): 127-149. Wunderlin, R. P. 1998. Guide to the Vascular Plants of Florida. University Press of Florida. Gainesville, FL. Wunderlin, R. P. and B. F. Hanson. 2000. Atlas of Florida Vascular Plants. Web page. Available at www.plantatlas.usf.edu. Yoder, C. O. and E. T. Rankin. 1995. Biological criteria program development in Ohio. Pp. 109-144 in Biological Assessment and Criteria. Edited by W. S. Davis and T. P. Simon. Lewis Publishers. London. Zar, J.H. 1999. Biostatistical Analysis, 4th ed. Prentice-Hall. Englewood Cliffs, NJ.



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The Wetland Condition Index (WCI): Biological Indicators of Wetland Condition for Isolated Depressional Herbaceous Wetlands in Florida Report Submitted to the Florida Department of E nvironmental Protection under Contract #WM-683 By Charles R. Lane with Mark T. Brown, Mike Murray-Hudson, and M. Benjamin Vivas H.T. Odum Center for Wetlands University of Florida Gainesville, FL 32611-6350 September 2003

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ACKNOWLEDGMENTS This research was supported under a research contract from the Florida Department of Environmental Protection (FDEP); M.T. Brown, principal investigator. We would like to acknowledge the support of FDEP staff, especially Russ Frydenborg, Ashley ONeal, Ellen McCarron, Liz Miller, Lori Wolfe, Joy Jackson, Johnny Richardson, and the FDEP Central Laboratory in Tallahassee. Additional acknowledgement is due to the research group of the H.T. Odum Center for Wetlands, especially Kelly Reiss, Matt Cohen, Jim Surdick, and Susan Carstenn. We also thank the members of the 1999 and 2000 field crew for their tireless and enthusiastic work, especially Mark Fowlkes, Mark Otto, and Michael Stevens. Steven Doherty was an integral part of the initial stages of this research, and his perseverance and hard work helped to ensure this research to fruition. This project and the preparation of this report were funded in part by a Section 319 Nonpoint Source Management grant from the U.S. Environmental Protection Agency through a contract with the Florida Department of Environmental Protection. ii

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TABLE OF CONTENTS Page ACKNOWLEDGMENTS..................................................................................................ii LIST OF TABLES............................................................................................................vii LIST OF FIGURES...........................................................................................................xi EXECUTIVE SUMMARY.............................................................................................xiii CHAPTER 1 INTRODUCTION AND OVERVIEW........................................................................1 Introduction...................................................................................................................1 GIS Measurements and Wetland Metrics..............................................................2 Regional Composition...........................................................................................4 Environmental Correlates and Assemblage Response..........................................4 Background...................................................................................................................4 Wetland Trends.............................................................................................................6 Effect of Land Use Change on Wetland Systems.........................................................7 Nutrient and Chemical Loading............................................................................9 Selective Herbivory and Trampling....................................................................10 Ancillary Impacts from Landscape Modification................................................10 Wetland Assemblages and Biological Assessment....................................................11 Project Overview........................................................................................................12 2 DIATOMS AS BIOINDICATORS............................................................................13 Introduction.................................................................................................................13 Methods......................................................................................................................14 Site Selection and Agricultural Development Gradient......................................14 Field Data Collection, Sample Preparation and Laboratory Procedures.............15 Diatoms........................................................................................................15 Soil and water physical-chemical sampling and analysis............................16 Data Analyses......................................................................................................16 Summary statistics........................................................................................16 Diatoms-compositional tests........................................................................17 Diatoms community composition and correlation with soil and water parameters...............................................................................................17 Metric Development............................................................................................18 iii

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Sensitive and tolerant taxa............................................................................19 Autecological metrics...................................................................................19 Constructing the Multimetric Index....................................................................20 Results.........................................................................................................................20 Wetland Diatom Composition.............................................................................20 Diatom Composition and Environmental Correlates..........................................26 Metric Development............................................................................................29 Regional composition...................................................................................29 Indicator species analyses............................................................................31 Autecological indices...................................................................................37 The Multimetric Index.........................................................................................42 Discussion...................................................................................................................44 Diatom Composition and Environmental Correlates..........................................44 Diatom Composition and Wetland Regions........................................................46 Metric Development............................................................................................46 Indicator species analysis.............................................................................46 Autecological indices...................................................................................47 The Diatom Multimetric IndexConclusion and Recommendations..................47 3 MACROPHYTES AS BIOINDICATORS................................................................49 Introduction.................................................................................................................49 Methods......................................................................................................................50 Site Selection and Disturbance Gradient.............................................................50 Field Data Collection...........................................................................................52 Database Development........................................................................................53 Species characteristics..................................................................................53 Coefficient of Conservatism.........................................................................54 Soil and Water Physical-Chemical Sampling and Analysis................................54 Data Analyses......................................................................................................55 Summary statistics........................................................................................55 Macrophytes-compositional analysis...........................................................55 Macrophyte composition and soil and water parameter correlates..............55 Metric Development............................................................................................55 Sensitive and tolerant species.......................................................................56 Exotic species...............................................................................................56 Annual to perennial ratio..............................................................................56 Average Coefficient of Conservatism..........................................................56 Vegetative Index of Wetland Condition..............................................................57 Results.........................................................................................................................57 Field Data............................................................................................................57 Ancillary Data.....................................................................................................57 Compositional Analysis.......................................................................................59 Community Composition and Environmental Gradients....................................60 Metric Development............................................................................................62 Sensitive and tolerant species.......................................................................62 Percent exotic...............................................................................................69 iv

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Annual to perennial ratio..............................................................................70 Average Coefficient of Conservatism..........................................................71 Vegetative Index of Wetland Condition..............................................................72 Discussion...................................................................................................................75 Environmental Gradients and Species Distributions...........................................75 Metric Development............................................................................................77 Sensitive and tolerant species.......................................................................77 Percent exotic...............................................................................................78 Annual to perennial ratio..............................................................................79 Average Coefficient of Conservatism..........................................................80 Vegetative Index of Wetland Condition..............................................................81 Field Data Collection...........................................................................................81 Conclusions and Recommendations....................................................................82 4 MACROINVERTEBRATES AS BIOINDICATORS...............................................83 Introduction.................................................................................................................83 Methods......................................................................................................................85 Site Selection and Agricultural Development Gradient......................................85 Macroinvertebrate Collection and Identification.................................................85 Water and Soil Physical-Chemical Sampling and Analysis................................86 Macroinvertebrate Composition and Environmental Correlates.........................86 Macroinvertebrate Compositional Analyses.......................................................86 Summary statistics........................................................................................86 Regional composition of macroinvertebrates...............................................86 Macroinvertebrate Metric Development......................................................87 Categorical metrics.......................................................................................87 Ancillary data...............................................................................................88 Sensitive and tolerant species.......................................................................88 Macroinvertebrate Index of Wetland Condition..................................................89 Results.........................................................................................................................89 Wetland Macroinvertebrate Composition...........................................................89 Community Composition and Environmental Gradients....................................92 Metric Development............................................................................................94 Sensitive and tolerant taxa............................................................................96 Percent predators..........................................................................................98 Percent Odonata...........................................................................................98 Percent Orthocladiinae.................................................................................99 Macroinvertebrate Index of Wetland Condition................................................100 Discussion.................................................................................................................101 Environmental Correlates and Macroinvertebrate Composition.......................101 Regional Data Analyses....................................................................................104 Final Metrics......................................................................................................104 Sensitive and tolerant genera......................................................................105 Categorical metricspredators....................................................................105 Categorical metricsOdonates....................................................................105 Categorical metricsOrthocladiinae...........................................................106 v

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Macroinvertebrate Index of Wetland Condition................................................107 Field Sampling and Macroinvertebrate Identification.......................................107 Field sampling............................................................................................107 Macroinvertebrate identification and enumeration...........................................108 Conclusions and Recommendations..................................................................109 5 SUMMARY AND SYNTHESIS.............................................................................111 Metric Summary.......................................................................................................111 Landscape Assessment and Index Development......................................................111 Environmental Variables Driving Wetland Composition Across Assemblages......113 Environmental Variables and Management Concerns.............................................114 Conclusions and Recommendations.........................................................................114 APPENDIX A Site Descriptions.......................................................................................................116 B Soil and Water Sampling Methods and Results.......................................................118 C Diatom Autecological Values...................................................................................121 D Coefficient of Conservatism.....................................................................................125 LIST OF REFERENCES.................................................................................................130 vi

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LIST OF TABLES Table page 1-1. Landscape Development Intensity Disturbance Coefficients......................................3 1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida landscape and concurrent increases in agricultural and urban land use.....................7 1-3. National Wetland Inventory categories and landscape abundance of freshwater wetlands in Florida.....................................................................................................8 2-1. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for benthic diatoms...................................................22 2-2. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for epiphytic diatoms................................................23 2-3. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for phytoplanktonic diatoms.....................................24 2-4. Summary statistics and diatom similarities using Tukeys HSD..............................25 2-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes within benthic, epiphytic, and phytoplanktonic diatom groups...........25 2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland condition...26 2-7. MRPP analyses of the compositional similarity between benthic, epiphytic, and phytoplanktonic diatoms..........................................................................................27 2-8. Comparison of the medians of water and soil variables between LDI classes with the Mann-Whitney U-test...............................................................................................27 2-9. Correlations of environmental variables and ordination scores for benthic diatoms.....................................................................................................................32 2-10. Correlations of environmental variables and ordination scores for epiphytic diatoms.....................................................................................................................32 2-11. Correlations of environmental variables and ordination scores for phytoplanktonic diatoms.....................................................................................................................33 vii

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2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of South, Central, and North wetland regions..............................................................33 2-13. Reference site diatom indicator taxa identified using Indicator Species Analysis for each wetland region..................................................................................................34 2-14. Impaired site diatom indicator taxa identified using Indicator Species Analysis for each wetland region..................................................................................................35 2-15. Statewide indicators of reference conditions as determined from Indicator Species Analysis....................................................................................................................36 2-16. Statewide indicators of impaired conditions as determined from Indicator Species Analysis....................................................................................................................37 2-17. Correlations of autecological abundance data and LDI score.................................39 2-18. Mann-Whitney U-test of autecological abundance values between impaired and reference conditions.................................................................................................39 2-19. Quadrisect values and the 95 th percentile data for each proposed biological indicator....................................................................................................................42 2-20. Diatom Index of Wetland Condition scores for sampled sites................................43 3-1. Advantages and disadvantages of using macrophytes as biological indicators of wetlands condition....................................................................................................50 3-2. Sampling dates for each region.................................................................................53 3-3. Ancillary data added to the database for each plant species......................................53 3-4. Scoring Criteria for the Coefficient of Conservatism................................................54 3-5. Summary statistics of richness (S), Simpsons diversity index (H) and Shannon diversity index (D) for macrophytes.......................................................................58 3-6. Co-occurrence matrices of macrophytes by region and impairment condition.........60 3-7. Simultaneous and iterative tests of community composition among regions...........60 3-8. MRPP comparison of the median values of water and soil variables between reference and impaired sites.....................................................................................61 3-9. Correlations of environmental variables and ordination scores................................62 3-10. Regionally derived species indicative of reference conditions...............................64 3-11. Regionally derived species indicative of impaired conditions................................65 viii

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3-12. Spearman correlations of the adundance of regional sensitive and tolerance macrophyte species with LDI scores for each site...................................................65 3-13. Indicator species of reference conditions derived from the peninsular dataset.......66 3-14. Indicator species of impaired conditions derived from the peninsular dataset........67 3-15. Exotic taxa encountered and region(s) of occurrence.............................................69 3-16. Quadrisect values and 95th percentile for metric scoring.......................................72 3-17. Site scores for each metric and the summed VIWC................................................73 4-1. Advantages and disadvantages of using macroinvertebrates in wetland bioassessment...........................................................................................................84 4-2. Compositional metrics, definition, and expected response.......................................87 4-3. Trophic metrics, definition, and expected response..................................................88 4-4 Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for macroinvertebrates..............................................90 4-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes and between regional datasets..............................................................91 4-6. MRPP analyses of the macroinvertebrate compositional similarity between South, Central, and North wetland regions..........................................................................91 4-7. MRPP analyses of the macroinvertebrate compositional similarity for reference sites between South, Central, and North wetland regions................................................92 4-8. MRPP analyses of the macroinvertebrate compositional similarity for impaired sites between South, Central, and North wetland regions................................................93 4-9. Comparison of the medians of water and soil variables between reference and impaired conditions with the Mann-Whitney U-test................................................93 4-10. Correlations of environmental variables and ordination scores for macroinvertebrates...................................................................................................94 4-11. Statewide indicators of reference conditions as determined from Indicator Species Analysis....................................................................................................................96 4-12. Statewide indicators of impaired conditions as determined from Indicator Species Analysis....................................................................................................................97 4-13. Quadrisect values and the 95 th percentile data for each proposed biological indicator..................................................................................................................100 ix

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4-14. Macroinvertebrate Index of Community Condition scores for sampled sites.......102 A-1. Site coordinates and LDI score...............................................................................116 B-1. Soil characteristics measured at each study site.....................................................119 C-1. Diatom Autecological Values.................................................................................121 D-1. Coefficient of Conservatism scores for sampled macrophytes...............................125 x

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LIST OF FIGURES Figure page 1-1. Schematic of the relationship between various ecosystem influences and biological integrity. ....................................................................................................................5 1-2. Approximate landscape extent of wetlands in Florida. ..............................................7 2-1. Algal study site locations and encounter probability for isolated depressional wetlands. ..................................................................................................................15 2-2. Hypothesized example of metric scoring using the 95 th percentile of the dataset. ...21 2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly correlated environmental variables. ........................................................................29 2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly correlated environmental variables..........................................................................30 2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and strongly correlated environmental variables............................................................31 2-6. Indicator species abundance data plotted against the LDI........................................38 2-7. Diatom abundance for autecological metrics plotted against the LDI gradient........30 2-8. Diatom Index of Wetland Condition scores for each site plotted against the disturbance gradient.................................................................................................44 3-1. Study site locations and encounter probability for isolated depressional wetlands..52 3-2. Transect and quadrat locations in a hypothetical depressional wetland....................52 3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted scores for wetland macrophytes..........................................................................................59 3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly correlated environmental variables...........................................................................................63 3-5. Abundance of sensitive species along the disturbance gradient................................68 3-6. Abundance of tolerant species along the disturbance gradient..................................68 xi

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3-7. Abundance of exotic taxa at each site along the disturbance gradient......................70 3-8. Annual to perennial ratio at each site along the disturbance gradient.......................71 3-9. Average Coefficient of Conservatism value for each site along the disturbance gradient.....................................................................................................................72 3-10. Relationship between the VIWC and the LDI.........................................................75 3-11. Environmental optima along a hypothetical environmental gradient......................78 4-1. Biplot of macroinvertebrate NMDS ordination scores for each site and strongly correlated environmental variables..........................................................................95 4-2. Abundance of sensitive taxa plotted against the LDI................................................97 4-3. Abundance of tolerant taxa plotted against the LDI..................................................98 4-4. Predator abundance plotted against the LDI..............................................................99 4-5. Odonata abundance plotted against the LDI..............................................................99 4-6. Abundance of Orthocladiinae plotted against the LDI............................................100 4-7. Macroinvertebrate Index of Wetland Condition plotted against the LDI................101 xii

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EXECUTIVE SUMMARY THE WETLAND CONDITION INDEX: BIOLOGICAL INDICATORS FOR ISOLATED DEPRESSIONAL WETLANDS IN FLORIDA With the passage of the Water Pollution and Control Act (1972, Clean Water Act), states were charged with the task to [r]estore and maintain the chemical, physical, and biological integrity of the Nations waters (Water Pollution and Control Act (a)). Biological integrity can be defined as, the ability of an aquatic ecosystem to support and maintain a balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of the natural habitats of the region (Karr and Dudley 1981). The State of Florida has developed measurements of the biological integrity of freshwater aquatic systems through the use of biological indicators, or measurable attributes of the biota that respond to anthropogenic stressors. This has been completed for streams (Stream Condition Index, Barbour et al. 1996) and lakes (Lake Condition Index, Gerritsen et al. 2000). The development of the index of Florida wetland resource condition, or the Wetland Condition Index, has followed from those earlier works assessing streams and lakes of Florida. The goal of this project was to identify characteristics of herbaceous wetland organismal structure, composition, and function that may serve as biological indicators of the condition of Floridas wetland resources. Intermediate and often concurrent goals of the project have included: The development of a wetland classification system and geographic regionalization to increase the sensitivity of biometrics; The development of measures of anthropogenic disturbance affecting the organismal assemblage of a given wetland; The development and implementation of sampling protocols for macrophytes, macroinvertebrates, and algal wetland assemblages; The identification of indicators of wetland condition along the disturbance gradient within each of the three focal assemblages; The development of the Wetland Condition Index (WCI), an assessment method of assemblage-specific indices of community condition for diatoms (the Diatom Index of Wetland Condition), vegetation (the Vegetative Index of Wetland Condition), and macroinvertebrates (the Macroinvertebrate Index of Wetland Condition), for wetland systems throughout Florida. This report addresses the last four of the goals described above. The first goal was addressed in earlier reports to FDEP (see Doherty et al. 2000, Lane 2000). The approach has included a review of technical and scientific literature, development of a wetland classification system and crosswalk with other classifications, xiii

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wetland regionalization of Florida, and 3 years of wetland biological surveys in the growing seasons of 1998 (pilot study), 1999, and 2000. The biological surveys were designed to test the validity (and necessity) of the proposed wetland regions and to identify the appropriate biological indicator taxa. The wetland classification scheme was organized with major classes defined from three variables: 1) dominant vegetation (forested, shrub, herbaceous); 2) geomorphic position (stream channel (floodplain), flat topography, sloped topography, lake fringe, depressional); and 3) primary water source (rainfall, surface water, ground water). Subclasses are discriminated by modifiers (hydroperiod and plant community associations). Eleven wetland classes were identified: forested (river swamp, slough/strand/seepage swamp, lake swamp, depression swamp, flatland swamp); shrub dominated (shrub-scrub swamp); and herbaceous (river marsh, wet prairie, lake marsh, depressional marsh, seepage marsh). An HTML electronic data base has been completed and delivered to the FDEP that cross walks existing wetland classifications to the new simplified, classification scheme developed for the bio-assessment project. Regionalization of the State was considered necessary since there is significant variation in climatic and physical features of the Florida peninsula and it was believed that these regional differences could equate to variations in biological indicator signals. Map coverages of physical and climatic variables of the Florida landscape were used to develop regions that had different characteristic driving energies and landscape structural characteristics (see Lane 2000). The map coverages were combined with GIS map algebra to create a spatial hydrologic budget equation for the State. The equation modeled the movement of water on the landscape during the ecologically sensitive spring growing season. The output of the model was a Potential Soil Moisture Index (PSMI). The PSMI was separated into four regions based on both the critical depth of saturation and on a statistical clustering of the PSMI values. The classified regions were tested for similarities and differences to determine if between region variation in wetland type and environmental variables was greater than within region variations. A quantitative index of the human disturbance gradient has been developed using energy intensity of land uses as the metric. Called a Landscape Development Intensity index (LDI), the LDI is a land use based index of human disturbance. It is calculated spatially from aerial photographs of each site using coefficients applied to land uses within a 100 meter buffer surrounding the wetlands. Development intensity factors are a function of the energy use per unit area of land use. A total area weighted LDI is calculated for the 100-meter area of influence (see Brown and Vivas submitted). Three years of biological surveys of wetlands through out the state were designed to test regionalization as well as for metric and bio-indicator development. A 1998 pilot study involved surveying 24 herbaceous and forested depression wetlands in north and central Florida. Major taxonomic assemblages were characterized and ranked along a gradient of disturbances. Sites were located within multiple land uses such as parks, preserves, pasture, farm fields, well fields, silviculture plots, and urban matrix. Impacts that were assessed included hydrological modifications, nutrient loading, and altered hydroperiod. The first years sampling resulted in development of standardized sampling procedures, design and implementation of a statewide sampling program, and identification of community attributes and candidate metrics. xiv

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In the second and third years field seasons, 75 herbaceous, depressional wetlands were surveyed in three regions (22 sites in the North, 30 in the Central, and 23 in the South region, see Figures 2-1 and 3-1). Approximately half of the wetlands were located in developed landscapes (i.e. agricultural setting) and half were reference locations. Many of the sites were paired sites (impacted and reference at close proximity). Three indices of wetland integrity were developed based on measurable attributes (metrics) of the assemblages sampled from the 75 isolated depressional wetlands (see table below): the Diatom Index of Wetland Condition (DIWC, 14 metrics), Vegetative Index of Wetland Condition (VIWC, 5 metrics), and Macroinvertebrate Index of Wetland Condition (MIWC, 5 metrics). These indices were not regionally dependent and were thus applicable to the entire peninsula. Each index was significantly correlated (Spearmans r|0.75|, p<0.0001) with an independent geographic information systems-based measure of human landscape modification, the Landscape Development Intensity index (see Brown and Vivas submitted). Diatom Index of Wetland Condition Vegetative Index of Wetland Condition Macroinvertebrate Index of Wetland Condition % Sensitive Spp. % Sensitive Spp. % Sensitive Genera % Tolerant Spp. % Tolerant Spp. % Tolerant Genera % Sensitive Elevated pH % Exotic Taxa % Predators % Tolerant Elevated pH Annual:Perennial Ratio % Odonata % Sensitive Elevated Salinity Average Coefficient of Conservatism Score % Orthocladiinae % Tolerate Elevated Salinity % Sensitive Elevated Nitrogen % Tolerate Elevated Nitrogen % Sensitive Low D.O. % Tolerate Low D.O. % Meso& Polysaprobous % Oligotrophic % Eutrophic % Pollution Tolerant An ancillary goal of this research was to elucidate the various landscape and soil/water physio-chemical constituents responsible for determining the community composition of the sampled wetlands, as understanding the driving forces may aid in managing wetland resources. Four variables were strongly associated with community composition across all three assemblages (diatoms, macrophytes, and macroinvertebrates) sampled: soil pH, water column specific conductivity, water column total phosphorous, and Landscape Development Intensity index score. In addition, water color and latitude were also associated with macroinvertebrate and macrophyte community composition, respectively. The indices of biotic integrity developed from this research may be used to provide quantitative and objective measurement of the wetland resources of peninsular Florida and may form the scientific basis for an objective and quantifiable rapid assessment procedure. In addition, results from this study suggested that efforts to restore xv

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community composition and associated processes and functions should focus on amending inflows and fluxes of water, materials, and energy that affect soil pH, specific conductivity, and water TP, as well as decreasing the abundance of human-developed lands within 100m of wetlands. xvi

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CHAPTER 1 INTRODUCTION AND OVERVIEW Introduction Wetlands are defined as areas that are inundated or saturated by surface or ground water at a frequency and duration to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (42 Fed. Reg. 37, 125-126, 37128-29; July 19, 1977). Wetlands on the landscape provide many important functions, including biogeochemical cycling, wildlife habitat, floodwater attenuation, and water quality improvement. In the mid-1970s the United States Environmental Protection Agency (U.S. EPA) mandated that wetlands, as protected under the Clean Water Act (Clean Water Act 1(a)), required biological monitoring and assessment to ensure that the biological integrity (sensu Karr 1981) of these systems was not diminished. Wetland biological monitoring and assessment, as differing from synoptic water or soil chemistry sampling, characterizes the wetland flora and fauna to measure the relative state of wetland resources. The use of biotic characteristics, including taxonomic composition and the abundance of functional guilds (i.e., scrapers), has provided robust assessments of the relative state of various aquatic systems (see Barbour et al. 1996, Gerritsen and White 1997), as organisms integrate exogenous perturbations that occur at local (i.e., nutrient loading) and landscape scales (i.e., increases in residential land use) (Karr and Chu 1999). These observations have led to the development of indices of biological integrity (IBIs, Karr 1981), which relate measured attributes (or metrics) of various assemblages measured on-site to changes in human disturbance (Karr and Chu 1999, U.S. EPA 2002a). Often, the human disturbance gradient is interpreted subjectively (i.e., best professional judgment Adamus et al. 1991, Miller and Gunsalus 1997) or confounded through circular logic (i.e., a metric correlated to the disturbance gradient may also be directly incorporated into scoring the disturbance gradient Miller and Gunsalus 1997). To decrease these problems associated with on-site assessments, as well as the costs and logistics related to on-site visits, techniques have also been developed to examine biological response to landscape scale measurements through the use of geographic information systems (GIS) analysis (OConner et al. 2000, Cuffney et al. 2000). As compared with gradients assessed on-site that examine conditions within the system, landscape scale measurements assume a direct relationship between land use surrounding an aquatic body and the composition and relative condition of the system (Galatowitsch et al. 1999a). For example, studies have related biological data (e.g., richness) to the abundance of particular land use measurements (e.g., percent impervious surface meters Doberstein et al. 2000, percent agricultural land use within watershed Roth et al. 1996). However, GIS based analyses are subject to errors of land use interpretation from aerial photos, as well as delays (often of several years) between flight dates and available geo1

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2 rectified and digitized information, which can affect their accuracy. On the other hand, GIS based analyses of relative condition do not require an on-site visit, which decreases sampling effort and thus increases the number of sites quantifiable. In addition, GIS based analyses have been reported as generally precise and correlated with biological conditions within nested systems (Roth et al. 1996, Galatowitsch et al. 1999a, Karr and Chu 1999). These attributes increase the allure of GIS based analyses in assessing the relative condition of isolated depressional herbaceous wetlands on the Florida landscape. However, a disconnection may exist between the wetland system and the GIS-based assessment method due to the assumption of causal mechanisms between land use within a given distance from the wetland and relative wetland condition. For instance, a site may be perched on the landscape and thus not as highly affected by inputs from surrounding lands as a site in a low-lying area within the same land use. In this example, the expected variance in the biological data vis--vis the two hypothetical sites would not be assessed through GIS analyses as such biological analyses would be at too coarse a scale for spatial analyses. However, incorporating on-site measurements of biota, although more difficult than GIS analyses due to sampling and identification efforts, provides additional information germane to accurately assessing relative wetland condition (Karr and Chu 1999). In addition, combining GIS analyses with on-site biological data can improve the accuracy, precision, and sensitivity of spatial metrics by providing causal pathways to perceived variance in the dataset, and may instigate future improvements in assessment methods. These observations lead to the following goals of this report. First, to identify measurable attributes (or metrics, such as the abundance of exotic taxa) of the flora (diatoms and macrophytes) and fauna (macroinvertebrates) of isolated depressional marshes in Florida that are highly correlated with a GIS based measurement of landscape modification, the Landscape Development Intensity index, which is described below. Second, to test interregional compositional differences attributed to latitudinal/physiological gradients between the organisms sampled from within three wetland regions of peninsular Florida (after Lane 2000) that, if present, may necessitate the development of unique measurable attributes for each wetland region. Third, to identify significant associations between floral and faunal assemblage composition and measured soil and/or water parameters collected from sampled wetlands to aid in synecological understanding and resource management. GIS Measurements and Wetland Metrics The Landscape Development Intensity index (LDI, Brown and Vivas submitted) was used to assess the development intensity of lands within 100m around each sampled wetland, independent of the wetland biota. The LDI was developed by Brown and Vivas (submitted) and assesses the intensity of various land uses by measuring the annual non-renewable energy flow, given in terms of emergy, or embodied energy (Odum 1995), for each land use. They calculated their emergy values by identifying the energy pathways for each land use (land use data obtained from local water management districts, based on 1995 aerial photos), obtaining the value in joules/year from published sources, and multiplying the joules/year value by solar-emjoules/joule (sej/J, Odum 1995) to relate the amount of energy to a solar unit per year (see Brown and Vivas submitted). The use of an independent energy-based spatial measurement in this study permitted the incorporation

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3 of many disparate processes (e.g., pesticide use, water diversion and ditching, plowing, road building) into a single, agglomerative value. The actual LDI calculation was made for a 100m buffer directly surrounding each wetland using the following equation: LDI = (LDC % LU); where LDI is the Landscape Development Intensity index, LDC is the Landscape Development Coefficient (Table 1-1), the %LU is the percent of each land use within the 100m buffer directly surrounding each wetland. The relationship of land use intensity with other buffer sizes (18m, 250, 500m, 1000m) is currently being investigated (M.B. Vivas, Department of Environmental Engineering Sciences, University of Florida, personal communication). Table 1-1. Landscape Development Intensity Disturbance Coefficients. Land Use Non-Renewable Empower Density(E14 sej/ha/yr) Ln Non-Renewable Empower Density LDI Coefficients Natural System 0 1.00 Natural Open water 0 1.00 Pine Plantation 5.10 1.63 1.58 Woodland Pasture (with livestock) 8.00 2.08 2.02 Pasture (Bahia) (without livestock) 17.20 2.84 2.77 Recreational / Open Space (Low-intensity) 17.20 2.84 2.77 Low Intensity Pasture (Bahia) (with livestock) 33.31 3.51 3.41 Citrus 44.00 3.78 3.68 High Intensity Pasture (Bahia, with livestock) 46.74 3.84 3.74 Row crops 107.13 4.67 4.54 Single Family Residential (Low-density) 1077.00 6.98 6.79 Recreational / Open Space (High-intensity) 1230.00 7.11 6.92 High Intensity Agriculture (Dairy farm) 1349.20 7.21 7.00 Note: Modified from Brown and Vivas (submitted).

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4 Strong correlations between measured wetland attributes and the LDI would suggest a connection between surrounding land use and nested community composition (Roth et al. 1996, Brown and Vivas submitted). The relationship between any given metric and the LDI would be further strengthened through evidence of accuracy, precision, and sensitivity to changes in the LDI. High variance within metric responses for any given LDI could suggest causal mechanisms affecting community composition that were not accurately captured by the LDI, such as sources of stress not visible to GIS analyses (i.e., low relief ditch from degraded water source). An examination of metric sensitivity to LDI values would permit the development of land use thresholds for various assemblages, and furthermore may provide predictive ability for future wetland composition in areas undergoing land use change. Regional Composition Testing the effects of physiographic and/or climatic regions on wetland community composition can provide germane information on the development of ground-based biometrics. Lane (2000) delineated freshwater wetlands of Florida into four regions based on a climatic and physiographic model. Composition may differ between regions due to physiographic and climatic differences and possibly render biometrics developed in one area of the state impotent in another wetland region. Environmental Correlates and Assemblage Response Strong correlations between LDI values and community composition would suggest a causal mechanism and may assist in explaining metric relationships with the LDI. Developing an understanding of water and soil environmental parameters correlated with community composition may also provide the means for environmental managers to address specific ecosystem driving forces affecting wetland systems. In addition, strong correlations between environmental parameters and community composition can advance the knowledge of autecological relationships for diatom, macrophyte, and macroinvertebrate taxa. Background With passage of the Clean Water Act (1972, Water Pollution and Control Act), states were charged with the task to restore and maintain the chemical, physical, and biological integrity of the Nations waters, including wetlands (Water Pollution and Control Act (a), Danielson 1998). Adhering to this mandate for wetland systems required first that a working definition for wetland biological integrity be defined, and second that a method to ascertain the relative ecological state of wetlands be developed. Integrity, as it has been applied to Clean Water Act mandates and thus may be applied to Floridas wetlands, has been defined as the ability of an aquatic ecosystem to support and maintain a balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of the natural habitats of the region (Karr and Dudley 1981, pg. 60). Implicit within this definition is maintenance of ecosystem driving forces that operate at different spatial and temporal scales to maintain the resilience and pattern of the ecosystem, such as the proper

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5 Figure 1-1. Schematic of the relationship between various ecosystem influences and biological integrity. (Modified from U.S. EPA 2002a). hydrology, fire regime, and cross-scale community interactions (Figure 1-1, Peterson et al. 1998, Gunderson and Pritchard 2002). Historically, aquatic monitoring and assessment inferred ecosystem condition from either toxicity samples or ambient water quality monitoring (Karr 1981, 1993, McCarron and Frydenborg 1997). At best, these data were rudimentary in their ability to reflect more than a temporal constituent concentration within the water body. If a toxicity parameter was not specifically targeted for detection, then the water body could be

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6 considered clean yet replete with undetected toxics, metals, or physically altered such that it no longer resembled a fully functioning water body. Additionally, synergisms within water bodies from multiple impacts or spike loading events were typically not accounted for in toxicity or ambient monitoring programs (Karr 1993, Karr and Chu 1997). In the late 1980s, the United States Environmental Protection Agency realized the potential of biological criteria to assess the Nations waters and mandated states to use biological indicators to achieve the goals of the Clean Water Act (United States General Accounting Office 1988, U.S. EPA 1990, Karr 1995). A premise behind the use of biological indicators versus synoptic physical or chemical sampling to assess aquatic condition was that due to their intricate relationship with their environment, organisms in situ reflect current conditions as well as integrate cumulative impacts (Karr 1981, Hunsaker and Carpenter 1990, Karr and Chu 1999). Biological criteria and monitoring programs embraced by the U.S. EPA have since been utilized to assess lakes and streams throughout the United States (Barbour et al. 1996, Karr and Chu 1999, Barbour et al. 1999, Gerritsen et al. 2000). Only recently have efforts be undertaken to assess wetland condition using biological criteria (U.S. EPA 2002a). While other assessment methods exist, such as the hydrogeomorphic (HGM) approach (Brinson and Reinhardt 1996), or rapid, best scientific judgment approaches (e.g., Wetland Evaluation TechniqueWET, Adamus et al. 1991; Wetland Rapid Assessment ProcedureWRAP, Miller and Gunsalus 1997), the U.S. EPA has supported the use of multimetric indices of biotic integrity, or IBIs (sensu Karr 1981), to assess the condition of wetland resources (U.S. EPA 2002a). A multimetric index of biotic integrity combines measured biological attributes (or metrics) of trophic, community, and/or functional structure of various species assemblages within a wetland ecosystem into a single value. Ideal metrics are accurate, highly sensitive to change, and precise. The developed index can then be compared to either a reference condition (a suite of previously characterized wetlands located in undisturbed landscapes such as state parks and preserves) or along a gradient defined by changes in land use (Reynoldson et al. 1997, Karr and Chu 1999, Brown and Vivas submitted). The condition of the aquatic system in question is based on the relative similarity of the metric value obtained from that system vis--vis previously measured metrics in similar aquatic systems located in reference conditions. Wetland Trends Wetlands on the Florida landscape provide services to the state including water retention and flood attenuation, water quality improvement and nutrient immobilization, aquifer recharge, biogeochemical processes, wildlife habitat, and climate regulation. Historically, wetlands covered more than half of Florida, approximately 8.2 million hectares (Figure 1-2). Ditching and filling for agricultural operations, water control, and urban development over the past 200 years have substantially decreased the abundance and functional capacity (i.e., habitat, water storage) of wetlands on the Florida landscape (Dahl 1990, Kautz 1993). A historical perspective of the areal extent of marshes in Florida and concurrent increases in agricultural and urban landscapes from 1936 1987 is presented in Table 1-2. Approximately 23% of Florida (3.6 million ha) is currently classified as inland freshwater wetlands by the National Wetlands Inventory (Table 1-3),

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7 Figure 1-2. Approximate landscape extent of wetlands in Florida. Riverine, palustrine, and estuarine wetlands are indicated in black on the map. (Modified from Lane 2000). Table 1-2. Historical perspective of marsh extent (in millions of hectares) on the Florida landscape and concurrent increases in agricultural and urban land use. Land Use 1936 1949 1959 1970 1980 1987 Marsh 2.82 2.15 2.45 1.48 1.23 1.25 Agriculture 2.45 2.73 3.29 4.13 4.38 4.17 Urban 0.29 0.43 0.72 1.16 1.46 1.89 Notes : Values from 1936 are estimates. Modified from Kautz (1993). of which greater than 34% are palustrine emergent marshes, the focal wetland class for this study (Doherty et al. 2000). Wetlands are typically found in topographic lows in the landscape and tend to accumulate nutrients, metals, and toxins from up-slope sources as rainfall percolates through the wetland basin (Kirkman et al. 1998, Mitsch and Gosselink 2000). The constituents of surface and sub-surface flow, if transported into down-slope wetlands, can result in changes in processes and floral and faunal composition of receiving wetlands. Effect of Land Use Change on Wetland Systems Changes in land use within wetland watersheds (hydrologic units where precipitation falling within will move via percolation and interstitial flow or overland

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8 Table 1-3. National Wetland Inventory categories and landscape abundance of freshwater wetlands in Florida. NWI Code Wetland Class Description % Wetland Area % State Area R 2 AB Riverine, Lower Perennial, Aquatic Bed <1 <1 R 2 EM Riverine, Lower Perennial, Emergent, non-persistent <1 <1 R 3 AB Riverine, Upper Perennial, Aquatic Bed <1 <1 R 4 SB Riverine, Intermittent, Streambed <1 <1 L 1 AB Lacustrine, Limnetic, Aquatic Bed <1 <1 L 2 AB Lacustrine, Littoral, Aquatic Bed 1 <1 L 2 EM Lacustrine, Littoral, Emergent, non-persistent <1 <1 P AB 3 Palustrine, Aquatic Bed, Rooted Vascular 1 <1 P AB 4 Palustrine, Aquatic Bed, Floating Vascular <1 <1 P EM Palustrine, Emergent 34 8 P SS Palustrine, Scrub Shrub 11 3 P FO 1 Palustrine, Forested, Broad-Leaved Deciduous 6 1 P FO 2 Palustrine, Forested, Needle-Leaved Deciduous 9 2 P FO 3 Palustrine, Forested, Broad-Leaved Evergreen 5 1 P FO 4 Palustrine, Forested, Needle-Leaved Evergreen 11 2 P FO 6 Palustrine, Forested, Deciduous (mixed) <1 <1 P FO 7 Palustrine, Forested, Evergreen (mixed) 22 5 ~100 % NWI inland freshwater wetlands 23 % upland area 63 % other (estuarine) wetlands and deepwater habitats 14 State total area 100 Source : Doherty et al. (2000) flow to the wetland) can cause significant changes in wetland structure and function. Some of these changes are: 1) increased nutrient (mainly phosphorus) and chemical loading from lands shifted into production (Flaig and Reddy 1995, Bedford 1999, Daoust and Childers 1999, Maul and Cooper 2000), 2) selective herbivory and trampling from cattle (Winchester et al. 1985, Long et al. 1986, Blanch and Brock 1994, van Oene et al. 1999, Grace and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000), 3) altered hydroperiod due to ditching or filling (Anderson and Vondracek 1999, Euliss and Mushet 1999, Kirkman et al. 2000, Babbit and Tanner 2000), 4) increased sedimentation due to ditching or removing topsoil (Martin and Hartman 1987, Freeland et al. 1999, Shutler et al. 2000), 5) colonization of invasive exotic organisms (Bedford 1999), 6) destruction of wetland/upland transition zones (Winchester et al. 1985), and 7) alteration of landscape-level processes such as fire frequency (Moss 1992, Kirkman et al. 1998, Bedford 1999, Semlitsch 2000). Of particular relevance to this study are the effects of nutrient and chemical loading, selective herbivory and trampling by cattle, and ancillary effects of

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9 changes in wetland watershed land use. As such, a review of those three effects is provided below. Nutrient and Chemical Loading Nutrient and chemical loading of wetland systems alters community composition (Davis and Ogden 1994, Freeland et al. 1999, Doherty et al. 2000). Changes in land use development surrounding wetlands can create large stores of exogenous nutrients, which can act as potential sources for ecosystem-altering nutrients and chemicals. Graetz and Nair (1995), studying dairy and beef ranching lands in Okeechobee County, Florida, found mean concentrations of total phosphorus (TP) in the soil of 5300 ug/kg, approximately 40% of which was soluble reactive phosphorus readily available to organisms. Graetz and Nair (1995) also found significant differences in soil phosphorus along a gradient of grazing intensity from 79 kg/ha in natural areas (zero grazing pressure) to 4939 kg/ha in intensely grazed dairy feedlots. Rainfall and the subsequent movement of surface and sub-surface flows through phosphorus (P) laden landscapes can mobilize and deliver P into wetlands and other aquatic systems, resulting in alterations in community composition, structure, and function with potential effects on food web dynamics (Winchester et al. 1985, Moss 1992, Flaig and Reddy 1995, Daoust and Childers 1999, Freeland et al. 1999, Maul and Cooper 2000). For instance, Freeland et al. (1999) reported that periphyton assimilating increased exogenous P caused shifts in macrophyte species composition (Freeland et al. 1999). In studies in the Everglades (Davis and Ogden 1994), higher plants, such as Typha spp. tolerate nutrient loading and out-compete other less tolerant macrophytes, such as Cladium jamaicense. Likewise, floating plants Lemna spp., which grow readily in nutrient enriched waters, can become so prolific to create oxygen stress for aquatic communities in the water column (e.g., fish, macroinvertebrates, microbes, macrophytes) through shading of photosynthetic, oxygen-producing algae and other macrophytes (Dierberg and Brezonik 1984). The direct nutrient loading of wetland systems can also occur as a result of land use development intensity in the surrounding wetland watershed (Graetz and Nair 1995). Tanner et al. (1984) tracked cattle movements on a South Florida rangeland and found that cattle spent the majority of time in herbaceous wetlands (fall months) or upland/herbaceous wetland ecotones (summer months). They also reported no significant difference in cattle defecation/urination location among herbaceous wetlands, upland/herbaceous wetland ecotones, canal banks, or flat woods, suggesting near constant landscape loading of available nutrients. Several authors suggested encouraging cattle to graze in marshes during summer as Panicum spp. and Andropogon spp. typically have the highest crude protein levels of any available forage during that period (Tanner et al. 1984, Kalmbacher et al. 1984, Long et al. 1986). Direct grazing within the marsh could lead to higher concentrations of P and N as there would be no biochemical degradation of the nutrient constituents in the process of overland or interstitial flow before their deposition in the wetland. Reddy et al. (1996) reported that the uptake of available phosphorous by wetland vegetation was estimated at 28%-70% of the available P transported to the wetland. This P uptake is dependent upon plant growth rate, growth structure (woody or herbaceous material), P concentration in the soil, and the physical and chemical characteristics of the soil (Agami et al. 1990, Flaig and Reddy 1995). However, aquatic plant storage of P is a

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10 temporary phenomenon as approximately 80% of the nutrients are released to the water column by decaying vegetation (Agami et al. 1990, Reddy et al. 1996), suggesting that wetland plants are nutrient storages, and not sinks. Agrochemical application within a wetland basin may also affect wetland processes and functions. Movement of pesticides, herbicides, and agrochemical fertilizers into wetlands is generally related to either direct or drift application or absorption of the chemical onto soil particles, which are subsequently mobilized into the wetlands during rainfall events (Anderson and Vondracek 1999, Freeland et al. 1999). Martin and Hartman (1987) reported influx of sediments to wetlands in cultivated landscapes at twice the rate from uncultivated landscapes. Euliss and Mushet (1999) noted that chemicals and chemical-laden soil particles transported from uplands into wetlands could be toxic to zooplankton and reduce foraging and food assimilation rates of aquatic invertebrates. Semlitsch (2000) and Shutler et al. (2000) reported impacts to non-target wetland organisms from pesticides. Several authors found changes in wetland community assemblages due to agrochemical loading (Anderson and Vondracek 1999, Bedford 1999, Kolozsvary and Swihart 1999, Maul and Cooper 1999). Selective Herbivory and Trampling While low-density grazing in rangeland (native forage) maintains species richness and mimics natural processes, such as foraging by deer or other herbivores (Blanch and Brock 1994), high-density herbivory by cattle can alter native upland and wetland vegetation communities and have long-term successional consequences (Dobkin et al. 1998). Tanner et al. (1984) and others (Kalmbacher et al. 1984, Long et al. 1986) noted that cattle selectively graze wetland plants on the landscape, thus altering community composition. Van Oene et al. (1999) found that grazing prevented dominance of tall wetland species of grasses, shrubs, and trees, as they were selectively harvested by cattle, which led to structural and functional changes in the wetland, such as decreased wildlife habitat. Vulink et al. (2000) reported that wetland vegetation community changes occurred due to modifications of light availability as livestock consumed the shading vegetation. Additionally, Vulink et al. (2000) found that grazing substantially impacted plants with apical meristems within the reach of livestock, which altered community composition and structure. Reader and Craft (1999) and Vulink et al. (2000) demonstrated that the trampling and physical destruction of wetland vegetation by livestock directly altered community structure and composition. In addition, several authors have noted increased fluxes of nutrient and sediment flow into wetlands through destruction of vegetative buffers, such as the fringing Hypericum spp. or Serenoa repens (Winchester et al. 1985, Blanch and Brock 1994, Vulink et al. 2000). Ancillary Impacts from Landscape Modification Changes in landscape level processes as a result of modification of wetland watershed land use have effects on wetland composition and function (Bedford 1999). Wetlands in cultivated and urban landscapes have highly variable water-level fluxes compared to wetlands in non-developed landscapes, which can affect soil anoxia and wildlife habitat (Rushton and Carr 1993, Tilley and Brown 1998, Euliss and Mushnet

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11 1999). In order to facilitate movement of water off the landscape, wetlands in agricultural land use matrices are often inter-connected by ditches that can decrease the hydroperiod of all wetlands if attached to an outflow (such as a canal or stream), which can provide conditions for colonization by upland taxa. If not connected to an outflow, an increased hydroperiod may result from ditching as water is rapidly shunted off the landscape and into the wetland, instead of moving slowly via overland and sub-surface flows. In some cases, canals and streams can back-flood connected marshes, altering hydrology and possibly allowing marsh access to stream/canal species (such as predatory fish), with potential impacts to wetland fauna that require fish-free habitat for breeding (Babbit and Tanner 2000). Florida ecosystems have evolved with fire as a driving force to the extent that some organisms require fire for reproductive success (Ewel 1990). In wetland watersheds used for agricultural purposes, fire is typically excluded (Kirkman et al. 1998). Whereas the fire season in Florida is related to lightning strikes, which are highest in summer, prescribed burns currently occur in spring (Kirkman et al. 1998). This alteration to the timing and extent of natural processes may affect reproduction and foraging success of wetland organisms, which have evolved with seasonal fire. Wetland diversity across the landscape (i.e., the number of wetlands in a given area) is also affected through alterations of wetland watershed land use that include ditching, draining, and filling (Kirkman et al. 1996, Kirkman et al. 1998, Kolozsvary and Swihart 1999). Whereas depressional marshes may be scattered on the landscape and provide metapopulation dynamics (i.e., increased gene flow) of organisms between wetlands, loss of wetlands on the landscape decreases landscape diversity and can cause increased crowding and subsequent decreases in population as organisms compete for decreasing resources and space (Pearlstine et al. 1997). Wetland Assemblages and Biological Assessment Various assemblages (i.e., macrophytes, macroinvertebrates, microbes, birds, etc.) within an ecosystem have been used as biological indicators for aquatic systems, including wetlands (U.S. EPA 2002b-e). Appropriate indicator assemblages are those that measurably respond to the gradient defined along the abscissa (i.e., land use change, total phosphorus, etc.), and ideal indicator assemblages are also composed of organisms relatively easy to identify, abundant, and available for sampling or mensuration for an extended period (Karr and Chu 1999). Appropriate metrics derived from indicator assemblages are accurate, exhibit high precision, and are likewise sensitive to increases in change along the abscissa (Karr and Chu 1999). As most aquatic assemblages respond to alterations occurring at both large (i.e., abundance of croplands in a wetland basin) and small scales (i.e., pH alterations; Allan and Johnson 1997), determining the particular stressor or component of anthropogenic disturbance that an aquatic assemblage responds to is often difficult. Various scales of temporal response further compound the identification of stressors. Incorporating multiple assemblages (i.e., macrophytes and macroinvertebrates) can assist in determining sources of perturbations, especially if the autecological requirements of the selected assemblages are well established (e.g., Reed 1986, Lenat 1993, Van Dam et al. 1994). Characterizing various edaphic, hydrologic or landscape variables and identifying trends can also assist in elucidating sources of wetland perturbation.

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12 By including multiple assemblages in the initial development of biological indicators, the likelihood increases that a suite of potential metrics can be identified that are strongly correlated with the abscissa. In addition, sampling multiple assemblages permits an examination of the temporal responses of wetland organisms to perturbations, which, depending on the speed of community change, has the potential to alter conclusions. For instance, diatoms respond extremely rapidly to environmental conditions, on the order of a few hours to a few days, macroinvertebrates respond slower (with turnover times ranging from hours to years), and macrophytes generally react the slowest to alterations (responses occur over days to decades). Substantial information also exists on the natural history and autecological requirements of diatoms (Bahls 1993, Van Dam et al. 1994), macroinvertebrates (Hilsenhoff 1988, Lenat 1993, Barbour et al. 1999), and macrophytes (Reed 1997, Taft et al. 1997). Project Overview In this study, diatoms, macrophytes, and macroinvertebrates were sampled from isolated depressional herbaceous wetlands located within human-modified land use matrices throughout peninsular Florida. Compositional differences among sampled assemblages driven by latitudinal or physiographical regions were examined to ascertain the importance in developing regionally specific biological assessment metrics. Analysis of water and soil physical-chemical parameters and land use identified variables affecting the composition and structure of sampled biotic assemblages in the study wetlands. GIS analyses assigned empirically derived values to each wetland based on the abundance (% area) and land use intensity of developed lands within a 100m boundary around each wetland site. Compositional and functional attributes, or metrics, that correlated with the empirically derived GIS land use measure were identified from each assemblage and combined into three unique assemblage-specific field based indices of biological integrity. In addition, the ability of the GIS land use measure to accurately and precisely reflect the environmental conditions on-site was assessed through examination of the variance within metric responses. Conclusions on the use of the wetland organisms and GIS based measures of relative wetland condition and suggestions for improvements were made.

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CHAPTER 2 DIATOMS AS BIOINDICATORS Introduction Diatoms (Class Bacillariophyceae) are important components of wetlands and other aquatic systems and provide several functions including: 1) primary production, 2) nutrient and biogeochemical cycling, 3) oxygen cycling, and 4) water chemistry regulation (Rader and Richardson 1992, Stevenson et al. 1996, Goldsborough and Robinson 1996, McCormick et al. 1997, Doherty et al. 2000, U.S. EPA 2002e). Stream and lake researchers, and more recently wetland researchers, noted the response of diatoms to land use changes, increases in nutrient loading, alterations in pH, and changes in specific conductivity (Lange-Bertalot 1979, Whitmore 1989, Bahls 1993, Van Dam et al. 1994, Pan and Stevenson 1996, McCormick and Cairns 1997, Danielson 1998, Barbour et al. 1999, Stevenson 2001, U.S. EPA 2002e). The U.S. EPA (2002e, p.2) reports diatoms as amongst the most widely used indicators of biological integrity and physico-chemical conditions in aquatic ecosystems. Changes in diatom taxonomic composition correlated with changes in physical-chemical parameters have been noted in the Florida Everglades (Raschke 1993), prairie potholes (Adamus 1996), riverine bottomland wetlands, marshes, swamps, and bogs (Pan and Stevenson 1996, Stevenson et al. 1999), streams (Bahls 1993, McCormick and Cairns 1997, Barbour et al. 1999, Winter and Duthie 2000, Munn et al. 2002), large rivers (Fore and Grafe 2002), lakes in Florida (Whitmore 1989), and other systems (see McCormick and Cairns 1997). The diatom community response has also been examined for heavy metals (Charles et al. 1996), pH (Pan and Stevenson 1996), saprobity levels (Lange-Bertalot 1979), nutrient and physical-chemical parameters (Van Dam et al. 1994), and other perturbations (see reviews in Stoermer and Smol 1999). In this chapter, diatoms community attributes were correlated with the Landscape Development Intensity index (LDI, Brown and Vivas submitted). Strongly correlated attributes (or metrics) identified through regression with the LDI were scaled so disparate metrics could be combined. The scaled metrics were summed to create the Diatom Index of Wetland Condition (DIWC). Analysis of measured abiotic and biotic environmental data identified parameters strongly correlated with diatom composition to advance synecological understanding on driving forces affecting the distribution and composition of wetland diatoms. Variance within diatom metrics was examined to explore relationships between landscape scale measurements and local, wetland specific responses. 13

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14 Methods Site Selection and Agricultural Development Gradient Seventy isolated depressional marshes throughout peninsular Florida were sampled a single time in landscape matrices with varying amounts of human-modified land uses during summer 1999 (n=35) and 2000 (n=35). Using best scientific judgment, sites were initially stratified into reference (no obvious human modified landscapes within >100m), and impaired (obvious human landscape modification within 100m) categories. The Landscape Development Intensity index (LDI, Brown and Vivas submitted) was later independently calculated through GIS analyses for each site by identifying varying land use abundance within each wetland basin (100m around wetland edge). LDI scores of <2.0 were characteristic of minimally disturbed (reference) wetlands and allowed the reference condition to incorporate small disturbances such as low density park paths. Slightly less than half the sites (33) were defined as reference sites, which were generally located in state and federal parks, preserves, and state forests. The remaining 37 wetlands were located within agricultural landscape matrices and were considered impaired sites (LDI > 2.0). Twenty-seven impaired sites were located in cattle ranches of varying stocking densities, 7 were located in truck crops (tomatoes, peppers), 2 were in citrus groves, and 1 was sampled in a silvicultural forest. All sites selected were hydrated when sampled. Site coordinates and LDI score for each sampled wetland may be found in Appendix A. As isolated depressional marshes are not uniformly distributed throughout Florida, the sites were likewise generally located in counties with the proper wetland hydrology and geomorphic setting (Lane 2000, Figure 2-1). The sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions (after Lane 2000). A compositional test, the multiple response permutation procedures (MRPP) available in PCOrd (MjM Software, Gleneden Beach, Oregon, version 4.10) was used to identify the ecological significance of the modeled wetland regions for diatom distribution. MRPP (Mielke 1984, Mielke and Berry 2000) provides a rank-based non-parametric multivariate test of the difference between n samples based on a distance matrix calculated between sites in ordinate space. The Sorensen distance measure was used for this test, as it is an effective distance measure for use in community data (McCune and Grace 2002). MRPP returns a statistic, A, which is the chance-corrected within group agreement (McCune et al. 2002). Zero values for A indicate that heterogeneity within groups equals that expected by chance, and values of 1.0 indicate perfect agreement between groups (McCune and Grace 2002, McCune et al. 2002). MRPP also returns a T value test statistic. The more negative the test statistic T the greater the separation between test groups (McCune and Grace 2002). The probability value, p, is based on the calculated possibility of finding differences as or more extreme than the observed group differences (Lesica et al. 1991). MRPP was calculated to compare composition across all regions (e.g., South versus Central versus North), and was also iteratively calculated to compare between individual wetland regions (e.g., South region composition versus North region composition). Significance for this test, as for all tests unless otherwise noted, was set at the conventional significance of 0.05.

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15 Figure 2-1. Algal study site locations and encounter probability for isolated depressional wetlands. Counties shaded darker have a higher density of isolated depressional wetlands <1ha (from U.S. Fish and Wildlife Service 2000). Field Data Collection, Sample Preparation and Laboratory Procedures Diatoms Diatom, soil, and water physical-chemical samples were taken at each wetland, and care was exercised to ensure minimal cross-sample contamination of diatom communities. Three different types of diatoms were sampled: benthic, epiphytic, and phytoplanktonic. Benthic diatoms were collected from wetland sediments. Epiphyton was collected from submerged portions of macrophytes. Phytoplankton was sampled from the water column. Benthic diatoms were sampled throughout hydrated areas of each wetland. Ten samples were proportionally distributed in a randomized fashion among the vegetation zones and a composite sample fixed. For each sample, a hollow cylinder with a diameter of approximately 10 cm was placed on the substrate, and a bulb pipette was used to

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16 mobilize the material at the water/sediment interface. A 10mL sample was taken with the bulb pipette and placed in a composite sampling jar. The total sampled volume in the composite sample was approximately 100mL. Epiphytic diatoms were sampled at ten locations in the wetland by snipping representative submersed and floating vegetation and placing the samples into a 3.8L Ziploc bag. Approximately 0.5L of wetland water was added and the bag gently kneaded to mobilize the epiphyton. A 10mL sample was obtained using a bulb pipette rinsed with wetland water and placed into a composite sampling jar. Total volume of the composite sample was approximately 100mL. Phytoplanktonic diatoms were sampled at ten different locations through the wetland in areas of at least 10cm of water. A sealed 100mL cylinder was placed under the surface of the water, the cap was removed and the cylinder filled. The cap was replaced underwater, the cylinder removed, and a composite sample taken. The total volume of the composite phytoplankton sample was approximately 1L. Once all ten samples were taken of each diatom type, the composite samples were preserved using M3 (APHA 1995): 5mL for benthic and epiphytic diatoms, and 20mL for phytoplanktonic diatoms. All samples were homogenized prior to subsampling for identification. To clean organic matter from the diatom frustules for identification the subsamples were digested following Hasle and Fryxell (1970). The samples were rinsed using distilled water and mounted on microscope slides using Naphrax (Northern Biological Supplies Limited, Ipswich, England). Following FDEP procedures (SOP #AB-03.1, available at www.dep.state.fl.us/labs/sop/), 250 diatom valves were then counted along microscope transects and identified to the lowest taxonomic level possible (usually species). For samples that were sparse (i.e., phytoplankton), sampling effort was capped at 1 hour. Diatom data were combined and entered into the FDEP database for further analysis. Soil and water physical-chemical sampling and analysis To relate the distribution of wetland diatoms to environmental parameters, soil and water physical and chemical parameters were obtained at each site and determined in the laboratory as described in Appendix B. The following soil chemistry parameters were determined in the lab: total phosphorous (soil TP, mg/kg), percent total nitrogen (%TN), percent total carbon (%TC), percent organic matter (%OM), and pH. The following water chemistry parameters were obtained from samples collected from each site: color (PCU), specific conductivity (umhos/cm), turbidity (NTU), pH, ammonia (mg/L), nitrate/nitrite (mg/L), total Kjeldahl Nitrogen (TKN, mg/L), and total Phosphorus (water TP, mg/L). In the event that the constituent measured was below detection levels, the value was entered for analysis was half of the lowest detectable level. See Appendix B for additional information. Data Analyses Summary statistics Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity were calculated for each site and diatom type and provided information on the distribution of species vis--vis land use. Richness is a measure of the total number of taxa found in a sample (Whittaker 1972). Evenness is a measure of distribution among

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17 taxa at a site. Shannon diversity and Simpson diversity indices measure the diversity of a site based on the abundance and total number of taxa (Brower et al. 1990). Two additional diversity indices were also calculated from the diatom data and compared between LDI classes of <2.0 or 2.0: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Gamma diversity, or species richness over a range of habitat (i.e., reference conditions, Whittaker 1972), was calculated as the total richness of a class of samples (LDI classes of <2.0 or 2.0). Beta diversity incorporates gamma diversity and indicates compositional variation in a sample. Beta diversity was calculated as gamma diversity divided by the average richness at a site (McCune and Grace 2002). Diatoms-compositional tests The Percent Similarity Index (PSI, Wolda 1981) and MRPP were used to assess the fidelity of habitat types for each of the three types of diatoms sampled. PSI (Wolda 1981) provides an index of overlap between diatom types and was calculated as PSI = [ (minimum pij, ) ] 100 where PSI is the percentage similarity between diatom types j and k (for instance benthic and epiphytic diatoms), p ij is the percentage of species i in diatom type j, and p ik is the percentage of species i in diatom type k. PSI was calculated to compare local, within-site diatom community composition (i.e., benthic, epiphytic, and phytoplanktonic diatom types from a single site) and for a global comparison (i.e., the abundance of all benthic, epiphytic, and phytoplanktonic diatoms identified were compared across all sites). While no significance was calculated, PSI values greater than 0.70 are generally considered highly similar (Matthews et al. 1988). MRPP, using the Sorensen distance measure, was also used to identify global group differences and provided a measure of the significance of the difference. Differences in summary statistics, such as evenness and diversity indices, were examined between landscape development classes (i.e., LDI <2.0 and LDI 2.0) with the Mann-Whitney U-test, and among diatom types using Tukeys Honest Significant Difference (HSD) test (Zar 1999). The Mann-Whitney U-test and Tukeys HSD test are non-parametric comparison procedures that test for equal medians between groups. The Mann-Whitney U-test was performed using two classes (i.e., LDI <2.0 and LDI 2.0) and Tukeys HSD was calculated for tests of more than two classes (i.e., South, Central, and North regions). Diatoms community composition and correlation with soil and water parameters The following soil variables were arcsine square root transformed to decrease measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Log 10 transformations were completed on soil TP, color, specific conductivity, turbidity, ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity among environmental variables, described as strong correlations between independent variables (Zar 1999), was tested using two multicolinearity diagnostic statistics available through linear regression analysis in SAS, the variance inflation factor and tolerance (SAS 1990). While no formal cutoff value exists, a conservative measure was used, and variables were considered collinear if they had a variance inflation factor (VIF) of 5.0 and a tolerance of <0.20 (ter Braak 1987, SAS 1990). The Mann-Whitney U-test was

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18 used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). The relationship between measured environmental values (including LDI score) and species composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS; Kruskal 1964, Mather 1976), both available in PCOrd. A Mantel test, which evaluates the correlation between distance measures of two matrices (McCune and Grace 2002), was computed to test the null hypothesis of no relationship between the arcsine square root transformed diatom species abundance and measured environmental parameters. The Sorensen distance measure was used for the abundance matrix, and the Euclidean distance measure was utilized for the second matrix due to the negative values of the log-transformed environmental parameters. The significance of the hypothesis of no relationship between the matrices was tested with a Monte Carlo simulation of 9999 randomizations. The standardized Mantel statistic (Mantels r), a t statistic, and the significance of the relationship were calculated for each test. NMDS was used to ordinate the samples based on arcsine square root transformed species abundances and to correlate environmental parameters to sites in ordination space. NMDS is an ordination method well suited for data that are non-normal, as it uses ranked distances to avoid the assumption of linear relationships among variables (Waichler et al. 2001, McCune and Grace 2002). To decrease chances of finding local minima, twenty-five runs with random seeds were made using six-dimensional starting space and the Sorensen distance measure. The instability criterion was set at 0.00001, the maximum number of iterations to find a stable solution was set to 400, 50 runs were conducted with real data, and 50 randomized runs were completed to calculate a p-value of the solution. The number of dimensions that accurately described the data set was obtained as a measure of the stress (or fit) of the ordination. A final run was made with the starting seed that provided the best final fit. A two-dimension solution was selected for benthic and epiphytic diatoms, and a three-dimension solution was selected for phytoplanktonic diatoms, as increased dimensionality only marginally improved the fit. The final NMDS solution was repeated several times to ensure stability of the solution. Pearsons correlation coefficients between site scores and environmental parameters, including LDI score, were calculated. A bi-plot of environmental parameters with Pearson correlations to site scores >0.30 was constructed. Metric Development Diatom metrics were developed using literature sources and iterative tests (i.e., Bahls 1993, Van Dam et al. 1994, McCormick and Cairns 1997, Stevenson 2001, U.S. EPA 2002e, Fore and Grafe 2002, Fore 2003) and correlated using Spearmans r with the Landscape Development Intensity index (Brown and Vivas submitted). Final metrics were those with significance values of <0.05 and Spearman correlations of |0.50| with the LDI. Final metrics were also tested for bivariate correlation using Spearmans r. Metrics with bivariate correlations (r |0.80|) reduced to one metric based on the strength of the correlations with the LDI. All metric evaluation were conducted with SAS (SAS Institute, Cary N.C., version 8.02).

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19 Sensitive and tolerant taxa The use of Indicator Species Analysis (ISA) as a method of identifying species with specificity (i.e., exclusive to a given group) and fidelity (i.e., always present within a given group) to ecological conditions is growing in ecological literature (Chytry et al. 2002). The randomization test and the corresponding p-value provide a statistically rigorous and defensible presentation of identified species (McCune and Grace 2002). Indicator Species Analysis (Dufrene and Legendre 1997) with non-transformed abundance data identified species with significant association to LDI classification of impaired or reference conditions. ISA, available in PCOrd, contrasts the fidelity of species between a priori defined groups (in this case, sites with LDI<2.0 or LDI2.0) using the algorithms of Dufrene and Legendre (1997). First, the mean abundance (xkj) of species j in group k was calculated by examining the proportional abundance of species j in group k relative to species j in all groups. Second, the relative abundance (RAkj) of species j in group k was calculated by dividing the mean abundance (xkj) by abundance in each group. The proportional frequency (RFkj) of species j in group k was then calculated by summing the total occurrences (presence) of species j in group k and dividing by the number of sample units in group k. The two proportions (RAkj and RFkj) combined in the following equation that solves for IndValkj, the indicator value of species j for group k: IndValkj = 100 (RAkj RFkj) As RA and RF are multiplied, both must be high for IndVal to be high. Additional descriptions of ISA may be found in McCune and Grace (2002). A Monte Carlo test with 10,000 permutations and p-value of 0.10 was used to test significance of the indicator species for a particular group k (i.e., sites with LDI<2.0 or LDI2.0). The abundance of species with significant specificity and fidelity to reference or impaired conditions (i.e., sensitive and tolerant taxa) was assessed for each site and correlated with the LDI. Autecological metrics An ecological indicator value based on published tolerances to particular physical/chemical condition for each diatom species identified was determined using a coded checklist of autecological guilds (Appendix C; Bahls 1993, Van Dam et al. 1994). Bahls (1993) categorized diatoms in Montana streams as very tolerant, tolerant, or sensitive to pollution based on initial classifications of Lange-Bertalot (1979) and Lowe (1974). Van Dam et al. (1994) provided a list of attributes describing the tolerance of European diatoms to varying pH, salinity, dissolved oxygen content, nutrient enrichment, and saprobic conditions, which Fore (2003) and Fore and Grafe (2002) used to develop indicators for streams in Mid-Atlantic states and large rivers in Idaho, respectively. As agricultural operations can increase soil alkalinity through fertilizer application, and evaporative salts from irrigation can be transported into wetlands through precipitation (Leland and Porter 2000, Fore and Grafe 2002), it was expected that alkaliphilous diatoms and diatoms that tolerate higher salinity would increase with increasing agricultural operations (and hence LDI scores). Agrochemical fertilizers, as well as direct application of cattle wastes on the landscape, increase nutrient loading into aquatic systems (Flaig and Reddy 1995, Reddy et al. 1996, Reddy et al. 1998). It was

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20 therefore anticipated that diatoms tolerant of higher nutrient levels and saprobity (or biodegradable organic matter and low dissolved oxygen levels), as well as higher trophic state (driven by high levels of inorganic nutrients), would increase with increasing LDI scores. In contrast, acidophilous diatoms and those indicative of low salinity would be expected to dominate wetlands in reference conditions. Similarly, diatoms sensitive to nutrient enrichment, low dissolved oxygen and saprobic conditions would be expected to decrease with increasing LDI scores. For each of the autecological guilds identified by Van Dam et al. (1994) and the pollution tolerance value of Bahls (1993), diatoms were coded (guilds with between 3 and 7 categories) to denote tolerance to environmental variables. The ordinal trophic classes of Van Dam et al. (1994), oligotraphentic and oligo-mesotraphentic, were combined into a single class as these diatoms indicative of low-trophic status were expected to respond in a similar fashion to increasing LDI scores. The abundance of diatoms for each class was determined for each autecological index. The abundance of diatoms for each class was then correlated (Spearmans r) with the LDI score for each site. Bivariate correlations between taxa guild values were assessed using Spearmans r, and a tolerance of r |0.80| was arbitrarily established to delimit highly correlated guild values. Guilds having lower correlations with the LDI were parsed. The median abundances for potential metrics based on autecological indices between LDI classes were tested with the Mann-Whitney U-test. Constructing the Multimetric Index To complete development of the multimetric index of wetland condition based on diatom metrics, it was necessary to scale the metrics to a uniform ranking so they could be added together and a single value representative of wetland condition be obtained (Karr and Chu 1999). In this study, metrics were scored into four categories: 0,3,7, and 10, based on quartile scores for the 95th percentile of each metric (Mack 2001). A hypothetical example of this scoring is presented in Figure 2-2. Using the 95 th percentile decreases the influence of outliers on metric scoring (Mack 2001). For measures that decreased in abundance with increasing LDI scores, the lowest quartile was given a 0, the next quartile a 3, the third a 7, and the highest and last quartile a 10. This scale was inverted for measures that increased in abundance with increasing LDI scores. Results Wetland Diatom Composition Seventy herbaceous depressional wetlands throughout peninsular Florida with standing water were sampled in 1999 and 2000. Twenty-three were sampled in the South region, thirty in the Central region, and seventeen in the North region. Based on the dominant land use around the wetland, twelve sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. Two hundred ninety-nine diatom taxa from the combined three diatom types were identified. Seventy benthic and sixty-nine epiphytic and phytoplanktonic samples were enumerated and identified, as data were incomplete for two sites: (IFASII epiphyton and CMWRef phytoplankton). The average count of frustules for benthic diatoms was

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21 4321 6050403020100 LDI Proposed Metric Score: 10Score: 7Score: 3Score: 0 Figure 2-2. Hypothesized example of metric scoring using the 95 th percentile of the dataset. The scoring would switch for metrics that increase with increasing LDI scores. 261.6 (+/19.7) and for epiphytic diatoms, 265.5 (+/31.9). The sparse nature of the phytoplanktonic diatoms resulted in an average of 67.9 diatoms identified in each sample and a high standard deviation of 57.7. One hundred ninety-five diatom taxa were identified in the benthic samples, one hundred seventy-four in the epiphytic samples, and two hundred forty-four in the phytoplankton samples. Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity were calculated for each site (Brower et al. 1990). Summary statistics are presented in Tables 2-1 to 2-3. Tukeys HSD results (Table 2-4) indicated that richness was significantly higher in phytoplankton and benthic diatoms than in epiphyton. No significant differences were found for measures of evenness and Simpsons diversity measure, but phytoplankton and benthic diatoms, and benthic diatoms and epiphytic diatoms, did not significantly differ for Shannon diversity values (see Table 2-4). No significant differences were found for measures of richness, evenness, Shannon diversity, or Simpsons diversity between impaired and reference sites for all diatom types (Mann-Whitney U-test, Table 2-5). Alpha (richness), beta, and gamma diversity values for each diatom type and wetland condition are given in Table 2-6. Beta and gamma diversity were higher in phytoplankton samples than at the other samples despite the low numbers of diatoms identified at each site. Beta diversity was higher in impaired sites for epiphytic and phytoplanktonic diatoms, while gamma diversity in impaired sites was higher than in reference sites for all three diatom types sampled.

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22 Table 2-1. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for benthic diatoms. Name S E H D` Name S E H D` Audubon 14 0.824 2.176 0.8380 Immokalee 23 0.879 2.756 0.9206 BearScat 32 0.884 3.064 0.9336 IRBlueCypress 21 0.627 1.908 0.6833 BigCow 33 0.866 3.028 0.9296 IRCanal 12 0.675 1.676 0.6772 BRSebastian 14 0.791 2.088 0.8246 IROJ 28 0.857 2.857 0.9191 CabPatch 10 0.705 1.623 0.6885 JD6 14 0.818 2.159 0.8373 Caravelle 22 0.884 2.731 0.9194 KellyPark 11 0.847 2.031 0.8318 Chuluota 23 0.817 2.561 0.8862 LCork 26 0.847 2.759 0.8962 CLBayard 13 0.752 1.928 0.8053 LEGo 17 0.864 2.449 0.8913 CLCove 19 0.805 2.370 0.8694 LESuwan 20 0.861 2.579 0.9081 CMWPast 24 0.820 2.606 0.8885 LLeeCounty 21 0.828 2.522 0.8769 CMWRef 20 0.760 2.277 0.8359 MALudy 16 0.712 1.973 0.7781 COBurgle 21 0.827 2.518 0.8887 MASpray 15 0.643 1.741 0.7564 COHole 22 0.848 2.622 0.8872 McArthur 23 0.666 2.089 0.7236 Crew 24 0.799 2.540 0.8654 MNElmer 16 0.725 2.009 0.7628 Deerfly 21 0.899 2.737 0.9171 MNOcala 14 0.862 2.275 0.8769 DEMelon 18 0.661 1.912 0.7495 MRPepper 26 0.813 2.649 0.8819 Garber 18 0.734 2.122 0.8230 Myakka 14 0.827 2.182 0.8504 GbarE 18 0.751 2.171 0.7914 OKCara 17 0.861 2.439 0.8854 GLDonut 28 0.797 2.654 0.8967 OKKISS 14 0.842 2.221 0.8476 GLPont 26 0.797 2.597 0.8624 OKPast 22 0.807 2.493 0.8791 Goethe 14 0.820 2.165 0.8536 PacificTom 17 0.825 2.338 0.8697 GreenSwamp 23 0.893 2.800 0.9212 PallMar 14 0.717 1.892 0.7778 HagueI 18 0.812 2.346 0.8759 PBCorbett 11 0.745 1.787 0.7686 HagueII 33 0.894 3.126 0.9424 PBEnjay 10 0.738 1.698 0.7783 HalfMoon 16 0.827 2.294 0.8711 Penner 13 0.483 1.240 0.4755 HARare 19 0.766 2.255 0.8575 POWales 10 0.757 1.744 0.7956 HEBad 9 0.796 1.748 0.7885 POWeowak 19 0.816 2.404 0.8797 HEL2 16 0.768 2.129 0.8178 RiceCreek 20 0.895 2.680 0.9178 HEOkay 20 0.869 2.605 0.8998 SandhillCrane 11 0.661 1.585 0.6512 HighPast 23 0.828 2.597 0.8884 SANorthMya 11 0.815 1.954 0.8178 HighRef 22 0.882 2.726 0.9160 SAOscer 12 0.733 1.820 0.7762 HillsRef 23 0.914 2.865 0.9322 Savannas 16 0.811 2.250 0.8412 HuntCamp 30 0.879 2.989 0.9298 STCow 14 0.672 1.773 0.7398 IFASI 15 0.802 2.173 0.8431 UNHealthy 19 0.846 2.491 0.8915 IFASII 12 0.791 1.966 0.8210 Weikiva 9 0.481 1.057 0.4270

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23 Table 2-2. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for epiphytic diatoms. Name S E H D` Name S E H D` Audubon 14 0.736 1.943 0.7716 IRBlueCypress 16 0.673 1.865 0.7372 BearScat 19 0.858 2.526 0.8888 IRCanal 20 0.753 2.255 0.8312 BigCow 27 0.862 2.841 0.9220 IROJ 18 0.813 2.350 0.8597 BRSebastian 10 0.784 1.806 0.7785 JD6 14 0.754 1.989 0.8054 CabPatch 33 0.916 3.201 0.9493 KellyPark 11 0.733 1.758 0.7610 Caravelle 16 0.833 2.309 0.8732 LCork 13 0.716 1.836 0.7423 Chuluota 12 0.756 1.878 0.7772 LEgo 11 0.920 2.206 0.8808 CLBayard 7 0.713 1.388 0.7151 LESuwan 20 0.883 2.645 0.9126 CLCove 9 0.760 1.669 0.7463 LLeeCounty 20 0.870 2.607 0.9034 CMWPast 12 0.756 1.879 0.7944 MALudy 16 0.705 1.954 0.7649 CMWRef 18 0.846 2.445 0.8841 MASpray 8 0.662 1.376 0.7101 COBurgle 15 0.706 1.912 0.7493 McArthur 14 0.602 1.589 0.6392 COHole 12 0.759 1.885 0.8026 MNElmer 13 0.769 1.973 0.8199 CREW 21 0.888 2.705 0.9168 MNOcala 14 0.817 2.156 0.8464 Deerfly 16 0.792 2.197 0.8366 MRPepper 28 0.834 2.778 0.8810 DEMelon 23 0.802 2.516 0.8770 Myakka 16 0.802 2.224 0.8477 Garber 16 0.642 1.779 0.6725 OKCara 18 0.828 2.394 0.8739 GbarE 12 0.437 1.086 0.4106 OKKiss 13 0.736 1.889 0.7722 GLdonut 15 0.774 2.097 0.8129 OKPast 21 0.709 2.159 0.7994 GLpont 14 0.866 2.287 0.8775 PacificTom 19 0.837 2.465 0.8755 Goethe 14 0.798 2.106 0.8367 PallMar 10 0.818 1.884 0.8183 GreenSwamp 18 0.895 2.588 0.9078 PBCorbet 20 0.786 2.355 0.8742 HagueI 15 0.750 2.031 0.8071 PBenjay 11 0.815 1.955 0.8175 HagueII 28 0.902 3.006 0.9359 Penner 9 0.507 1.114 0.4502 HalfMoon 13 0.826 2.118 0.8475 POWales 7 0.889 1.730 0.8078 HARare 14 0.853 2.250 0.8660 POWeowak 16 0.847 2.349 0.8795 HEBad 7 0.793 1.544 0.7242 RiceCreek 16 0.766 2.123 0.8107 HEL2 18 0.678 1.960 0.7955 SandhillCrane 25 0.821 2.642 0.8872 HEOkay 19 0.818 2.409 0.8620 SANorthmya 17 0.796 2.257 0.8646 HighPast 17 0.806 2.285 0.8490 SAOscer 13 0.583 1.494 0.6955 HighRef 19 0.767 2.258 0.8243 Savannas 12 0.633 1.574 0.7035 HillsRef 23 0.788 2.471 0.8733 STCow 18 0.758 2.191 0.8224 HuntCamp 12 0.747 1.856 0.7757 UNHealthy 12 0.794 1.973 0.8097 IFASI 15 0.752 2.036 0.8096 Weikiva 11 0.573 1.373 0.5789 Immokalee 12 0.880 2.188 0.8668

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24 Table 2-3. Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for phytoplanktonic diatoms. Name S E H D` Name S E H D` Audubon 18 0.739 2.137 0.8197 IRBlueCypress 22 0.864 2.671 0.9004 BearScat 27 0.874 2.881 0.9152 IRCanal 12 0.749 1.862 0.7750 BigCow 36 0.864 3.096 0.9344 IROJ 24 0.868 2.760 0.8998 BRSebastian 14 0.712 1.879 0.7611 JD6 14 0.728 1.921 0.7687 CabPatch 35 0.925 3.290 0.9541 KellyPark 13 0.446 1.143 0.4485 Caravelle 26 0.960 3.129 0.9486 LCork 20 0.704 2.109 0.7544 Chuluota 40 0.998 3.680 0.9744 LEGo 13 0.858 2.201 0.8565 CLBayard 13 0.709 1.819 0.7172 LESuwan 17 0.907 2.569 0.9078 CLCove 14 0.651 1.718 0.6958 LLeeCounty 16 0.824 2.285 0.8569 CMWPast 27 1.000 3.296 0.9630 MALudy 21 0.732 2.230 0.7943 COBurgle 13 0.748 1.920 0.7610 MASpray 10 0.625 1.439 0.6719 COHole 19 0.813 2.394 0.8667 McArthur 15 0.439 1.189 0.4819 CREW 25 0.968 3.116 0.9506 MNElmer 13 0.748 1.919 0.7845 Deerfly 22 0.922 2.850 0.9304 MNOcala 14 0.838 2.211 0.8381 DEMelon 19 0.781 2.299 0.8441 MRPepper 25 1.000 3.219 0.9600 Garber 19 1.000 2.944 0.9474 Myakka 20 0.878 2.631 0.9061 GbarE 16 0.651 1.804 0.6838 OKCara 18 0.852 2.462 0.8854 GLDonut 15 0.719 1.948 0.7634 OKKiss 32 0.975 3.377 0.9612 GLPont 22 0.816 2.521 0.8902 OKPast 22 0.917 2.835 0.9211 Goethe 15 0.986 2.670 0.9273 PacificTom 36 0.952 3.410 0.9595 GreenSwamp 23 0.940 2.949 0.9275 PallMar 16 0.812 2.250 0.8086 HagueI 20 0.974 2.918 0.9408 PBCorbett 16 0.793 2.199 0.8473 HagueII 24 1.000 3.178 0.9583 PBEnjay 12 0.838 2.081 0.8379 HalfMoon 14 0.871 2.300 0.8773 Penner 14 0.750 1.979 0.7628 HARare 15 0.710 1.923 0.7543 POWales 10 0.835 1.922 0.7937 HABad 8 0.690 1.434 0.6892 POWeowak 19 0.801 2.358 0.8736 HEL2 21 0.774 2.356 0.8325 RiceCreek 19 0.833 2.453 0.8782 HEOkay 29 0.883 2.973 0.9313 SandhillCrane 29 0.893 3.005 0.9326 HighPast 8 0.660 1.372 0.6048 SANorthMya 12 0.827 2.056 0.8262 HighRef 12 0.887 2.203 0.8715 SAOscer 9 0.402 0.883 0.3623 HillsRef 21 0.781 2.378 0.8048 Savannas 18 0.736 2.128 0.8048 HuntCamp 9 0.702 1.542 0.6503 STCow 17 0.771 2.183 0.8442 IFASI 11 0.663 1.590 0.6957 UNHealthy 15 0.818 2.215 0.8473 IFASII 26 0.992 3.233 0.9592 Weikiva 12 0.924 2.296 0.8852 Immokalee 24 0.939 2.985 0.9348

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25 Table 2-4. Summary statistics and diatom similarities using Tukeys HSD. Standard Deviation Variable Algal Type N Mean Median S Benthic a 70 18.4 18.0 5.9 Epiphytic b 69 15.7 15.0 5.2 Phyto. a 69 18.8 18.0 7.1 E Benthic a 70 0.792 0.814 0.087 Epiphytic a 69 0.773 0.788 0.094 Phyto. a 69 0.815 0.827 0.132 H Benthic ab 70 2.280 2.276 0.431 Epiphytic b 69 2.101 2.118 0.418 Phyto. a 69 2.236 2.296 0.609 D Benthic a 70 0.834 0.860 0.095 Epiphytic a 69 0.808 0.820 0.097 Phyto. a 69 0.831 0.857 0.124 Note: Diatom types (Benthic, Epiphytic, Phytoplanktonic) with a similar letter superscript were not significantly different at p=0.05. Table 2-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes within benthic, epiphytic, and phytoplanktonic diatom groups. Benthic Diatoms Epiphytic Diatoms Phytoplanktonic Diatoms S (Richness) -1.515 (0.130) -1.780 (0.075) -1.175 (0.240) E 1.306 0.560 0.595 (Evenness) (0.192) (0.576) (0.551) H -0.077 -0.746 -0.169 (Shannon Diversity) (0.939) (0.456) (0.866) D 0.435 0.048 -0.078 (Simpsons Diversity) (0.663) (0.962) (0.938) Comparisons of the fidelity of species to particular habitats (benthic, epiphytic, and phytoplanktonic) were made using PSI and MRPP. For benthic versus epiphytic diatoms, within site PSI ranged from 6% to 89%, and averaged 55% (+/17.2%). Within site PSI ranged from 2% to 78%, and averaged 42% (+/19.0%) for benthic versus phytoplanktonic diatoms. The range between epiphytic and phytoplanktonic diatoms was 1% to 77%, and averaged 46% (+/19.4%). Global comparisons using pooled data (i.e., all benthic diatoms from all sites pooled into a benthic heading versus all epiphytic diatoms from all sites pooled into an epiphytic heading) indicated a

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26 Table 2-6. Alpha, Beta, and Gamma diversity between diatom types and wetland condition. Alpha Diversity Beta Diversity Gamma Diversity All Benthic (n=70) 18.4 10.60 195 Impaired 19.4 7.94 154 Reference 17.4 8.05 140 All Epiphyton (n=69) 15.7 11.08 174 Impaired 16.9 8.70 147 Reference 14.4 6.81 98 All Phytoplankton (n=69) 18.8 12.98 244 Impaired 19.5 10.00 195 Reference 17.9 9.11 163 remarkable lack of fidelity to specific habitats among the diatom community as the benthic and epiphytic communities were 84% similar, the benthic and phytoplanktonic communities were 75% similar, and the epiphytic and phytoplanktonic communities were 76% similar. MRPP results supported the lack of uniqueness between benthic, epiphytic, and phytoplanktonic communities. MRPP analyses (Table 2-7), were completed using both abundance data and simple presence data, and were calculated for both a simultaneous comparison of all three diatom types and an iterative comparison of one type versus another. In all cases, MRPP results indicated no significant differences between the benthic, epiphytic, and phytoplanktonic communities at the conventional p-value of 0.05. Diatom Composition and Environmental Correlates As a lack of habitat fidelity was demonstrated by the benthic, epiphytic, and phytoplanktonic communities, it was necessary to select one community to pursue the development of biological indicators of wetland condition. Selecting multiple communities would double-count the effect of landscape influences on the wetland environment. The criterion for further metric development was to identify the diatom community with the strongest relationship to the environmental parameters, including the LDI score. This was accomplished by examining matrix correlations between abundance values and environmental parameters using the Mantel test, and by examining the NMDS ordination of the abundance values for each diatom community and the correlation of site scores with environmental parameters. Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in Appendix B. Significant differences between impaired and reference conditions, as measured by the Mann-Whitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 2-8). Water color was significantly lower in reference conditions at p<0.10. Colinearity among the variables was recognized for %TC,

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27 Table 2-7. MRPP analyses of the compositional similarity between benthic, epiphytic, and phytoplanktonic diatoms. Test A T p-value Abundance Global Test B vs. E vs. P -0.0005 0.321 0.558 Presence Global Test B vs. E vs. P -0.0008 -0.492 0.262 Abundance B vs. E -0.0020 1.186 0.994 Iterative B vs. P 0.0013 -0.841 0.166 Tests E vs. P -0.0004 0.252 0.503 Presence B vs. E -0.0019 1.012 0.916 Iterative B vs. P 0.0021 -1.262 0.108 Tests E vs. P 0.0016 -0.951 0.151 Note : Abbreviations are B (benthic), E (epiphyton), P (phytoplankton). Global tests refer to simultaneous multivariate tests of the pooled diatoms from all benthic, epiphytic, and phytoplanktonic samples. Iterative tests exclude one group (of three) during the MRPP procedure. Table 2-8. Comparison of the medians of water and soil variables between LDI classes with the Mann-Whitney U-test. Water Values Statistic (Z) p-value Color -1.868 0.062 Specific Conductivity -3.919 <0.001 Turbidity -1.524 0.127 Water pH -4.677 <0.001 Ammonia -2.690 0.007 Nitrates/Nitrites 0.771 0.441 TKN -2.932 0.003 TP -4.836 <0.001 Soil Values Statistic (Z) p-value Soil pH -3.036 0.002 %TC -0.818 0.414 %OM -1.253 0.210 %TN -1.147 0.251 %TP -2.771 0.006

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28 TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the abundance data for benthic, epiphytic, and phytoplanktonic diatoms and the measured environmental parameters and LDI score. The relationship between the matrices was strongest for epiphytic diatoms (Mantels r=0.49, p<0.001). Benthic diatoms (Mantels r=0.39, p<0.001) and phytoplanktonic diatoms (Mantels r=0.30,p<0.001) were also significantly correlated to the environmental parameters, albeit not as strongly as the epiphyton. NMDS ordinations of the diatom community abundance data were able to capture approximately equal total variance in the dataset for each of the three diatom types (total variance for Benthic: 81.1%; Epiphyton: 77.4%; Phytoplankton 80.1%). The stress, or goodness of fit of the ordination was also approximately equal, and indicated an adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). The calculated stress for each diatom was: benthic diatoms: 16.68; epiphytic diatoms: 18.45; phytoplanktonic diatoms: 15.66. Site scores for each diatom community type, overlaid by a vector diagram of environmental variables with strong (r20.30) correlations to the first two axes, are presented in Figures 2-3 to 2-5. A two-dimensional solution was identified for benthic and epiphytic diatoms, and a three dimensional solution was identified for phytoplankton. Total variance accounted for by the ordination of the diatoms was approximately equal between types. The benthic diatom ordination accounted for 81.1% of the variation in the dataset (first axis: 26.2%, second axis 54.9%); 77.4% of the variation in the epiphytic diatom dataset was accounted for by the ordination (first axis: 49.2%, second axis: 28.2%); and 80.1% of the variation was reflected in the ordination of the phytoplankton (first axis: 28.7%, second axis: 36.5%, third axis: 14.8%). The relationship between the first two axes for phytoplankton are shown in Figure 2-5 as the third axis, despite accounting for approximately 15% of the variation in the dataset, had no strongly correlated environmental variables. Correlations of environmental variables with the ordination score for benthic, epiphytic, and phytoplanktonic diatoms are presented in Tables 2-9 to 2-11. Four environmental variables were correlated 0.30 with the ordination scores of benthic and epiphytic diatoms (LDI, soil pH, specific conductivity, and water TP). Three variables were correlated with phytoplanktonic diatoms (LDI, specific conductivity, and soil pH). None of the environmental variables were correlated 0.50 for phytoplanktonic diatoms, while one of four were 0.50 for benthic diatoms and three of four were 0.50 for epiphytic diatoms. Based on results of the Mantel tests and the NMDS ordination scores and correlations, as well as the lack of significant differences between the benthic, epiphytic, and phytoplanktonic communities as measured by MRPP and indicated by high PSI values, a decision to base bioassessment metric development on the epiphytic community was made. The results of the Mantel test indicated that the epiphytic diatom community had a stronger relationship with the measured environmental parameters than either the benthic diatoms or phytoplankton. NMDS ordinations also suggested stronger correlations between epiphytic diatoms and environmental parameters, notably LDI score and water TP, than were found with benthic diatoms, although goodness of fit and percent of variance explained were slightly lower. Phytoplanktonic diatoms were

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29 removed from consideration due to the low Mantel statistic values and weaker NMDS correlations with environmental parameters, most notably the LDI score, as compared to epiphyton or benthic diatoms. Metric Development Regional composition MRPP analyses of the arcsine square root transformed abundance data were completed for epiphytic diatoms to determine if regional factors contributed to epiphyton community composition. When simultaneously compared (i.e., South vs. Central vs. North), diatom distribution did not differ significantly (at p<0.05). However, when Figure 2-3. Biplot of benthic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of original length for clarity. The percent variance explained by each axis is noted on the axis. The length of the vectors represents the strength of the correlation (all >|0.30|) and the angle represents the direction of maximum change. Four variables are shown: pH (soil pH), Cond (specific conductivity), TP (water total phosphorus), and LDI (Landscape Development Intensity index).

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30 iteratively tested, diatom distribution differed significantly (p<0.05) between the South and North regions, but the differences were insignificant between the South and Central, and the Central and North regions. This was examined further by testing the regional distribution of reference sites and impaired sites. When simultaneously tested, the reference sites differed across all regions (Table 2-12). Reference sites also differed between South and Central regions, and South and North regions, but not between Central and North regions. In contrast, the impaired sites did not differ when simultaneously compared, nor when regions were contrasted, indicating similar species composition across peninsular Florida in disturbed landscapes. Figure 2-4. Biplot of epiphytic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 125% of the original length for clarity. The percent of variance explained by each axis is given on each axis. Four environmental variables were strongly (r>|0.30|) correlated with NMDS ordination scores: pH (soil pH), Cond (specific conductivity), TP (water TP), and LDI.

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31 Figure 2-5. Biplot of phytoplanktonic diatom NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 200% of the original length for clarity. The percent of variance explained by each axis is given on each axis. Three environmental variables were strongly (r>|0.30|) correlated with NMDS ordination scores: Cond (specific conductivity), TP (water TP), and LDI. Indicator species analyses Indicator Species Analysis was used to identify species that exhibited specificity and fidelity to LDI scores of <2.0 (i.e., reference indicators) and 2.0 (i.e., impaired indicators) for each region. The significant species for reference indicators and impaired indicators are presented in Tables 2-13 and 2-14, respectively. Ten indicators of reference conditions were identified in the South region, 12 in the Central region and 4 in the North region. Five impaired indicators were identified in the South region, 12 in the Central region, and 6 in the North region. There was substantial overlap of indicator species between regions.

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32 Table 2-9. Correlations of environmental variables and ordination scores for benthic diatoms. Axis 1 (26.2%) Axis 2 (54.9%) Parameter r 2 tau r 2 tau Soil pH 0.62 -0.55 0.20 0.25 % TN 0.03 0.08 0.02 0.17 TP (mg/kg) 0.01 0.07 0.09 0.23 % OM 0.07 0.14 0.01 0.14 Color (PCU) 0.18 0.25 0.05 0.18 Spec. Cond. (umhos/cm) 0.28 -0.39 0.48 0.51 Turbidity (NTU) <0.01 -0.02 0.06 0.17 Ammonia (mg/L) <0.01 -0.09 0.05 0.19 Nitrate/Nitrite (mg/L) 0.02 0.10 0.02 -0.08 Water TP (mg/L) <0.01 -0.04 0.42 0.49 LDI Score 0.06 -0.20 0.42 0.36 Note : Underlined correlations were 0.30 and were considered strongly correlated with NMDS ordination scores. Kendals tau, a non-parametric measure of association, is also given. Table 2-10. Correlations of environmental variables and ordination scores for epiphytic diatoms. Axis 1 (49.2%) Axis 2 (28.2%) Parameter r 2 tau r 2 tau Soil pH 0.23 -0.34 0.59 -0.58 % TN <0.01 -0.07 0.03 0.08 TP (mg/kg) 0.11 -0.24 <0.01 0.06 % OM <0.01 -0.07 0.08 0.14 Color (PCU) 0.07 -0.17 0.22 0.26 Spec. Cond. (umhos/cm) 0.46 -0.50 0.19 -0.32 Turbidity (NTU) 0.06 -0.15 0.02 0.06 Ammonia (mg/L) 0.03 -0.21 0.02 <-0.01 Nitrate/Nitrite (mg/L) <0.01 <-0.01 0.03 0.17 Water TP (mg/L) 0.53 -0.55 <0.01 0.05 LDI Score 0.63 -0.50 0.02 -0.11 Note : Underlined correlations were r 2 0.30 and were considered strongly correlated with NMDS ordination scores for each site. Kendals tau, a non-parametric measure of association, is also given.

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33 Table 2-11. Correlations of environmental variables and ordination scores for phytoplanktonic diatoms. Axis 1 (28.7%) Axis 2 (36.5%) Axis 3 (14.8%) Parameter r 2 tau r 2 tau r 2 tau Soil pH 0.40 -0.49 0.16 0.27 0.06 0.15 % TN <0.01 0.02 <0.01 0.09 0.040 -0.11 TP (mg/kg) <0.01 <-0.01 0.02 0.11 0.05 -0.15 % OM <0.01 0.03 0.02 0.01 0.05 -0.17 Color (PCU) 0.13 0.20 0.03 0.15 0.19 -0.27 Spec. Cond. (umhos/cm) 0.19 -0.34 0.35 0.45 0.02 0.11 Turbidity (NTU) <0.01 -0.02 <0.01 0.03 0.07 -0.24 Ammonia (mg/L) <0.01 -0.06 <0.01 0.18 0.01 -0.03 Nitrate/Nitrite (mg/L) 0.03 0.12 0.04 -0.15 0.05 -0.18 Water TP (mg/L) <0.01 -0.08 0.28 -0.22 0.11 -0.27 LDI Score 0.11 -0.25 0.38 0.38 0.05 -0.15 Note : Underlined correlations were 0.30 and were considered strongly correlated with NMDS ordination scores for each site. Kendals tau, a non-parametric measure of association, is also given. Table 2-12. MRPP analyses of the compositional similarity between epiphytic diatoms of South, Central, and North wetland regions. Test A T p-value Simultaneous %: S vs. C vs. N 0.0056 -1.254 0.111 Tests P/A: S vs. C vs. N 0.0096 -1.794 0.057 Abundance S vs. C 0.0045 -1.080 0.132 Iterative S vs. N 0.0113 -2.038 0.045 Tests C vs. N -0.0015 0.320 0.533 Presence S vs. C 0.0086 -1.843 0.057 Iterative S vs. N 0.0195 -2.818 0.019 Tests C vs. N -0.0040 0.662 0.711

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34 Table 2-13. Reference site diatom indicator taxa identified using Indicator Species Analysis for each wetland region. Region Indicator Species (LDI <2.0) Observed Ind. Value p-value South Anomoeneis serians acuta 45.5 0.013 Reference Anomoeneis serians brachysira 43.8 0.046 Anomoeneis serians 27.3 0.092 Anomoeneis vitrea 59.5 0.015 Eunotia bilunaris mucophila 45.8 0.054 Eunotia flexuosa eurycephala 27.3 0.091 Eunotia naegelii 63.0 0.014 Frustulia rhomboides crassinerva 32.0 0.084 Frustulia rhomboides saxonica 70.2 0.006 Navicula mediocris 36.4 0.035 Central Anomoeneis serians acuta 38.5 0.009 Reference Anomoeneis serians brachysira 45.9 0.016 Desmogonium rabenhorstianum 44.0 0.016 Eunotia bilunaris mucophila 43.1 0.033 Eunotia denticulata 23.1 0.069 Eunotia paludosa 53.8 0.001 Eunotia paludosa trinacria 46.2 0.002 Eunotia pirla 38.5 0.009 Eunotia soleirolii 30.8 0.027 Eunotia zygodon 38.5 0.010 Frustulia rhomboides 50.3 0.021 Frustulia rhomboides saxonica 81.2 <0.001 North Desmogonium rabenhorstianum 50.0 0.081 Reference Frustulia rhomboides 58.7 0.024 Frustulia rhomboides saxonica 72.0 0.050 Pinnularia subcapitata 68.3 0.098

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35 Table 2-14. Impaired site diatom indicator taxa identified using Indicator Species Analysis for each wetland region. Region Indicator Species (LDI 2.0) Observed Ind. Value p-value South Gomphonema parvulum 58.3 0.005 Impaired Navicula confervacea 58.3 0.005 Nitzschia palea debilis 85.2 <0.001 Nitzschia sociabilis 41.7 0.038 Pinnularia acrosphaeria 33.3 0.094 Central Gomphonema angustatum 29.4 0.054 Impaired Gomphonema gracile 52.9 0.002 Gomphonema parvulum 60.1 0.004 Navicula confervacea 70.3 0.001 Navicula minima 33.9 0.060 Navicula seminulum 45.8 0.018 Nitzschia frustulum 35.3 0.038 Nitzschia gracilis 29.4 0.072 Nitzschia palea 52.2 0.026 Nitzschia palea debilis 77.0 <0.001 Nitzschia sociabilis 30.8 0.089 Pinnularia gibba 37.3 0.067 North Gomphonema parvulum 62.5 0.026 Impaired Navicula difficillima 62.5 0.027 Navicula minima 49.2 0.080 Navicula seminulum 50.0 0.081 Nitzschia palea 58.3 0.033 Nitzschia palea debilis 63.3 0.066 ISA was also used to identify significant indicator species for impaired and reference sites for the combined peninsular regions (South, Central, and North regions; n=69). A total of 43 indicator species were identified for the combined analysis, 22 reference condition indicators and 21 impaired condition indicators (Tables 2-15 and 2-16, respectively). With the exception of two indicators of reference conditions (Eunotia soleirolii and Pinnularia subcapita) and two indicators of impaired conditions (Nitzschia frustulum and N. gracilis) found in regional analyses, there was complete overlap of regional and peninsular indicator species. This was not unexpected considering the lack of significance when composition between regions was simultaneously tested with MRPP. The larger n allowed for greater statistical power in the analysis of indicator species, thus 5 reference indicator species and 9 impaired indicator species were

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36 identified using the peninsular (n=69) dataset that were not in any regional indicator species. Little additional information was garnered from identifying regionally specific indicator species, and 14 additional indicator species were identified using the peninsular dataset. Furthermore, no significant difference was found in the simultaneous multivariate MRPP test of regional significance of community composition. Thus, it was concluded that the remaining analyses would utilize the peninsular dataset. Therefore metrics developed are not regionally specific but apply throughout peninsular Florida. Using the peninsular dataset of indicator species (n=43), the abundance of the indicator species for both impaired and reference conditions were calculated for each site and correlated with the LDI using Spearmans r (Figure 2-6). Correlations for the abundance of reference indicators and impaired indicators are: % Reference Indicators r = -0.66, p<0.001; % Impaired Indicators r = 0.60, p<0.001. The abundance of reference indicators demonstrated a highly variable distribution, especially for LDI values of approximately <3.2. In general, sites with LDI scores of >3.2 were composed of <10% reference indicators. The abundance of impaired indicators suggested a low correlation Table 2-15. Statewide indicators of reference conditions as determined from Indicator Species Analysis. Indicator Species (LDI <2.0) Observed Ind. Value p-value Anomoeneis serians acuta 34.4 <0.001 Anomoeneis serians brachysira 39.1 <0.001 Anomoeneis serians 9.4 0.099 Anomoeneis vitrea 22.0 0.052 Desmogonium rabenhorstianum 26.6 0.027 Eunotia bilunaris mucophila 41.4 0.003 Eunotia denticulata 17.5 0.021 Eunotia flexuosa 20.2 0.099 Eunotia flexuosa eurycephala 9.4 0.093 Eunotia monodon 9.4 0.095 Eunotia naegelii 59.5 0.002 Eunotia paludosa 29.4 0.007 Eunotia paludosa trinacria 29.7 0.017 Eunotia pirla 27.7 0.005 Eunotia rhomboidea 37.0 0.029 Eunotia zygodon 23.1 0.015 Frustulia rhomboides 46.3 <0.001 Frustulia rhomboides crassinerva 17.8 0.046 Frustulia rhomboides saxonica 75.1 <0.001 Navicula mediocris 25.0 0.001 Navicula subtilissima 17.3 0.030 Stauroneis kriegeri 16.6 0.084

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37 Table 2-16. Statewide indicators of impaired conditions as determined from Indicator Species Analysis. Indicator Species (LDI 2.0) Observed Ind. Value p-value Caloneis bacillum 16.2 0.030 Gomphonema angustatum 22.8 0.020 Gomphonema gracile 46.4 0.002 Gomphonema lanceolatum 21.6 0.005 Gomphonema parvulum 60.9 <0.001 Melosira italica 18.9 0.014 Navicula confervacea 59.3 <0.001 Navicula difficillima 35.4 0.001 Navicula minima 33.8 0.002 Navicula molestiformis 13.5 0.053 Navicula pupula rectangularis 15.9 0.057 Navicula seminulum 42.2 <0.001 Nitzschia amphibia 21.2 0.041 Nitzschia microcephala 13.5 0.058 Nitzschia palea 48.4 0.005 Nitzschia palea debilis 76.3 <0.001 Nitzschia palea tenuirostris 15.5 0.065 Nitzschia perminuta 12.3 0.010 Nitzschia sociabilis 32.8 0.002 Pinnularia acrosphaeria 21.6 0.006 Pinnularia gibba 27.5 0.036 with increasing LDI scores until a threshold at approximately 3.7 was reached. At that point, the abundance of impaired indicators increased markedly. Autecological indices One hundred thirty-four of the 174 epiphyton diatom taxa (approximately 77%) had one or more autecological, or ecological indicator, values obtained from Van Dam et al. (1994) and Bahls (1993). On a site-by-site basis, approximately 82% of diatoms found at a given site had ecological indicator values. This ranged from approximately 56% to 100% of the diatoms found in the 69 sampled wetlands. The abundance of each class for the autecological indicator guilds of Van Dam et al. (1994) and Bahls (1993) was calculated for each site and correlated (Spearmans r) with the LDI. Responsive metrics were those with correlations of >|0.50| and significant (p<0.05) correlation coefficients. Bivariate correlations using Spearmans r were calculated for the autecological indices having negative (n=6 metrics) and positive (n=7 metrics) responses with increasing LDI scores. The abundance of diatoms sensitive to nitrogen levels, or tolerating very small concentrations of organically bound nitrogen, was strongly (r = 0.86) correlated with oligosaprobous diatoms (Van Dam et al. 1994, p.

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38 A B Figure 2-6. Indicator species abundance data plotted against the LDI. A) Abundance of Reference Indicators vs. the LDI. B) Abundance of Impaired Indicators vs. the LDI.

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39 120). The percent of diatoms sensitive to elevated nitrogen levels index was maintained, as the abundance of nitrogen-sensitive diatoms was more strongly correlated with the LDI than the abundance of oligosaprobous diatoms (Spearmans r = -0.67 for percent nitrogen sensitive diatoms, r = -0.58 for oligosaprobous taxa). The remaining autecological indices of Van Dam et al. (1994) and Bahls (1993) were significantly (p<0.001) correlated (Spearmans r) |0.50| with the LDI (Table 2-17). A plot of the abundance of diatoms for each uncorrelated metric along the disturbance gradient is Table 2-17. Correlations of autecological abundance data and LDI score. Metric Spearman s r p-value Notes % Tolerate High pH 0.65 <0.001 VD 3 % Require Low pH -0.68 <0.001 VD Class 1 % Require Low Salinity -0.51 <0.001 VD Class 1 % Tolerate High Salinity 0.62 <0.001 VD Class 3 % Sensitive High Nitrogen -0.66 <0.001 VD Class 1 % Tolerate High Nitrogen 0.68 <0.001 VD Class 3 % Require Elevated D.O. -0.63 <0.001 VD Class 1 % Tolerant Low D.O. 0.64 <0.001 VD Class 4 % Meso& Polysaprobous 0.69 <0.001 VD Class 4 % Oligotrophic -0.59 <0.001 VD Classes 1 & 2 % Eutrophic 0.67 <0.001 VD Class 5 % Pollution Tolerant 0.67 <0.001 Bahls Class 1 Note : VD Class and Bahls class represent the autecological index value from Van Dam et al. (1994) and Bahls (1993). Table 2-18. Mann-Whitney U-test of autecological abundance values between impaired and reference conditions. Metric Statistic (Z) p-value % Tolerate High pH -5.288 <0.001 % Require Low pH 5.433 <0.001 % Require Low Salinity 4.067 <0.001 % Tolerate High Salinity -5.171 <0.001 % Sensitive High Nitrogen 5.475 <0.001 % Tolerate High Nitrogen -5.595 <0.001 % Require Elevated D.O. 5.379 <0.001 % Tolerant Low D.O. -5.287 <0.001 % Meso& Polysaprobous -5.381 <0.001 % Oligotrophic 5.048 <0.001 % Eutrophic -5.580 <0.001 % Pollution Tolerant -5.474 <0.001

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40 A) % Sensitive Elevated pH B) % Tolerate Elevated pH C) % Salinity Sensitive D) % Salinity Tolerant E) % Sensitive Elevated Nitrogen F) % Tolerant Elevated Nitrogen Figure 2-7. Diatom abundance for autecological metrics plotted against the LDI gradient. A) % Sensitive Elevated pH, B) % Tolerate Elevated pH, C) % Salinity Sensitive, D) % Salinity Tolerant, E) % Sensitive Elevated Nitrogen, F) % Tolerant Elevated Nitrogen, G) % Sensitive Low D.O., H) % Tolerant Low D.O., I) % Oligotrophic, J) % Eutrophic, K) % Meso-Polysaprobous, L) % Pollution Tolerant.

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41 G) % Sensitive Low D.O. H) % Tolerant Low D.O. I) % Oligotrophic J) % Eutrophic K) % Meso-Polysaprobous L) % Pollution Tolerant Figure 2-7 (Continued).

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presented in Figure 2-7. The Mann-Whitney U-test (Table 2-18) indicated that all medians were significantly different (p0.001) between reference and impaired sites. In general, autecological metrics that decreased with increasing LDI values appeared to have a greater goodness of fit and to be less sensitive to changes in the LDI. The results suggest metrics that increase with increasing LDI score approach a threshold near approximately 3.8. Thereafter, the abundance of the various metrics increases markedly, but with a high variance. The Multimetric Index Two metrics derived from indicator species analysis (Dufrene and Legendre 1997), one metric based on pollution tolerance (Bahls 1993) and eleven metrics identified from autecological indicator values of Van Dam et al. (1994), were selected as final metrics based on the significance and strength of the correlations with the LDI. The quartile values of 95 th percentile and the corresponding values of 0,3,7,10 for each metric are given in Table 2-19. The fourteen metrics were summed to create the Diatom Index of Wetland Condition (DIWC), with a possible range of value from 0 to 140. One site had a summed DIWC value of zero, and one site scored a perfect 140 (Table 2-20). Reference sites averaged 114.5 points, with a standard deviation of 26.3 points and a median value of 122.5. Impaired sites averaged 42.1 points (+/38.3) and had a median value of 33.0. DIWC scores were correlated with the LDI Score for each site: Spearmans r = 0.79, p < 0.001 (Figure 2-8). However, similar to the metrics that comprised the index, the results appear to be highly variable for any given LDI score. Metric sensitivity appears to increase near LDI scores of 3.2. Mann-Whitney U-test results indicate a significant difference between DIWC scores for impaired and reference sites (Z=5.991, p<0.001). Table 2-19. Quadrisect values and the 95 th percentile data for each proposed biological indicator. Metric 95 th Percentile 0 Scores 3 Scores 7 Scores 10 Scores % Reference Indicators 0.789 <0.0279 0.0279 0.2328 >0.2328 0.5620 >0.5620 % Impaired Indicators 0.934 >0.5512 >0.1094 0.5512 0.0001 0.1094 0 % Sensitive Elevated pH 0.445 0 0.0001 0.0234 >0.0234 0.2000 >0.2000 % Tolerant Elevated pH 0.818 >0.4820 >0.2300 0.4820 0.0571 0.2300 <0.0571 % Sensitive Elevated Salinity 0.840 <0.2361 0.2361 0.4221 >0.4221 0.5889 >0.5889 % Tolerate Elevated Salinity 0.405 >0.1000 >0.035 0.1000 0.0001 0.035 0 % Sensitive Elevated Nitrogen 0.811 <0.1349 0.1349 0.3506 >0.3506 0.5590 >0.5590 % Tolerate Elevated Nitrogen 0.589 >0.1622 >0.0118 0.1622 0.0001 0.0118 0 % Sensitive Low D.O. 0.840 <0.1471 0.1471 0.3274 >0.3274 0.5551 >0.5551 % Tolerate Low D.O. 0.350 >0.1195 >0.0228 0.1195 0.0001 0.0228 0 % Meso& Polysaprobous 0.209 >0.1400 >0.0250 0.1400 0.0001 0.0250 0 % Oligotrophic 0.932 <0.2830 0.2830 0.4582 >0.4582 0.6667 >0.6667 % Eutrophic 0.592 >0.2101 >0.0152 0.2101 0.0001 0.0152 0 % Pollution Tolerant 0.368 >0.1594 >0.0239 0.1594 0.0001 0.0239 0 42 42

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43 Table 2-20. Diatom Index of Wetland Condition scores for sampled sites. Sites DIWC Sites DIWC Audubon 36 IRBlueCypress 53 BearScat 72 IRCanal 41 BigCow 18 IROJ 48 BRSebastian 137 JD6 140 CabPatch 28 KellyPark 91 Caravelle 39 LCork 100 Chuluota 131 LLeeCounty 70 CLBayard 100 LEGo 106 CLCove 16 LESuwan 49 CMWPast 111 MALudy 9 CMWRef 134 MASpray 124 COBurgle 15 McArthur 6 COHole 70 MNElmer 55 Crew 118 MNOcala 140 DEMelon 9 MRPepper 35 Deerfly 105 Myakka 100 Garber 86 OKCara 21 Gbare 20 OKKiss 137 GLDonut 9 OKPast 36 GLPont 3 PacificTom 43 Goethe 106 PallMar 140 GreenSwamp 113 PBCorbett 96 HARare 3 PBEnjay 137 HagueI 3 Penner 140 HagueII 22 POWales 137 HalfMoon 134 POWeowak 134 HEBad 29 RiceCreek 93 HEL2 6 SANorthMya 115 HEOkay 49 SAOscer 127 Highpast 33 SandhillCrane 103 HighRef 87 Savannas 140 HillsRef 83 STCow 0 HuntCamp 137 UNHealthy 13 IFASI 128 Weikiva 140 Immokalee 110

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44 Figure 2-8. Diatom Index of Wetland Condition scores for each site plotted against the disturbance gradient. Discussion Diatom Composition and Environmental Correlates It was anticipated that environmental variables would drive the wetland community composition such that low overlap (as measured by PSI and MRPP) would occur between benthic, epiphytic, and phytoplanktonic diatoms, as reported by Pan and Stevenson (1996) and U.S. EPA (2002e). Benthic diatoms were expected to respond strongly to the nutrient and chemical condition of the wetland sediments (Stevenson 2001). Epiphytic diatoms were expected to respond to nutrients from both the soils and water column, as nutrients taken up by plants from sediments are released and readily absorbed by epiphytic biofilms (Stevenson 2001, p. 121). Phytoplanktonic diatoms were expected to respond most strongly to the nutrients and physical/chemical characteristics of the enveloping waters. However, as found by Van Meter-Kasanof (1973), Moss (1981), de Jonge and van Beusekom (1992), there was substantial overlap for each of the wetland diatom communities, indicating a similar response to forcing functions (i.e., pH, specific conductivity, nutrients). The similarities may also be a result of the spatial location of the sampled diatoms. The benthic community, due to the spatial position at the bottom of the water column, likely integrated not only benthic, but also epiphytic and phytoplanktonic diatoms. This purported ability of benthic diatoms to integrate a longer temporal signature of wetland

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45 conditions vis--vis the epiphytic or phytoplanktonic diatoms is a reflection of their position within the wetland and could be considered an advantage to using diatoms for biological assessment (Stevenson 2001, U.S. EPA 2002e). Benthic diatoms were thus likely composed not only diatoms of the benthos, but also of the rain of dead and sloughed-off diatoms from the phytoplankton and epiphyton communities. Epiphytic diatoms were composed not only of the diatoms equipped to thrive on macrophytes, but also of phytoplanktonic and mobilized benthic diatoms that became entangled in the often thick web of tendrils of soft algae growing from the macrophytes. U.S. EPA (2002e, p. 6) considers wetland epiphytic diatoms a reflection of the last couple of months generally meaning the hydrated period for the wetland, although many of the diatoms may persist during periods of drought. The phytoplankton community was composed of diatoms evolved to move within the water column, as well as organisms mobilized from the sediments and plant matter by wind action or disturbances from vertebrates. The phytoplanktonic diatoms generally reflect the shortest period of wetland conditions, as once they fall from suspension, they become assimilated into the benthos (U.S. EPA 2002e). While high similarities (75%) existed on a global level between diatoms found in benthic, epiphytic, and phytoplanktonic communities, a moderate ~50% within-site similarity was identified (using PSI) for the sampled diatom assemblages. These results may be indicative of temporal variations of within-site species abundances, perhaps a reflection of slower or faster responses of diatoms within a particular community to hydrologic or physical/chemical parameters. Strong correlations were found for soil pH, specific conductivity, and LDI score for the sampled assemblages, and benthic and epiphytic diatoms were also strongly correlated with water TP (see Tables 2-9 to 2-11). It is well established that pH and specific conductivity have a controlling effect on diatom species composition (Lowe 1974, Pan and Stevenson 1996, U.S. EPA 2002e), and that these variables are altered by anthropogenic disturbances such as agro-fertilizer application and hydrologic modifications (Fore and Grafe 2002, U.S. EPA 2002e). Likewise, the link between phosphorus and diatom composition is well established (Lowe 1974, Pan and Stevenson 1996, Stevenson et al. 1999 Barbour et al 1999), and a link would be expected between a general impairment indicator (LDI score), which reflects the physical, chemical, and nutrient alterations to the landscape, and wetland diatom species composition (Carpenter and Waite 2000, OConner et al. 2000, Cuffney et al. 2000, Munn et al. 2002, Fore and Grafe 2002, Fore 2003). Despite the high similarity identified with PSI and MRPP, and similar driving forces identified with NMDS, a much stronger relationship with environmental variables (as measured by Mantel tests) was identified with epiphyton than with benthic or phytoplanktonic diatoms. These results (Mantels r values for each assemblage) do not change by more than 0.01 when species that occur in <2 sites are removed (C. Lane, unpublished data). This suggests that the higher richness found in phytoplanktonic and benthic assemblages do not affect the relationship between a particular assemblage and the measured environmental variables through the addition of ecological noise from rare species (Marchant 2002). These results further support the use of epiphytic diatoms as the selected diatom assemblage for analyses.

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46 Diatom Composition and Wetland Regions The lack of significant differences in the composition of epiphytic diatoms between regions, when simultaneously tested with MRPP, was driven by the lack of significant differences in the composition of impaired sites (see Table 2-12). It is theorized that once a wetland crossed a threshold of impairment (e.g., McCormick and Stevenson 1998), whatever effect physiographic (i.e., mineral or organic soil) or climatic variables may have on the community is muted by the driving energies of the impairment (i.e., alterations to specific conductivity, pH, or phosphorus levels). Thus, there were no significant differences among epiphytic diatoms in impaired sites throughout peninsular Florida, but a significant difference between diatoms found in reference conditions in each region was identified. The environmental driving forces strongly were specific conductivity, soil pH, water color, and TP (C. Lane, unpublished data). Adding latitude and longitude of each site to the second (environmental variables) matrix resulted in the addition of latitude as a strongly correlated variable (C. Lane, unpublished data). These results again distinguish the importance of specific conductivity, pH, and TP as driving variables of diatom community composition, and also suggest that physiographic or climatic variables associated with the North to South axis of peninsular Florida affect the distribution of diatoms located in reference conditions. The addition of water color as a driving variable in diatom communities follows from the negative effect of darker waters on photosynthesis rates, and the necessity of adaptations to such environments. Metric Development Indicator species analysis Indicator species analysis identified 43 taxa with specificity and fidelity to LDI scores of <2.0 and 2.0. Using the abundance of these taxa provided a metric to measure the relationship between the land use around the wetland and the identified sensitive or tolerant taxa within the wetland. Increased sampling would likely affect the composition of the sensitive and tolerant taxa lists as additional taxa would be found that were significantly related to reference or impaired conditions, while some taxa currently listed as sensitive or tolerant would likely be not significantly related to either classification due to increased sampling size clarifying the relationships in the data. The highly variable abundance of reference indicators, when plotted along the LDI, suggests that reference indicators are likewise highly variable in assessing wetland condition, at least until a threshold of LDI scores of approximately 3.2. After that threshold of measured disturbance is reached, the abundance of reference indicators plummets. Impaired indicator abundance appears to react similarly to increasing LDI values, with a similar threshold of approximately 3.4. However, the accuracy and precision of the impaired indicator abundance at LDI values greater than 3.4, appears to be improved vis--vis the abundance of reference indicators at low development intensity values.

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47 Autecological indices The indices of Van Dam et al. (1994) and Bahls (1993) combined autecological values for diatoms of European and the Mountain-west environments, respectively. That the indices developed elsewhere appear to be valid for diatoms of herbaceous depressional wetlands in peninsular Florida is not surprising, considering their use in identifying various disturbance gradients in large rivers of Idaho (Fore and Grafe 2002), streams of the mid-Atlantic states (Fore 2003), Wyoming (Peterson and Porter 2002), and Maine wetlands (U.S. EPA 2002esee case studies). Not only are many of the diatoms cosmopolitan in their worldwide distribution, but they also exhibit fidelity of response to disturbance gradients throughout the world. As in the abundance of indicator taxa, a threshold near 3.2-3.4 appears to dramatically affect the distribution of site scores. For instance, the abundance of diatoms that tolerate elevated pH, salinity, nitrogen, low D.O., and pollution, as well as the eutrophic and meso-polysaprobous all increase markedly in that range, although there are highly variable distributions for any given LDI above a 3.0. This suggests a threshold of tolerance exists up to approximate LDI values of 3.2. Most metrics that decrease with increasing development intensity do so with accuracy and precision (albeit low), especially when compared with metrics that increase with increasing development intensity. A highly variable response is nevertheless evident for those six metrics, although it appears that the highest variability in the data exists near values of 1.0, as well as around LDI values of 3.2. The Diatom Multimetric IndexConclusion and Recommendations The DIWC, which combines species composition and autecological response for diatoms of herbaceous depressional marshes in Florida, was correlated |>0.75| (p<0.001) with increasing land use modification scores. The high number of metrics (14) provided for a wide-range of responses to various possible perturbations from hydrologic alterations to nutrient loading. However, the metric responses, including that of the DIWC, highlighted discrepancies within the distribution of values along the LDI. The highly variable distribution of metrics for any given LDI value was exhibited by all identified metrics. Thresholds appeared to exists at LDI values near 1.0 and 3.3, although these threshold were muted in the DIWC. These results suggest that LDI values of less than 3.2 could most likely be grouped together into a suite of highly variable reference sites little structure in the data (i.e., correlation with the LDI) appeared to be manifested for values of <3.2. Similarly, the rapid increase in most metric values after 3.2 was also highly variable by site. The sites analyzed in the development of this multimetric index were sampled during the late summer. Research on seasonal and annual variation in the distribution of diatoms, and of the variation in the DIWC for diatoms sampled in different years and seasons is currently underway. In addition, the current DIWC requires that the wetland be hydrated for sampling. However, in this study it was unknown how long a given wetland had been hydrated prior to sampling. Thus, although diatoms may respond very quickly to hydration (Stoermer and Smol 1999), sampling response and subsequent analyses may be confounded by temporal variation in hydration. Current research underway (K. Reiss, University of Florida Department of Environmental Engineering Sciences, personal

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48 communication) will determine the utility of benthic diatoms sampled during dry periods to adequately and accurately reflect the condition of the wetland in question. Should the benthic diatoms prove to be year-round indicators of community condition, this multimetric index constructed on epiphytic diatoms should be reassessed. Finally, epiphytic diatoms are generally expected to change in community composition depending on the macrophytes species to which they are attached (Stevenson 2001). It would be well worth examining, in laboratory settings, community variations among epiphytic diatoms when several different wetland macrophytes species common in both impaired and reference conditions are available for colonization.

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CHAPTER 3 MACROPHYTES AS BIOINDICATORS Introduction Wetland macrophytes are well suited for use as reliable biological indicators of the relative condition of Florida freshwater depressional marshes. Defined as plants growing in water or on a substrate that is at least periodically deficient in oxygen as a result of excess water(Cowardin et al. 1979, pg. 40), wetland macrophytes are ubiquitous and identifying features of marshes throughout Florida. Since wetland plants are sessile (save for a few free-floating species), they are unable to actively avoid perturbations through flight mechanisms. Thus, the community composition of marsh macrophytes, reflect[s] the temporal, spatial, chemical, physical, and biological dynamics of a [wetland] system(Fennessy et al. 2001, pg. 3), and changes in wetland macrophyte community composition may be used to indicate both past perturbations and current conditions (Doherty et al. 2000, Adamus et al. 2001, Fennessy et al. 2001). Reliable biological indicators provide information on the condition of a resource relative to reference, or least disturbed conditions, within an ecologically meaningful region (Barbour et al. 1996, Karr and Chu 1999). Wetland macrophytes possess many advantages for use as reliable biological indicators, most notably their prevalence in wetland systems and response to land use changes (Table 3-1). Wetland macrophytes respond to hydrologic, nutrient, and chemical perturbations associated with increased development to wetland landscape matrices (Adamus and Brant 1990, Adamus 1996, Doherty et al. 2000, Fennessy et al. 2001, Adamus et al. 2001). Changes in wetland macrophyte species abundance and composition along nutrient gradients have been noted Bedford et al. 1999). Compositional changes due to chemical loading (i.e., herbicides; McIntyre et al. 1988), hydrologic alterations (Wood and Tanner 1990, Rochow 1994, David 1994, Busch et al. 1998, MaGee et al. 1999) and to destruction of habitat (Blanch and Brock 1994, Winchester et al. 1995, Dobkin et al. 1998, van Oene et al. 1999, Grace and Jutila 1999, Reader and Craft 1999, Vulink et al. 2000) have also been described for wetland macrophytes. Additionally, well-documented collection methods exist for wetland plants (e.g., Brown 1991, Peet et al. 1996, Fennessy et al. 2001), and definitive identification texts abound that permit identification to the species level in most cases (e.g., Godfrey and Wooten 1979, 1981, Wunderlin 1998). Moreover, unlike typical macroinvertebrate and algal indicators, standing water need not be present for the collection of wetland macrophytes, thus increasing the sampling opportunities for wetland assessment. The use of macrophytes as biological indicators is not without disadvantages. There are seasonal differences in species composition and potential lag times between perturbations and responses (Fennessy et al. 2001). While most wetland plants are easily identified with basic field training, some species may lack diagnostic parts during the sampling window or require expert skills to identify. While detractions from using 49

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50 Table 3-1. Advantages and disadvantages of using macrophytes as biological indicators of wetlands condition. Advantages of Macrophyte Biological Indicators Ubiquitous Features of Wetlands Sessile Organisms Established Taxonomy Great Diversity of Species Ecological Tolerances Well-Known Well-developed Sampling Techniques Disadvantages of Macrophyte Indicators Possible lag time between disturbance and response Field Identification Difficult in Certain Seasons Sampling Window May Only Be the Growing Season Some Species Non-responsive to Perturbations Few Published Documentations of Response to Certain Stressors Note: Modified from Cronk and Fennessy (2001). macrophytes exist (see Table 3-1), wetland macrophytes nevertheless provide clear and robust signals of human disturbance (Cronk and Fennessy 2001, p. 373). Recognizing the ability and sensitivity of macrophyte bioindicators to differentiate wetland condition along a gradient of landscape modification, several states have included or are exploring the use of macrophytes in their wetland biological assessment programs (e.g., Ohio: Mack 2001, Montana: Apfelbeck 2000, Minnesota: Gernes and Helgen 1999, Galatowitsch et al. 1999a, North Dakota: Mushet et al. 2002). Additionally, the U.S. Environmental Protection Agencys Biological Assessment of Wetlands Working Group (BAWWG) has supported development of biological assessment criteria, including macrophytes, through funding for state initiatives, workshops, and technical publications (e.g., Doherty et al. 2000, Fennessy et al. 2001, U.S. EPA 2002a). In this chapter, details regarding methods of data analyses and final choices for macrophyte metrics for use in developing biological indicators of wetland condition were given. Analyses of environmental parameters measured (both abiotic and biotic) were also conducted to assess the environmental variables that affected the distribution of macrophyte taxa within wetlands. In addition, metric variation for a given LDI score for the macrophyte metrics was also examined to assess the accuracy and precision of the LDI. Methods Site Selection and Disturbance Gradient Seventy-five isolated depressional marshes (Figure 3-1) were sampled a single timefor macrophyte community composition throughout peninsular Florida in the summers of 1999 (n=35) and 2000 (n=40). Using best scientific judgment, sites were

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51 Figure 3-1. Study site locations and encounter probability for isolated depressional wetlands. Counties shaded darker have a higher density of isolated depressional wetlands <1ha (from U.S. Fish and Wildlife Service 2000). initially stratified into reference (no obvious human modified landscapes within >100m), and impaired (obvious human landscape modification within 100m) categories. Site condition was independently assessed later with the LDI (Brown and Vivas submitted), as noted in the diatom methods section (Chapter 2: Site Selection and Agricultural Development Gradient). Slightly less than half the sites (35) were considered reference sites, generally located in state and federal parks, preserves, and state forests. Wetlands that comprised the remaining 40 sites were located within agricultural landscape matrices and were considered impaired sites (LDI > 2.0). Thirty impaired sites were located in cattle ranches of varying stocking densities, 7 in truck crops (tomatoes, peppers), 2 in citrus groves, and 1 was sampled in a silvicultural forest. Site coordinates and LDI score for each sampled wetland are found in Appendix A. All but five sites were hydrated when sampled.

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52 Field Data Collection Wetland macrophytes were identified and counted in 1m x 5m quadrats along four belt transects. Transects were laid out along each cardinal direction (North, South, East, West) beginning at the wetland edge and extending to the center of the wetland (Figure 3-2). The wetland/upland boundary was determined in the field through plant status (i.e., facultative, obligate, upland) from Tobe et al. (1998) and hydric soil parameters (see U.S. Department of Agriculture 1998). In 1999, the transects continued from the wetland edge until the center was reached or until 15m2 (3 consecutive quadrats) did not change in species composition. (Approximately 2% of the sites had transects not reaching the measured center of the wetland in 1999.) This was changed in 2000 to ensure full characterization of the wetland macrophyte community by collecting data along the entire length of each transect. The presence of living plants was noted within 0.5m along each side of the transect tape for each quadrat from the wetland edge to the center of the wetland. Unknown species were collected, labelled, and pressed for later identification by David Hall of the University of Florida. All collected species were stored in the Howard T. Odum Center for Wetlands herbarium. Figure 3-2. Transect and quadrat locations in a hypothetical depressional wetland.

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53 Drought conditions during 1999 and 2000 field seasons forced the sampling period to be both delayed in its onset and extended in duration to ensure hydration of the sampled wetlands (Table 3-2). Thus, some species encountered lacked the fruiting bodies, flowers, and other parts requisite for identification due to seasonal vagaries in reproduction or growth. All macrophytes found were identified to the lowest level possible, generally species, and entered into the database for further use in metric development. This study focused on taxa identified to species. Table 3-2. Sampling dates for each region. Region Earliest Date 1999 Latest Date 1999 Earliest Date 2000 Latest Date 2000 South Central North August 3 July 23 July 28 November 4 August 17 November 11 August 29 September 9 October 16 October 25 October 26 November 1 Database Development Field data sheets denoting presence of macrophytes within each 1m x 5m quadrat along each of the four transects were transcribed into Microsoft Excel spreadsheets and a Microsoft Access database and error-checked by two people: the person who originally transcribed the data into Microsoft Excel, and another person who reread the original datasheet back to the original transcriber who reviewed the Microsoft Excel output. A master plant list of all plants identified was developed, and ancillary species characteristics from the literature, as well as Coefficient of Conservatism scores (described below), were added to the list. The plant database was linked in such a way that all characteristics could be analyzed by site, transect, or quadrat. Species characteristics Plant species characteristics (listed in Table 3-3) were taken from the literature for use in developing biological indicators. The primary source for these data was Wunderlin (1998), but other sources were also consulted, including Godfrey and Wooten (1979, 1981), Tobe et al. (1998), and the internet-based Atlas of Florida Vascular Plants (Wunderlin and Hansen 2000). Table 3-3. Ancillary data added to the database for each plant species. Family Annual or perennial (biennial plants were incorporated in the annuals) Form: grass, sedge, rush, forbs, vine, fern, tree, shrub, aquatic Deciduous or evergreen Native or exotic Coefficient of Conservatism score

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54 Coefficient of Conservatism Ten expert botanists (Anthony Arcuri, Keith Bradley, Kathy Burks, David Hall, Ashley ONeal, Jim Poppleton, Nina Raymond, Bruce Tatje, John Tobe, and Wendy Zomlefer) were enlisted to assist in identifying species characteristics for use in developing a Coefficient of Conservatism score. The Coefficient of Conservatism (CC) was developed by Wilhelm and Ladd (1988) as part of the Floristic Quality Assessment Index, a method of assessing vegetation in the Chicago area based on expert botanists opinion on the fidelity of a plant species to particular environments. Since its inception, this method has been utilized to assess wetland condition based upon species present in numerous studies (Herman et al. 1997, Fennessey et al. 1998, Mack 2001, Mushet et al. 2002, Cohen et al. submitted). To determine CC scores, the botanists were sent the full list of species encountered during the two sampling seasons (n=397), and were asked to score the plants using the coefficients and definitions given in Table 3-4. The botanists were also asked to weight the confidence of their answers on a 1-3 scale (3 being the most confident). Subsequently, each botanists CC value for each plant was multiplied by each botanists confidence weight for that plant, increasing the proportional representation for extremely confident scores. The score for each plant after confidence weighting was summed and averaged across all botanists, and normalized to a 1-10 scale. See Cohen et al. (submitted) for additional information. Table 3-4. Scoring Criteria for the Coefficient of Conservatism. C of C Description 0 1 3 4 6 7 8 9 10 Alien taxa and those native taxa that are opportunistic invaders or common components of disturbed communities. Widespread taxa that are found in a variety of communities, including disturbed sites. Taxa that display fidelity to a particular community, but tolerant of moderate disturbance to that community. Taxa that are typical of well-established communities that have sustained only minor disturbances. Taxa that exhibit a high degree of fidelity to a narrow set of ecological conditions. Soil and Water Physical-Chemical Sampling and Analysis To relate the distribution of wetland macrophytes to environmental parameters, soil and water physical and chemical parameters were measured at each site as described in Chapter 2 (Methods: Field Data Collection, Sample Preparation and Laboratory Procedures) and Appendix B.

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55 Data Analyses Summary statistics Summary measures of sample richness, Shannon diversity, Simpson diversity, beta, and gamma diversity were calculated for each site and provided information on species distributions vis--vis land use as described in Chapter 2: Data Analyses. Macrophytes-compositional analysis While wetlands throughout peninsular Florida were sampled, the sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions (after Lane 2000, see Figure 3-1). Through examination of data at the regional level, it was expected that variations in species assemblages due to climatic or physiographic differences between sites within a given region would be minimized (Gerritsen et al. 2000, Smogor and Angermeier 2001). To test the significance of the modeled wetland regions on species distribution, a compositional test, the multiple response permutation procedures (MRPP,) available in PCOrd (MjM Software, Gleneden Beach, Oregon, version 4.10) and described in Chapter 2 (Methods: Site Selection and Agricultural Development Gradient), was used. Macrophyte composition and soil and water parameter correlates The following soil variables were arcsine square root transformed to decrease measured skewness and kurtosis in the dataset: %TN, %OM, and %TC. Log10 transformations were completed on soil TP, color, specific conductivity, turbidity, ammonia, nitrate/nitrite, TKN, and water TP for similar reasons. Multivariate colinearity among the environmental variables, described as strong correlations between independent variables (Zar 1999), was tested for using the variance inflation factor and tolerance, described in Chapter 2 (Methods: Data Analyses). The non-parametric Mann-Whitney U-test was used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). The relationship between measured environmental values (including LDI score) and species composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS, Kruskal 1974, Mather 1976), both available in PCOrd and described in Chapter 2 (Methods: Data Analyses). A two-dimension NMDS solution was selected for macrophyte taxa as increased dimensionality only marginally improved the fit. Correlations of site scores with environmental parameters, including LDI score and latitude and longitude (decimal degrees), were calculated and a bi-plot of parameters with correlations (Pearsons r 2 0.30) to site scores was constructed. Metric Development Macrophyte metrics were identified from the literature (e.g., Wilhelm and Ladd 1988, Adamus and Brant 1990, Andreas and Lichvar 1995, Adamus 1996, Kantrud and Newton 1996, Gernes and Helgen 1999, Cronk and Fennessy 2001, Mack 2001, Fennessy et al. 2001) or developed from iterative analyses of data response. Metrics were selected

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56 for inclusion in the preliminary Vegetative Index of Wetland Condition (VIWC) if they demonstrated a constant and predictable change with increasing Landscape Development Intensity (LDI) scores as measured by the Spearman correlation coefficient. Final metrics were those with significant (p<0.05) Spearmans correlations |0.50| with the LDI. Metrics were also tested for their ability to discern between the classification of sampled wetlands in impaired (LDI 2.0) and reference (LDI <2.0) landscapes using the nonparametric Mann-Whitney U-test. Additionally, to normalize wetlands of different sizes, metrics that incorporated the enumeration of species (such as the count of exotic species encountered at a site) were changed into abundance values by dividing the sum of the metric by the total number of plants identified to species at a site. All evaluations of potential metrics were conducted with SAS (SAS Institute, Cary N.C., version 8.02). Based on preliminary data analysis and the strength of the metric correlation with the LDI, the macrophyte metrics described below were selected for inclusion in each wetland region. Sensitive and tolerant species Indicator Species Analysis (ISA, Dufrene and Legendre 1997) was utilized to identify species with a significant association with LDI classification of impaired (LDI2.0) or reference conditions (LDI<2.0) as described in Chapter 2 (Metric Development). Exotic species The percent of total species exotic to Florida at a wetland site was calculated by dividing the number of exotic species encountered by the total number of species found at the site. Native or exotic plant status was determined using Tobe et al. (1998), Wunderlin (1998), Godfrey and Wooten (1979, 1981), Langeland and Burks (1998), and Wunderlin and Hansen (various dates 2000). In general, exotic species were those thought to have not been present in Florida before European settlement of North America. The abundance of exotic species was expected to increase with increasing development of the landscape surrounding the wetland (Fennessy et al. 2001). Annual to perennial ratio The ratio of annual to perennial (A:P) species was calculated for each wetland. The trend expected was that as development increased in a wetland landscape matrix, the proportion of weedy, or annual species versus perennial species would increase (Edwards and Weakley 2001). Life-history status (i.e., annual/perennial) was determined from the literature for each species identified, and a ratio was determined for each wetland. Average Coefficient of Conservatism To obtain an average CC score for each wetland sampled, the sum of the confidence weighted CC values for each plant found at the sampled wetland was divided by the total number of plants sampled. The resultant CC score provided an estimate of the

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57 conservatism of the plants encountered. As development increased within the wetland landscape matrix, the CC score for the wetland was expected to decrease, indicating the presence of both plants with more general habitat requirements and exotics. Vegetative Index of Wetland Condition To create a multi-metric index of wetland condition based on metrics that were strongly correlated with the LDI, it was necessary to score the proposed metrics. Scoring allows the disparate metrics (i.e., such as ratios and relative abundance metrics) to be summed to provide a numerical score for the condition of the wetland to compare vis--vis a set of reference wetlands within a given region (Karr and Chu 1997). Scoring methods are described in Chapter 2 (Methods: Constructing the Multimetric Index). Following the metric scoring, the Vegetative Index of Wetland Condition was determined for each wetland sampled by summing the scored metrics. Results Field Data Seventy-five herbaceous depressional wetlands throughout peninsular Florida were sampled in 1999 and 2000. Twenty-three were sampled in the South region, thirty in the Central region, and twenty-two in the North region. Based on the predominant land use around the wetland, twelve of the sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. Three hundred and ninety-seven different taxa from 207 plant genera representing 111 families were identified during the 1999 and 2000 field seasons. Two hundred twenty-six taxa were identified in the South region, 270 taxa were identified in the Central region, and 242 taxa were identified in the North region; many species were found in more than one region. Summary measures of sample richness, Shannon diversity, and Simpson diversity were calculated for each site (Brower et al. 1990). Summary statistics are presented in Table 3-5. Mann-Whitney U-tests indicated no significant difference between reference and impaired sites for richness, Shannon diversity, or Simpson diversity (all tests Z = -0.005, p = 0.996). Two additional indices were also calculated from the macrophyte data: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Beta and gamma diversity were higher in impaired sites than in reference sites (impaired sites average richness: 31.60, beta diversity: 9.81, gamma diversity: 310; reference sites average richness: 31.66, beta diversity: 8.18, gamma diversity: 259). Ancillary Data A histogram of the distribution of CC scores for the species identified is given in Figure 3-3. As the data were normalized, the mean of the distribution is 5.0, while the median value is 5.56, and the standard deviation is 2.57. The plant with the highest conservatism score (10) was Coelorachis tuberculosa. In general, exotic species and invasive native species were given scores of zero. However, several exotic species, such as Xyris jupicai (CC = 3.51), were given higher scores by the botanists, indicating a

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58 Table 3-5. Summary statistics of richness (S), Simpsons diversity index (H) and Shannon diversity index (D) for macrophytes. Site Name S H D` Site Name S H D` ALPaynes 28 3.332 0.9643 IRCanal 22 3.091 0.9545 Audobon 16 2.773 0.9375 IROJ 43 3.761 0.9767 Bear Scat 39 3.664 0.9744 JD6 33 3.497 0.9697 Big Cow 34 3.526 0.9706 Kelly Park 27 3.296 0.963 BRSebastian 24 3.178 0.9583 LCork 48 3.871 0.9792 CabPatch 34 3.526 0.9706 LLeeCounty 58 4.06 0.9828 Caravelle 22 3.091 0.9545 LEGo 41 3.714 0.9756 Chuluota 41 3.714 0.9756 LESuwan 42 3.738 0.9762 CLBayard 20 2.996 0.95 MALudy 54 3.989 0.9815 CLCove 34 3.526 0.9706 MASpray 24 3.178 0.9583 CMWPast 39 3.664 0.9744 McArthur 29 3.367 0.9655 CMWRef 21 3.045 0.9524 MNElmer 45 3.807 0.9778 COBurgle 16 2.773 0.9375 MNErik 38 3.638 0.9737 COHole 25 3.219 0.96 MNOcala 38 3.638 0.9737 Crew 31 3.434 0.9677 MRPepper 46 3.829 0.9783 DEMelon 41 3.714 0.9756 Myakka 35 3.555 0.9714 Deerfly 31 3.434 0.9677 OKCara 47 3.85 0.9787 GarberRanch 22 3.091 0.9545 OKKiss 37 3.611 0.973 GBarE 28 3.332 0.9643 OKPast 28 3.332 0.9643 GLDonut 24 3.178 0.9583 PacificTom 37 3.611 0.973 GLPont 20 2.996 0.95 Pall-Mar 17 2.833 0.9412 Goethe 24 3.178 0.9583 PBCorbett 33 3.497 0.9697 GreenSwamp 34 3.526 0.9706 PBEnjay 43 3.761 0.9767 HaRare 33 3.497 0.9697 Penner 14 2.639 0.9286 HagueI 27 3.296 0.963 POWales 18 2.89 0.9444 HagueII 21 3.045 0.9524 POWeowak 44 3.784 0.9773 Half Moon 37 3.611 0.973 PUPond 19 2.944 0.9474 HEBad 37 3.611 0.973 RiceCreek 16 2.773 0.9375 HEL2 18 2.89 0.9444 SANorthMya 31 3.434 0.9677 HEOKAY 46 3.829 0.9783 SAOscer 38 3.638 0.9737 HighPast 16 2.773 0.9375 SandhillCrane 35 3.555 0.9714 HighRef 23 3.135 0.9565 Savannas 41 3.714 0.9756 HillsRef 43 3.761 0.9767 STCow 40 3.689 0.975 Hunt Camp 26 3.258 0.9615 SUVaca 37 3.611 0.973 IFASI 26 3.258 0.9615 SUWarhol 33 3.497 0.9697 IFASII 27 3.296 0.963 UNHealthy 30 3.401 0.9667 Immokalee 26 3.258 0.9615 Wekiva 15 2.708 0.9333 IRBlueCypress 42 3.738 0.9762

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59 Figure 3-3. Normalized Coefficient of Conservatism Histogram for confidence weighted scores for wetland macrophytes. perceived higher fidelity to a narrower set of ecological conditions. A list of species identified and their corresponding CC scores is given in Appendix D. Compositional Analysis A matrix of the co-occurrence of identified species in the wetland regions of Florida is presented in Table 3-6. The co-occurrence of species found in reference and impaired sites for the three wetland regions are also given in Table 3-6. The South and North regions shared the fewest species, slightly more than half, while approximately 60% of the plants found in the Central region were also found in the North or South regions. The Central region was also most similar to the North and the South regions for both impaired and reference plants. Tests of compositional similarities between wetland regions (Lane 2000) were conducted using MRPP (Table 3-7). Significant differences in compositional similarity among wetland regions were identified for both simultaneous (i.e., South vs. Central vs. North) and iterative tests (i.e., South vs. Central, South vs. North, Central vs. North). When reference sites were compared, significant differences were also identified for both simultaneous and iterative tests. Tests of impaired sites indicated significant differences when simultaneously tested, however, iterative tests found only significant difference between impaired sites of the South and North regions at p<0.05. The iterative tests of impaired sites between all regions were significantly different at p<0.10.

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60 Table 3-6. Co-occurrence matrices of macrophytes by region and impairment condition. Condition Region South Central North All Sites South 100.0 %61.9 %52.3 % (n=75) Central 73.4 %100.0 %66.9 % significant lower in reference conditions at p<0.10. North 56.6 %60.0 %100.0 % Reference South 100.0 %54.4 %47.8 %(n=35) Central 58.1 %100.0 %65.7 % North 43.2 %55.7 %100.0 % Impaired South 100.0 %58.2 %47.9 %(n=40) Central 67.9 %100.0 %55.8 % North 56.2 %56.1 %100.0 % Table 3-7. Simultaneous and iterative tests of community composition among regions. Test Comparison A T p-value Simultaneous Tests: All Sites S vs. C vs. N 0.0211 -6.235 < 0.001 Simultaneous Reference Only S vs. C vs. N 0.0502 -7.198 < 0.001Simultaneous Impaired Only S vs. C vs. N 0.0176 -3.137 0.005 Iterative S vs. C 0.0120 -3.330 0.010Tests: S vs. N 0.0323 -8.066 < 0.001All Sites C vs. N 0.0075 -2.156 0.039 Iterative S vs. C 0.0300 -4.156 0.001Tests: S vs. N 0.0690 -7.492 < 0.001Reference Only C vs. N 0.0204 -2.961 0.010 Iterative S vs. C 0.0094 -1.703 0.060Tests: S vs. N 0.0022 -3.096 0.009Impaired Only C vs. N 0.0110 -1.873 0.050 Note : S = South region, C = Central region, N = North region Community Composition and Environmental Gradients Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in the Appendix B. Significant differences between impaired and reference conditions, as measured by the MannWhitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 3-8). Water color was

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61 Table 3-8. MRPP comparison of the median values of water and soil variables between reference and impaired sites. Water Values Statistic (Z) p-value Color -1.868 0.066 Specific Conductivity -3.919 < 0.001 Turbidity -1.524 0.127 Water pH -4.700 < 0.001 Ammonia -2.707 0.007 Nitrates/Nitrites 0.782 0.437 TKN -2.932 0.003 TP -4.836 < 0.001 Soil Values Statistic (Z) p-value Soil pH -2.894 0.004 %TC -0.616 0.538 %OM -1.105 0.269 %TN -0.924 0.356 %TP -2.719 0.008 Colinearity among variables, which was identified as a VIF>5.0 and a tolerance of <0.20, was recognized for %TC, TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the identified macrophytes and the measured environmental parameters, including LDI score. Results indicated a strong and significant relationship (Mantels r = 0.49, p=0.001). An NMDS ordination was completed to examine the underlying structure of the sites in ordination space and to ascertain the environmental variables driving the composition of sites sampled. Correlations for all measured environmental variables are presented in Table 3-9, and a biplot of site ordination overlaid with vectors representing the environmental variables is presented in Figure 3-4. The stress, or goodness of fit of the ordination was 21.11 and indicated a marginally adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). Likewise, the final instability after 400 iterations was 0.00399, which was higher than the ideal instability (<0.001) but nevertheless a generally acceptable instability value (McCune and Grace 2002). The ordination indicated that 74.5% of the variance in the dataset was captured by the two dimensional ordination (first axis: 42.5%, second axis:33.0%). The ordination scores for each site were linearly correlated (Pearsons r) with the measured environmental values, including LDI, latitude, and longitude. Correlations (Pearsons r2) > 0.30 were found for LDI: 0.66, soil pH 0.57, water TP: 0.48, latitude: 0.39, and specific conductivity: 0.33, indicating their importance in driving the structure of the wetland macrophyte community.

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62 Table 3-9. Correlations of environmental variables and ordination scores. Axis 1 (42.5%) Axis 2 (33.0%) Parameter r2 tau r2 tau Soil pH 0.14 0.26 0.57 0.57 % TN <0.01 0.14 0.16 -0.21 TP (mg/kg) 0.20 0.32 0.05 -0.13 % OM 0.02 0.14 0.22 -0.27 Color (PCU) 0.11 0.21 0.08 -0.17 Spec. Cond. (umhos/cm) 0.33 0.40 0.10 0.23 Turbidity (NTU) 0.07 0.15 0.01 -0.05 Ammonia (mg/L) 0.07 0.24 0.03 -0.07 Nitrate/Nitrite (mg/L) <0.01 -0.05 0.05 -0.20 Water TP (mg/L) 0.48 0.52 <0.01 -<0.01 LDI Score 0.66 0.56 0.11 0.22 Latitude (decimal degrees) 0.01 0.07 0.39 -0.45 Longitude (decimal degrees)0.01 0.04 0.03 -0.14 Metric Development Significant regional differences were identified in species composition, hence initial metric development focused on identifying regionally specific bioindicators with strong correlations with the LDI. It was anticipated that due to the regionally distinct composition of the isolated depressional herbaceous wetlands, the final metrics would likewise vary for each region. However, though the composition of the wetlands varied between regions, the suite of final metrics that had significant correlations with p-values <0.05 and Spearmans correlation coefficients of r >|0.50| with the LDI gradient (% Sensitive, % Tolerant, % Exotic, Average CC, and A:P ratio) did not vary, indicating a common response of wetland systems to increases in land use development. Sensitive and tolerant species Indicator species analysis (ISA) identified 39 taxa as indicative of reference conditions and 26 taxa as indicative of impaired conditions (Tables 3-10 and 3-11, respectively). Thirty-four were identified in the South region (22 reference, 12 impaired), 45 in the Central region (27 reference, 18 impaired), and 8 in the North region (2 reference, 6 impaired). Correlations of the abundance of species indicative of reference conditions (% Sensitive) and impaired conditions (% Tolerant) with the LDI were significant (p<0.001) and >|0.70| for all regions (Table 3-12). There was moderate overlap of indicator species between regions, with 33.9% (22/65) occurring in more than one region.

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63 Figure 3-4. Biplot of macrophyte NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of original length for clarity. The percent variance explained by each axis is noted on the axis. The length of the vectors represents the strength of the correlation (all >|0.30|) and the angle represents the direction of maximum change. Five variables are shown: soil pH, Cond (specific conductivity), water TP, latitude, and LDI. ISA was also used to identify species with specificity and fidelity to reference and impaired conditions using the peninsular dataset (n=75). While compositional differences existed between regions, it was hypothesized that some taxa would be robust indicators throughout peninsular Florida. It was also hypothesized that increasing the n of the dataset would provide additional power in identifying indicator species. Forty-six species were identified as reference indicator species and 36 were identified as impaired indicators using the peninsular dataset (Tables 3-13 and 3-14, respectively). There was substantial overlap between regional and peninsular indicator species. Three regional impaired indicator species (South Region: Axonopus furcatus, Central Region:

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64 Table 3-10. Regionally derived species indicative of reference conditions. Reference Indicator Species (Sensitive Species) South Central North Amphicarpum muhlenbergianum (50.1, 0.074) Andropogon virginicus (49.9, 0.010) (61.1, 0.019) Aristida purpurascens (38.5, 0.007) Blechnum serrulatum (47.3, 0.026) Cassytha filiformis (27.3, 0.095) Cladium jamaicense (38.4, 0.070) Eriocaulon decangulare (41.8, 0.086) (69.2, <0.001) Eupatorium leptophyllum (36.4, 0.039) Fuirena scirpoidea (62.7, <0.001) Gratiola ramosa (45.5, 0.015) (38.5, 0.011) Hedyotis uniflora (23.1, 0.074) Hypericum brachyphylum (38.5, 0.008) Hypericum fasciculatum (41.8, 0.088) (61.5, <0.001) Ilex glabra (27.3, 0.087) (38.5, 0.009) Ipomoea sagittata (27.3, 0.090) Iva microcephala (27.3, 0.096) Lachnanthes caroliniana (44.5, 0.062) (49.5, 0.084) Ludwigia linifolia (30.8, 0.027) Lycopodium appressum (27.3, 0.087) Lyonia lucida (23.1, 0.071) Oxypolis filiformis (38.4, 0.069) Panicum erectifolium (85.7, <0.001) (48.5, 0.005) Panicum rigidulum (38.4, 0.069) (30.8, 0.026) Panicum spretum (23.1, 0.073) Panicum tenerum (48.5, 0.005) Paspalum monostachyum (27.3, 0.090) Pinus elliottii (54.5, 0.003) (73.6, 0.002) Proserpinaca pectinata (66.7, <0.001) Rhynchospora fascicularis (23.1, 0.070) Rhynchospora filifolia (36.4, 0.037) (30.8, 0.028) Rhynchospora tracyi (50.4, 0.037) (40.9, 0.027) Scleria baldwinii (23.1, 0.077) Serenoa repens (53.8, 0.001) Stillingia aquatica (45.5, 0.015) Syngonanthus flavidulus (33.4, 0.056) Utricularia purpurea (23.1, 0.072) Woodwardia virginica (58.9, 0.007) Xyris elliottii (23.1, 0.068) Xyris jupicai (38.4, 0.066) (38.5, 0.009) Note: Calculated indicator values and the significance of the indicator value for each species, respectively, are given in parentheses.

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65 Table 3-11. Regionally derived species indicative of impaired conditions. Impaired Indicator Species (Tolerant Species) South Central North Alternanthera philoxeroides (36.4, 0.090) Axonopus furcatus (33.3, 0.087) Bacopa monnieri (41.7, 0.036) Centella asiatica (64.3, 0.002) Commelina diffusa (50, 0.014) (41.2, 0.01) Cuphea carthagenensis (50, 0.013) (41.2, 0.010) Cyperus haspan (40.4, 0.036) Cyperus odoratus (41.2, 0.009) Cyperus polystachyos (58.8, 0.001) (45.5, 0.034) Cyperus surinamensis (29.4, 0.050) Diodia virginiana (70.6, <0.001) (46.8, 0.062) Eclipta prostrata (52.9, 0.003) Eupatorium capillifolium (42.2, 0.072) Hydrochloa caroliniensis (33.3, 0.093) Juncus effusus (75.3, <0.001) (54.5, 0.011) Lindernia grandiflora (33.3, 0.090) Ludwigia octovalvis (33.3, 0.092) Ludwigia peruviana (33.3, 0.095) (41.2, 0.010) Panicum repens (41.2, 0.009) Paspalum notatum (41.2, 0.010) Paspalum urvillei (41.2, 0.010) (36.4, 0.086) Phyla nodiflora (42.3, 0.070) (47.1, 0.010) Polygonum hydropiperoides (52.9, 0.088) Polygonum punctatum (47.3, 0.099) (41.2, 0.010) Pontederia cordata (68.7, 0.005) Setaria parviflora (41.7, 0.040) (29.4, 0.050) Note: Calculated indicator values and the significance of the indicator value for each species, respectively, are given in parentheses. Table 3-12. Spearman correlations of the adundance of regional sensitive and tolerance macrophyte species with LDI scores for each site. Region Comparison Spearmans r p-value South % Sensitive Spp. -0.75 < 0.001 % Tolerant Spp. 0.72 < 0.001 Central % Sensitive Spp. -0.77 < 0.001 % Tolerant Spp. 0.78 < 0.001 North % Sensitive Spp. -0.73 < 0.001 % Tolerant Spp. 0.86 < 0.001

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66 Table 3-13. Indicator species of reference conditions derived from the peninsular dataset. Reference Indicator Species (Sensitive Species) Observed Ind. Val.pvalue Reference Indicator Species (Sensitive Species) Observed Ind. Val.p-value Amphicarpum muhlenbergianum 37.5 0.023 Panicum rigidulum 27.1 0.004 Andropogon virginicus 56.2 <0.001 Panicum tenerum 29.3 0.007Aristida purpurascens 22.6 0.034 Paspalum monostachyum 8.6 0.097Brasenia schreberi 11.4 0.043 Paspalum praecox 8.6 0.100Drosera capillaris 11.4 0.042 Pinus elliottii 47.7 <0.001Eriocaulon decangulare 39.3 <0.001 Proserpinaca pectinata 47.6 <0.001Fuirena scirpoidea 39.8 0.007 Rhexia mariana 30.5 0.009Gratiola ramosa 28.6 <0.001 Rhexia nashii 8.6 0.097Hypericum brachyphylum 24.3 0.011 Rhynchospora filifolia 22.9 0.002Hypericum fasciculatum 44.0 <0.001 Rhynchospora rariflora 14.3 0.019Ilex glabra 29.1 <0.001 Rhynchospora tracyi 29.3 0.005Iva microcephala 11.4 0.046 Rhynchospora wrightiana 8.6 0.098Lachnocaulon anceps 8.6 0.094 Scleria baldwinii 12.2 0.089Lachnanthes caroliniana 37.0 0.007 Scleria reticularis 30.4 0.024Lachnocaulon minus 11.4 0.040 Serenoa repens 30.9 0.002Ludwigia linifolia 18.8 0.036 Stillingia aquatica 14.3 0.019Lycopodium appressum 11.4 0.040 Syngonanthus flavidulus 19.9 0.059Nymphaea odorata 19.9 0.089 Utricularia purpurea 12.2 0.094Nyssa biflora 16.0 0.076 Viola lanceolata 8.6 0.099Oxypolis filiformis 22.6 0.029 Woodwardia virginica 38.4 0.002Panicum chamaelonche 12.2 0.094 Xyris elliottii 17.8 0.025Panicum erectifolium 45.3 <0.001 Xyris jupicai 27.1 0.005Panicum hemitomon 52.5 0.027 Xyris smalliana 16.0 0.073 Note : Taxa marked () were not significant indicator species at the regional level. Calculated indicator values and the significance of the indicator value for each species are also presented. Eupatorium capillifolium, and North Region: Polygonum hydropiperoides), all of which have a statewide distribution (Tobe et al. 1998), were not calculated to be peninsularwide indicator species. Nine regional reference indicator species (South Region: Blechnum serrulatum, Cassytha filiformis, Cladium jamaicense, Eupatorium leptophyllum, and Ipomea sagittata, Central Region: Hedyotis uniflora, Lyonia lucida,Panicum spretum, and Rhyncospora fascicularis), all of which have statewide distributions (with the exception of Cassytha filiformis, which is limited to south and central Florida Wunderlin 1998, Tobe et al. 1998), were not significant indicator species using the peninsular dataset. However, 88.5% (23 of 26) of the regional impaired indicator species and 76.9% (30 of 39) of the regional reference indicator species were also indicator species with the peninsular dataset. The additional power from combining the regional data into a peninsular dataset also allowed for an additional 17 species to be identified as indicator species of reference (7 species) or impaired (10 species) conditions (noted in Tables 3-13 and 3-14).

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67 Table 3-14. Indicator species of impaired conditions derived from the peninsular dataset. Impaired Indicator Species (Tolerant Species) Observed Ind. Val.pvalue Impaired Indicator Species (Tolerant Species) Observed Ind. Val. pvalue Alternanthera philoxeroides 20.0 0.007 Kyllinga brevifolia 12.5 0.058 as the number of reference and impaired sites sampled was not equal for the regions (South reference = 11, Central reference = 13, North reference = 11; South impaired = Aster subulatus 27.4 0.002 Lindernia grandiflora 20.0 0.007 Bacopa monnieri 21.7 0.086 Ludwigia octovalvis 24.9 0.005 Carex albolutescens 12.5 0.059 Ludwigia peruviana 35.0 <0.001 Centella asiatica 43.4 0.032 Ludwigia repens 33.4 0.014 Commelina diffusa 39.8 <0.001 Melochia corchorifolia 12.5 0.058 Cuphea carthagenensis 37.3 <0.001 Panicum repens 32.4 0.006 Cynodon dactylon 12.5 0.057 Paspalum acuminatum 20.0 0.015 Cyperus haspan 24.0 0.052 Paspalum notatum 30.0 0.004 Cyperus odoratus 20.0 0.006 Paspalum urvillei 24.9 0.003 Cyperus polystachyos 45.0 <0.001 Phyla nodiflora 37.3 <0.001 Cyperus retrorsus 12.5 0.055 Polygonum punctatum 38.3 <0.001 Cyperus surinamensis 20.0 0.006 Pontederia cordata 43.4 0.057 Diodia virginiana 53.8 <0.001 Sacciolepis striata 26.7 0.080 Eclipta prostrata 30.0 <0.001 Sesbania herbacea 15.0 0.029 Galium uniflorum 12.5 0.060 Setaria parviflora 25.0 <0.001 Hydrochloa caroliniensis 24.0 0.050 Thelypteris interrupta 12.5 0.058 Juncus effusus 52.3 <0.001 Typha latifolia 12.5 0.056 Note : Taxa marked () were not significant indicator species at the regional level. Calculated indicator values and the significance of the indicator value for each species are also presented. Using the peninsular indicator species (n=82 species), the abundance of indicator species for both reference (% Sensitive) and impaired (% Tolerant) conditions was calculated for each site and correlated with the LDI. A plot of the relationship between LDI score and % Sensitive and % Tolerant species are presented in Figures 3-5 and 3-6, respectively. The Spearmans correlation coefficients were significantly and highly correlated with the LDI (% Sensitive r = -0.76, p<0.001; % Tolerant r = 0.75, p<0.001). The abundance of sensitive taxa plotted in Figure 3-5 suggested a relatively accurate and precise distribution, with fair goodness of fit. There was substantial variation in the data for sites with LDI scores of approximately 1.0, but a noticeable and linear decreasing trend with increasing LDI values was evident. Distribution of the % Tolerant data indicated a low correlation between the LDI and the % Tolerant until LDI scores of approximately 3.5. At that point, substantial variation in the dataset was evident, with abundance values ranging from approximately 10% to 75%. The peninsular dataset was utilized to identify the proposed bioassessment metrics. The apparent advantage of utilizing the peninsular dataset lay in the higher number of significant indicator species identified for community condition assessment and the strength and significance of the correlations with the LDI. The combined dataset provided 48 additional indicator species in the South region, 37 additional indicators in the Central region, and 74 additional significant indicators in the North region. However,

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68 Figure 3-5. Abundance of sensitive species along the disturbance gradient. Figure 3-6. Abundance of tolerant species along the disturbance gradient.

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69 12, Central impaired = 17, North reference = 11), Kruskal-Wallis tests were employed to ensure that the median abundance of sensitive and impaired indicators were equal for each region. The Kruskal-Wallis test null hypothesis was equal medians for all groups. Unequal medians would indicate a regional bias in the distribution of indicator species Whitney U-test Z= -5.379, p<0.001). Median values between regions did not differ and likely predispose a reference or impaired site in a particular region to lower assessment values vis--vis reference or impaired sites in the other regions. No significant difference in median values between regions for either % Sensitive or % Tolerant species were identified using the Kruskal-Wallis test (% Sensitive H=0.076, p=0.963, % Tolerant H=1.598, p=0.450). Thus, the abundance of sensitive and tolerant species identified using ISA and the peninsular dataset were selected as metrics. Table 3-15. Exotic taxa encountered and region(s) of occurrence. Exotic Species S C N Exotic Species S C N Aeschynomene indica Alternanthera philoxeroides Alternanthera sessilis Alternanthera tenella Amaranthus blitum Amaranthus spinosus Caperonia palustris Chenopodium ambrosioides Cuphea carthagenensis Cynodon dactylon Cyperus lanceolatus Desmodium triflorum Digitaria bicornis Echinochloa colona Echinochloa crusgalli Eichhornia crassipes Eleusine indica Eragrostis atrovirens Fimbristylis miliacea Gomphrena serrata Hedyotis corymbosa Hymenachne amplexicaulis Ipomoea quamoclit Kyllinga brevifolia Ludwigia peruviana Lygodium microphyllum Macroptilium lathyroides Melaleuca quinquenervia Melochia corchorifolia Mollugo verticillata Murdannia keisak Murdannia nudiflora Panicum maximum Panicum repens Paspalum acuminatum Paspalum notatum Paspalum urvillei Phyllanthus urinaria Polygonum lapathifolium Portulaca amilis Richardia scabra Sacciolepis indica Salvinia minima Schinus terebinthifolius Scleria vaginata Senna occidentalis Solanum viarum Sporobolus indicus Urena lobata Verbena bonariensis Xyris jupicai Percent exotic Fifty-one exotic species were identified throughout peninsular Florida (Table 3-15). Exotics, which included pasture grasses planted for forage, were significantly more abundant in impaired conditions than in reference conditions (peninsular dataset, Mann-

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70 (Kruskal-Wallis H = 0.740, p=0.691), nor were significant differences identified when the abundance of exotic species was compared between regions for both impaired sites (Kruskal-Wallis H=0.247, p=0.884) and reference sites (Kruskal-Wallis H=0.998, p=0.607). The abundance of exotic species was significantly correlated with the LDI in each region (Spearmans r: South = 0.71, p=<0.001; Central = 0.54, p=0.002; North = 0.74, p<0.001). The Spearman correlation coefficient was also calculated for the abundance of exotic species and the LDI using the peninsular data set (Spearmans r = 0.67, p<0.001, Figure 3-7). The abundance of exotic taxa appeared to not be strongly correlated with increases in LDI value until a threshold of approximately 3.5 was reached. Many sites before LDI values of approximately 3.5 appeared to have background values for exotic taxa of less than 10%, suggesting a nearly universal distribution of exotic taxa throughout Florida. Near LDI values of 3.5, however, marked increases in the abundance of exotic taxa suggested a threshold value had been crossed, although substantial variation in the dataset remained. Figure 3-7. Abundance of exotic taxa at each site along the disturbance gradient. Annual to perennial ratio The median annual to perennial ratio was significantly higher in impaired conditions versus reference conditions for the peninsular dataset (Mann-Whitney U-test Z = -5.122, p<0.001). The correlation between the A:P ratio and the LDI was significant

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71 when the peninsular dataset was examined (Spearmans r = 0.65, p< 0.001, Figure 3-8). Spearmans correlation coefficient between the A:P ratio and the LDI was also significant for each region: South r = 0.60, p=0.002; Central r = 0.69, p<0.001; North r = 0.65, p=0.001. The median value for the A:P ratio did not differ between regions (KruskalWallis H = 0.938, p=0.626), nor did median values differ between regions for reference conditions (Kruskal-Wallis H = 2.130, p=0.344) or impaired conditions (Kruskal-Wallis H = 0.114, p=0.945). Variance in the A:P ratio dataset, as well as sensitivity and accuracy appeared to be minimal until a threshold value of approximately 3.2 was passed. At that point, the ratio increased, as did the variance in the data. Figure 3-8. Annual to perennial ratio at each site along the disturbance gradient. Average Coefficient of Conservatism Significant differences in the median CC value between reference and impaired conditions using the peninsular dataset were identified (Mann-Whitney U-test Z = 6.510, p< 0.001). A significant correlation was calculated between the peninsular dataset average CC and the LDI score (Spearmans r = -0.78, p< 0.001, Figure 3-9). Median values between regions were not significantly different (Kruskal-Wallis H = 0.501, p= 0.778). Kruskal-Wallis tests also indicated that the median average CC value did not differ between regions for reference sites (H = 0.501, p= 0.778) or impaired sites (H = 0.140, p= 0.932). Significant (Spearmans r) correlations between the LDI and the average CC were identified for each region (South r = -0.74, p< 0.001; Central r = -0.75, p< 0. 001, North r = -0.76, p< 0.001). The average CC appeared to be sensitive to increases in LDI value once a threshold of approximately 3.0 was passed. Marked

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72 increases in variance within the dataset followed, although in general a trend of decreasing average CC values continued. Figure 3-9. Average Coefficient of Conservatism value for each site along the disturbance gradient. Vegetative Index of Wetland Condition The Vegetative Index of Wetland Condition (VIWC) was calculated for each site by scoring the 95th percentile of each metric based on the peninsula dataset (n=75). The peninsular dataset was utilized as no significant regional effects were found in the distribution of the five metrics between reference and impaired conditions, as previously described. The 95th percentile and the scoring breaks for each metric are given in Table 3-16, and the scores for each site and metric are given in Table 3-17. The scored metrics were summed to calculate the VIWC. The relationship between the LDI and the VIWC for each site is presented in Figure 3-10. The VIWC ranged from 0 (the lowest score Table 3-16. Quadrisect values and 95th percentile for metric scoring. Metric 95th Percentile 0 Scores 3 Scores 7 Scores 10 Scores % Sensitive Spp. 0.5834 < 0.0820 0.0820 0.2308 > 0.2308 0.4474 > 0.4474 % Tolerant Spp. 0.6321 > 0.3723 > 0.1081 0.3723 0.0597 0.1081 < 0.0597 % Exotic Taxa 0.2742 > 0.1198 > 0.0385 0.1198 0.0001 0.0385 0 A:P Ratio 0.3105 > 0.1231 > 0.0625 0.1231 0.0352 0.0625 < 0.0352 Average CC 6.352 < 3.7015 3.7015 5.4085 > 5.4085 5.8874 > 5.8874

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73 Table 3-17. Site scores for each metric and the summed VIWC. Site % Sensitive% Tolerant % Exotic Spp. Average CC A:P Ratio VIWC ALPaynes 7 710107 41 Audobon 3 0000 3Bear Scat 3 7101010 40Big Cow 0 3330 9BRSebastian 10 103107 40CabPatch 3 3337 19Caravelle 3 3337 19Chuluota 7 107107 41CLBayard 7 1010710 44CLCove 0 0000 0CMMPas 7 7101010 44CMWRef 7 3101010 40COBurgle 0 0030 3COHole 3 71037 30Crew 10 77103 37DEMelon 3 0000 3Deerfly 7 10773 34Garber 3 03310 19GbarE 0 0030 3GLDonut 0 3003 6GLPont 0 0000 0Goethe 10 71077 41GreenSwamp 10 1010710 47HaRare 0 0000 0HagueI 0 3000 3HagueII 0 0000 0HalfMoon 7 7101010 44HEBad 0 0000 0HEL2 0 0000 0HEOKAY 7 3373 23HighRef 7 71077 38HighPast 0 0003 3HillsRef 10 710710 44Hunt Camp 10 101077 44IFAS I 3 371010 33IFAS II 7 107107 41Immokalee 10 71077 41IRBlueCypress 3 0333 12IRCanal 0 0000 0IROJ 0 0030 3JD6 10 1071010 47

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74 Table 3-17. Continued. Site % Sensitive% Tolerant% Exotic Spp. Average CC A:P Ratio VIWC Kelly Park 3 31030 19 Lcork 7 7773 31LLeeCounty 7 7333 23LEGo 7 310710 37LESuwan 3 31077 30MALudy 3 0000 3MASpray 7 31037 30McArthur 3 0300 6MNElmer 3 3733 19MNErik 7 7333 23MNOcala 7 710710 41MRPepr 3 3033 Myakka 10 310107 OKCara 3 0030 6OKKiss 10 710107 44OKPast 3 0333 12PacTom 0 0003 3Pall-Mar 5040Penner 10 10101010 50POWales 101040POWeowak 1010107 4710 33 10 737330SANorthMya 107377 31SandhillCrane 3 3330 12Savannas 10 1071010 47STCow 0 0000 0SUVaca 7 1010710 44SUWarhol 0 3000 300 010 12 40 10 10 10 10 10 PBCorbett 10 7 7 10 3 37 PBEnjay 10 10 7 10 3 10 3 7 10 PUPond 10 10 36 RiceCreek 10 3 10 40 SAOscer 7 7 UNHealthy 0 0 0 Wekiva 10 10 10 10 50 possible) to 50 (the highest possible score), with 9 sites scoring 0 and 3 scoring 50. The nine low-scoring sites were all located in cattle pastures with high densities (C. Lane, personal observation) in the South (3 sites), Central (3 sites), and North (3 sites) regions. The three high-scoring sites were also evenly distributed with one in each region: South (on conservation lands owned by the South Florida Water Management District), Central (in a state park), and North (in a national forest). The VIWC was significantly correlated to the LDI score (Spearmans r = -0.75, p< 0.001) and was significantly different between reference and impaired classes (Mann-Whitney U-test Z = 6.496, p< 0.001). No difference between regions was found for the summed VIWC (Kruskal-Wallis H = 0.865,

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75 p= 0.649), nor between regions and impaired sites (Kruskal-Wallis H = 0.438, p= 0.804) or between regions and reference sites (Kruskal-Wallis H = 4.534, p= 0.104). As in the metrics that comprised the VIWC, variance within the dataset appeared to be manifested most strongly at approximate LDI values of 3.5. In addition, higher variance than was expected was also evident at LDI values of approximately 1.0, based on the distribution of the metric values that comprised the VIWC. Figure 3-10. The relationship between the VIWC and the LDI. Discussion Correlations between metrics and LDI scores suggested landscape modification affected that the composition and structure of the wetland flora, although the variance in the dataset was substantial, especially for LDI values near 3.5. Five metrics were correlated >|0.50| with the LDI: abundance of sensitive and tolerant taxa, abundance of exotic taxa, annual to perennial ratio, and average coefficient of conservatism score. The VIWC, which combines the macrophyte metrics into a single value, defined the condition of each wetland such that the lowest scoring wetlands tended to have the highest landscape development intensity scores, while the wetlands with the highest VIWC scores were in areas with lower LDI values. Environmental Gradients and Species Distributions Macrophytes respond strongly to anthropogenic modifications of wetland ecosystems and surrounding landscapes (Doherty et al. 2000, Adamus et al. 2001), including alterations in community composition due to hydrology (van der Valk 1981, David 1996), nutrient loading (Koch and Reddy 1992, Doren et al. 1997, Bedford et al. 1999), physical/chemical alteration (Latham et al. 1994, Adamus et al. 2001),

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76 sedimentation (Waldrop and Brooks 1998), and other factors such as selective herbivory (Reader and Craft 1999), trampling (Blanch and Brock 1994), or modification of fire regime (Bayley and Odum 1976, Winchester et al. 1985, Newman et al. 1998). The wetlands sampled in this study were subjected to a myriad of anthropogenic composition was also correlated with ordination scores. The Florida peninsula, which juts modifications, with the strongest gradient being of increased agricultural land use intensity and associated nutrient loading and chemical modification, along with hydrologic alterations and herbivory/trampling. These vectors of disturbance were manifested by significant differences between the constituents measured (Table 3-8). Five measured constituents or calculated values were of particular importance in driving community structure based on the relationship (Pearsons r2 > 0.30) between the NMDS ordination scores and the LDI, site soil pH, water TP, specific conductivity, and latitude (Table 3-9). Macrophyte composition was most strongly correlated with the LDI score, which is an agglomerative disturbance index capturing landscape modification due to altered hydrology, nutrient loading, and predicted agrochemical application and other disturbances associated with various land uses (Brown and Vivas submitted). As the LDI captures many disturbance vectors, the strength of the relationship between macrophyte distribution and LDI score was not surprising. The ordination results buttress the use of GIS-based independent measures of general impairment, such as the LDI, in identifying modifications to landscapes and predicting wetland community condition (Johnson 1994, Adamus and Bergman 1995, Roth et al. 1996, Miller et al. 1997, Cuffney et al. 2000, 106 Carpenter and Waite 2000, OConner et al. 2000, Munn et al. 2002, Fore and Grafe 2002, Fore 2003). The strength of the relationship between site ordination structure and the LDI also supported the metrics developed with the LDI as the abscissa, or measured disturbance gradient. The ordination scores were also correlated with soil pH, specific conductivity, and water TP. Wetlands are generally low-lying landscape features, which predisposes these ecosystems to down-slope accumulations of nutrients from cattle grazing (Reddy et al. 1998) and crop and citrus agrochemical application and drift (Euliss and Mushet 1999, Anderson and Vondracek 1999). In a south-central Florida study by Graetz and Nair (1995), nutrient augmentation through fertilizers and cattle wastes in pastureland soils augmented background levels, such that approximately 40% of the phosphorous became bioavailable (labile), whereas only 2% was bioavailable in native areas. These massive loading rates may allow nutrients to be moved directly or indirectly into wetland systems from overland or interstitial flow, and can be manifested by drastic alterations in wetland community composition (Craft et al. 1995, Newman et al. 1998, Mitsch and Gosselink 2000). Beyond altering species composition in wetland systems directly down-slope of anthropogenic land uses, sufficient nutrient loading of wetland systems can occur such that wetlands, rather than being nutrient sinks (Flaig and Reddy 1995), may end up as nutrient sources for water bodies farther down-slope including wetlands, streams, and lakes (Agami et al. 1990). Alterations in soil pH, specific conductivity, and available nutrients, among other changes, may be indicative of wetland loading from agrochemical fertilizers and cattle wastes (Fore and Grafe 2002, U.S. EPA 2002e). In addition to the LDI and physical/chemical determinants of community composition from the NMDS ordination, a latitudinal gradient affecting species

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77 into the Gulf of Mexico and Atlantic Ocean, is tempered from climatic extremes by the heat absorbing/desorbing nature of water. This protects many species that have evolved in south Floridas sub-tropical environment. Northern Florida, however, is somewhat exposed to the temperate climate of mainland North America, with many freezing days considered to have optima within the range of environmental conditions often found in and different precipitation patterns than southern Florida (Fernald and Purdum 1998). As suggested by significant compositional differences (Table 3-7) between wetland macrophytes of northern, central, and southern Florida, different species have autecological requirements associated with latitudinal changes. Metric Development The results suggested that while macrophytes responded to increased development intensity, as measured by increased LDI values, substantial variance was evidenced by the five metrics that comprised the VIWC. In addition, the metrics appeared to be marginally sensitive to changes in LDI values until an LDI score of approximately 3.5 was reached. Throughout peninsular Florida, the metrics appeared able to approximate the condition of the sampled wetlands along increases in landscape modification, however, the substantial variance within each of the metric values, especially after LDI values of approximately 3.5, indicated that additional information relating the plant metrics to the landscape metrics was required to more fully understand the relationship between plant metrics and landscape development. The results of the analysis for each of the final metrics are described below. Sensitive and tolerant species It is generally accepted that most organisms have autecological optima, or environmental conditions most suited for the highest possible productivity and/or fitness (Ricklefs 1990, Gaiser et al.1998, Stevenson et al. 1999, U.S. EPA 2002e). These conditions can include adequate water, nutrients, photoperiod, and temperature. A hypothetical gradient (Figure 3-11) is thus likely to exist for each species. As optima exist, there are likewise extremes where conditions are unfavorable for growth, let alone survival, for species not adapted to the environment. Environmental extremes can include altered salinity, pH, hydropatterns, nutrients, physical disturbances, chemical disturbances, anoxia, or photoperiod. In this study, the environmental conditions generally found at reference sites were significantly different in many physical/chemical constituents than those found in impaired sites (Table 3-8). A review of the literature suggests that other constituents of the soil and water, such as metals or pesticides/herbicides, likely differ between reference and impaired conditions (Purvis et al. 1991, Euliss and Mushet 1999, Mitsch and Gosselink 2000). Likewise, though not quantified, pressures associated with browsing and selective grazing were likely significantly different in reference than in impaired conditions. The abiotic and biotic factors listed above could be considered to define the range of environmental conditions acceptable for the plants identified in this study. The LDI was utilized in Indicator Species Analysis as an analog for the acceptable environmental conditions of various species. Species with significant fidelity and specificity to low LDI scores were thus

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78 Figure 3-11. Environmental optima along a hypothetical environmental gradient. reference sites. Those species indicative of higher LDI values were conversely considered to have optima within the range of conditions expressed by impaired sites. It is beyond the scope of this research to explore the autecologies of the sensitive and tolerant plants listed in Tables 3-13 and 3-14 further, but the significance of the relationship suggests proclivities towards particular environmental conditions for those indicator macrophytes. In this study, Indicator Species Analysis was able to discern 82 plants with fidelity and specificity to a particular landscape development condition throughout peninsular Florida. The abundance of these sensitive and tolerant plants was correlated with the LDI (Spearmans r >|0.70|), and not significantly affected by regional vagaries in species composition. However, the highly variable relationship between the abundance of sensitive and tolerant plants and the LDI indicated limitations to conclusions drawn. The abundance of sensitive plants demonstrated high variance throughout the plot along the LDI, although lower values appeared near LDI scores of approximately 3.5. Tolerant plants, which expressed a minimal relationship with the LDI until a threshold of approximately 3.5 was reach, were also highly variable, although not as sensitive to changes in LDI values for the low scores. Percent exotic Increased development has the potential of promoting the spread of exotic species into wetlands where they can alter community composition, patterns, processes, and even functioning (Leibowitz and Brown 1990, Hobbs and Huenneke 1992, Cronk and Fennessy 2001). Disturbance within the wetland itself from activities such as cattle grazing provides a pathway for exotic propagules through cattle feces or by seeds

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79 adhering to the coats of domestic herbivores. The heavy machinery used in typical cropping or citrus operations can also provide a pathway for propagules. The trampling associated with cattle grazing can provide patches of bare ground for colonization of exotic species. Drift of herbicides into wetlands from agricultural practices can alter the plants, by dint of their storage/reproductive structures such as rhizomes, tubers, and corms, are thus better able to pass through the Gleasonian sieve that regulates the composition or fitness of wetland flora and create patches of bare ground, which can subsequently be colonized by exotic species. Drainage of landscapes for development can provide direct conduits to wetlands for exotic species, if those drainages directly link to the wetland (Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). Altering the natural sheet flow pattern through landscape level drainages can also affect the species composition of wetlands by providing drier conditions conducive to colonization by exotic annual species (David 1999). Increased development that affects the landscape surrounding the wetland may also cause a potential increase in exotic propagules entering the wetland system through the increase in the proportion of the perimeter of the wetland that is subjected to seed sources of exotic species. The results, however, suggested that the abundance of exotic taxa was marginally sensitive to increases in land development intensity until a threshold had been crossed, approximately 3.2. Once that threshold had been passed, substantial variance was manifested in the dataset, which suggested additional processes not captured by the LDI were affecting the distribution of exotic taxa throughout peninsular Florida. These processes may be further understood through the collection of additional data (i.e., requesting planting history from land owners) or through additional observations (i.e., the distance from the nearest road to the wetland, or the existence of perches within the site; both would potentially increase the abundance of propagules). Several species found in the wetlands sampled are on the Florida Exotic Pest Plant Councils list of Category I exotics (Eichornia crassipes, Hymenachne amplexicaulis, Lygodium microphyllum, Melaleuca quinquenervia, Panicum repens, Schinus terebinthifolius, and Solanum viarum). Category I exotic species are those considered to alter native plant communities by directly displacing native species, changing the structures or ecological functions within a community, or hybridizing with native species (FLEPPC 2003). Two plants identified were FLEPPC Category II exotic species (Alternanthera philoxeroides and Urena lobata). These plants are increasing in abundance throughout Florida but have not yet affected the natural areas, as have Category I exotics (FLEPPC 2003). It is interesting that not all of the exotic species found appear to possess such damning traits. Richards yellow-eyed grass, Xyris jupicai, native to French Guiana (Wunderlin and Hansen 2000), is one such species. This species was found frequently enough in reference conditions to be considered a sensitive indicator species. Annual to perennial ratio As hydrologic conditions in wetlands are dynamic, many wetland plants have evolved life-history traits to maintain themselves during periods of endogenous environmental perturbations. In an adaptation that enables wetland plants to combine reproductive structures with storage devices, most wetland plants are vegetatively reproducing perennials (Galatowitsch et al. 1999b, Cronk and Fennessy 2001). Perennial

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80 presence and abundance of species within the confines of the wetland system (van der Valk 1981). However, exogenous perturbations that disrupt natural processes, such as hydroperiod alterations, nutrient loading, and trampling, may provide opportunities for the generally faster-growing annual species to out-compete perennial species for nutrients, water, and light. Annual species (often considered weedy species) increase in wetlands undergoing anthropogenic perturbations, while perennial species decline (Hobbs and Huenneke 1992, Galatowitsch et al. 1999b). The results of the annual to perennial ratio metric generally support the conclusions from the literature, as the ratio of annuals to perennials increases with increasing development. However, at low levels of measured disturbance (LDI scores), the results suggested that the A:P ratio was marginally sensitive to change. Only once an LDI threshold of approximately 3.2 was passed were changes evident in A:P ratio. This suggests that wetland processes maintain A:P ratios until development intensity increases sufficiently to alter those processes, for instance through decreased hydroperiod as a result of ditching and draining associated with higher LDI values. Average Coefficient of Conservatism Since its inception by Wilhelm and Ladd (1988) as a method to measure the quality of the vegetation in the Chicago area, the Floristic Quality Assessment Index (FQAI, originally called the Natural Area Index), and the associated Coefficient of Conservatism have found widespread use in a variety of different ecosystems (Southern Ontario Woodlands: Francis et al. 2000; Illinois uplands, flatwoods, and prairies: Taft et al. 1997; North Dakota wetlands: Mushet et al. 2002). Many authors have utilized the FQAI, calculated as the average CC value for the site multiplied by the square root of the total number of species at a site. This inherently rewards systems richer in species and assumes that such a system is more ecologically desirable (Fennessy et al. 1998, Cohen et al. submitted). Like Francis et al. (2000), in this study the average CC score was utilized as a metric. This decreased the influence of species richness on the site score and more accurately reflected the ecological data collected as the average species richness for sites with an LDI score of less than 2.0 (31.70 +/10.80) was not significantly different (Mann-Whitney U-test Z = -0.005, p= 0.990) than those sites scoring greater than 2.0 (31.68 +/9.51). The lack of richer systems in reference wetlands may be a function of the strong hydrological driving forces maintained on the minimally developed landscape. Whereas developed landscapes often drain the wetland area, which can allow species into the wetland proper that would otherwise be excluded due to anoxic soil conditions, the wetlands located in reference landscapes generally have zones where species tolerant of different hydroperiods and anoxia can thrive. Thus the richness found in developed sites may be an artifact of the drainage associated with development. Landscape drainage may have also affected the highly variable distribution of CC values associated with LDI scores of approximately 3.5. As noted, drainage increases the area available for colonization by upland and facultative plants due to decreases in soil anoxia. However, the slope and additional site-specific factors (e.g., the presence of perches, as discussed in the % Exotic metric) may have decreased the opportunity for plants with low CC scores to colonize wetland zones.

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81 Vegetative Index of Wetland Condition The VIWC, developed for isolated depressional herbaceous wetlands in peninsular Florida, combined five biological measurements into a single score to nature and pervasive throughout Florida, the effects were likely evenly distributed in both impaired and reference sites. It was noted, however, that sites in impaired landscapes ascertain the relative condition of a sampled wetland vis--vis a suite of reference wetlands located in low development landscapes (Karr and Chu 1999). While significantly correlated with the disturbance gradient, the VIWC appeared to be highly variable for any given LDI score, especially scores located near LDI values of 1.0 and 3.5. The high variance in each of the metrics, as well as in the final correlation between the LDI and VIWC may have been in locations with a time delay between impairment activity and the manifestation of that impairment in the wetland macrophyte community (i.e., a field, long held fallow, that is now in crop rotation). Conversely, LDI scores, based on landscape values, may not have accurately quantified the condition of a site that was in rotation or grazed that was sampled months or years after such deleterious activities had ceased. While ground-verification occurred, in some cases accurate land use maps or site histories could not be obtained, and best scientific judgment was employed in spatial off-site GIS analysis. While a few outliers appeared to exist in the relationship between the LDI and VIWC, the focus of this analysis was on the utility of macrophytes as indicators of wetland condition. An assumption inherent in this study, as in most analyses utilizing bioindicators, was that should environmental conditions be such that the macrophytic community was characteristic of sites in reference conditions, then the integrity (c.f. PL 92-500, Clean Water Act, (a)) of the site was not suspect. On the other hand, sites with vegetation characteristic of impaired conditions were assumed to be under various degrees of human modification of deterministic, driving variables. In this manner, the VIWC, which directly compares wetland vegetation, may be best employed as an accurate assessment tool for isolated depressional herbaceous wetlands in Florida. Field Data Collection Florida was in the midst of a significant drought during the study period (Lawrimore et al. 2001), which was manifested by decreased hydroperiod, extent, and depth of inundation in many of the sampled wetlands. Many wetlands identified as potential sites were not sampled during the study period due to the lack of standing water originally a prerequisite for inclusion that was slackened as the sampling season waned in 2000. Five of the ephemeral wetlands sampled in this study (all in the North region) were not hydrated during the sampling window, and may not have been hydrated to the point of standing water at any point during the study period. In addition, the hydroperiod may have been significantly decreased in many, if not all, of the wetlands sampled. This may have affected the species composition in both reference and impaired wetlands for instance through the increased abundance of weedy annuals such as Eupatorium capillifolium. The effect of the drought on the macrophytes identified would likely have been most pronounced on the wetland fringe, as macrophytes typically found in more upland conditions may have colonized the non-hydrated wetland fringe and out-competed typical (i.e., obligate or facultative) wetland plants. As the drought was endogenous in

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82 often expressed modified hydrological functioning due to drainage ditches (C. Lane, personal observation) that may have caused a greater response to the effects of the drought. As mentioned, the sampling protocol was modified between sampling years. The slight changes in the sampling protocols between 1999 and 2000 were not expected to have had a noticeable effect on the accurate characterization of the 2% of sampled wetlands without 4 full transects from the wetland edge to the center. No wetland had all 4 transects halted before the center, and the additional information possibly gathered from the extended transects after 15m2 had been sampled without a change in species composition would likely be minimal. Conclusions and Recommendations This chapter of the study quantified the condition of sampled wetlands through an assessment of the structure and composition of the wetland macrophyte community. However, the VIWC, should be seen as a model that must be verified and calibrated to decrease the variability between metric response and the LDI. A recommended calibration for the proposed metrics and the VIWC that is currently underway (C. Lane, unpublished results) includes re-sampling a number of study wetlands to ascertain yearly fluctuations in species assemblages and the subsequent effect on the VIWC. To sample study wetlands twice within a given year but during different seasons would provide the opportunity to examine seasonal effects on the composition and structure of wetlands and the corresponding alterations to the individual metrics and VIWC. Model verification would also increase the value of the proposed VIWC. Florida, by nature of rainfall and topography, is a state rich in wetland resources. Increasing the number of sampled wetlands across all landscape types would increase the power, precision, and accuracy of the individual metrics as well as the multi-metric VIWC. The addition of larger isolated herbaceous wetland systems into the calibration and verification of the VIWC would also permit the expression of the VIWC across wetlands of different scales.

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83 1999, Ludden and Hauer 2000). Macroinvertebrates are well suited for the effective measurement of the spatial and temporal impacts of human-induced disturbances (Table CHAPTER 4 MACROINVERTEBRATES AS BIOINDICATORS Introduction Shallow, isolated depressional wetlands typically support a variety of aquatic, semi-aquatic, and terrestrial invertebrates that are important components of wetland and local terrestrial food webs (Kushlan 1990, Evans 1996, Sharitz and Batzer 1999, Evans et al. 1999, Leslie et al. 1999). Because of the nature of depressional wetlands, invertebrates associated with these ecosystems are regularly subjected to endogenous environmental stresses such as anoxia, wide salinity fluxes, and hydroperiod fluctuations. Invertebrates in depressional wetlands may be further stressed by exogenous (human-induced) factors such as nutrient and organic loading, contaminant toxicity, acidification, salinization, sedimentation, changes in vegetation cover, thermal alteration, dehydration, hydrologic alterations, and habitat fragmentation (Adamus and Brandt 1990, Adamus 1996, Danielson 1998, Doherty et al. 2000). Measured changes in invertebrate community structure and function relative to these exogenic perturbations may be used to assess the ecological condition of the depressional wetland ecosystem through development of a multimetric index of biologic integrity (Adamus 1996, Danielson 1998, Galatowitsch et al. 1999a, Karr and Chu 1999, Kashian and Burton 2000). Multimetric indices utilizing macroinvertebrates have been used in biological monitoring to determine the relative quality of lentic and lotic aquatic ecosystems throughout the country (Hellawell 1986, Plafkin et al. 1989, Cairns and Pratt 1993, Kerans and Karr 1994, Rosenberg and Resh 1996, Karr and Chu 1999). As of 1997, forty-eight states, including Florida, have implemented or have begun developing macroinvertebrate assessment methods for lakes or streams (Karr and Chu 1999). In Florida, the Florida Department of Environmental Protection (FDEP) combined metrics that measure diversity, composition, and functional feeding groups in the development of the Stream Condition Index (SCI) for the evaluation of lotic systems (Barbour et al. 1996). Metrics were likewise identified by the FDEP to assess the biological integrity of lakes in the state (Gerritsen and White 1997, Gerritsen et al. 2000). Macroinvertebrate assemblages in Florida have also been utilized to develop a bio-monitoring program in southern Florida canal systems (Snyder et al. 1998, in Doherty et al. 2000), for evaluating the success of restoration projects (e.g., Merritt et al. 1999) constructed wetlands (e.g., Erwin et al. 1997, Crisman et al. 1997), and for assessing the impact of human-induced disturbances on cypress domes and the Everglades (i.e., Brightman 1984, Leslie et al. 1999, Rader 1999). Multimetric assessments of wetland condition using macroinvertebrates as indicator organisms have been conducted in a growing number of states and agencies (e.g., Yoder and Rankin 1995, Danielson 1998, Burton et al. 1999, Gernes and Helgen

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84 Table 4-1. Advantages and disadvantages of using macroinvertebrates in wetland bioassessment. Advantages Disadvantages identify metrics, or measurable components of the wetland macroinvertebrate Widely distributed in wetlands Easily sampled and generally abundant Some organisms have known response to perturbations Many are sedentary within a single wetland Important components of trophic webs Respond quickly to perturbations Some are long-lived Some are extremely difficult to identify Many short-lived Identification is labor intensive May be sparse in some wetlands or seasonally abundant Hydrated wetlands generally required Poor taxonomic knowledge of some groups Some taxa migrate from other water bodies Sources : Danielson (1998), Doherty et al. (2000), U.S. EPA (2002c) 4-1). Macroinvertebrates are typically abundant in wetlands, easily sampled, and relatively easily identified (Rosenberg and Resh 1993). Additionally, there is ample literature on various sampling methods (Cheal et al. 1993, Adamus 1996), taxonomic keys (i.e., Merrit and Cummins 1996), and macroinvertebrate tolerance values for pollutants in lotic environments (Hilsenhoff 1987, Lenat 1993, Barbour et al. 1996), as well as a growing array of metrics that have responded to the effects of episodic or constant human disturbances on aquatic systems (see Yoder and Rankin 1995, Barbour et al. 1996, Gerritsen and White 1997, Galatowitsch et al. 1999a, Karr and Chu 1999, Gernes and Helgen 1999, Kashian and Burton 2000, Ludden and Hauer 2000, Doherty et al. 2000, U.S. EPA 2002c). While the advantages of macroinvertebrates have dictated their use in biological assessments throughout the country, disadvantages to using them in biological assessments exist (see Table 4-1). Detailed taxonomic keys are necessary to identify most organisms to genus or species levels, and often the keys do not address the diagnostic features of larvae or instars. Sample processing time is large with macroinvertebrates (e.g., sorting, subsampling, enumeration and identification) and some families (e.g., Chironomidae) require mounting specimens on slides for identification. Most wetland macroinvertebrates emerge after the wetland has hydrated, thus requiring adequate rainfall and/or standing water, which typically is seasonal in Florida. The time since the wetland was hydrated will also affect the sampled community composition (e.g., predators typically emerge later than their prey). Additionally, many macroinvertebrate responses to perturbations in the literature are from lotic or lentic systems as data on macroinvertebrate responses to perturbations in wetland systems are sparse, but growing (Danielson 1998, Adamus et al. 2001, U.S. EPA 2002c). In this chapter, results of testing and evaluating community structural and functional measurements for macroinvertebrates (insect and noninsect taxa) of isolated herbaceous depressional wetlands in peninsular Florida are given. The goal was to

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85 community, that showed an empirical and predictable change in value along increases in a landscape-level measure of human disturbance, the Landscape Development Intensity index (Brown and Vivas submitted). Those metrics were selected for use in the creation of the multimetric Macroinvertebrate Index of Wetland Condition, or MIWC. The variation between LDI values and developed metrics was examined to address the sensitivity and precision of macroinvertebrate metrics and the relationship of the metrics to the LDI. Additionally, analyses of environmental parameters measured (both abiotic and biotic) were conducted to assess the environmental variables that affect the distribution of macroinvertebrate taxa within wetlands. Methods Site Selection and Agricultural Development Gradient Seventy isolated depressional marshes were sampled a single time for macroinvertebrate community composition throughout peninsular Florida in the summers of 1999 (n=35) and 2000 (n=35). Site condition was independently assessed using geographic information systems (GIS) and the Landscape Development Intensity index (LDI, Brown and Vivas submitted). Additional information on the sites sampled and the LDI may be found in Chapter 2 (Methods: Site Selection and Agricultural Development Gradient). Macroinvertebrate Collection and Identification Macroinvertebrates were collected using standard U.S. 30-mesh D-frame dip-nets. Twenty sweeps were collected at each site, proportionally divided according to the different vegetation/habitat zones present. Vegetation zones (such as a fringing Panicum spp. zone or a deep water Pontederia sp. zone) were determined from an on-site assessment of dominant wetland plants. A typical marsh had between one and four primary vegetation zones. A single dip-net sweep was one net width and two net lengths covering an area of 0.5m2. The contents of each sweep were deposited into a labeled 3.8L plastic composite jar. When all 20 sweeps were completed, the sample was preserved with buffered formalin at a rate of approximately 10% of the sample volume. The preserved macroinvertebrate samples were stored at the Howard T. Odum Center for Wetlands and delivered to the FDEP for enumeration and identification by FDEP personnel. At FDEP Central Laboratories, the material was sieved and washed following DEP Standard Operating Protocols and placed on a pan with twenty-four numbered cells. Eight random cells were selected (a third of the sample) and placed in another numbered tray. From the second numbered tray a single sub-sample was taken and all organisms enumerated and identified. If fewer than 100 organisms were encountered, a second randomly chosen cell from the second numbered tray was selected and all organisms within that cell enumerated and identified and added to the total of the first count. Identifications by FDEP were made to the lowest taxonomic level possible following FDEP Standard Operating Procedure #IZ-06. Data were error-checked following FDEP protocols and entered into the FDEP database for analysis.

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86 Water and Soil Physical-Chemical Sampling and Analysis To relate the distribution of wetland diatoms to environmental parameters, soil and water physical and chemical parameters were measured at each site as described in Chapter 2 (Methods: Field Data Collection, Sample Preparation and Laboratory Procedures) and Appendix B. Soil variables were transformed to decrease measured skewness and kurtosis in the dataset as described in Chapter 2 (Methods: Data Analyses). Multivariate colinearity among the environmental variables was also examined as described in Chapter 2 (Methods: Data Analyses). In addition, the non-parametric Mann-Whitney U-test was used to test the null hypothesis of equal medians between reference and impaired classes for each environmental variable (Zar 1999). Macroinvertebrate Composition and Environmental Correlates The relationship between measured environmental values (including LDI score) and wetland macroinvertebrate community composition was examined with the Mantel test (Mantel 1967) and with non-metric multidimensional scaling (NMDS, Kruskal 1974, Mather 1976) as described in Chapter 2 (Methods: Data Analyses). A three-dimension NMDS solution was selected for macroinvertebrate taxa as increased dimensionality only marginally improved the fit. Correlations of site scores with environmental parameters, including LDI score and latitude and longitude (decimal degrees), were calculated and a bi-plot of parameters with Pearsons correlations (r2 0.30) to site scores was constructed. Macroinvertebrate Compositional Analyses Summary statistics Summary measures of sample richness, Shannon diversity, Simpson diversity, beta, and gamma diversity were calculated for each site and provided information on species distributions vis--vis land use as described in Chapter 2: Data Analyses. Regional composition of macroinvertebrates As isolated depressional marshes are not uniformly distributed throughout Florida, the sites were likewise generally located in counties with the necessary hydrology and geomorphic setting (Lane 2000, see Figure 2-1). The sites were initially stratified into three peninsular wetland regions, or areas of similar climatic and physiographic conditions after Lane (2000). Two compositional tests, the multiple response permutation procedures (MRPP) available in PCOrd and the Percent Similarity Index (PSI, Wolda 1981), were used to identify the ecological significance of the modeled wetland regions for macroinvertebrate distribution and are described further in Chapter 2 (Methods: Data Analyses).

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87 Macroinvertebrate Metric Development Metrics based on richness, taxonomic composition, and structural/feeding guilds were identified from literature sources and iterative tests of the dataset (e.g., Barbour et Sources : 1=Barbour et al. (1996); 2=Barbour et al. (1999); 3=Gernes and Helgen (1999); 4=Fore et al. (1996) al. 1996, Gerritsen and White 1997, Burton et al. 1999, U.S. EPA 2002c). Metrics were tested for the strength of Spearmans coefficient of correlation (Spearmans r) with the LDI. Final metrics were selected as those with significant (p<0.05) correlations and Spearman correlation coefficients with the LDI of at least |0.30|. All evaluations of potential metrics were conducted with SAS (SAS Institute, Cary N.C., version 8.02). Categorical metrics Categorical metrics were based on the relative abundance of a specific taxonomic or functional group. The categorical metrics tested provided information on the composition and trophic relationships of the assemblages of macroinvertebrates along the LDI gradient and between development classes. Categorical metrics tested were initially based on studies of Florida macroinvertebrates by Barbour et al. (1996) and Gerritsen and White (1997). As these authors examined macroinvertebrates within lentic and lotic environments, additional categorical metrics focusing on macroinvertebrates common in wetland environments were tested for their correlation with the LDI. Composition measures (Table 4-2) provide information regarding the relative contribution of a population to the community structure of the wetland system (Barbour et al. 1996, Barbour et al. 1999). To compensate for species rich or species poor sites where richness may not be a reflection of the condition of the wetland (King and Richardson 2002), relative rather than absolute values were used for this measurement. In general, wetland systems without landscape modification will remain relatively consistent in proportional representation vis--vis other unperturbed wetlands, although individual abundance may vary in magnitude (Barbour et al. 1999). Variations in the Table 4-2. Compositional metrics, definition, and expected response. Composition Metrics Definition ResponseSource Dominant taxon (%) Abundance of the single most abundant taxon Increase 1 % Diptera % of dipterans Increase 1 % Coleoptera % of beetles Decrease 1 % Odonata % of dragonflies and damselflies Variable 1 % Ephemeroptera % of mayflies Decrease 1 % Oligochaeta % of aquatic worms Increase 4 % Hemiptera % of true bugs Variable 3 % Gastropoda % of snails Decrease 1 % Decapoda % of individuals classed as crustaceans Decrease 2 % Tricoptera % of caddis flies Decrease 1 % Trombidiformes % of mites ? % Amphipoda % of amphipods Decrease 1 Florida Index Weighted sum of intolerant taxa, which are classed as Decrease 1 1 (least tolerant) or 2 (intolerant).

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88 representational proportion of taxonomic groups may indicate the encroachment of exogenous perturbations (Barbour et al. 1999). In addition to the measures listed in Table 4-2, compositional measures of each order, family, and genus were examined along the disturbance gradient and within each development classification for each site. Trophic categorical measures provide information on trophic relations, production, and feeding strategies (Resh and Jackson 1993, Barbour et al. 1999). A list of trophic measures examined, and the expected response to exogenous perturbations are given in Table 4-3. As in compositional measures, the trophic relationships in wetland systems with low LDI scores are expected to remain relatively stable vis--vis other wetlands in reference landscapes (Barbour et al. 1999). Increased landscape modification to the system was expected to alter the relative proportions of different trophic classes. Table 4-3. Trophic metrics, definition, and expected response. Trophic Metrics Definition ResponseSource Predator % % of the predator functional feeding group Variable 4 Shredder (macr) (fw) % % of the plant shredders functional feeding group Decrease 2 Scraper (peri) (fw) % % of the periphyton scrapers functional feeding group Decrease 2 Col-fltr/susp fdr % % collector-filterers/suspended feeders functional group Variable 1 Plant piercer % % of the macrophyte piercing functional feeding group Decrease 1 Sub col-gthr/dep fdr % % collector-gatherers/deposit feeders functional group Variable 1 Epi col-gthr/dep fdr % % collector-gatherers/deposit feeders functional group Variable 1 Scavenger (animals) % % of macrofauna that feed on dead animals ? Browser-grazer % % of macrobenthos that browse/graze upon periphyton Decrease 3 Parasite % % of the parasite functional feeding group ? 2 Sources : 1=Barbour et al. (1996); 2=Gerritsen and White (1997); 3=Barbour et al. (1999); 4=Kerans and Karr (1994) Ancillary data Ancillary data for categorical analyses described above were obtained from the literature and the United States Department of Agricultures Integrated Taxonomic Information System on-line database (United States Department of Agriculture 2003). The feeding strategy or trophic position of each organism was determined through literature reviews, particularly the text by Merritt and Cummins (1996) on aquatic invertebrates. Sensitive and tolerant species Indicator Species Analysis (ISA, Dufrene and Legendre 1997) was utilized to identify macroinvertebrate taxa having significant association with LDI classification of impaired (LDI2.0) or reference conditions (LDI<2.0). ISA is described in Chapter 2 (Methods: Metric Development). The abundance of species with significant specificity and fidelity to reference or impaired conditions was assessed for each site and correlated (Spearmans r) with the LDI.

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89 Macroinvertebrate Index of Wetland Condition To create a multimetric index of wetland condition using macroinvertebrates, it was necessary to score the proposed metrics. The scoring was completed by taking the th while South and North regions only shared 56%. Central and North regions were 64% similar. MRPP results using the full dataset were equivocal as abundance measures and quartile of the 95 percentile of the measured results for each metric. Doing this decreases the influence of outliers on the distribution of metric scores (Mack 2001). For metrics decreasing with increasing LDI scores, the lowest quartile was given a score of 0, the second quartile 3, the third quartile 7, and the highest quartile 10. Score values were switched for metrics that decreased with increasing LDI scores. A hypothetical example of this scoring method is presented in Figure 2-2. The Macroinvertebrate Index of Wetland Condition was determined for each wetland by summing the scores of the metrics. Results Wetland Macroinvertebrate Composition Seventy herbaceous depressional wetlands throughout peninsular Florida with standing water were sampled in 1999 and 2000 (see Figure 2-1). Twenty-three were sampled in the South region, thirty in the Central region, and seventeen in the North region. Based on the dominant land use around the wetland, twelve of the sites sampled in the South region were a priori considered impaired, sixteen in the Central region, and eight in the North region. The organisms identified in the samples from the studied wetlands represent 24 orders, 81 families, 182 different genera, and 120 different species. Of the organisms sampled and enumerated, 82% were identified to at least the genus level, but identification to the species level was possible for only 48% of the organisms due to lack of diagnostic features. While each site averaged 23.9 (+/5.7) taxa identified at least to genus, on average only 10.4 taxa (+/3.7) were identified to species. Analyses to develop indicators of wetland condition using macroinvertebrates and all subsequent analyses were therefore completed at the genus level. Summary measures of sample richness, evenness, Shannon diversity, and Simpson diversity using the genus-level data were calculated for each site (Table 4-4). Mann-Whitney U-tests indicated no significant difference between reference and impaired sites for richness, evenness, Shannon diversity, or Simpson diversity (Table 4-5). No significant differences were found between wetland regions (e.g., South, Central, North) for summary metrics (see Table 4-5). Two additional indices were also calculated from the macroinvertebrate data and compared between wetland condition classes: beta and gamma diversity (Ricklefs 1990, McCune and Grace 2002). Both were higher in reference sites than in impaired sites (reference sites average richness: 20.82, beta diversity: 7.06, gamma diversity: 147; impaired sites average richness: 21.03, beta diversity: 6.56, gamma diversity: 138). Macroinvertebrate compositional similarities between wetland regions (sensu Lane 2000) were made using PSI and MRPP. In general, the South region and North region were most dissimilar, but the differences were slight. Comparisons using PSI indicated that South and Central regions shared 71% of the macroinvertebrate genera,

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90 Table 4-4 Summary statistics of richness (S), evenness (E), Simpsons diversity index (H) and Shannon diversity index (D) for macroinvertebrates. Name S E H D` Name S E H D` Audubon 8 0.602 1.2530.5789 Immokalee 15 0.761 2.060 0.8198 BearScat 22 0.892 2.7570.9106 IRBlueCypress 26 0.689 2.246 0.7960 BigCow 25 0.794 2.5570.8695 IRCanal 22 0.685 2.117 0.8146 BRSebastian 26 0.923 3.0060.9383 IROJ 29 0.892 3.003 0.9365 CabPatch 21 0.802 2.4430.8704 JD6 11 0.907 2.175 0.8685 Caravelle 23 0.758 2.3770.8446 KellyPark 16 0.783 2.170 0.8219 Chuluota 28 0.759 2.5280.8702 LCork 21 0.656 1.996 0.7086 CLBayard 10 0.727 1.6750.7653 LEGo 16 0.722 2.003 0.8031 CLCove 11 0.467 1.1210.4518 LESuwan 22 0.814 2.518 0.8812 CMWPast 27 0.903 2.9750.9351 LLeeCounty 30 0.879 2.989 0.9321 CMWRef 29 0.828 2.7900.8989 MALudy 20 0.781 2.339 0.8697 COBurgle 25 0.730 2.3500.8384 MASpray 20 0.776 2.326 0.8475 COHole 24 0.803 2.5510.8651 McArthur 17 0.646 1.829 0.6840 Crew 21 0.773 2.3530.8479 MNElmer 30 0.905 3.077 0.9354 Deerfly 21 0.832 2.5320.8843 MNOcala 22 0.842 2.601 0.8832 DEMelon 14 0.798 2.1070.8269 MRPepper 19 0.790 2.326 0.8498 Garber 20 0.875 2.6200.9023 Myakka 18 0.688 1.988 0.7861 GbarE 27 0.782 2.5780.8747 OKCara 18 0.736 2.128 0.8230 GLDonut 18 0.709 2.0500.7880 OKKISS 18 0.736 2.128 0.8277 GLPont 23 0.790 2.4780.8615 OKPast 25 0.773 2.487 0.8582 Goethe 23 0.631 1.9790.7073 PacificTom 27 0.784 2.583 0.8568 GreenSwamp 24 0.870 2.7640.9147 PallMar 21 0.777 2.367 0.8256 HagueI 20 0.721 2.1610.7877 PBCorbett 23 0.748 2.344 0.8296 HagueII 12 0.760 1.8880.8100 PBEnjay 16 0.885 2.455 0.8953 HalfMoon 20 0.866 2.5930.8974 Penner 17 0.725 2.053 0.7967 HARare 25 0.818 2.6320.8915 POWales 25 0.814 2.621 0.8831 HEBad 25 0.756 2.4350.8637 POWeowak 27 0.701 2.311 0.7625 HEL2 18 0.506 1.4640.6243 RiceCreek 18 0.860 2.485 0.8930 HEOkay 14 0.552 1.4580.5600 SandhillCrane 30 0.782 2.658 0.8710 HighPast 25 0.849 2.7330.9209 SANorthMya 24 0.705 2.241 0.7867 HighRef 19 0.838 2.4670.8674 SAOscer 22 0.865 2.673 0.9067 HillsRef 18 0.887 2.5640.9020 Savannas 15 0.793 2.146 0.8178 HuntCamp 31 0.728 2.5000.8720 STCow 17 0.684 1.939 0.7770 IFASI 21 0.483 1.4710.5149 UNHealthy 16 0.735 2.038 0.8350 IFASII 19 0.785 2.3110.8541 Weikiva 15 0.873 2.365 0.8864

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91 Table 4-5. Mann-Whitney U-test results of summary statistics between reference and impaired LDI classes and between regional datasets. S E H (Shannon D (Simpsons there were no significant differences between the composition of impaired sites when (Richness) (Evenness) Diversity) Diversity) Peninsular Dataset Impaired vs. Reference Z-statistic (p-value) -0.301 (0.764) 1.418 (0.156) 0.847 (0.398) 0.971 (0.332) Regional Dataset Regional Comparison Z-statistic (p-value) 1.998 (0.368) 2.111 (0.348) 2.901 (0.235) 1.913 (0.384) presence measures differed in interpretation. Global tests (South vs. Central vs. North) of genera abundance data indicated a significant compositional difference between wetland regions (A = 0.009, T = -2.41, p= 0.019). However, global test using genus presence, which is less subjected to temporal variation in data structure than abundance measures (McCune and Grace 2002), did not indicate a significant difference between wetland regions at p<0.05 (A = 0.006, T = 1.674, p=0.060). Thus, while the abundance of macroinvertebrate genera differed between regions, the genera that comprised the macroinvertebrates assemblages identified did not. Iterative tests of both abundance and presence data indicated significant compositional differences between the South and North regions (Table 4-6), suggesting that SouthNorth compositional variations were likely driving the differences identified in the global abundance MRPP tests. Table 4-6. MRPP analyses of the macroinvertebrate compositional similarity between South, Central, and North wetland regions. Test A T p-value Abundance S vs. C 0.003 -0.787 0.195 Iterative S vs. N 0.017 -3.622 0.004 Tests C vs. N 0.004 -1.017 0.015 Presence S vs. C -0.001 0.155 0.502 Iterative S vs. N 0.015 -2.974 0.010 Tests C vs. N 0.004 -1.001 0.155 Note : Abbreviations are S (South Region), C (Central Region), N (North Region). Iterative tests exclude one group (of three) during the MRPP procedure. Simultaneous and iterative MRPP tests were also conducted using only the impaired (n = 37) or reference (n = 33) sites data. The composition of reference sites was significantly different across regions when simultaneously tested (Table 4-7) with both abundance and presence data, and significant between all regions except Central and North when both abundance and presence data were iteratively tested. In stark contrast,

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92 either simultaneously or iteratively tested using either abundance or presence data (Table 4-8). Thus, while differences in the composition of reference sites were found through peninsular Florida, the composition of impaired sites was generally static. Table 4-7. MRPP analyses of the macroinvertebrate compositional similarity for reference sites between South, Central, and North wetland regions. Test A T p-value Abundance Global Test S vs. C vs. N 0.016 -2.171 0.028 Presence Global Test S vs. C vs. N 0.0177 -2.375 0.017 Abundance S vs. C 0.0192 -2.478 0.019 Iterative S vs. N 0.0231 -2.693 0.013 Tests C vs. N -0.0049 0.574 0.683 Presence S vs. C 0.0180 -2.671 0.022 Iterative S vs. N 0.0260 -2.816 0.011 Tests C vs. N -0.0030 0.041 0.636 Note: Abbreviations are S (South Region), C (Central Region), N (North Region). Global tests refer to simultaneous multivariate tests of the pooled macroinvertebrates from all three wetland regions. Iterative tests exclude one group (of three) during the MRPP procedure. Community Composition and Environmental Gradients Including the LDI, fourteen environmental variables were measured at each site. The measured water and soil parameters are given in the Appendix B. Significant differences between impaired and reference conditions, as measured by the Mann-Whitney U-test, were found for the following parameters: soil pH, soil TP, specific conductivity, water pH, ammonia, TKN, and water TP (Table 4-9). Water color was significant lower in reference conditions at p<0.10. Colinearity among variables, which was identified as a VIF>5.0 and a tolerance of <0.20, was recognized for %TC, TKN, and water pH following regression analyses of the transformed data (SAS 1990). These variables were removed. The Mantel test was used to test the hypothesis of no relationship between the identified macroinvertebrates and the measured environmental parameters, including LDI score. Results indicated a moderate and significant relationship (Mantels r =0.35, p=0.001), suggesting that the genus-level composition of peninsular herbaceous marshes was determined by the measured environmental driving factors.

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93 Table 4-8. MRPP analyses of the macroinvertebrate compositional similarity for impaired sites between South, Central, and North wetland regions. Test A T p-value Abundance Global Test S vs. C vs. N 0.0005 -0.064 0.431 Presence Global Test S vs. C vs. N 0.0029 -0.410 0.319 Abundance S vs. C -0.0037 0.583 0.687 Iterative S vs. N 0.0044 -0.430 0.290 Tests C vs. N 0.0031 -0.434 0.293 Presence S vs. C -0.0059 0.946 0.831 Iterative S vs. N 0.0122 -1.134 0.130 Tests C vs. N 0.0064 -0.910 0.178 Note : Abbreviations are S (South Region), C (Central Region), N (North Region). Global tests refer to simultaneous multivariate tests of the pooled macroinvertebrates from all three wetland regions. Iterative tests exclude one group (of three) during the MRPP procedure. Table 4-9. Comparison of the medians of water and soil variables between reference and impaired conditions with the Mann-Whitney U-test. Water Values Statistic (Z) p-value Color -1.868 0.062 Specific Conductivity -3.919 <0.001 Turbidity -1.524 0.127 Water pH -4.677 <0.001 Ammonia -2.690 0.007 Nitrates/Nitrites 0.771 0.441 TKN -2.932 0.003 TP -4.836 <0.001 Soil Values Statistic (Z) p-value Soil pH -3.036 0.002 %TC -0.818 0.414 %OM -1.253 0.210 %TN -1.147 0.251 %TP -2.771 0.006

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94 An NMDS ordination was completed to examine the underlying structure of the sites in ordination space and to ascertain the environmental variables driving the composition of the sites sampled. Correlations for all measured variables are presented in Table 4-10, and a biplot of site ordination overlaid with vectors representing the environmental variables is presented in Figure 4-1. The stress, or goodness of fit of the ordination was 19.32 and indicated an adequate and representative decreased dimensionality of the dataset (Kruskal 1964, Clarke 1993). Approximately sixty-eight percent of the variance in the dataset was captured by the three-dimensional NMDS ordination (first axis: 12.9%, second axis: 25.3%, third axis: 30.3%). In NMDS, unlike other ordination methods (e.g., principal components analysis, detrended correspondence analysis), axes are not necessarily ordered based on their importance. The third axis contained the most data in the NMDS ordination. As the second and third axes accounted for most of the variance in the dataset, the plot in Figure 4-1 is of sites along these two axes. The ordination scores for each site were linearly correlated (Pearsons r) with the measured environmental values, including LDI, latitude, and longitude. Correlations (Pearsons r2) > 0.30 were found for LDI, specific conductivity, soil pH, water TP, and color, suggesting their importance in driving the structure of the wetland macroinvertebrate community. Table 4-10. Correlations of environmental variables and ordination scores for macroinvertebrates. Axis 1 (12.9%) Axis 2 (25.3%) Axis 3 (30.3%) Parameter r2 tau r2 tau r2 tau LDI Score 0.12 -0.24 0.06 -0.18 0.42 0.41 Soil pH 0.34 -0.39 0.11 0.21 0.19 0.36 % TN <0.01 0.04 0.06 -0.22 <0.01 0.01 TP (mg/kg) 0.03 -0.15 0.09 -0.26 0.03 0.11 % OM 0.02 0.02 0.11 -0.26 <0.01 -0.03 Color (PCU) <0.01 -0.03 0.30 -0.33 0.03 0.10 Spec. Cond. (umhos/cm) 0.30 -0.37 0.02 -0.14 0.36 0.45 Turbidity (NTU) 0.01 -0.03 0.10 -0.11 0.09 0.18 Ammonia (mg/L) <0.01 -0.10 0.07 -0.17 0.08 0.31 Nitrate/Nitrite (mg/L) 0.01 <0.01 0.01 -0.12 <0.01 0.04 Water TP (mg/L) 0.07 -0.19 0.25 -0.38 0.33 0.43 Longitude <0.01 <0.01 0.13 -0.24 <0.01 -0.07 Latitude 0.03 0.10 0.20 -0.32 0.01 -0.08 Metric Development Compositional analyses between wetland regions equivocated on the ecological significance of the modeled wetland regions (Lane 2000) to macroinvertebrate distribution in isolated depressional marshes. Initial metric development utilized regional data sets however, the small n of the regional data and the low to moderate correlation of macroinvertebrates to the disturbance gradient (C. Lane unpublished research, see also

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95 Figure 4-1. Biplot of macroinvertebrate NMDS ordination scores for each site and strongly correlated environmental variables. The vectors are shown at 150% of their original length for clarity. The length of the vectors represents the strength of the Pearsons correlation (all r2 >0.30) and the angle represents the direction of maximum change. Four variables are shown: LDI (Landscape Development Intensity index), wTP (water total phosphorus), Spec (specific conductivity), and color. Soil pH was strongly correlated with the first axis, not shown. Tangen et al. 2003) limited development of regionally significant biological indicators of wetland condition. Perhaps due to the greater power of analysis, responsive patterns in the structure and composition of macroinvertebrate communities along the landscape modification gradient were discerned when the combined peninsular dataset (n=70) was examined. Thus, metrics to assess the condition of Floridas isolated herbaceous wetlands were identified utilizing the peninsular data set. In an effort to discern potential macroinvertebrate metrics, more than 60 categorical and compositional metrics were examined for the strength of the correlation

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96 with the LDI. Five metrics were developed that were selected based on the strength of their correlations with the LDI. These metrics are described below: % Sensitive Taxa, % Tolerant Taxa, % Predators, % Odonata, and % Orthocladiinae. Sensitive and tolerant taxa Indicator species analysis (calculated using genus-level data) identified twenty-seven genera with specificity and fidelity to reference or impaired conditions. Fourteen genera were significantly associated with reference conditions (Table 4-11), and thirteen genera were significantly associated with impaired conditions (Table 4-12). The taxa, calculated indicator species value, and p-value of the Monte Carlo test are also given in Tables 4-11 and 4-12. Once the sensitive and tolerant taxa were identified, a metric was developed based on the abundance of the indicator taxa. The relationship between the abundance of sensitive and tolerant genera, respectively, and the LDI is presented in Figures 4-2 and 4-3. The abundance of sensitive and tolerant genera were correlated with the LDI: % Sensitive Spearmans r = -0.65, p< 0.001; % Tolerant Genera Spearmans r = 0.71, p< 0.001. The distribution of the abundance of sensitive taxa appeared to be highly variable for any given LDI value, although a decreasing trend with increasing LDI scores was evident. The abundance of tolerant taxa did not appear to correlate strongly with the LDI until a threshold of approximately 3.2 was reached. The abundance of tolerant taxa was also highly variable, although this was only evidenced after LDI values of 3.2 were obtained. Table 4-11. Statewide indicators of reference conditions as determined from Indicator Species Analysis. Indicator Genera (LDI <2.0) Observed Ind. Value p-value Ablabesmyia 48.9 <0.001 Chaoborus 54.1 0.004 Clinotanypus 12.1 0.042 Corethrella 9.1 0.099 Hydroporus 9.1 0.097 Ischnura 16.0 0.088 Labrundinia 50.2 <0.001 Larsia 48.9 0.014 Lestes 12.1 0.046 Limnochares 9.1 0.097 Orthotrichia 9.1 0.097 Piona 12.1 0.045 Procladius 24.9 0.005 Sminthurinus 9.1 0.098

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97 Table 4-12. Statewide indicators of impaired conditions as determined from Indicator Species Analysis. Indicator Genera (LDI 2.0) Observed Ind. Value p-value Atrichopogon 26.5 0.041 Beardius 27.7 0.071 Enochrus 25.4 0.060 Goeldichironomus 70.7 <0.001 Haliplus 13.5 0.055 Mansonia 21.6 0.006 Micromenetus 23.1 0.025 Monopelopia 62.5 <0.001 Odontomyia 27.7 0.004 Pachydrus 21.1 0.028 Physella 20.9 0.076 Ranatra 16.2 0.025 Zavreliella 16.3 0.079 Figure 4-2. Abundance of sensitive taxa plotted against the LDI.

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98 Figure 4-3. Abundance of tolerant taxa plotted against the LDI. Percent predators The abundance of organisms classified in the predator functional feeding group was expected to decrease with increasing LDI scores (U.S. EPA 2002c). As demonstrated in Figure 4-4, these results support that hypothesis, as the abundance of predators decreased significantly (Spearmans r = -0.32, p= 0.007) along the increasing LDI gradient. Additionally, predators were significantly more abundant in reference conditions than in impaired conditions (Mann-Whitney U-test Z = 2.900, p= 0.004). However, the data were highly variable with any given LDI value, indicating marginal precision and accuracy, despite the significant correlation. Percent Odonata The abundance of members of the order Odonata (dragonflies and damselflies; class Insecta) was identified as an indicator of wetland condition in isolated depressional wetlands across peninsular Florida. With increasing LDI scores, the abundance of odonates decreased. A plot of the relationship between the abundance of odonates and the LDI is presented in Figure 4-5. Results of the Mann-Whitney U-test indicated a significant difference in Odonata abundance between reference and impaired wetlands (Z = 2.334, p= 0.020). The metric was significantly but moderately correlated (Spearmans r = -0.33, p= 0.005) with the disturbance gradient. The weak relationship between the LDI and the abundance of Odonata was also evidenced by highly variable values along the LDI gradient.

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99 Figure 4-4. Predator abundance plotted against the LDI. Figure 4-5. Odonata abundance plotted against the LDI Percent Orthocladiinae The abundance of the Orthocladinae tribe (midges, class Insecta, Chironomidae family) was correlated with disturbance gradient. Increases in LDI scores were generally reflected by increased abundance of Orthocladiinae midges (Figure 4-6), although the variance in the data was very high for any given LDI score. Orthocladinae were

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100 Figure 4-6. The abundance of Orthocladiinae plotted against the LDI. significantly more abundant at impaired than reference sites (Mann-Whitney U-test Z = 3.100, p = 0.002). The abundance of Orthocladiiae midges was moderately but significantly correlated with the LDI (Spearmans r = 0.33, p= 0.006). Macroinvertebrate Index of Wetland Condition The five final metrics were scaled, scored, and summed to create the Macroinvertebrate Index of Wetland Condition (MIWC). The 95th percentile and the quartile scores for each of the five metrics are presented in Table 4-13. The relationship between the MIWC and the LDI is presented in Figure 4-7. Scores for the MIWC range from 0 (three sites) to 50 (one site) (Table 4-14). Two of the three low-scoring sites were located in cattle pastures, while the third was surrounded by a watermelon farm. The highest scoring site was located in Ocala National Forest. The MIWC was correlated with the LDI: (Spearmans r = 0.79, p< 0.001). Data distribution was highly variable, although a decreasing linear trend was apparent. A Mann-Whitney U-test of the difference in median MIWC scores between reference and impaired sites indicated a highly significant difference (Z = 5.331, p< 0.001). Table 4-13. Quadrisect values and the 95th percentile data for each proposed biological indicator. Metric 95th Percentile0 Scores 3 Scores 7 Scores 10 Scores % Sensitive Genera 28.31 < 1.27 1.27 5.28 > 5.28 13.06 > 13.06 % Tolerant Genera 46.00 > 12.58 > 3.45 12.58 0.85 3.45 < 0.85 % Predators 59.74 < 17.85 17.85 25.78 > 25.78 37.98 > 37.98 % Odonata 13.15 < 0.81 0.81 2.25 > 2.25 5.02 > 5.02 % Orthocladiinae 44.52 > 22.40 > 15.06 22.407.95 15.06 < 7.95

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101 Figure 4-7. The Macroinvertebrate Index of Wetland Condition plotted against the LDI. Discussion Increases in land use intensity directly surrounding the study wetlands were manifested within the wetland through alterations in the composition of the macroinvertebrate community when compared with systems in reference, or low development intensity landscapes. Five metrics were discerned that permitted a measurement of the effect of increased landscape development on the macroinvertebrate community: the abundance of sensitive and tolerant genera, predators, odonates, and Orthocladiinae. The results of this study suggest that macroinvertebrate metrics, both compositional and categorical, were able to discern the relative condition of isolated depressional wetlands throughout peninsular Florida. Likewise, strong correlations between the LDI and the Macroinvertebrate Index of Wetland Condition, which synthesizes scores of each metric, supports macroinvertebrates indicators of freshwater wetland condition, although the relationships were not highly sensitive or precise. Environmental Correlates and Macroinvertebrate Composition A premise behind the biological assessment of aquatic systems is the intimate relationship of organisms and the environment. Both exogenous and endogenous alterations to the environment, if sufficiently intense (or if synergistic relationships are sufficiently intense), are manifested in the community characteristics of various assemblages (Karr and Chu 1997). Allan and Johnson (1997) and Hynes (1975) theorized that aquatic communities (i.e., riverine and lacustrine systems) respond to environmental

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102 Table 4-14. Macroinvertebrate Index of Community Condition scores for sampled sites. Sites MIWCSites MIWC Audubon 0 Immokalee 17 BearScat 23 IRBlueCypress 16 variables such as water TP, soil pH, color, and specific conductivity affected community BigCow 3 IRCanal 3 BRSebastian 41 IROJ 29 CabPatch 9 JD6 26 Caravelle 33 KellyPark 6 Chuluota 37 LCork 20 CLBayard 40 LLeeCounty 36 CLCove 14 LEGo 31 CMWPast 27 LESuwan 43 CMWRef 27 MALudy 10 COBurgle 16 MASpray 34 COHole 22 McArthur 27 Crew 27 MNElmer 33 DEMelon 40 MNOcala 50 Deerfly 0 MRPepper 3 Garber 23 Myakka 34 GBarE 9 OKCara 16 GLDonut 10 OKKiss 47 GLPont 30 OKPast 20 Goethe 41 PacificTom 24 GreenSwamp 43 PallMar 27 HARare 10 PBCorbett 34 HagueI 3 PBEnjay 37 HagueII 7 Penner 43 HalfMoon 40 POWales 47 HEBad 16 POWeowak 47 HEL2 0 RiceCreek 37 HEOkay 20 SANorthMya 34 Highpast 33 SAOscer 20 HighRef 47 SandhillCrane 27 HillsRef 44 Savannas 43 HuntCamp 27 STCow 10 IFASI 13 UNHealthy 7 IFASII 20 Weikiva 40 stimuli that operate at various spatial and temporal scales. In this study, the ordination of macroinvertebrate genera abundance data identified LDI score, specific conductivity, soil pH, water TP, and water color as significant variables determining macroinvertebrate community composition (see Table 4-10). Temporal and spatial changes in landscape-scale development intensity, as well as daily, weekly, and seasonal changes in localized

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103 composition. Thus, the results of this study suggested that the notions proffered by Allen and Johnson (1997) and Hynes (1975) can also be applied to wetland systems. As macroinvertebrates are responsive to a suite of anthropogenic alterations (this study; Adamus and Brant 1990, Adamus 1996, Danielson 1998, Anderson and be hypothesized, however, that increasing the opaqueness of the water may affect diatom Vondracek 1999, Euliss and Mushet 1999, Adamus et al. 2001, but see also Tangen et al. 2003), it is not surprising that a significant relationship with a general impairment indicator was identified. The use of a general, independent disturbance gradient to measure anthropogenic disturbance has enjoyed recent successes in biological assessment (Carpenter and Waite 2000, Cuffney et al. 2000, OConner et al. 2000, Munn et al. 2002, Fore and Grafe 2003). Landscape-scale assessment methods, such as the LDI, are generally adept at indirectly or directly capturing alterations not easily quantified such as hydrologic modification through ditching, draining, and berm building, changes due to landscape variables such as fire frequency and intensity, and modifications to physical, chemical, and nutrient loading rates as landscapes change. However, including smaller-scale (temporal and spatial) measurements such as soil and water chemistry are integral to understanding particular deterministic variables affecting aquatic communities and may assist in explaining high variance for given LDI values. As noted, in addition to LDI value, this study determined specific conductivity, (soil) pH, water TP, and water color to be important structuring components of macroinvertebrate communities in isolated herbaceous depressional marshes of peninsular Florida. Elevated conductivity measures can generally affect aquatic organisms through osmotic regulatory alterations (Stevenson et al. 1999, Spieles and Mitsch 2000). Specific conductivity measures play an important part in macroinvertebrate community composition (Ormerod and Edwards 1987, Growns et al. 1992, Tate and Heiny 1995, Spieles and Mitsch 2000, Carlisle et al. 2003). Studies by Malmqvist and Maki (1994) and Evans et al. (1999) have indicated the responsiveness of aquatic macroinvertebrates to alterations in pH. Danielson (1998), Doherty et al. (2000), and Adamus et al. (2001), reviewing macroinvertebrates as biological indicators, noted their utility in identifying pH-modified wetland systems. It is well established that as a result of both the gradual translocation of materials available for cation exchange (Evans et al. 1999) and the extended anoxic conditions in inundated soils, wetlands in pine flatwoods are generally low pH systems characterized by organisms evolved to tolerate acidic conditions (Kushlan 1990, Evans et al. 1999). Conversely, elevated pH values are often found in agricultural settings due to application of agrochemicals composed of basic compounds, which can alter the pH of receiving water bodies and hence species composition (Fore and Grafe 2002). Macroinvertebrate communities respond to alterations in phosphorous concentrations (Brightman 1984, Adamus and Brandt 1990, Malmqvist and Maki 1994, Tate and Heiny 1995, Adamus 1996, Danielson 1998, Doherty et al. 2000). Nutrients, such as TP, can increase productivity but also increase community respiration and thus affect dissolved oxygen levels and physical/chemical characteristics of the water body with subsequent effects on wetland communities (Dierberg and Brezonik 1984). Few studies have implicated water color as directly affecting macroinvertebrate community composition (Malmqvist and Maki 1994, but see Crisman et al. 1998). It can

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104 productivity through decreases in the available light for photosynthetic processes. Possible decreases in macroinvertebrate assemblages consuming epiphytic and benthic algae (i.e., scrappers) could be expected, with potential interactions throughout the macroinvertebrate food web. In addition, increases in water color may affect visual predatory macroinvertebrates by decreasing the visibility of prey. Regional Data Analyses Data were initially analyzed at the regional level to account for differences between the macroinvertebrate composition of peninsular Florida wetlands that could be attributed to latitudinal, geophysical, or climatological vagaries. However, while significant differences were found between regions using the abundance dataset, no significant differences were identified using presence-absence data. While both presence and abundance may differ temporally, abundance data are much more dynamic and may be more a reflection of sampling period than of landscape characteristics affecting wetland communities. The lack of significant correlations between NMDS ordination scores and latitude and longitude (as analogs for wetland regions see Lane 2000) similarly decreased the importance of regions for macroinvertebrate analyses in herbaceous wetlands. In addition, the increased power of analyses using a larger dataset (i.e., not incorporating the modeled wetland regions) made for stronger, more significant relationships between site composition and landscape characteristics. It was therefore determined that regionally unique metrics were not necessary, and the final metrics described in this chapter were developed utilizing the peninsular dataset (n=70). However, additional sampling and analyses within each wetland region may provide fruitful information germane to regionally unique macroinvertebrate metrics, and the development of additional metrics for macroinvertebrates may utilize regions as reports developed for stream and lake biological assessment in Florida (Barbour et al. 1996, Gerritsen et al. 2000) have concluded. Final Metrics Five final metrics were significantly correlated with increasing LDI scores: the abundance of sensitive and tolerant taxa, the abundance of predators, the abundance of Odonata, and the abundance of Orthocladiinae. Final metric correlations with the LDI were significant (p< 0.05) and Spearmans correlation coefficients were greater than |0.30|. While significant trends in the dataset were identified, lower correlation coefficients were obtained than anticipated and reflected the lack of sensitivity and precision inherent within the data that comprised the MIWC. The variance within each metric was large for any given LDI value, and only general trends were evidenced in the relationship between the LDI and the metrics. However, information germane to the development of biological indicators was nevertheless obtained, as suggested by the significance of the correlation between the LDI and the summed MIWC. The five final metrics are discussed below.

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105 Sensitive and tolerant genera To be able to statistically evaluate the specificity and fidelity of taxa to a particular class through a Monte Carlo randomization algorithm is an alluring LDI scores, as occurred in this study, due to similar reasons described above (see Categorical Metrics Predators). However, the relationship between the LDI and the characteristic of Indicator Species Analysis (ISA). Indeed, the use of ISA in ecological literature is increasing (McCune and Grace 2002), although a recent report suggested that ISA was conservative in dealing with rare taxa (Chytry et al. 2002). Nevertheless, use of ISA in this analysis allowed for the identification of twenty-seven taxa indicative of reference or impaired conditions. However, the distribution of the data indicated that neither the abundance of sensitive taxa or tolerant taxa were particularly precise or accurate indicators of LDI values due to the highly variable nature of the relationship between the LDI and the metrics. A general trend, although highly variable, was evidenced by the abundance of sensitive taxa, while tolerant taxa did not appear to reflect greater than background values until LDI scores of approximately 3.3. The high variance in these metrics may be a result of the taxonomic level in the analyses. Additional analyses to develop optima (i.e., U.S. EPA 2002e) for indicator species, or to further determine which environmental factors were most responsible for the distribution of the indicator taxa are suggested by these results and would assist in determining the ecological significance of the indicator taxa and the relationship of metrics to the LDI gradient. Categorical metricspredators A general decline was apparent in the abundance of predators identified within each sample with increasing LDI value, indicating the increasing importance of generalists and lower-structured food webs. However, the variance within the dataset was very large regardless of LDI value. This may be explained by several factors acting independently or in concert. For instance, Chovanec and Raab (1997) found that a physical disturbance in wetlands (such as vegetation removal by ruminates and subsequent lack of perches) affected the abundance of predators. Altered timing, depth, and duration of water, which often occurs on managed landscapes, affected development of various instars of predatory macroinvertebrates (Anderson and Vondracek 1999). Agrochemical applications within a wetland watershed altered the trophic structure (i.e., increase the abundance of generalists) of wetlands in North Dakata (Euliss and Mushet 1999). A decrease in wetland water clarity from the constant re-suspension of flocculent materials in areas of high cattle densities (Newcombe and MacDonald 1991) negatively affected the abundance of predatory macroinvertebrates due to decreased success from visual predators. Categorical metricsOdonates Larval odonates comprise an important part of many aquatic system food webs, including fish, amphibians, birds, and other organisms (Merrit and Cummins 1996). As predators, members of the order Odonata would be expected to decrease with increasing

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106 abundance of Odonates was highly variable for any given LDI value, decreasing the information content of the relationship, as well as the sensitivity and accuracy. Odonates tend to equivocate on their response to disturbances, which may explain some of the variance in the dataset. Odonates are tolerant to many disturbances such as altered pH, assessment at a fine scale. It may be important in future analyses to target the Chironomidae and thus decrease the laboratory sampling time spent on other families, or and low to moderate nutrient loading (Chovanec and Raab 1997), which would tend to decrease their utility as biological indicators. However, they have been identified as indicators of, the ecological integrity of ecosystem structures, the ecological quality of the land-water interface, and the connectivity of aquatic ecosystems to other landscape units (Chovanec and Raab 1997, p. 383). These abilities may be due in part to the long life cycle of odonates, as they would be expected to integrate long term and short, episodic perturbations to the wetland. Conrad et al. (1999) also reported the importance of landscape-level connectivity and structure to odonate population dynamics. Often, marsh systems are drained and filled in the course of agricultural operationsdecreasing the abundance of these systems on a landscape scale when compared to marsh systems located in reference landscapes (Pearlstine et al. 1997). Categorical metricsOrthocladiinae That midges (Diptera: Chironomidae) comprise a metric for the assessment of wetland condition was not surprising, given that they are often the most numerous insects present in freshwater environments (Cranston 1995, Coffman and Ferrington 1996). Midges have been so abundant in the benthos of both lentic and lotic aquatic systems as to be used in classifying streams and lakes (Lindegaard 1995), and were used as some of the earliest indicator organisms of anthropogenic eutrophication as the Chironomidae family contains genera extremely sensitive to disturbances (such as nutrient enrichment, Rosenberg and Resh 1993). The Chironomidae also contain genera that are extremely tolerant of such conditions, which implies identification to at least sub-family, as suggested by Lindegaard (1995). The majority of biological assessment research on midges (and macroinvertebrates in general) has been conducted for assessment of streams and lakes, and not wetlands (Rosenberg and Resh 1993, but see Driver 1977, Delettre 1989, Streever et al. 1995, Leeper and Taylor 1998, Gernes and Helgen 1999, Kashian and Burton 2000, King and Richardson 2002, U.S. EPA 2002c). Thus, many of the tolerance values or responses to disturbance present in the literature for cosmopolitan midges of those habitats (i.e., Beck 1954, Lenat 1993) may not be viable for the assessment of wetland environments due to the different driving forces acting on them. Despite apparent benefits in the assessment of herbaceous wetland systems, use of the Chironomidae in biotic assessment should include caveats: first, many chironomids may only be identified to species after being mounted on microscope slides and examined under high-magnification, with complimentary increases in sample processing time and cost. To wit, the time spent in-lab washing, sorting, subsampling, and identifying 100 to 150 organisms, including the Chironomidae, averaged over 20 hours per site (R. Frydenborg, FDEP, personal communication). Second, the variance within the dataset indicated that the relationship between the LDI and the Chironomidae was highly variable for any given LDI score, which would decrease their relative utility in wetland

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107 to examine larval Chironomidae further for developmental abnormalities as deformations have been correlated to exogenous perturbations (Johnson et al. 1993). Macroinvertebrate Index of Wetland Condition sampled in late summer to early fall. Most sites identified in spring were dry, yet all sites studied (for macroinvertebrate analyses) were hydrated when sampled. However, no The macroinvertebrate metrics were significantly correlated with the LDI, although the data were generally neither sensitive nor precise at that scale, as reflected by high variance for any given LDI value. While many agencies and researchers have touted use of macroinvertebrates to assess stream and lake systems (Barbour et al. 1996, Gerritsen and White 1997), as well as wetland systems (U.S. EPA 2002c), recent literature has indicated that the macroinvertebrate community may not be particularly responsive to agricultural perturbations (Tangen et al. 2003). These results support the use of macroinvertebrates as biological indicators of wetland condition in agricultural settings at the scale provided, but also suggest exploration of macroinvertebrate composition and structure along additional scales to increase the strength of the relationship. Field Sampling and Macroinvertebrate Identification Field sampling The very nature of wetlands predisposes macroinvertebrates to wide fluctuations in hydrology, as well as associated fluctuations in temperature, salinity, and dissolved oxygen levels (Sharitz and Batzer 1999, Leslie et al. 1999, Evans et al. 1999). Florida is generally wettest during summer and driest during late winter and early spring (Chen and Gerber 1990). However, an expansive drought subjected many peninsular Florida wetlands to depressed or non-existent hydroperiods during the sample period of 1999 and 2000 (Lawrimore et al. 2001). As such, the study wetlands were sampled late in the summer growing season to ensure that the wetlands were sufficiently hydrated (mean sampling date in 1999 was September 5, and September 29 in 2000). This late sampling date, and the range in dates for each region and year (Table 3-2), may have had ramifications on the observed macroinvertebrates, since the late summer to fall sampling window may have excluded some species that complete their life cycle early in the growing season (Anderson and Vondracek 1999). Additionally, the range in sampling dates from July and August to early November could affect the results, and thus comparative site scoring as some sites might have been sampled early in the summer while others in the same region were sampled in the fall, yet they were compared in the analyses to each other. In essence, some organisms might have been collected early in the season but were not found later in the season not as a function of the land use around the wetland but as a function of the date sampled. Thus, the presence or abundance of an organism at a site may be related to the sampling date instead of the character of the landscape surrounding the wetland. Sites were selected for inclusion based on the providence of supportive landowners and managers and the prevalent land use around each wetland. The sites sampled were generally identified in early spring to mid summer, and subsequently

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108 gauges were placed on-site to discern the time span between wetland hydration and the sampling date. Some sites sampled may have only recently been hydrated and thus may have supported only a paltry abundance of organisms or a particular composition not due to landscape factors but due to the short window of opportunity for emergence for many fixed count results in substantial information loss in analyses of stream biota. In a study of wetlands of the Everglades, King and Richardson (2002) found that fixed counts of macroinvertebrates (Wiggins et al. 1980, Wallace and Anderson 1996). Many authors have noted seasonal differences in the emergence of macroinvertebrates (Anderson and Vondracek 1999, Stewart and Loar 1994, Wallace and Anderson 1996) and the existence of delay between hydration and emergence of macroinvertebrates (Sharitz and Batzer 1999, Wallace and Anderson 1996, Battle and Golladay 2001, Euliss and Mushet 1999). Current research (C. Lane, unpublished research), including resampling studied wetlands across years and various seasons, may assist in understanding these relationships and their effect on biological assessment. Macroinvertebrate identification and enumeration Taxonomic resolution. Macroinvertebrates were identified to the lowest possible taxon, with 82% being identified to genus. Incomplete specimens, early instars, or lack of diagnostic features hampered identification to species level. With only 48% of the organisms encountered identified to species, a substantial amount of information was lost from the inability to identify the organism to a lower phylogenic level. For instance, Bailey et al. (2001) reported that there was substantial variation in the response of organisms at the family, genus, and species level to perturbations. Resh and Unzicker (1975) reported that assessment analyses conducted at the species level differed from results obtained when the data were analyzed at the genus level. In the only analysis of taxonomic resolution in wetland macroinvertebrate data to date, King and Richardson (2002) found that metrics consisting of family-level indicators were inferior in their environmental relationship to genus and species level indicators. However, multivariate analyses completed by Bowman and Bailey (1998) and Furse et al. (1984) indicated that the difference between lentic study sites in ordinate space was very similar between genus and order levels, indicating that they both reflect similar site information. Many state wetland bioassessment programs incorporate analyses at the family level (Montana, Ohio, Minnesota, cited in U.S. EPA 2002c) or order level (Maine, Minnesota, Montana, Ohio, cited in U.S. EPA 2002c). Often, these programs are trying to categorize aquatic systems as impaired or unimpaired, or as good, fair, or poor, and not attempting to delve into the specific impairments. Using a coarse taxonomic resolution appears to permit such statements but may prevent elucidation of a more detailed assessment regarding the types of perturbations affecting a target aquatic system (Bailey et al. 2001). Fixed count methodology. The Florida Department of Environmental Protection mandates fixed counts of approximately 100 organisms for both the Stream Condition Index (Barbour et al. 1996) and Lake Condition Index (Gerritsen et al. 2000). The organisms colleted in this study were identified by the FDEP Central Lab utilizing the same 100-count protocols as these indices. There has been substantial dialogue in the literature regarding the efficacy of fixed-count subsampling to 100 organisms in rapid assessment programs. Doberstein et al. (2000) agreed with Courtemanch (1996), Sovell and Vondracek (1999), and Karr and Chu (1999) that subsampling using a 100-organism

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109 200 did substantially better at determining impairment than counts of 100 organisms, but increases above 200 organisms resulted in no change in impairment detection ability. Doberstein et al. (2000) also commented that counting 100 organisms introduces within-site variability with subsampling replicates, and that the variance decreases with window expanded to both increase the power of the analyses and to expand the applicability of the results. As these metrics were developed with genus-level data, increasing subsample size. The results of this study suggest that fixed count sampling to approximately 100 organisms provides adequate information to characterize the fauna and to discern the relative quality of the sampled isolated depressional herbaceous wetlands. As the metrics proposed are abundance metrics, they are less affected by the increases in sampling effort due to expected isometric responses (Barbour and Gerritsen 1996). However, the sites sampled in this study were generally polarized along the disturbance gradient. Classification into two (or three) groups (such as good, fair, or poor) is generally reliable under such circumstances (Karr and Chu 1999, but see Doberstein et al. 2000, King and Richardson 2002). It may be more difficult to discern differences in mid-quality wetland assessments using fixed counts of 100 organisms (Doberstein et al. 2000), and more organisms or additional search methods (i.e., select for large, rare macroinvertebrates) may be warranted under such circumstances (Barbour et al. 1999). Another criticism of fixed-count subsampling is that rare species are often overlooked (Sovell and Vondracek 1999, Cao et al. 2001, Bailey et al. 2001). This study did not analyze species-level information, which decreases the likelihood of rare taxa. Including species-level information may provide additional data from which metrics may be identified, however, additional costs and time are involved. The relationship between rare species and wetland characterization warrants additional attention. Conclusions and Recommendations Five attributes of macroinvertebrate community composition or structure were identified for use as biological indicators. The summed value of these five metrics, creating the Macroinvertebrate Index of Wetland Condition (MIWC), was correlated with the LDI gradient >0.75, although the precision and sensitivity of the metrics that comprise the MIWC was generally low. The macroinvertebrate composition of isolated systems in Florida was driven by variation in Landscape Development Intensity, soil pH, specific conductivity, and water TP. Specific actions to decrease the influence of these deterministic environmental variables in isolated wetland systems may result in wetland systems with community structure and function more similar to reference sites. Additional information on the relationship of the macroinvertebrate community along a disturbance gradient may be gleaned from a more detailed taxonomic examination of the composite samples. Stronger correlations, including the development of optima may be ascertained from species-level studies, although generalizations could be made using genus-level (or perhaps higher, e.g., Hilsenhoff 1988). However, as previously mentioned, laboratory identification to species of certain families of macroinvertebrates can be laborious and difficult. Also, as diagnostic features may be temporally available, or development seasonally dependent, species identification may be fortuitous at best. It is suggested, therefore, that additional sites be sampled and the temporal study

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110 increasing the sample size will necessarily increase the power of the analyses and also decrease variation in the data due to the relatively coarse level of identification. For instance, some taxa have species that are sensitive to, and species that are tolerant of, measured changes such as decreased dissolved oxygen (Barbour et al. 1999). Increasing sample size may assist in further elucidating trends between environmental variables of interest and macroinvertebrate community response. In addition, increasing sample size will likewise increase the likelihood of improved taxonomic resolution as laboratories become more familiar with taxa of isolated depressional wetlands and increase their reference collections. Increase in sample size may also permit the development of additional metrics or the exploration of different disturbances (e.g., urban systems). Finally, as wetland macroinvertebrate community composition was also related to environmental gradients (such as TP, specific conductivity, pH, etc.), additional laboratory studies of the relationship between particular gradients (i.e., increases in pH) may be fruitful. Controlling for particular effects may further the knowledge of the response of wetland macroinvertebrates to anthropogenic disturbances and assist in identifying optima and other discursive and useful information on wetland macroinvertebrates autecology.

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CHAPTER 5 SUMMARY AND SYNTHESIS Metric Summary A Wetland Condition Index (WCI) of twenty-four metrics was developed from the three assemblages sampled from isolated depressional herbaceous wetlands located throughout peninsular Florida: fourteen algal metrics, five macrophyte metrics, and five macroinvertebrate metrics. The metrics identified were comprised of compositional, trophic, and autecological attributes that varied with respect to changes in the development intensity within a 100m buffer immediately surrounding the study wetlands. Correlations between the three indices (Diatom Index of Wetland Condition, Vegetative Index of Wetland Condition, and Macroinvertebrate Index of Wetland Condition) and the measured Landscape Development Intensity index (LDI) were each greater than |0.65| and were highly significant (p<0.001), although also highly variable. Landscape Assessment and Index Development An assumption inherent in this study is the direct relationship between the land use within the wetland basin and the composition and function of the wetland itself. This assumption was predicated on the use of landscape-scale characteristics obtained from the literature to quantify the level of disturbance within a system (Cuffney et al. 2000, Galatowitsch et al. 1999a). Landscape-scale measurements of human disturbance, such as the Landscape Development Intensity index (LDI), provided an independent assessment of possible deleterious inputs (e.g., phosphorous loading from agricultural operations) and alterations to the proper functioning of the wetland (e.g., changes in fire or hydrologic regime due to land use change). Landscape-scale measurements, when coupled with GIS analyses, also provided repeatable measurements when compared with subjective on-site procedures (e.g., Wetland Rapid Assessment Procedure, Miller and Gunsalus 1997). The scale of the disturbance assessment may have had ramifications on the correlation coefficient of the measured ecological condition of the wetland sampled. For instance, the LDI does not incorporate slope, elevation, or direction of flow into the assessment. Thus, a system with a potentially disruptive land use (e.g., a dairy farm) within the 100m buffer but down hill would have the same score as a site with a dairy farm within the 100m buffer but uphill despite the obvious advantages to being located uphill of such a potential perturbation. This landscape assessment artifact may be reflected in the high variance, low precision, and low sensitivity of the metric values for any given LDI score (i.e., Figure 2-6). Improvements to the LDI, such as incorporating the existence of buffers to flow (i.e., berms) or access (i.e., Serenoa repens) may improve the relationship between organismal response and landscape perturbation. 111

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112 The Landscape Development Intensity index, as an agglomerative measure, incorporates and assigns disturbance coefficients to multiple land uses based on non-renewable fuel use (Brown and Vivas submitted). However, ecological responses to increases in non-renewable fuel use may not follow the rank order inherent within the LDI. For instance, agricultural practices generally use less non-renewable fuel per hectare than single family residential land use (Table 1-1). The pesticides and fertilizers used in agricultural practices, however, have a direct effect on the composition and functioning of wetland systems (Euliss and Mushet 1999). Single family residential land use may use pesticides and fertilizers, but likely at a much lower per hectare dosage in other words the direct effect on ecosystems may not be as intense. Thus higher LDI scores may not be directly analogous to increased stressors on wetland assemblages. This may led to highly variable responses from metrics for any given LDI score (e.g., Figure 2-6). The LDI was developed as an agglomerative index of energy intensity, but based on the highly variable metric response in these analyses, it appears that additional information germane to development intensity might improve the relationship between the biological data and the landscape data. For instance, improvements to the development index could come from separating out the effect of altered hydrology from other values due to its relative importance to wetlands (Mitsch and Gosselink 2000). In the current LDI, hydrological alterations are impossible to identify due to the methodology inherent within the LDI (Brown and Vivas submitted). With two exceptions (mean Coefficient of Conservatism and Annual to Perennial ratio), metrics identified in this analysis are based on the abundance of various compositional, functional, or trophic assemblages. Data are constrained (Aitchison 1986) due to the abundance values necessarily ranging from 0% 100%. The use of constrained data in developing the three indices of wetland condition may be implicated in the highly variable empirical scores for metrics along increasing LDI values. Membership in one group (e.g., % Orthocladiinae) may be inversely related to membership in another group (e.g., % Tolerant). For instance, a high abundance of Orthocladiinae in any given sample necessitates a lower abundance of tolerant organisms, as the non-Orthocladiinae portion of the sample would be small (i.e., 100% Orthocladiinae % = remaining sample for categorizing). Thus, some metric values may be lower than anticipated for any given LDI score not as a function of the surrounding land use but due to the effects of constrained data. In summary, as a general, landscape level development intensity index, the LDI was significantly correlated with each of the metric developed, although the results were highly variable. However, the LDI remains a useful relative indicator of wetland condition despite the relatively low resolution as conclusions may be drawn regarding the expected landscape relationship to down-slope wetlands. In addition, the LDI, compared to field work, provides a relatively simple assessment for a minor expenditure of effort and money. In addition, the use and acceptability of GIS in landscape assessment is increasing as the number of available coverages and GIS applications continues to increase (Cuffney et al. 2000).

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113 Environmental Variables Driving Wetland Composition Across Assemblages Soil and water samples from wetlands in reference and developed landscapes were shown to be significantly different for the following non-collinear environmental anoxia, such as the release of bound phosphorous from the soil, could further alter community composition. variables: soil pH, soil TP, specific conductivity, ammonia, and water TP. Dimension-reducing ordination with non-metric multidimensional scaling (NMDS) and subsequent correlations of environmental variables with ordination scores indicated that for algal, macrophyte, and macroinvertebrate assemblages, LDI score, soil pH, specific conductivity, and water TP were important components driving wetland composition. Latitude and water color were also correlated with ordination scores for macrophytes and macroinvertebrates, respectively. While the relationship of each assemblage with the four (or five, in the case of macrophytes and macroinvertebrates) environmental variables was discussed, the strong correlation of the composition of these three very different assemblages with the variables LDI, soil pH, specific conductivity, and water TP warrants additional attention. The four driving environmental variables were measures that acted on various scales. LDI was a coarse measurement of human landscape modification. Specific conductivity and water TP were finer-scale measurements that typically emanated from the interaction of precipitation and constituent mobilization and runoff into the wetland system. These two variables may also have been modified by human landscape alterations such that irrigation, rather than natural rainfall, may have played a role in either mobilizing the constituents to the wetland or in increasing the specific conductivity of the receiving water body (Fore and Grafe 2002). Soil pH, another environmental variable operating on a finer scale, would be expected to be less reactive to landscape modifications since direct pH loading generally does not occur. However, agrochemicals are typically more basic, thus runoff and transportation of agrochemicals into receiving water bodies such as wetlands may affect not only the nutrient levels in the receiving waters, but also the pH of the system (Fore and Grafe 2002). Since the LDI was a general landscape modification measurement, it was expected that wetland species composition would be correlated with changes in the LDI across each assemblage. The results suggested that the LDI was able to couple the disparate effects of human landscape modification, such as altered hydrology (strongly affecting diatoms and macroinvertebrates) or trampling/selective herbivory (strongly affecting macrophytes), into a single value, which was assumed to be manifested by changes in assemblage composition. Phosphorous in the system would be expected to increase metabolic rates throughout the aquatic system. Thus, diatoms and macrophytes would increase production due to increased availability of a typically limiting nutrient, and macroinvertebrates would likewise increase in abundance as additional resources would be made available from plant production and subsequent decay. Increases in nutrient levels, however, can have deleterious impacts on wetland systems that can cascade through the various assemblages. For instance, increased nutrient loading can affect dissolved oxygen levels with the water body as chemical and biological oxygen demand may surpass available oxygen levels. This would drastically affect the three assemblages sampled (as well as most other organisms within the system). Chemical reactions to

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114 Specific conductivity and soil pH directly affect diatom community composition, generally through decreases in bio-available constituents (Pan and Stevenson 1996, U.S. EPA 2002e). Compositional changes related to either variable were generally less pronounced for macroinvertebrates (Spieles and Mitsch 2000) and macrophytes (Adamus integrity of wetland systems, methods to assess the relative condition of these systems et al. 2001). As diatoms are an important component of macroinvertebrate food webs, alterations to the macroinvertebrate food base may be manifested through compositional changes of the macroinvertebrate assemblage. Macrophytes are affected minimally by alterations in specific conductivity and pH (Danielson 1998, Adamus et al. 2001), although changes in these constituents may often indicate increased nutrient loading or groundwater irrigation (and associated landscape changes). Environmental Variables and Management Concerns Four environmental variables (LDI, soil pH, specific conductivity, and water TP) were strongly correlated with the community composition of diatoms, macrophytes, and macroinvertebrates of isolated herbaceous depressional wetlands of peninsular Florida. As the assemblages sampled represent primary, secondary, and tertiary trophic classes, structural components of the wetland itself, and a portion of the landscape food web (i.e., food source for passerines and wading birds, reptiles and amphibians, small mammals, etc.), changes in wetland management to decrease the effect of the controlling environmental variables would be advantageous to meeting the goals of the Clean Water Act. To ameliorate the impact of human landscape modification on wetland systems, it is hypothesized that creating buffer zones around wetlands would improve the community composition (i.e., the system would become more similar to wetlands in reference conditions) and improve biotic integrity. Buffer zones emanating from the wetland/upland boundary would likely improve wetland water quality through particle retention and nutrient uptake by upland/facultative plants of the buffer zone. Preventing domestic herbivores from grazing in the wetland through fencing or shrubbery (e.g., Serenoa repenssaw palmetto) would decrease damage from selective herbivory, as well as decrease nutrient loading from cattle wastes. Specific conductivity may decrease as a result of constituent uptake by buffer vegetation and immobilization of micro-constituents of the overland or subsurface flow. Soil pH in the wetland, considered a function of agrochemical loading, may also decrease as a result of wetland buffers as agrochemicals of the overland flow could be assimilated by buffer vegetation, and agrochemicals adsorbed onto soil particles would be sequestered in buffer vegetation. Conclusions and Recommendations Isolated, depressional wetlands provide many functions to the landscape and to the State of Florida. However, their spatial location, generally smaller size, and irregular or patchy distribution on the landscape have contributed to their filling or destruction such that they have been greatly reduced in number (Kirkman et al. 1999). Those that remain, if in developed landscapes, often have decreased functionality and integrity (sensu Karr 1981) due to anthropogenic inputs or landscape activities. To attempt to meet the goals of the Clean Water Act, which include maintaining the chemical, physical, and biological

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115 had to be developed. Once the relative condition was known, efforts to restore wetland systems could be undertaken. In this study, methods were developed to assess the relative condition of isolated herbaceous wetland systems in peninsular Florida using endemic wetland flora and fauna. Seventy-five isolated wetlands were sampled throughout peninsular Florida, and twenty-four metrics were developed from the algal, macrophyte, and macroinvertebrate assemblages identified. Individual metrics were summed for each of the assemblages and three indices developed for the Wetland Condition Index: the Diatom Index of Wetland Condition, the Macrophyte Index of Wetland Condition, and the Macroinvertebrate Index of Wetland Condition. Correlations of these three indices with the Landscape Development Intensity index, an independent, GIS analysis of human landscape modification were significant and >|0.65| (Spearmans r). In addition to developing biometrics for the three assemblages, environmental variables responsible for algal, macrophyte, and macroinvertebrate community composition were discerned. The parameters responsible, identified through site ordination, were of both coarse (LDI scores, and latitude for macrophytes) and finer scales (soil pH, water TP, and specific conductivity, as well as water color for macroinvertebrates). Efforts to decrease the impact of these inputs on wetland community composition through the development of wetland buffers were proffered. Due to the highly variable response of the twenty-four metrics identified vis--vis the LDI, efforts to improve the goodness of fit between the LDI and the biological data are warranted. Significant correlations were identified, however improvements in the correlation may be obtained through modifying the LDI (e.g., revising calculations) or changing the scale of the landscape analyses to include hydrologic alterations (currently not an itemized perturbation). An additional method to improve the fit of the data would through multiple regression analyses of sampled data and land use (before combined into the LDI). Recommendations for future work following these analyses are of two veins: validation (expanding the current n to compare and contrast how additional sites relate to the sites used to develop these indices) and calibration (amending the metrics developed from these analyses based on the results of the validation and the larger n), and expansion. Revisiting sites, increasing the dataset through the addition of new sites, and reevaluating the metrics developed based on the additional sampling effort are the hallmarks of a thorough validation and calibration program. An n of 75, while statistically satisfying, should be increased to capture the breadth and depth of the wetland systems of peninsular Florida more thoroughly. An expansion of this research into other impairments and marshes of varying size and location (i.e., the Florida panhandle) is also recommended. Impairments of different intensity, such as industrial or urban development, may be manifested by markedly different attributes in isolated wetlands located in those landscape matrices. Finally, including additional assemblages, such as reptiles/amphibians, soil microbes, or birds, could increase the information obtained from the wetland systems and perhaps permit a deeper understanding of the relationship between stressors, sources of stress, and the manifestation of exogenous perturbations on the flora and fauna, and ultimately the integrity itself, of isolated depressional wetlands throughout Florida.

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116 APPENDIX A SITE DESCRIPTIONS Seventy-five sites were sampled throughout peninsular Florida. Access to many sites was obtained through cooperation with landowners and was often contingent on site anonymity. Coordinates for sites sampled, exclusive of the anonymous sites, are given below (Table A-1), as are Landscape Development Intensity (LDI) scores. Additional information on LDI scores may be found in Brown and Vivas (submitted). Table A-1. Site coordinates and LDI score. Site LDI Latitude Longitude Site LDILatitude Longitude ALPaynes 1.38 29.60210 -82.23563HARare 3.58n/a n/a Audobon 3.54 28.11827 -82.11629HEBad 3.4926.30340 -81.24560 Bear Scat 1.18 26.18502 -81.25442HEL2 3.43n/a n/a Big Cow 3.58 26.23075 -81.26520HEOkay 1.0526.59035 -81.32581 BRSebastian 1.09 27.83263 -80.58833HighPast 3.7127.42338 -81.56088 CabPatch 3.54 29.43420 -81.34030HighRef 1 27.48100 -81.55022 Caravelle 3.54 29.51767 -81.72119HillsRef 1.2328.14610 -82.23110 Chuluota 1.00 28.61731 -81.05781Hunt Camp 1 29.32275 -81.74680 CLBayard 1.07 29.96117 -81.61504IFASI 2.2529.72395 -82.40680 CLCove 3.54 29.95187 -81.66341IFASII 1.8429.72678 -82.40619 CMWPast 2.14 26.85486 -81.78479Immokalee 2.6 26.46316 -81.44605 CMWRef 1.62 26.94567 -81.84494IRBlueCypress3.58n/a n/a COBurgle 3.36 n/a n/a IRCanal 3.59n/a n/a COHole 1.11 26.02437 -81.26467IROJ 3.68n/a n/a CREW 1.78 26.48973 -81.53834JD6 1.2427.00147 -80.14629 Deerfly 2.39 29.17017 -81.62333Kelly Park 3.6528.79637 -81.43891 DEMelon 4.20 n/a n/a LCork 1 26.47915 -81.54871 GarberRanch 2.75 27.21615 -82.15127Lego 1 29.13782 -82.63217 GBarE 3.38 n/a n/a LESuwan 2.1229.31693 -83.04337 GLDonut 3.59 n/a n/a LLeecounty 1.0226.70824 -81.65356 GLPont 3.29 n/a n/a MALudy 3.5 n/a n/a Goethe 1.52 29.16072 -82.59969MASpray 3.8 n/a n/a GreenSwamp 1.60 28.35458 -82.01761McArthur 3.7527.16536 -81.19631 HagueI 4.12 29.78267 -82.41186MNElmer 3.13n/a n/a HagueII 5.63 29.78350 -82.41133MNErik* 3.06n/a n/a Half Moon 1.99 28.91872 -82.25719MNOcala 1.5829.10181 -81.89731

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117 Table A-1. Continued. Site LDI Latitude Longitude Site LDILatitude Longitude MRPepper 4.54 n/a n/a PUPond* 1.4229.71649 -81.96575 Myakka 1.25 27.23684 -82.33043RiceCreek 1.8829.68086 -81.74208 OKCara 4.79 n/a n/a Sandhillcrane 3.1026.86677 -80.21878 OKKiss 1.20 27.55004 -81.00910SANorthmya 1.2027.27050 -82.25933 OKPast 3.58 27.59890 -81.03172SAOscer 1.1227.19536 -82.45383 PacificTom 4.54 26.52025 -81.67369Savannas 1.1327.30214 -80.27348 PallMar 1.00 26.94969 -80.31057STCow 3.94n/a n/a PBCorbett 1.13 26.94206 -80.36113SUVaca* 3.1728.91047 -82.25994 PBEnjay 1.00 26.95468 -80.18508SUWarhol* 3.66n/a n/a Penner 1.27 29.49614 -81.82489UNHealthy 3.9 30.04499 -82.17451 POWales 1.26 27.66359 -81.42379Weikiva 1.0028.73703 -81.48396 POWeowak 1.53 27.77768 -81.44651 Note: Latitude and longitude positions marked with n/a were accessed through agreements with anonymous landowners.

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118 of the lowest detectable level. APPENDIX B SOIL AND WATER SAMPLING METHODS AND RESULTS To relate the distribution of sampled communities to environmental parameters, soil and water physical and chemical constituents were measured (Tables B-1 and B-2, respectively). Soil chemistry samples were obtained at each site and the following parameters determined in the lab: total phosphorous (soil TP, mg/kg), percent total nitrogen (%TN), percent total carbon (%TC), percent organic matter (%OM), and pH. For soil samples the study wetland was separated in to dominant vegetation zones and four soil cores were proportionally distributed within the dominant vegetation zones (e.g., if 75% of the wetland was Panicum hemitomon and 25% Pontederia cordata, 3 samples would be taken in the Panicum zone and 1 sample in the Pontederia zone). The cores were taken with an approximately 8cm inner-diameter beveled PVC pipe. At each sample location, the duff layer was removed and the PVC pipe outline traced with a 15cm knife to reduce sample compaction. The PVC pipe was pounded into the wetland soil to an approximate depth of 10cm and extracted using a trowel. The surficial water was gently poured from the top, and the 10cm sample extruded. Samples from the same zone were mixed and a composite sample of approximately one liter scooped into a labeled container. All samples were placed on ice in the field and stored in a laboratory refrigerator until analyzed by the University of Florida Soil Science Department. In the lab, pH readings were taken and subsamples were dried to a constant weight and finely ground (<0.2 mm). Percent C and N were obtained from the ground samples utilizing a Carlo-Erba NA-1500 CNS Analyzer (Haak-Buchler Instruments, Saddlebrook, NJ). Total P analysis was performed by ashing additional subsamples at 550oC for 4 hours, dissolving the dried sample in 6M HCl (Anderson 1976), and analyzing the digestate for P following U.S. EPA method 365.4 (U.S. EPA 1983). Percent organic matter was obtained during the analysis of the total P. For subsequent site-specific analyses, a weighted average for each soil constituent was obtained by utilizing the percent extent of each wetland vegetation zone sampled. Samples for analysis of water chemistry parameters were collected at each site. Water samples for nutrient analysis were taken from the center of the wetland at an approximate depth of 10cm with a 0.5L pre-rinsed Polypropylene bottle and preserved with 2mL 1:1 H2SO4. The same method was used for chemical analysis (color, specific conductivity, turbidity, and pH) samples, with the exception that no preservative was added. Both bottles were placed on ice and delivered overnight to the FDEP Central Laboratories for processing. The following parameters were measured by FDEP following FDEP protocols (SOP #TA-06.04-5): color (PCU), specific conductivity (umhos/cm), turbidity (NTU), pH, ammonia (mg/L), nitrate/nitrite (mg/L), total Kjeldahl Nitrogen (TKN, mg/L), and total Phosphorus (water TP, mg/L). In the event that the constituent measured was below detection levels, the value entered for analysis was half

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119 Table B-1. Soil characteristics measured at each study site. Sites pH % TC % OM % TN TP (mg/kg) ALPaynes 3.82 42.73 3.00 787.40 83.91 Audubon 4.25 9.11 16.48 0.72 659.83 BearScat 7.12 5.75 10.76 0.53 81.16 BigCow 6.87 4.09 6.35 0.39 67.82 BRSebastian 4.12 9.71 19.58 0.50 99.78 CabPatch 5.66 7.46 15.71 0.52 321.64 Caravelle 4.75 11.98 24.32 0.64 251.89 Chuluota 3.90 19.34 36.63 1.17 223.45 CLBayard 3.65 19.07 34.94 0.88 16.36 CLCove 5.52 10.66 22.87 0.78 591.44 CMWPast 5.91 1.93 4.53 0.12 46.94 CMWRef 5.33 2.10 3.97 0.12 53.65 COBurgle 6.29 17.95 29.32 1.38 6.48 COHole 7.35 11.90 14.66 0.72 137.28 Crew 5.28 3.91 9.75 0.24 59.30 DEMelon 5.66 6.47 11.67 0.46 202.29 Deerfly 4.79 46.55 83.95 2.68 340.87 Garber 5.13 16.52 31.34 0.94 394.21 GBarE 3.98 48.07 3.19 371.79 91.88 GLDonut 4.90 9.43 19.39 0.68 73.36 GLPont 5.22 17.01 33.33 1.14 292.14 Goethe 4.09 14.42 26.73 0.88 200.91 GreenSwamp 4.60 13.83 25.09 0.87 372.60 HaRare 6.18 11.43 20.66 0.79 144.37 HagueI 5.51 7.22 98.80 0.49 969.13 HagueII 6.28 3.47 7.46 0.23 803.59 HalfMoon 4.11 15.91 29.18 1.07 95.75 HEBad 6.42 10.53 17.63 0.82 470.63 HEL2 6.53 22.57 49.44 1.81 418.91 HEOkay 5.10 21.02 5.03 1.43 37.16 Highpast 5.01 3.31 6.13 0.23 105.21 HighRef 4.26 8.81 18.83 0.56 325.15 HillsRef 5.13 10.21 20.73 0.57 185.93 HuntCamp 4.55 34.83 57.02 2.53 271.52 IFASI 4.39 49.08 96.15 3.42 649.48 IFASII 4.60 37.62 72.61 2.75 1011.63 Immokalee 4.47 8.53 14.94 0.50 145.91 IRBlueCypress 5.67 17.56 22.43 1.34 322.85

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120 Table B-1. Continued. Sites pH % TC % OM % TN TP (mg/kg) IRCanal 5.9515.6329.151.03521.02 IROJ 6.098.4615.850.68317.99JD6 4.923.057.770.1825.93KellyPark 3.9149.4589.953.33460.89LCork 6.350.774.350.0653.64LLeeCounty 5.307.5512.540.57138.68LEGo 4.239.8711.030.67110.37LESuwan 5.026.7311.170.4177.94MALudy 5.535.429.180.34209.99MASpray 4.1525.7211.581.4145.99McArthur 4.7116.1028.671.07300.08MNElmer 4.2326.5954.121.37790.86MNErik 3.9848.073.19371.7991.88MNOcala 4.5211.8622.510.81166.61MRPepper 4.8348.0293.752.72492.98Myakka 4.567.6213.150.4242.16OKCara 5.764.187.690.3058.68OKKiss 4.853.109.210.1977.80OKPast 6.102.465.770.1767.25PacificTom 5.980.984.830.0632.54PallMar 5.506.3711.360.3740.47PBCorbett 5.825.4213.240.25262.93PBEnjay 4.782.815.370.2042.87Penner 4.758.309.880.4691.55POWales 4.225.027.960.3273.44POWeowak 5.0611.7321.320.87312.90PUPond 3.8242.733.00787.4083.91RiceCreek 4.3114.1227.890.84478.98SANorthMya 4.883.534.340.2653.16SAOscer 4.893.314.940.2955.46SandhillCrane 4.803.058.670.2061.06Savannas 4.667.3313.080.3742.67STCow 5.5513.7725.171.01393.92SUVaca 3.9848.073.19371.7991.88SUWarhol 3.9848.073.19371.7991.88UNHealthy 6.633.148.740.21261.10Weikiva 3.3845.0285.242.16518.94 Note: Average values of impaired site soil parameters were given to site GBarE as access for soil sampling was not available.

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121 APPENDIX C DIATOM AUTECOLOGICAL VALUES Autecological values (Bahls 1993, Van Dam et al. 1994) for the epiphytic diatoms are given below. For metric development, the values were recoded as given in Table 2-19. Table C-1. Diatom Autecological Values. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Achnanthes exilis 5 2 1 1 1 2 3 Achnanthes hungarica 4 2 2 4 3 6 3 Achnanthes minutissima 3 2 2 1 2 7 3 Achnanthes minutissima scotica 3 2 Amphora veneta 5 3 2 3 4 5 2 Anomoeneis serians 1 1 1 2 1 1 Anomoeneis vitrea 4 2 1 2 1 2 Asterionella formosa 4 2 2 2 2 4 3 Aulacoseira alpigena 2 1 1 1 1 1 3 Aulacoseira crenulata 3 1 1 1 1 1 Aulacoseira granulata 4 2 2 3 2 5 3 Caloneis bacillum 4 2 1 2 2 4 2 Cocconeis placentula lineata 4 2 2 3 2 5 3 Cyclotella meneghiniana 4 3 3 5 4 5 2 Cyclotella pseudostelligera 3 2 2 3 3 5 2 Cymbella cesatii 3 1 1 1 1 1 3 Cymbella gracilis 2 1 1 1 1 2 3 Cymbella microcephala 4 2 1 1 1 4 2 Cymbella minuta 3 2 2 Diploneis parma Eunotia bilunaris 6 2 2 2 2 7 Eunotia bilunaris mucophila 2 2 2 2 1 2 Eunotia circumborealis 1 Eunotia faba 2 1 1 1 1 2 Eunotia fallax 2 1 1 1 1 1 Eunotia flexuosa 2 1 1 1 1 2 3 Eunotia formica 2 2 1 1 1 3 Eunotia glacialis 2 1 1 1 1 2 3 Eunotia implicata 2 1 Eunotia incisa 2 1 1 1 1 1 3

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122 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Eunotia monodon 2 1 1 1 1 1 3 Eunotia monodon bidens 2 1 1 1 1 1 Eunotia naegelii 2 1 1 1 1 1 Eunotia paludosa 1 1 1 1 1 1 Eunotia paludosa trinacria 1 1 1 1 1 1 Eunotia pectinalis 2 1 2 1 2 3 3 Eunotia pectinalis undulata 2 1 2 1 2 1 3 Eunotia pirla Eunotia praerupta 2 1 1 1 1 2 3 Eunotia rhomboidea 2 1 1 1 1 1 Eunotia soleirolii 3 1 2 1 2 1 Eunotia veneris 2 1 1 1 1 2 Fragilaria vaucheriae 4 2 2 3 3 5 2 Frustulia rhomboides 2 1 1 1 1 1 3 Frustulia rhomboides amphipleuroides2 1 1 1 1 1 3 Frustulia rhomboides crassinerva 2 1 1 1 1 1 Frustulia rhomboides saxonica 1 1 1 1 1 1 3 Gomphonema affine 4 2 1 1 2 3 3 Gomphonema angustatum 2 Gomphonema augur turris Gomphonema clavatum 3 1 1 1 1 4 2 Gomphonema gracile 3 2 1 1 1 3 2 Gomphonema parvulum 3 2 3 4 4 5 1 Gomphonema pseudotenellum Hantzschia amphioxys 3 2 2 2 3 7 2 Mastogloia smithii 4 4 2 2 Navicula accommoda 4 2 4 5 5 6 Navicula arvensis 4 2 3 4 4 5 2 Navicula bicephala 3 Navicula clementis 4 3 2 1 2 4 2 Navicula cohnii 4 3 2 1 2 5 2 Navicula confervacea 3 3 3 3 3 5 2 Navicula cryptocephala 3 2 2 3 3 7 3 Navicula cryptotenella 4 2 2 7 2 Navicula detenta 3 Navicula erifuga 4 3 5 2 Navicula evanida 3 2 1 1 1 3 Navicula festiva 1 1 1 1 1 1 2 Navicula hambergi 2 1 Navicula kotschyi 4 2 1 1 2 Navicula kriegerii Navicula laevissima 3 1 1 1 1 3 3 Navicula mediocris 2 1 1 1 1 1 Navicula minima 4 2 3 4 4 5 1 Navicula molestiformis 4 2 3 4 4 5 1

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123 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Navicula mutica 3 3 2 1 3 5 2 Navicula notha 2 1 1 1 1 2 2 Navicula pseudoventralis 4 2 1 1 1 2 2 Navicula pupula 3 2 2 3 3 4 2 Navicula pupula elliptica 4 2 4 2 Navicula pupula mutata 3 2 2 2 2 Navicula pupula rectangularis 3 2 2 3 3 4 2 Navicula pygmaea 5 3 3 3 3 5 2 Navicula radiosa 3 2 2 2 2 4 3 Navicula schadei 3 2 1 1 1 3 Navicula seminulum 3 2 3 4 4 5 1 Navicula subtilissima 1 1 1 1 1 1 2 Navicula tenelloides 4 2 1 1 1 5 1 Navicula trivialis 4 3 2 3 3 5 2 Navicula viridula rostellata 4 2 2 2 2 5 2 Neidium alpinum 2 1 1 1 3 Neidium bisulcatum 3 1 1 1 1 1 Neidium hercynicum 2 2 3 Neidium javanicum Nitzschia acidoclinata 3 1 1 1 2 3 3 Nitzschia agnita 4 1 Nitzschia amphibia 4 2 3 3 3 5 2 Nitzschia brevissima 3 3 3 2 5 2 Nitzschia capitellata 4 4 5 6 2 Nitzschia debilis 4 2 2 1 3 Nitzschia dissipata 4 2 2 2 2 4 3 Nitzschia frustulum 4 3 4 3 2 5 2 Nitzschia gracilis 3 1 2 2 3 2 Nitzschia intermedia 3 2 2 5 3 Nitzschia microcephala 4 2 4 3 3 5 1 Nitzschia nana 3 2 1 2 3 Nitzschia palea 3 2 4 4 5 6 1 Nitzschia palea debilis 3 1 1 1 Nitzschia palea tenuirostris 3 2 1 Nitzschia paleaformis 1 2 2 2 2 7 Nitzschia perminuta 4 2 1 1 1 2 3 Nitzschia pura 2 1 2 Nitzschia pusilla 3 2 2 2 2 7 1 Nitzschia solita 3 5 Nitzschia subacicularis 4 2 1 1 2 7 2 Nitzschia terrestris 3 2 1 Pinnularia braunii 1 1 1 1 Pinnularia gibba 3 2 2 3 3 7 3 Pinnularia gibba mesogongyla 3 1 Pinnularia interrupta 3 1 1 1 1 2

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124 Table C-1. Continued. Site pH Salin. Nitro. D.O. Sapro. Troph.Poll. Pinnularia maior 3 2 2 2 2 4 3 Pinnularia microstauron 3 2 2 3 2 7 2 Pinnularia obscura 3 2 1 1 1 3 Pinnularia subcapitata 2 2 2 3 2 2 3 Pinnularia subrostrata 3 Pinnularia viridis 3 2 2 3 2 7 3 Rhopalodia gibberula 3 Stauroneis anceps 3 2 2 2 2 4 3 Stauroneis kriegeri 3 2 2 2 2 4 3 Stauroneis phoenicenteron 3 2 2 3 2 4 2 Stauroneis thermicola 3 2 2 1 2 7 3 Stenopterobia curvula 2 1 1 1 1 1 Stenopterobia delicatissima 2 1 1 1 1 1 Synedra tenera 2 1 1 1 1 2 3 Note: Abbreviations are as follows: Salin. (Salinity); Nitro (Nitrogen); D.O. (Dissolved Oxygen); Sapro. (Saprobity); Troph. (Trophic); Poll. (Pollution Tolerance).

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125 APPENDIX D COEFFICIENT OF CONSERVATISM Each macrophyte taxon identified was given a Coefficient of Conservatism (CC) score (Wilhelm and Ladd 1988) as detailed in Cohen et al. (submitted). The table below provides a list of the average confidence-weighted Coefficient of Conservatism for each species identified. Table D-1. Coefficient of Conservatism scores for sampled macrophytes. Site Name CC Site Name CC Acalypha gracilens 3.29 Axonopus furcatus 2.12 Acer rubrum 4.65 Azolla caroliniana 1.81 Aeschynomene indica 0.49 Baccharis glomeruliflora 6.12 Agalinis filifolia 6.69 Baccharis halimifolia 2.53 Agalinis linifolia 7.04 Bacopa caroliniana 5.31 Agalinis obtusifolia 6.50 Bacopa inominata 7.48 Alternanthera philoxeroides 0.00 Bacopa monnieri 4.49 Alternanthera sessilis 0.11 Bidens laevis 7.19 Alternanthera tenella 0.00 Bidens mitis 6.31 Amaranthus blitum 0.00 Bigelowia nudata 7.59 Amaranthus spinosus 0.04 Blechnum serrulatum 7.15 Ambrosia artemisiifolia 0.95 Boehmeria cylindrica 5.91 Ammannia latifolia 4.55 Boltonia diffusa 4.96 Ampelopsis arborea 3.25 Brasenia schreberi 8.79 Amphicarpum muhlenbergianum 5.70 Burmannia capitata 8.13 Andropogon glomeratus 3.90 Canna flaccida 6.75 Andropogon virginicus 3.44 Caperonia castaneifolia 4.94 Aristida affinis 8.23 Caperonia palustris 0.52 Aristida lanosa 8.73 Cardamine pensylvanica 4.42 Aristida palustris 8.84 Carex alata 4.27 Aristida patula 4.85 Carex albolutescens 3.47 Aristida purpurascens 5.58 Carex fissa 3.90 Aristida stricta 8.67 Carex stipata 4.46 Asclepias lanceolata 6.73 Carex verrucosa 7.97 Aster dumosus 2.53 Carphephorus odoratissimus 6.93 Aster elliottii 6.76 Cassytha filiformis 3.34 Aster subulatus 5.74 Celtis laevigata 5.08 Axonopus affinis 1.89 Centella asiatica 1.92

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126 Table D-1. Continued. Site Name CC Site Name CC Cephalanthus occidentalis 7.27 Eclipta prostrata 3.21 Echinochloa walteri 3.36 Helianthus floridanus 5.85 Chenopodium album 0.78 Eichhornia crassipes 0.00 Chenopodium ambrosioides 0.59 Eleocharis atropurpurea 5.69 Chrysobalanus icaco 5.63 Eleocharis baldwinii 2.82 Cirsium nuttallii 3.08 Eleocharis cellulosa 7.80 Cladium jamaicense 9.04 Eleocharis elongata 6.97 Coelorachis rugosa 8.91 Eleocharis equisetoides 9.10 Coelorachis tuberculosa 10.00 Eleocharis interstincta 7.80 Commelina diffusa 2.02 Eleocharis microcarpa 5.78 Conoclinium coelestinum 4.37 Eleocharis vivipara 3.81 Conyza canadensis 1.01 Elephantopus elatus 2.72 Crinum americanum 8.67 Eleusine indica 0.00 Cuphea carthagenensis 1.92 Eragrostis atrovirens 1.58 Cynodon dactylon 0.29 Eragrostis elliottii 4.14 Cyperus articulatus 6.64 Eragrostis spectabilis 3.44 Cyperus compressus 2.74 Erechtites hieracifolia 1.37 Cyperus croceus 1.30 Erianthus giganteus 6.34 Cyperus distinctus 5.00 Erigeron quercifolius 3.31 Cyperus haspan 5.68 Eriocaulon compressum 7.50 Cyperus lanceolatus 2.04 Eriocaulon decangulare 7.50 Cyperus odoratus 4.25 Eupatorium capillifolium 0.83 Cyperus polystachyos 1.56 Eupatorium compositifolium 2.72 Cyperus retrorsus 1.79 Eupatorium leptophyllum 4.94 Cyperus strigosus 4.49 Eupatorium mohrii 6.87 Cyperus surinamensis 2.03 Eupatorium perfoliatum 5.85 Cyperus virens 5.70 Euthamia carolinana 3.25 Decodon verticillatus 7.80 Ficus aurea 3.38 Desmodium triflorum 0.43 Fimbristylis dichotoma 3.55 Dichromena colorata 6.18 Fimbristylis miliacea 1.95 Dichromena latifolia 6.62 Fuirena breviseta 7.60 Digitaria bicornis 0.00 Fuirena pumila 5.92 Digitaria ciliaris 1.30 Fuirena scirpoidea 6.50 Digitaria serotina 1.39 Galactia elliottii 5.54 Diodia virginiana 4.96 Galium pilosum 4.77 Diospyros virginiana 5.76 Galium uniflorum 5.80 Drosera brevifolia 8.21 Gaylussacia dumosa 5.44 Drosera capillaris 7.09 Gomphrena serrata 0.87 Drosera intermedia 8.23 Gordonia lasianthus 9.03 Drymaria cordata 2.72 Gratiola pilosa 6.63 Dulichium arundinaceum 7.31 Gratiola ramosa 6.87 Echinochloa colona 0.24 Habenaria repens 4.58 Echinochloa crusgalli 0.22 Hedyotis corymbosa 2.31 Echinochloa muricata 6.01 Hedyotis uniflora 4.04

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127 Table D-1. Continued. Site Name CC Site Name CC Hibiscus grandiflorus 6.86 Ludwigia alata 5.85 Hydrochloa caroliniensis 4.79 Ludwigia alternifolia 6.24 Hydrocotyle umbellata 1.92 Ludwigia arcuata 5.32 Hydrolea corymbosa 5.85 Ludwigia decurrens 6.76 Hymenachne amplexicaulis 0.00 Ludwigia lanceolata 6.15 Hypericum brachyphylum 7.55 Ludwigia linearis 5.72 Hypericum cistifolium 6.32 Ludwigia linifolia 7.04 Hypericum fasciculatum 7.27 Ludwigia maritima 5.85 Hypericum hypericoides 5.44 Ludwigia microcarpa 4.81 Hypericum mutilum 4.04 Ludwigia octovalvis 4.09 Hypericum myrtifolium 6.56 Ludwigia palustris 4.77 Hyptis alata 4.58 Ludwigia peruviana 0.62 Ilex cassine 7.66 Ludwigia repens 5.20 Ilex glabra 5.85 Ludwigia suffruticosa 6.23 Ipomoea quamoclit 0.26 Ludwigia virgata 6.73 Ipomoea sagittata 6.42 Lycopodiella alopecuroides 7.61 Iris hexagona 6.97 Lycopodium appressum 8.01 Itea virginica 7.09 Lycopus rubellus 6.75 Iva microcephala 4.68 Lygodium microphyllum 0.78 Juncus coriaceus 8.51 Lyonia ferruginea 8.39 Juncus effusus 3.25 Lyonia lucida 7.06 Juncus marginatus 3.65 Lythrum alatum 3.55 Juncus megacephalus 5.70 Macroptilium lathyroides 0.41 Juncus polycephalus 4.96 Magnolia virginiana 9.44 Juncus repens 6.91 Mayaca fluviatilis 8.45 Juncus scirpoides 4.33 Melaleuca quinquenervia 0.00 Justicia angusta 8.56 Melochia corchorifolia 2.24 Justicia ovata 8.88 Melothria pendula 3.31 Kosteletzkya virginica 7.49 Micranthemum umbrosum 5.66 Kyllinga brevifolia 1.42 Micromeria brownei 6.34 Kyllinga pumila 5.53 Mikania scandens 1.95 Lachnanthes caroliniana 3.76 Mollugo verticillata 1.30 Lachnocaulon anceps 7.15 Murdannia keisak 2.34 Lachnocaulon beyrichianum 9.18 Murdannia nudiflora 1.42 Lachnocaulon minus 7.97 Myrica cerifera 3.82 Lechea cernua 8.67 Myriophyllum laxum 5.85 Leersia hexandra 5.61 Nuphar luteum 6.09 Lemna minor 3.77 Nymphaea odorata 7.18 Leucothoe racemosa 9.44 Nymphoides aquatica 6.09 Limnobium spongia 4.79 Nyssa biflora 9.04 Lindernia grandiflora 3.60 Osmunda cinnamomea 6.44 Liquidambar styraciflua 5.56 Osmunda regalis 8.04 Lobelia glandulosa 6.03 Oxypolis filiformis 8.69 Lobelia paludosa 8.08 Panicum abscissum 9.22

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128 Table D-1. Continued. Site Name CC Site Name CC Panicum aciculare 6.01 Polygonum hydropiperoides 4.02 Panicum chamaelonche 7.69 Polygonum lapathifolium 1.95 Panicum ciliatum 7.15 Polygonum punctatum 4.02 Panicum commutatum 7.57 Polypremum procumbens 1.71 Panicum dichotomiflorum 4.96 Pontederia cordata 5.38 Panicum dichotomum 5.61 Portulaca amilis 0.87 Panicum ensifolium 6.50 Proserpinaca palustris 5.85 Panicum erectifolium 7.39 Proserpinaca pectinata 5.50 Panicum hemitomon 5.82 Pteridium aquilinum 3.90 Panicum hians 6.63 Quercus laurifolia 5.14 Panicum maximum 0.78 Quercus nigra 4.14 Panicum repens 0.41 Quercus virginiana 4.85 Panicum rigidulum 5.47 Rhexia cubensis 7.22 Panicum spretum 6.63 Rhexia mariana 5.50 Panicum tenerum 8.67 Rhexia nashii 7.80 Panicum tenue 5.85 Rhexia nuttallii 7.93 Panicum verrucosum 6.83 Rhexia petiolata 7.90 Parthenocissus quinquefolia 3.43 Rhus copallinum 3.65 Paspalum acuminatum 1.06 Rhynchospora cephalantha 6.19 Paspalum conjugatum 3.84 Rhynchospora debilis 7.80 Paspalum distichum 5.54 Rhynchospora divergens 5.53 Paspalum laeve 5.79 Rhynchospora fascicularis 5.92 Paspalum monostachyum 9.80 Rhynchospora fernaldii 4.77 Paspalum notatum 0.14 Rhynchospora filifolia 8.13 Paspalum praecox 6.50 Rhynchospora inundata 7.25 Paspalum repens 6.69 Rhynchospora microcarpa 5.29 Paspalum setaceum 3.44 Rhynchospora microcephala 6.50 Paspalum urvillei 0.00 Rhynchospora nitens 5.20 Persea borbonia 8.02 Rhynchospora perplexa 5.20 Persea palustris 8.31 Rhynchospora pusilla 7.54 Phyla nodiflora 1.92 Rhynchospora rariflora 8.63 Phyllanthus urinaria 0.22 Rhynchospora tracyi 9.03 Phytolacca americana 2.09 Rhynchospora wrightiana 7.80 Pinus elliottii 4.21 Ricciocarpus natans 4.55 Pinus palustris 4.77 Richardia scabra 0.00 Pinus taeda 5.34 Rosa palustris 6.01 Pluchea foetida 6.65 Rubus argutus 3.56 Pluchea longifolia 5.85 Rubus cuneifolius 3.90 Pluchea odorata 4.96 Rubus trivialis 2.60 Pluchea rosea 5.45 Sabatia grandiflora 7.09 Polygala cymosa 7.67 Sacciolepis indica 0.92 Polygala rugelii 8.17 Sacciolepis striata 5.35 Polygonum densiflorum 5.32 Sagittaria graminea 5.53 Polygonum hirsutum 8.17 Sagittaria lancifolia 4.96

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129 Table D-1. Continued. Site Name CC Site Name CC Sagittaria latifolia 6.50 Syngonanthus flavidulus 6.93 Salix caroliniana 2.95 Taxodium ascendens 7.21 Salvinia minima 2.03 Taxodium distichum 7.21 Sambucus canadensis 1.48 Teucrium canadense 6.44 Sarcostemma clausum 3.81 Thalia geniculata 7.12 Saururus cernuus 7.33 Thelypteris interrupta 6.74 Schinus terebinthifolius 0.00 Toxicodendron radicans 1.44 Schizachyrium scoparium 5.44 Triadenum virginicum 8.16 Schoenolirion albiflorum 9.10 Triadenum walteri 7.92 Scleria baldwinii 8.67 Tripsacum dactyloides 6.03 Scleria georgiana 8.78 Typha domingensis 0.59 Scleria reticularis 6.79 Typha latifolia 1.60 Scleria triglomerata 6.74 Ulmus americana 7.68 Scleria vaginata 0.00 Urena lobata 0.00 Scoparia dulcis 2.36 Utricularia cornuta 7.46 Senna occidentalis 0.00 Utricularia foliosa 6.44 Serenoa repens 7.03 Utricularia purpurea 6.50 Sesbania herbacea 1.49 Utricularia radiata 6.01 Sesbania vesicaria 1.44 Utricularia subulata 7.23 Setaria parviflora 3.40 Vaccinium corymbosum 5.63 Sida rhombifolia 1.65 Vaccinium darrowii 7.15 Smilax auriculata 3.96 Verbena bonariensis 0.56 Smilax bona-nox 3.78 Viola lanceolata 5.32 Smilax pumila 6.01 Viola primulifolia 6.11 Solanum americanum 1.16 Vitis rotundifolia 1.18 Solanum carolinense 2.13 Woodwardia areolata 7.68 Solanum viarum 0.00 Woodwardia virginica 6.50 Solidago fistulosa 4.49 Xyris ambigua 6.43 Solidago latissimifolia 7.51 Xyris baldwiniana 6.97 Solidago stricta 5.49 Xyris brevifolia 7.20 Solidago tortifolia 6.96 Xyris caroliniana 6.14 Sorghastrum secundum 7.73 Xyris difformis 7.50 Spartina bakeri 5.98 Xyris elliottii 6.69 Spermacoce assurgens 3.09 Xyris fimbriata 7.08 Spirodela polyrhiza 2.95 Xyris flabelliformis 7.43 Sporobolus domingensis 2.47 Xyris jupicai 3.51 Sporobolus indicus 0.99 Xyris platylepis 5.32 Stillingia aquatica 8.32 Xyris smalliana 7.80 Stillingia sylvatica 7.30

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130 ecoregions in the prairie pothole region. Wetlands 19(3): 648-664. LIST OF REFERENCES Adamus, C. and M. J. Bergman. 1995. Estimating non-point source pollution loads with a GIS screening model. Water Resources Bulletin 31(4): 647-655. Adamus, P. R. 1996. Bioindicators for Assessing Ecological Integrity of Prairie Wetlands, EPA/600/R-96/082. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, Corvallis, OR. Adamus, P. R and K. Brant. 1990. Impacts on Quality of Inland Wetlands of the United States: A Survey of Indicators, Techniques, and Applications of Community Level Bio-monitoring Data, EPA/600/3-90/073. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. Adamus, P.R., T. Danielson, and A. Gonyaw. 2001. Indicators for Monitoring Biological Integrity of Inland, Freshwater Wetlands: A Survey of North American Technical Literature (1990-2000). EPA843-R-01. U.S. Environmental Protection Agency, Office of Water, Wetlands Division. Washington, DC. Adamus, P.R., L. T. Stockwell, Jr. Ellis J. Clairain, Michael E. Rozas Lawrence P. Morrow, and R. Daniel Smith. 1991. Wetland Evaluation Technique. WRP-DE-2. U.S. Army Corp of Engineers. Washington, DC. Agami, M., K. R. Reddy, D. A. Graetz, L. J. Scinto, P. R. F. Barrett, M. P. Greaves, K. J. Murphy, A. H. Pieterse, P. M. Wade, and M. Walsten. 1990. Phosphorus and nitrogen storage/release capacity of aquatic macrophytes in two wetland stream systems of the Taylor Creek/Nubbins Slough and Kissimmee River basin, Florida. 8th International Symposium on Aquatic Weeds. Swedish University of Agricultural Sciences, Uppsala, Sweden, August 13-17 1990. European Weed Research Society. Wageningen, Netherlands. Allan, J. D. and L. B. Johnson. 1997. Catchment-scale analysis of aquatic ecosystems. Freshwater Biology 37: 107-111. American Public Health Association (APHA). 1995. Standard Methods for the Examination of Water and Wastewater. American Public Health Association. Washington, D.C Anderson, D. J. and B. Vondracek. 1999. Insects as indicators of land use in three

PAGE 147

131 Anderson, J. M. 1976. An ignition method for determination of total phosphorus in lake sediments. Water Research 10: 329-331. Andreas, B. K. and R. Lichvar. 1995. A Floristic Assessment System in Northern Ohio. WRP-DE-8. U.S. Army Corps of Engineers. Washington, DC. Apfelbeck, R. 2000. Developing Preliminary Bioassessment Protocols for Montana Wetlands, State of Montana Department of Environmental Quality. Helena, MT. Atchison, J. 1986. The Statistical Analysis of Compositional Data. Chapman and Hall. London. Babbitt, K. J. and G. W. Tanner. 2000. Use of temporary wetlands by anurans in a hydrologically modified landscape. Wetlands 20(2): 313-322. Bahls, L. L. 1993. Periphyton Bioassessment Methods of Montana Streams. Water Quality Bureau, Department of Health and Environmental Sciences. Helena, MT: Bailey, R. C. R. H. Norris and T. B. Reynoldson. 2001. Taxonomic resolution of benthic macroinvertebrate communities in bioassessments. Journal of the North American Benthological Society 20(2): 280-286. Barbour, M. T., J. Gerritsen, G. E. Griffith, R. Frydenborg, E. McCarron, J. S. White, and M. L. Bastian. 1996. A framework for biological criteria for Florida streams using benthic macroinvertebrates. Journal of the North American Benthological Society 15(2): 185-211. Barbour, M. T., J. Gerritsen, B. D. Snyder, and J. B. Stribling. 1999. Rapid Bioassessment Protocols For Use in Streams and Wadeable Rivers. 2nd ed.. EPA 841-B-99-002. U.S. Environmental Protection Agency, Office of Water. Washington, DC. Battle, J. and S. W. Golladay. 2001. Water quality and macroinvertebrate assemblages in three types of seasonally inundated limesink Journal of Freshwater Ecology 16(2): 189-207. Bayley, S., and H. T. Odum. 1976. Simulation of Interrelations of the Everglades' Marsh, Peat, Fire, Water, and Phosphorus. Ecological Modeling 2: 169-188. Beck, W. M. 1954. Studies in Stream Pollution Biology I. A Simplified Ecological Classification of Organisms. Quarterly Journal of the Florida Academy of Scientists 17(4): 211-227. Bedford, B. L. 1999. Cumulative effects on wetland landscapes: links to wetland restoration in the United States and southern Canada. Wetlands 19(4): 775-788.

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132 Bedford, B. L., M. R. Walbridge, and A. Aldous. 1999. Patterns in nutrient availability and plant diversity of temperate North American wetlands. Ecology 80(7): 2151-2169. Blanch, S. J. and M. A. Brock. 1994. Effects of grazing and depth on two wetland plant species. Australian Journal of Marine and Freshwater Research 45: 1387-1394. Bowman, M. F. and R. C. Bailey. 1998. Does taxonomic resolution affect the multivariate description of the structure of freshwater benthic macroinvertebrate communities? Canadian Journal of Fisheries and Aquatic Sciences 54: 1802-1807. Brightman, R. S. 1984. Benthic macroinvertebrate response to secondarily treated wastewater in north-central Florida cypress domes. Pp. 186-197 in Cypress Swamps. Edited by K. C. Ewel and H. T. Odum. University Press of Florida. Gainesville, FL. Brinson, M. M., and R. Reinhardt. 1996. The role of reference wetlands in functional assessment and mitigation. Ecological Applications 6(1): 69-76. Brower, J. E., J. H. Zar, and C. N. von Ende. 1990. Field and Laboratory Methods for General Ecology. W.C. Brown Publishers. New York, New York. Brown, M. T. 1991. Evaluating Created Wetlands Through Comparisons With Natural Wetlands. Environmental Research Laboratory. EPA/600/3-91/058. US Environmental Protection Agency, Corvallis, OR. Brown, M. T. and M. B. Vivas. submitted. A Landscape Development Intensity Index. Environmental Monitoring and Assessment. Ecological Monitoring and Assessment. Burton, T. M., D. G. Uzarski, J. P. Gathman, J. A. Genet, B. E. Keas, and C. A. Stricker. 1999. Development of a preliminary invertebrate index of biotic integrity for Lake Huron coastal wetlands. Wetlands 19(4): 869-882. Busch, D. E., W. F. Loftus, O. L. Bass. 1998. Long term hydrologic effects on marsh plant community structure in the southern Everglades. Wetlands 18(2): 230-241. Cairns, J. and J. R. Pratt. 1993. A History of Biological Monitoring Using Benthic Macroinvertebrates. Pp. 10-27 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. New York, New York. Cao, Y., D. P. Larsen, and R. S. J. Thorne. 2001. Rare species in multivariate analysis for bioassessment: some consideration. Journal of the North American Benthological Society 20(1): 144-153.

PAGE 149

133 Carlisle, D. M., P. M. Stewart, and J. T. Butcher. 2003. Macroinvertebrate assemblages associated with patterns in land use and water quality. Pp. 271-285 in Biological Response Signatures: Indicator Patterns Using Aquatic Communities. Edited by T.P. Simon. CRC Press. Boca Raton, Florida. Carpenter, K. D. and I. R. Waite. 2000. Relations of Habitat-Specific Algal Assemblages to Land Use and Water Chemistry in the Willamette Basin, Oregon. Environmental Monitoring and Assessment 64: 247-257. Charles, D., F. Aker, and N.A. Roberts. 1996. Diatom Periphyton in Montana Lakes and Wetlands: Ecology and Potential as Bioassessment Indicators. Patrick Center of Environmental Research, Environmental Research Division. The Academy of Natural Sciences. Philadelphia, PA. Cheal, F. J., A. Davis, J. E. Growns, J. S. Bradley, and F. H. Whittles. 1993. The influence of sampling method on the classification of wetland macroinvertebrate communities. Hydrobiologia 257(1): 47-56. Chen, E. and J. F. Gerber. 1990. Climate. Pp. 11-35 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Chovanec, A. and R. Raab. 1997. Dragronflies (Insecta, Odonata) and the Ecological Status of Newly Created Wetlands Examples for Long-term Bioindication Programmes. Limnologica 27(3-4): 381-392. Chytry, M., L. Tichy, J. Holt, and Z. Botta-Dukat. 2002. Determination of diagnostic species with statistical fidelity measures. Journal of Vegetation Science 13: 79-90. Clarke, K. R. 1993. Non-parametric multivariate analyses of changes in community structure. Australian Journal of Ecology 18: 117-143. Coffman, W. P. and L. C. Ferrington, Jr. 1996. Chironomidae. Pp. 635-754 in An Introduction to the Aquatic Insects of North America. 3rd ed.. Edited by R. W. Cummins and K. W. Merritt. Kendall/Hunt Publishers. Dubuque, IO. Cohen, M. J., S. Carstenn, and C. R. Lane. submitted. Floristic quality assessment of depressional marshes in Florida along an agricultural disturbance gradient. Ecological Applications. Conrad, K. F., K. H. Wilson, I. F. Harvey, C. J. Thomas, and T. N. Sherratt. 1999. Dispersal characteristics of seven odonate species in an agricultural landscape. Ecography 22: 524-531. Courtemanch, D. L. 1996. Commentary on the subsamlping procedures used for rapid bioassessments. Journal of the North American Benthological Society of America 15(3): 381-385.

PAGE 150

134 Cowardin, L. M., V. Carter, F. C. Goulet, and E. T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service. Washington DC. Restoration Ecology 7: 497-510. Craft, C. B., J. Vymazal, and C. J. Richardson. 1995. Response of Everglades plant communities to nitrogen and phosphorus additions. Wetlands 15(3): 258-271. Cranston, P. S. 1995. Introduction. Pp. 1-7 in The Chironomidae: Biology and Ecology of Non-Biting Insects. Edited by P.D. Armitage, P. S. Cranston, and L. C. V. Pinder. Chapman and Hall. Englewood Cliffs, NJ. Crisman, T.C., L.J. Chapman, C.A. Chapman. 1998. Predictors of Seasonal Oxygen Levels in Small Florida Lakes: The Importance of Color. Hydrobiologia 386(1-3): 149-155. Crisman, T. C., W. J. Streever, and D. L. Evans. 1997. An Evaluation of Plant Community Structure, Fish and Benthic Meioand Macrofauna as Success Criteria for Reclaimed Wetlands. Center for Wetlands Report 03-086-135. Center for Wetlands, University of Florida, Gainesville, FL. Cronk, J. K. and M. S. Fennessy. 2001. Wetland Plants: Biology and Ecology. Lewis Publishers. Boca Raton, FL. Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 2000. Responses of physical, chemical, and biological indicators of water quality to a gradient of agricultural land use in the Yakima River basin, Washington. Environmental Monitoring and Assessment 64: 259-270. Dahl, T. E. 1990. Wetlands Losses in the United States, 1780's to 1980's. Washington DC: U.S. Fish and Wildlife Service Report to Congress. Danielson, Thomas J. 1998. Indicators for Monitoring and Assessing Biological Integrity of Inland Freshwater Wetlands, Wetlands Division Office of Water. EPA843-R-98-002. United States Environmental Protection Agency, Washington, DC. Daoust R. J, and D. L. Childers. 1999. Controls on emergent macrophyte composition, abundance, and productivity in freshwater everglades wetland communities. Wetlands 19(1) 1:262-275. David, P G. 1996. Changes in plant communities relative to hydrologic conditions in the Florida Everglades. Wetlands 16(1): 15-23. David, P. G. 1994. The effects of regulating Lake Okeechobee water levels on flora and fauna. Lake and Reservoir Management. 9(2): 67-75. 1999. Response of Exotics to restored hydroperiod at Dupuis Reserve, Florida.

PAGE 151

135 Davis, S. M. and J. C. Ogden. 1994. Everglades. St. Lucie Press. Delray Beach, FL. de Jonge, V. N. and J. E. E. van Beusekom. 1992. Contribution of resuspended microphytobenthos to total phytoplankton in the Ems estuary and its possible role communities of temporary wetlands in the Prairie Pothole region of North Dakota, USA. Wetlands 19(3): 578-583. for grazers. Netherlands Journal of Sea Research 30: 91-105. Delettre, Y. R. 1989. Effects of the duration and intensity of drought on abundance and phrenology of adult Chironomidae (Diptera) in a shallow temporary pool. Archiv Fur Hydrobiologie 114: 383-399. Dierberg, F. E. and P. L. Brezonik. 1984. The effect of wastewater on the surface water and groundwater quality of cypress domes. Pp. 83-101 in Cypress Domes. Edited by K. C. Ewel and H. T. Odum. University Presses of Florida. Gainesville, FL. Doberstein, C. P., J. R. Karr, and L. L. Conquest. 2000. The effect of fixed-count subsampling on macroinvertebrate biomonitoring in small streams. Freshwater Biology 44: 355-371. Dobkin, D. S., A. C. Rich, and W. H. Pyle. 1998. Habitat and avifaunal recovery from livestock grazing in a riparian system of the Northwestern Great Basin. Conservation Biology 12(1): 209-221. Doherty, S., M. Cohen, C. Lane, L. Line, and J. Surdick. 2000. Biological Criteria for Inland Freshwater Wetlands in Florida: A Review of Technical and Scientific Literature (1990-1999). Report to the U.S. Environmental Protection Agency. Center for Wetlands, University of Florida, Gainesville, FL. Doren, R. F., T. V. Armentano, L. D. Whiteaker, and R. D. Jones. 1997. Marsh Vegetation Patterns and Soil Phosphorus Gradients in The everglades Ecosystem. Aquatic Botany 56(2): 145-163. Driver, E. A. 1977. Chironomid communities in small prairie ponds: some characteristics and controls. Freshwater Biology 7: 121-133. Dufrene, M. and P. Legendre. 1997. Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecological Monographs 67: 345-366. Edwards, A. L. and A. S. Weakley. 2001. Population Biology and Management of Rare Plants in Depression Wetlands of the Southeastern Coastal Plain, USA. Natural Areas Journal 21(1): 12-35. Erwin, K. L., S. J. Doherty, M. T. Brown, and G. R. Best. 1997. Evaluation of Constructed Wetlands on Phosphate Mined Lands in Florida. Center for Wetlands, University of Florida. Gainesville, FL. Euliss, N. H. and D. M. Mushet. 1999. Influence of agriculture on aquatic invertebrate

PAGE 152

136 Evans, D. L. 1996. Aquatic Macroinvertebrate Communities of Constructed and Natural Marshes in Central Florida. Ph.D. Dissertation, University of Florida. Gainesville, FL. floristic quality in southern Ontario woodlands. Natural Areas Journal 20: 66-77. Evans, D. L. W. J. Streever and T. L. Crisman. 1999. Natural Flatwoods Marshes and Created Freshwater Marshes of Florida: Factors Influencing Aquatic Invertebrate Distribution and Comparisons between Natural and Created Marsh Communities. Pp. 81-104 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. P. Batzer, R. B. Rader, and S. A. Wissinger. John Wiley and Sons. New Yokr, NY. Ewel, J. J. 1990. Introduction. Pp. 3-10 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Fennessy, S., M.Gernes, J. Mack, D. H. Waldrop. 2001. Methods for Evaluating Wetland Condition: Using Vegetation to Assess Environmental Conditions in Wetlands, EPA 822-R-01-007j. U.S. Environmental Protection Agency, Office of Water, Washington, DC. Fennessy, S., R. Geho, B. Elifritz and R. Lopez. 1998. Testing the Floristic Quality Assessment Index as an Indicator of Riparian Wetland Disturbance. Ohio EPA Wetlands Unit of Division of Surface Water. Columbus, OH. Fernald, E. A. and E. D. Purdum. 1998. Water Resources Atlas of Florida. Florida State University Institute of Science and Public Affairs. Tallahassee, FL. Flaig E. G., and K. R. Reddy. 1995. Fate of phosphorus in the Lake Okeechobee watershed, Florida, USA: Overview and recommendations. Ecological Engineering, 5(2-3): 127-142. Florida Exotic Plant Pest Council (FLEPPC). 2003. List of Florida's Invasive Species. Web page. Available at www.fleppc.org/01list.htm. Fore, L. S. 2003. Response of diatom assemblages to human disturbance: development and testing of a multimetric index for the mid-Atlantic region (USA). Pp. 445-471 in Biological Response Signatures: Indicator Patterns Using Aquatic Communities. Edited by T. P. Simon. CRC Press. Boca Raton, FL. Fore, L. S and C. Grafe. 2002. Using diatoms to assess the biological condition of large rivers in Idaho (U.S.A.). Freshwater Biology 47: 2015-2037. Fore, L. S., J. R. Karr, and R. W. Wisseman. 1996. Assessing invertebrate responses to human activities: evaluating alternative approaches. Journal of the North American Benthological Society 15(2): 212-231. Francis, C. M., M. J. W. Austen,. J. M. Bowles, and W. B. Draper. 2000. Assessing

PAGE 153

137 Freeland, J. A., J. L. Richardson, and L. A. Foss. 1999. Soil indicators of agricultural impacts on Northern Prairie wetlands: Cottonwood Lake research area, North Dakota, USA. Wetlands 19(1): 56-64. Furse, M. T., D. Moss, J. F. Wright, and P. D. Armitage. 1984. The influence of seasonal and taxonomic factors on the ordination and classification of running-water sites in Great Britain and on the prediction of their macro-invertebrate communities. Freshwater Biology 14: 257-280. Gaiser, E. E., T. E. Philippi, and B. E. Taylor. 1998. Distribution of diatoms among intermittent ponds on the Atlantic Coastal Plain: development of a model to predict drought periodicity from surface-sediment assemblages. Journal of Paleolimnology 20: 71-90. Galatowitsch, S. M., D. C. Whited, and J. R. Tester. 1999a. Development of community metrics to evaluate recovery of Minnesota wetlands. Journal of Aquatic Ecosystem Stress and Recovery 6: 217-234. Galatowitsch, S. M., N. O. Anderson, and P. D. Ascher. 1999b. Invasiveness in Wetland Plants in Temperate North America. Wetlands 19(4): 733-755. Gernes, M. C., and J. C. Helgen. 1999. Indexes of Biotic Integrity (IBI) for Wetlands: Vegetation and Invertebrate IBI's, Report CD995525-01. Minnesota Pollution Control Agency. St. Paul, MN. Gerritsen, J., M. T. Barbour and K. King. 2000. Apples, oranges, and ecoregions: on determining patern in aquatic assemblages. Journal of the North American Benthological Society 19(3): 487-496. Gerritsen, J. and J. White. 1997. Development of a Biological Index for Florida Lakes Tetra Tech, Inc., Owings Mills, MD. Godfrey, R. K. and J. W. Wooten. 1979. Aquatic and Wetland Plants of Southeastern United States: Monocotyledons. University of Georgia Press. Athens, GA. Godfrey, R. K. and J. W. Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States: Dicotyledons. University of Georgia Press. Athens, GA. Goldsborough, G. and G. G. C. Robinson. 1996. Pattern in Wetlands. Pp. 77-117 in Algal Ecology. Editors M. L. Bothwell and R. L. Lowe. Academic Press. San Diega, CA. Grace, J. B. and H. Jutila. 1999. The relationship between species density and community biomass in grazed and ungrazed coastal meadows. Oikos 85: 398-408. Graetz, D. A. and V. D. Nair. 1995. Fate of phosphorus in Florida Spodosols contaminated with cattle manure. Ecological Engineering: 5: 163-181.

PAGE 154

138 Growns, J. E., J. A. Davis, F. Cheal, L. G. Schmidt, R. S. Rosich, and S. J. Bradley. 1992. Multivariate pattern analysis of wetland invertebrate communities and environmental variables in Western Australia. Australian Journal of Ecology 17: 275-288. 5: 177-191. Gunderson, L. H. and L. Pritchard. 2002. Resilience and the Behavior of Large-Scale Systems. Island Press.Washington, DC. Hasle, G. R. and G. A. Fryxell. 1970. Diatoms: cleaning and mounting for light and electron microscopy. Transactions of the American Microscopy Society 89: 466-474. Hellawell, J. M. 1986. Biological Indicators of Freshwater Pollution and Environmental Management. Elsevier. London. Herman, K. D., A. A. Reznicek, L. A. Masters, G. S. Wilhelm, M. R. Penskar, and W. W. Brodowicz. 1997. Floristic Quality Assessment: Development and Application in the State of Michigan (USA). Natural Area Journal 17: 265-279. Hilsenhoff, W. L. 1988. Rapid field assessment of organic pollution with a family-level biotic index. Journal of American Benthological Society 7(1): 65-68. Hobbs, R. J. and L. F. Huenneke. 1992. Disturbance, Diversity, and Invasion: Implications for Conservation. Conservation Biology 6(3): 324-37. Hunsaker, C. T. and D. E. Carpenter. 1990. Ecological Indicators for the Environmental Monitoring and Assessment Program, EPA 600/3-90/060. U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC. Hynes, H. B. N. 1975. The stream and its valley. Verh.Interna.Verein.Limnol 19: 1-15. Johnson, R. K., T. Wiederholm and D. M. Rosenber. 1993. Freshwater Biomonitoring Using Individual Organisms, Populations, and Species Assemblages of Benthic Macroinvertebrates. Pp. 40-158 in Freshwater Biomonitoring and Benthic Macroinvertebrates. Edited by D.M. Rosenberg and V.H. Resh. Chapman and Hall. Englewood Cliffs, NJ. Johnston, C A. 1994. Cumulative impacts to wetlands. Wetlands 14(1): 49-55. Kalmbacher, R. S., K. R. Long, M. K. Johnson, and F. G. Martin. 1984. Botanical composition of diets of cattle grazing South Florida rangeland. Journal of Range Management 37(4): 334-340. Kantrud, H. A. and W. E. Newton. 1996. A test of vegetation related indicators of wetland quality in the prairie pothole region. Journal of Aquatic Ecosystem Health

PAGE 155

139 Karr, J. R. 1981. Assessment of biotic integrity using fish communities. Fisheries 6(6): 21-27. 1993. Defining and assessing ecological integrity: beyond water quality. Environmental Toxicology and Chemistry 12: 1521-1531. 1995. Protecting Aquatic Ecosystems: Clean Water is Not Enough. Pp. 7-15 in Biological Assessment and Criteria: Tools for Water Resource Planning and Decision Making. Edited by W. S. Davis and T. P. Simon. CRC Press. Boca Raton, FL. Karr, J. R., and E. W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively, EPA 235-R97-001. U.S. Environmental Protection Agency. Washington, DC. 1999. Restoring Life in Running Waters. Island Press. Washington, DC. Karr, J. R. and D. R. Dudley. 1981. Ecological perspective on water quality goals. Environmental Management 5: 55-68. Kashian, D. R. and T. M. Burton. 2000. A Comparison of Macroinvertebrates of Two Great Lakes Coastal Wetlands: Testing Potential Metrics for an Index of Ecological Integrity. Journal of Great Lakes Research 26(4): 460-481. Kautz, R. S. 1993. Trends in Florida wildlife habitat 1936-1987. Florida Scientist 56: 7-24. Kerans, B. L., and J. R. Karr. 1994. A benthic index of biotic integrity (B-IBI) for rivers of the Tennessee valley. Ecological Applications 4(4): 768-785. King, R. S. and C. J. Richardson. 2002. Evaluating subsampling approaches and macroinvertebrate taxonomic resolution for wetland bioassessment. Journal of the North American Benthological Society 21(1): 150-171. Kirkman, L. K., M. B. Drew, L. T. West, and E. R. Blood. 1998. Ecotone characterization between upland longleaf pine/wiregrass stands and seasonally ponded isolated wetlands. Wetlands 18(3): 346-364. Kirkman, L. K., P. C. Goebel, L. West, M. B. Drew, and B. J. Palik. 2000. Depressional wetland vegetation types: a question of plant community development. Wetlands 20(2): 373-385. Kirkman, L. K., R. F. Lide, G. Wein, and R. R. Sharitz. 1996. Vegetation changes and land-use legacies of depression wetlands of the western Coastal Plain of South Carolina: 1951-1992. Wetlands 16(4): 564-576.

PAGE 156

140 Koch, M. S. and K. R. Reddy. 1992. Distribution of soil and plant nutrients along a trophic gradient in Florida Everglades. Soil Science Society of America Journal 56(5): 1492-1499. tolerance values, with criteria for assigning water-quality ratings. Journal of the North America Benthological Society 12(3): 279-290. Kolozsvary, M. B. and R. K. Swihart. 1999. Habitat fragmentation and the distribution of amphibians: patch and landscape correlates in farmland. Canadian Journal of Zoology 77: 1288-1299. Kruskal, J. B. 1964. Nonmetric multidimensional scaling: a numerical method. Psychometrika 29: 115-129. Kushlan, J. A. 1990. Freshwater Marshes. Pp. 323-363 in Ecosystems of Florida. Edited by R. L. Myers and J. J. Ewel. University of Central Florida Press. Orlando, FL. Lane, C. R. 2000. Proposed Ecological Regions for Freshwater Wetlands of Florida. M.S. Thesis, University of Florida. Gainesville, FL. Lange-Bertalot, H. 1979. Pollution tolerance of diatoms as a criterion for water quality estimation. Nova Hedwigia 54: 285-304. Langeland, K. A. and K. C. Burks. 1998. Identification and Biology of Non-native Plants in Florida's Natural Areas. University of Florida Press. Gainesville, FL. Latham, P. J., L. G. Pearlstine, and W. M. Kitchens. 1994. Species association changes across a gradient of freshwater, oligohaline, and mesohaline tidal marshes along the lower Savannah River. Wetlands 14(3): 174-183. Lawrimore, J. H., M. S. Halpert, G. D. Bell, M. J. Menne, B. Lyon, R. C. Schnell, K. L. Gleason, D. R. Easterling, W. Thiaw, W. J. Wright, R. R. Heim, D. A. Robinson, and L. Alexander. 2001. Climate Assessment for 2000. Bulletin of the American Meteorological Society 82(6): 51-106. Leeper, D. A. and B. E. Taylor. 1998. Insect emergence from a South Carolina (USA) temporary wetland pond, with emphasis on the Chironomidae (Diptera). Journal of the North American Benthological Soicety 17(1): 54-72. Leibowitz, N. C. and M. T. Brown. 1990. Indicator Strategy for Wetlands. Pp. 5.1 5.15 in Environmental Monitoring and Assessment Program Ecological Indicators. Edited by C.T. Hunsaker and D. E. Carpenter. EPA/600/3-90/060. U.S. Environmental Protection Agency Office of Research and Development, Washington, DC. Leland, H. V. and S. D. Porter. 2000. Distribution of benthic algae in the upper Illinois River basin in relation to geology and land use. Freshwater Biology 44: 279-301. Lenat, D. R. 1993. A biotic index for the southeastern United States: derivation and list of

PAGE 157

141 Lesica, P., B. McCune, S. Cooper, and W. S. Hong. 1991. Differences in lichen and bryophyte communities between old-growth and managed second-growth forests. Canadian Journal of Botany 69: 1745-1755. Leslie, A. J., J. P. Prenger, and T. L. Crisman. 1999. Cypress Domes in North Florida: Invertebrate Ecology and Response to Human Disturbance. Pp. 105-119 in Invertebrates in Freshwater Wetlands of North America: Ecology and Management. Edited by D. P. Batzer, R. B. Rader, and S. A. Wissinger. John Wiley and Sons. London. Long, K. R., R. S. Kalmbacher, and F. G. Martin. 1986. Diet quality of steers grazing three range sites in south Florida. Journal of Range Management 39(5): 389-392. Lowe, R. L. 1974. Environmental requirements and pollution tolerance of freshwater diatoms. U.S. Environmental Protection Agency, National Environmental Research Center, Office of Research and Development. EPA-670/4-74-005. Cincinnati, OH. Ludden, V. E. and F. R. Hauer. 2000. The Effects of Natural Variability on the Use of Macroinvertebrates as Bioindicators of Disturbance in Intermontane Depressional Wetlands in Northwestern Montana, USA. Flathead Lake Biological Station: University of Montana., Bozeman, MT. Mack, J. 2001. Vegetation Index of Biologic Integrity (VIBI) for Wetlands: Ecoregional, Hydrogeomorphic, and Plant Community Comparisons with Preliminary Wetland Aquatic Life Use Designations, Ohio Environmental Protection Agency, Wetland Ecology Division, Columbus, OH. MaGee, T. K., T. L. Ernst, M. E. Kentula, and K. A. Dwire. 1999. Floristic comparison of freshwater wetlands in an urbanizing environment. Wetlands 19(3): 517-534. Malmqvist, B. and M. Maki. 1994. Benthic macroinvertebrate assemblages in north Swedish streams: environmental relationships. Ecography 17: 9-16. Mantel, N. 1967. The detection of disease clustering and generalized regression approach. Cancer Research 27: 209-220. Marchant, R. 2002. Do rare species have any place in multivariate analysis for bioassessment? Journal of the North American Benthological Society 21(2): 311-313. Martin, D. B. and W. A. Hartman. 1987. The effect of cultivation on sediment composition and deposition in prairie pothole wetlands. Water, Air, and Soil Pollution 34: 45-53. Mather, P. M. 1976. Computational Methods of Multivariate Analysis in Physical Geography. J. Wiley and Sons. London.

PAGE 158

142 Mathews, W. J., R. C. Cashner, and F. P. Gelwick. 1988. Stability and Persistence of Fish Faunas and Assemblages in Three Midwestern Streams. Copeia 4: 945-955. Maul, J. D. and C. M. Cooper. 2000. Water quality of seasonally flooded agricultural Approach. Springer-Verlag. New York, NY. fields in Mississippi, USA. Agriculture, Ecosystems, and Environment 81: 171-178. McCarron, E. and R. Frydenborg. 1997. The Florida Bioassessment Program: an Agent of Change. Human and Ecological Risk Assessment 3(6): 967-977. McCormick, P. V. and J. Cairns Jr. 1997. Algal indicators of aquatic ecosystem condition and change. Pp. 178-207 in Plants for Environmental Studies. Edited by W. Wang J. W. Gorsuch and J. S. Hughes. CRC Lewis. Boca Raton, FL. McCormick, P. V., M. J. Chimney, and D. R. Swift. 1997. Diel oxygen profiles and water column community metabolism in the Florida Everglades, U.S.A. Archiv Fur Hydrobiolog