• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Introduction
 Literature review
 Site descriptions
 Materials and methods
 Results
 Discussion
 Conclusions
 Reference
 Appendix
 Biographical sketch
 Copyright














Title: Canal-estuary nutrient exchange and metabolic levels in Florida residential canals
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Permanent Link: http://ufdc.ufl.edu/UF00089746/00001
 Material Information
Title: Canal-estuary nutrient exchange and metabolic levels in Florida residential canals
Series Title: Canal-estuary nutrient exchange and metabolic levels in Florida residential canals
Physical Description: Book
Language: English
Creator: Bailey, William Arthur
Publisher: William Arthur Bailey
Publication Date: 1977
 Record Information
Bibliographic ID: UF00089746
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000185249
oclc - 03334690

Table of Contents
    Title Page
        Page i
    Acknowledgement
        Page ii
        Page iii
    Table of Contents
        Page iv
        Page v
    List of Tables
        Page vi
        Page vii
        Page viii
    List of Figures
        Page ix
        Page x
        Page xi
    Abstract
        Page xii
        Page xiii
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
    Literature review
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Site descriptions
        Page 16
        Page 17
        Page 18
        Page 19
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    Materials and methods
        Page 40
        Page 41
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        Page 44
    Results
        Page 45
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    Discussion
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    Conclusions
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    Reference
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    Appendix
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    Biographical sketch
        Page 327
        Page 328
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    Copyright
        Copyright
Full Text










CANAL-ESTUARY NUTRIENT EXCHANGE AND METABOLIC LEVELS
IN FLORIDA RESIDENTIAL CANALS








By

WILLIAM ARTHUR BAILEY


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY

















UNIVERSITY OF FLORIDA

1977















ACKNOWLEDGMENTS


Numerous individuals, to whom I am much indebted, helped me with

the field collections. During the 1975 collections, William Marsh,

Deborah Lupton, and Warren and Ann Hansen forfeited many hours that are

normally devoted to sleeping. Florinus Kooijman volunteered to accom-

pany me to Marco Island and Boca Ciega Bay; David Price to Hillsboro

Inlet and Panama City; and Richard Brightman to Apollo Beach.

The members of the department's chemistry laboratory, particularly

Hugh Prentice and Lloyd Chesney, were invaluable as troubleshooters

when I was having problems with water analyses. Without the Department

of Environmental Engineering Science's truck and boat, and without

Dr. Patrick Brezonik's ability to keep the chemistry laboratory stocked

with chemicals, I would have been unable to collect and analyze samples

during 1976.

I am grateful to Dr. B.A. Christensen and Fred Morris of the

Hydraulic Laboratory, Department of Civil Engineering, for providing me

with the 1975 hydrographic data and for loaning me a tide recorder

during 1976. I am also grateful to Dr. Emmett Bolch for providing me

an assistantship on his Florida Power Corporation Project during 1976.

I would like to thank my committee members for their comments and

guidance throughout this investigation. Dr. Jackson L. Fox, my chairman,

has spent many hours listening to my problems. His efforts are greatly

appreciated.









The person most responsible for my completion of this study is my

wife. Mary worked beside me during more than half of the sampling

trips and encouraged me when things seemed hopeless. She taught school,

under less than ideal circumstances, in order to support us and to pay

for unfunded sampling trips in 1976. I doubt that I would have com-

pleted this work without her.















TABLE OF CONTENTS


Page

ACKNOWLEDGMENTS . . . . . . . . . .. . ii

LIST OF TABLES . . . . . . . . .. . . . vi

LIST OF FIGURES. . . . . .. . . . . . . ix

ABSTRACT . . . . . . . . . . . . . xii

CHAPTER 1 INTRODUCTION . . . . . . . .. . 1

CHAPTER 2 LITERATURE REVIEW. . . . . . . . . 6

CHAPTER 3 SITE DESCRIPTIONS. . . . . . . . .. 16

CHAPTER 4 MATERIALS AND METHODS. . . . . . . ... 40

Metabolism . . . . . . . . . . 40
Nutrient Exchange and Water Quality. . . . ... 42
Canal/Sampling Day Characteristics . ... .. . 44
Statistical Analyses . . . . . . . .. 44

CHAPTER 5 RESULTS . . . . . . . . . . .. 45

Metabolism . . . . . . . . .. . 46
Combined Data . . . . . . . ... 46
1975 Data . ... . . . . . . ... 58
Daily Variability in One Canal. . . . ... 65
Nutrient Exchange. .. . . . . . .... .. 67
Combined Data . . . . . . . ... 67
Diurnal Cycle of Nutrient Concentrations. . 84
1975 Data . . . . . . . . ... 86
Daily Variability in One Canal. . . . ... 91
Water Quality. . . . . . . . . ... 93
Structure of the Data Principal Components . 100
Combined Data . . . . . . . ... 102
Metabolism. . . . . . . . . ... 104
Exchange. . . . . . . . . . 106
Water Quality ................ 107
Canal/Sampling Day Characteristics. . . ... 110
Summary . . . . . . . . .. 113
Canonical Correlations . . . . . . ... 114
Metabolism vs. Exchange . . . . ... .117
Metabolism vs. Water Quality. . . . ... 120









TABLE OF CONTENTS
(Continued)


Page


Metabolism vs. Canal/Sampling Day
Characteristics . . . . .
Exchange vs. Water Quality. . . .
Exchange vs. Canal/Sampling Day
Characteristics . . . . ..
Water Quality vs. Canal/Sampling Day
Characteristics . . . . .
Summary . . . . . . . .
Regression Equations . . . . . .


CHAPTER 6 DISCUSSION . . . . . . . .


Metabolism . . . . . . . .
Water Quality. . . . . . .
Nutrient Exchange. . . . . . .
General Observations . . . . . .
"Average" Canal . . . . . .
Design and Management Implications. .


CHAPTER 7 CONCLUSIONS. . . . . . . . .... .193

LIST OF REFERENCES . . . . . . . . ... . .196

APPENDIX A Oxygen metabolism data for all individual stations. 201


APPENDIX B


APPENDIX C


APPENDIX D


Oxygen profiles for all stations and sampling
times . . . . . . . . . . . .

Nutrient and water quality data for each canal
entrance and sampling interval. . . . . .

Descriptive statistics and correlation coefficients
for all parameters. . . . . . . . .


BIOGRAPHICAL SKETCH. . . . . . . . . . . .


. . . 123
. . . 126

. . 126

. . . 130
. . . 138
. . . 140


155

156
164
171
178
179
183


211


235


276

327














LIST OF TABLES


Table Page

1. Canal and sampling day physical characteristics ... .19

2. Nomenclature for variables. . . . .. .. . .. 47

3. Metabolism results averaged by canal for each sampling
day . . . . . . . .. . . . . . 51

4. Results of the analyses of variance for the total com-
munity and planktonic metabolism data (1975). . . .. .61

5. Community and plankton gross primary production mean
values for the 1975 data. .. . . . . . . 64

6. Metabolism results for three consecutive days of
sampling on one canal (North Miami site) . . . 66

7. Canal-estuary exchange results for the nutrient and
water quality parameters. .... . . . . . . .69

8. Regression coefficients for the change in nutrient con-
centrations versus time of day. . . . . . .. 85

9. Mean values for 1975 net-exchange data. . . . .. 88

10. Descriptive statistics and analyses of variance results
for 1975 net-exchange data. . . . . . . .. 90

11. Nutrient/water quality exchange results for three
consecutive days at the North Miami site. . .. . 92

12. Water quality characteristics for all canal observations. 95

13. Principal components of the combined data (44 variables). 103

14. Principal components and correlation matrix for the
metabolism data . . . . . . . . .. ... . 105

15. Principal components and correlation matrix for the
net nutrient exchange data. . . . . . . .. 108

16. Principal components and correlation matrix for the
water quality data. . . . . . . . . .. 109









LIST OF TABLES
(Continued)


Table Page

17. Principal components and correlation matrix for the
canal/sampling day characteristics . . . . ... 111

18. Data set variables used in correlation analyses. ... .118

19. Canonical correlation analysis of the metabolism and
nutrient exchange data sets. . . . . . . ... 119

20. Canonical correlation analysis of the metabolism and
water quality data sets.. . . . . . . . . 121

21. Canonical correlation analysis of the metabolism and
canal/sampling day data sets . . . . . ... 124

22. Canonical correlation analysis of the exchange and
water quality data sets. . . . . . . . ... 127

23. Canonical correlation analysis of the exchange and
canal/sampling day characteristics. . . . ... 128

24. Canonical correlation analysis of the water quality and
canal/sampling day characteristics day sets. . . . 131

25. Summary table for canonical correlation results. ... .139

26. Dependent and independent variables used in the stepwise
regression analyses. . . . . . . . . 142

27. Descriptive models for 20 dependent response parameters. 143

28. Significant-factor frequencies for the metabolism,
exchange, and water quality models . . . . ... .149

29. Appearance frequencies of the grouped factor-types in
the metabolism, exchange, and water quality models
(grouped) . . . . . . . . . . . 152

30. Gross primary production levels for different aquatic
systems. . . . .. . . . . . . . 157

31. Significant factor effects on canal metabolic parameters 161

32. Significant factor effects on canal water quality
parameters . . . . . . . . . . . . 169

33. Organic carbon net-exchanges for several coastal systems 174









LIST OF TABLES
(Continued)


Table Page

34. Significant factor effects on canal-estuary net
exchange parameters ................... 176

35. Physical characteristics, water quality, metabolic
levels, and net canal-estuary exchanges for an "average"
residential canal ..................... 180


viii















LIST OF FIGURES


Figure Page

1. Sampling sites within Florida. . . . . . . ... 17

2. Canal and sampling stations at Punta Gorda sites . .. 23

3. Canal and sampling stations at Port Charlotte
site . . . . . . . . . . . . .. 25

4. Canal and sampling stations at Pompano Beach
site . . . . . . . . . . . . . 26

5. Canal and sampling stations at Loxahatchee River
site . . . . . . . . . . . . . 27

6. Canal and sampling stations at Marco Island site . .. 29

7. Canal and sampling stations at Boca Ciega Bay
site . . . . . . . . . . . . . 30

8. Canal and sampling stations at Hillsboro Inlet
site . . . . .. . . . . . . . . 32

9. Canal and sampling stations at Flagler Beach
site . . . . . . . . . . . . . 33

10. Canal and sampling stations at Apollo Beach site . .. 34

11. Canal and sampling stations at Goose Bayou (Panama City)
site . . . . . . . . .. . . . 36

12. Canal and sampling stations at Key Colony site . . . 37

13. Canal and sampling stations at North Miami site. .. .... 38

14. Frequency distribution and descriptive statistics for
total community gross primary production (g 02/m2-day),
averaged by canal. . . . . . . . ... . 54

15. Frequency distribution and descriptive statistics for
planktonic gross primary production (g 02/m2-day),
averaged by canal. . . . . . . . . ... 54

16. Frequency distribution and descriptive statistics for
total community respiration (g 02/m2-day), averaged by
canal. . . . . . . . . . . . . . 56









LIST OF FIGURES
(Continued)


Figure Page

17. Frequency distribution and descriptive statistics for
planktonic respiration (g 02/m2-day), averaged by
canal. . . . . . . . . . . . . ... 56

18. Frequency distribution and descriptive statistics for
total community production:respiration ratio, averaged
by canal . . . . . . . . . . ... 57

19. Frequency distribution and descriptive statistics for
planktonic production:respiration ratio, averaged by
canal. . . . . . . . . ... ...... 57

20. Frequency distribution and descriptive statistics for
plankton domination of community production. . . ... 59

21. Frequency distribution and descriptive statistics for
(a) weighted-average ebb total carbon concentration
(mg/l), and (b) the net change from average flood
concentrations . . . . . . ... . . . . 74

22. Frequency distribution and descriptive statistics for
(a) weighted-average ebb inorganic carbon concentrations
(mg/1), and (b) the net changes from average flood
concentrations . . . . . . . ... . . 75

23. Frequency distribution and descriptive statistics for
(a) weighted-average ebb total organic carbon concen-
trations (mg/l), and (b) the net changes from average
flood concentrations . . . . . . . . ... .76

24. Frequency distribution and descriptive statistics for
(a) weighted-average total phosphorus concentrations
(mg/l), and (b) the net changes from average flood
concentrations . . . . . . . . . . . 78

25. Frequency distribution and descriptive statistics for
(a) weighted-average ebb ortho-phosphate concentrations
(mg/l), and (b) the net changes from average flood
concentrations . . . .... . . . . . . 79

26. Frequency distributions and descriptive statistics for
(a) weighted-average ebb total organic phosphorus con-
centrations (mg/l), and (b) the net changes from average
flood concentrations . . . . . . . .... .81

27. Frequency distribution and descriptive statistics for
(a) weighted-average ebb ammonia concentrations (mg/l),
and (b) the net changes from average flood concentrations. 82









LIST OF FIGURES
(Continued)


Figure Page

28. Frequency distribution and descriptive statistics for
(a) weighted-average ebb turbidity levels (NTU), and
(b) the net changes from average flood concentrations. .. 83

29. Frequency distribution and descriptive statistics for
(a) average dissolved oxygen concentrations (mg/1), and
(b) minimum dissolved oxygen values recorded in all
canals . . . . . ... . . . . .. . . 98

30. Frequency distribution and descriptive statistics for
the average Secchi depths (m) recorded in all canals 99












Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy



CANAL-ESTUARY NUTRIENT EXCHANGE AND METABOLIC LEVELS IN
FLORIDA RESIDENTIAL CANALS

By

William Arthur Bailey

March 1977

Chairman: Jackson L. Fox
Major Department: Environmental Engineering Sciences

Sixty-one observations of oxygen metabolism, canal-estuary nutrient

exchange, and water quality in 35 residential canals at 12 locations in

the State of Florida were made over a 20 month period. The free-water

diurnal oxygen method and in situ light-dark bottle 24 hr oxygen in-

cubations were used to estimate the oxygen metabolism of the total canal

communities and the planktonic components. Total community gross

primary production varied from undetectable to 24.9 g 02/m2-day and

hadamean value of 8.59. Planktonic gross primary production varied

from 0.40 to 23.9 g 02/m2-day and had a mean value of 4.91. Community

gross primary production:community respiration ratios varied from 0.31

to 2.95 and had a mean value of 1.16. Regression equations for the

metabolic parameters explained more than 70 percent of the observed

variabilities using canal physical attributes, daylengths, solar in-

solation levels, and local estuarine water quality as independent

variables.

Net canal-estuary exchanges of carbon (total C mass and organic C),

phosphorus (total P mass, ortho-P, and total organic P), ammonia









turbidity, and color were determined from flow-weighted mean concen-

trations during flood and ebb tidal phases over complete tidal cycles

(24 hrs). Net exchanges varied from a substantial export to a sub-

stantial retention of these materials by canals. Most frequently, there

was little or no compositional change of the estuarine water than ex-

changed with the canal water. Canonical correlation analyses showed

that, in general, the net fluxes of materials across canal entrances

were independent of the metabolic levels within the canals and canal

water quality; the general correlation between material flux and canal/

sampling day characteristics seemed to be derived from an association

between turbidity and color exchanges and the current velocities within

the canals. Regression equations,however, explained more than 80 percent

of the observed exchange variabilities, except for that of ammonia and

ortho-P.

Daily and spatially averaged dissolved oxygen concentrations re-

corded in'the canals ranged from 1.78 to 9.07 mg/l and had a mean value

of 5.58. Most canals had average dissolved oxygen levels of 4 mg/l or

greater. Minimum oxygen values ranged from zero to 7.13 mg/l and had

a mean value of 2.05; 70 percent of the canals had minimum-oxygen values

below 4 mg/l. Regression equations for average and minimum dissolved

oxygen concentrations explained 91 and 88 percent, respectively, of the

observed variabilities.


xiii














CHAPTER 1
INTRODUCTION



Residential canals and canal construction in the coastal zone are

sensitive environmental and political issues in Florida and other

Atlantic and Gulf coast states. Land developers argue that they are

filling a need by providing the public with attractive waterfront

property. Environmentalists and regulatory agencies contend that the

loss of wetlands and shallow estuarine areas outweighs housing benefits.

Regional planners are in a dilemma because the principles governing the

behavior and conditions of canals in the coastal zone and the percentage

of the coastal wetlands that can be developed before the estuarine

systems suffer serious damage are unknown.

The conversion of wetlands (mangrove and salt marshes) and shallow

estuarine areas into waterfront developments via dredge and fill opera-

tions proceeded largely unchecked until the early 1970s. Following the

Earth Days of the late 1960s, the public became more environmentally

conscious and, therefore, more concerned about the destruction of

estuarine habitats. A widely circulated 1972 publication by Barada and

Partington, which portrayed residential canals as open sewers and as

sources of toxic materials to the adjoining estuaries, added impetus to

the movement against dredge and fill operations. In response to public

pressures, state legislators imposed a moratorium on dredge and fill

operations in Florida. The federal and state governments became

actively involved in attempts to curtail further dredging in the coastal









zone by strengthening the permitting requirements.

The development corporations were not prepared for the rather

sudden imposition of controls on their dredging plans. But, with their

businesses and livelihoods threatened, they resisted the controls by

litigation. In the courts, it became apparent that very little was

known about artificial canal systems and their impacts on the coastal

zone. The developers' lawyers were asking questions for which there

were no answers. Without facts to support their contentions, the

positions of state and federal agencies were weakened in the courts.

This study was initiated in response to the Florida Department of

Environmental Regulation's quest for more scientific facts. Data col-

lection occurred in two phases. The first phase was conducted as part

of a one year project (see Fox et al., 1976) funded by the Department

of Environmental Regulation. During the first phase, the metabolism

and canal-estuary nutrient exchange patterns of four pairs of similar

canals (Punta Gorda, Port Charlotte, Pompano Beach and Loxahatchee

River sites) were examined on four occasions in 1975. The second phase

of the study consisted of single sampling trips to eight additional

canal locations in 1976. The data from each phase and the combined

data provide different types of information.

The locations of the sampling sites covered most of Florida and

were approximately distributed in proportion to canal densities in

Florida. Most canal dredging has occurred in southern Florida, par-

ticularly along the southeast coast (Gold Coast). For example, the

City of Fort Lauderdale has over 150 miles of waterways. Extensive

dredging and filling has also taken place in the Tampa Bay area and,

more recently, along much of the southwest coast of Florida. The









varying densities of canal developments along Florida's coastline can

be seen in the sampling-site figures (Site Description).

A complete inventory of the number or acreage of Florida canal

developments has not been made. However, some reported figures will

illustrate the extent of this type of activity. Chesher (1974) estimated

that there were about 321 canals in the Florida Keys. Marshall (1968)

believes that 24000 ha or about 7 percent of Florida's estuarine habi-

tat less than 2 m deep has been filled by coastal developers. Castanza

and Brown (1975) found that 5,600 ha of mangroves (2.3 percent) in

south Florida (below Lake Okeechobee) have been developed since 1900.

Several classification schemes have been proposed to categorize or

distinguish the various types of dredged canals (or lagoons). Polis

(1974) distinguishes between dead-end canals and open-ended canals.

Within these two major categories, Polis classifies canals as "bay-fill"

or "upland" types; the former are created in shallow estuarine areas,

and the,latter, in upland areas. The presence of a sill at the canal

entrance is also thought by Polis to be a distinguishing feature.

Lindall and Trent (1975) classify canals as "bayfill, inland, and

intertidal"; the mean-low and mean-high tide marks separate the three

types of dredged areas. The Florida Department of Environmental

Regulation describes the extent of canal branching as first-order

canals, second-order canals, etc.

The canals examined during this study were mostly dead-ended

(exceptions are identified in Site Description section) and upland

(intertidal and inland).

This study was designed to increase the data base and the under-

standing of the role and behavior of Florida residential canals in the









coastal zone. The specific goals were to 1) evaluate the conditions

within canals, in terms of their metabolic levels and water qualities,

2) determine the magnitudes and direction of material exchanges across

canal entrances, 3) elucidate any recurring patterns or associations

between canals' behavioral and physical attributes, and 4) generate

and evaluate simple regression equations for the response variables

from relatively simple independent factors.

In order to achieve these objectives four types of data were col-

lected for each canal: 1) metabolism levels, 2) nutrient water quality

net-exchanges between the canals and adjacent estuaries, 3) several

basic water quality parameters, and 4) the canal and sampling day

physical characteristics. The metabolism and water quality data pro-

vide information on the conditions within the canals, whereas the

exchange data provide information on the nature of the canal-estuary

interactions.

Rather than intensively studying one or two canal systems over an

extended period, the strategy was to examine the short-term behavior of

a large number of canals around Florida. By sampling canals with wide

geographical distribution and varying physical attributes, the vari-

abilities of the response parameters were assessed for Florida resi-

dential canals. Once the variabilities of canal behavior and conditions

were known, then the degrees of interdependence among the response

parameters and the canal and sampling day characteristics, plus the

amounts of variability explained on the basis of canal physical attri-

butes, estuarine water quality, and local tidal dynamics, were evaluated

using standard statistical methods.

Multiple regression analysis was employed to determine quantitative


I









relationships among 20 response.parameters (metabolism, net-exchange,

and water quality) and their significant explanatory factors (canal

physical attributes, estuarine water quality, and local tidal dynamics).

The analysis did not provide the mechanistic relationships for the

response and explanatory variables but did, however, identify and

quantify the associations among the response parameters and the ex-

planatory factors. Since the regression equations have been derived

from data on existing canals, they constitute a foundation from which

future workers can develop canal design criteria, canal management

policies, and mechanistic theories for the controlling factors in

canals.

This study substantially increases the data base for the conditions

within Florida residential canals, provides heretofore lacking infor-

mation on the exchanges of materials between canals and estuaries, and

presents equations that can be cautiously used to estimate the condi-

tions and behavior of existing or future canal systems. It does not,

however, attempt a total evaluation of the ecological and socioeconomic

impacts of residential canals in the coastal zone.















CHAPTER 2
LITERATURE REVIEW



A review of the existing literature concerning dredged canals,

channels, and holes up to 1974 has been prepared by Polls (1974) under

a grant from the State of Maryland. His reviews that pertain to resi-

dential canals are described briefly below.

The work of Trent and associates (Moore and Trent, 1970; Corliss

and Trent, 1971; Trent et al., 1972) in West Bay, Texas includes

hydrographic, water quality, substrate, phytoplankton, benthic in-

vertebrate, oyster, fish, and crustacean data for canal, marsh, and

open bay stations. The canal stations were found to contain more silts

and clays than the marsh and bay stations. Turbidity was higher in the

bay than in the canals, but lower in the marsh than in the canal.

Benthic invertebrates, fish, and crustacean numbers were similar in the

marsh and canal, and tended to-be higher in the bay. Phytoplanktonic

primary production per unit surface area was greater in the canal than

in the marsh. A large standing crop of oysters was observed on the

bulkheads of the canal but growth and spatfall were reduced in the

canal relative to the marsh. Oyster mortality was greater in the canal

than in the marsh. Blue crabs and grass shrimp were more abundant in

the marsh than in the canal.

Taylor and Saloman (1968) examined the sediments, water quality,

and primary production of canals in Boca Ciega Bay, Florida. They found

dissolved oxygen levels of at least 3.5 ml/l (4.9 mg/l) at all times


I








and stations, lower turbidities in the canals than in the bay, and no

significant differences in phytoplankton primary production levels

between natural and dredged areas. Silts and clays predominated in

the canal sediments, as compared to sand and shell in the bay sediments.

Fewer species of fish were netted in the canals than in the bay (49

versus 80), but thirty percent more fish were caught in the canals.

Sykes and Hall (1970) sampled the mollusks of canals and natural

areas in Boca Ciega Bay, Florida, concomitantly with Taylor and Saloman.

Their results show a marked reduction in numbers of individuals and

species in the soft sediments of the canals as compared to those of

the bay.

Lindall, Hall and Saloman (1973) followed the fish populations of

a newly opened canal system off Tampa Bay, Florida. Only anchovies

(Anchoa mitchilli) were caught in the system three months after inunda-

tion, but during the following year 36 species were netted. Lindall

et al. thought that newer canals provide a more favorable habitat for

fishes than do older canals.

Barada and Partington's (1972) report on waterfront developments

in Florida, while supplying no new data on canals, was instrumental in

bringing the problem of canal dredging to the public's attention. Their

report, citing several of the above investigations, discusses the lack

of good circulation and flushing, excessive depths, stratification,

fish kills, odor, and bacterial problems of canals. An image of canals

as open sewers and as having detrimental effects on ground and surface

waters, was projected.

Godwin and Sholar (n.d.) found increased silt and clay fractions

and decreased benthic invertebrate diversities in dredged canal sediments,









relative to natural areas in North Carolina.

The work of Daiber et al. (1972, 1973) in Delaware provided at that

time the most comprehensive study of biological, chemical and physical

aspects of any canal system. Conditions were generally poorer in the

canals than in the adjacent natural salt marsh embayments, but the

uniqueness of each canal system was recognized. A dye flushing study

of one 800-meter canal showed that the initial surface concentration at

the dead-end was reduced by only 56 percent after five days, and that

the bottom water exchanged much more slowly.

Since Polis' review, several other studies have appeared. Chesher

(1974) reported biological and hydrological data on 50 canals in the

Florida Keys. Paulson et al. (1974, 1975) studied four canal systems

along the Gulf of Mexico. Nixon et al. (1973), in an ecological study,

compared a small boat marina with a natural marsh embayment in Rhode

Island. The Environmental Protection Agency (1973, 1975) has issued

preliminary reports on several canal systems in the Florida Keys,

Charlotte Harbor, Florida area, and North Carolina. Daiber et al.

(1974, 1975) have completed two more reports on Delaware canals. The

Marco Island, Florida project has been studied by a group from the

University of Miami (Van de Kreeke and Roessler, 1975a and b, and

Carpenter and Van de Kreeke, 1975) and by the Deltona Corporation

(1975). Adkins and Bowman (1976) have prepared an informative document

on the canals dredged for oil drilling rigs in Louisiana. Burk and

Associates, Inc. (1975) examined the condition of a residential canal

development in Louisiana, and evaluated several developments in Florida

in an attempt to forecast water quality in the Louisiana development.

Thurlow (1974) did research on the water quality and sediment





-9-


characteristics of four New Jersey canal developments. Substantial

data on four pairs of canals in Florida have been reported by Fox et al.

(1976) and by Piccolo et al. (1976).

Chesher (1974) discusses his physical, chemical, geological, and

biological work on 50 canals in the Florida Keys, and finds the canals

generally to be in good condition. Canal orientation to the wind and

the substrate type were found to be the most important factors affecting

canal water quality. Chesher feels that the advantages of such systems

outweigh the disadvantages to the productivity and economy of the Keys.

Paulson et al. (1974) report physical, hydrological, phytoplankton,

benthic fauna, and sediment composition data for single collections in

two canal systems in Florida and two in Texas. They believe that the

lower dissolved oxygen concentrations at the dead-end stations might be

alleviated by restricting the depths of the canals and eliminating

dead ends. Paulson's 1975 report includes physical, biological, and

chemical data for a canal system and a natural bayou in southern

Mississippi. They found essentially no differences in flushing rates

and biota between the two systems. However, dissolved oxygen values

tended to decrease and coliform levels tended in increase toward the

dead end of the canal. The canal was shallower than the adjacent water

body.

Nixon et al. (1973) evaluated the production, metabolism, suspended

material, dissolved organic, nutrients, phytoplankton,.bacteria, fish,

fouling communities, and sediments of a small boat marina and a natural

marsh embayment in Rhode Island. The two types of systems were similar

and were felt to be compatible coastal systems in Rhode Island. The

authors regarded the fouling communities of the bulkheads, pilings, and





-10-


boats as an important food source for juvenile fish populations and

which may serve the same detritus-producing role as do the marsh grass

in the natural marsh embayment. The fouling communities reached a

maximum biomass of 5,000 g/m2, about five times the standing crop of

marsh grass. The respiration rate of the fouling communities was quite

high (mean = 1.80 g 02/m2-hr) with no net production and was about 20

times the oxygen demand of the-sediments.

The preliminary E.P.A. (1973, 1975) reports represent the most

exhaustive sampling sessions on selected canals in Florida and North

Carolina. Impressive amounts of water quality, sediment, microbial,

hydrodynamic, mass transport, and biological data were collected twice

for two pairs of canals near Punta Gorda and Big Pine Key, Florida, and

once at sites in Marathon, Florida, Panama City, Florida, and Atlantic

Beach, North Carolina. Their preliminary but unofficial recommendations

were to restrict canal depths to 4-to 6 feet, to centralize the waste

treatment facilities of the development and discharge the effluent at

points remote from the canals, to have the developer provide sufficient

bonding to correct any water quality violations in the canals or to

isolate the canals from receiving waters, to design developments so

that stormwater runoff does not enter the waterways, to avoid sills at

the canal mouths, and to require an assessment of a proposed canal

development's impact on any local shallow freshwater aquifers.

Daiber et al. (1974) expanded on their earlier work and presented

seasonal data on seven canal systems in Delaware. Hydrological,

coliform, BOD, fish and benthic invertebrate results are reported along

with more flushing characteristics and a simple tidal excursion model

for transport within a canal. They concluded that the flushing rates






-11-


and general ecological condition of the canals are dependent on the

adjacent water body. It is difficult to obtain healthy canals on a

stressed bay.

Daiber et al. (1975) reported additional benthic invertebrate data

from the Little Bays area of Delaware, in addition to intertidal inver-

tebrates and vegetation, and ichthyoplankton results. The numbers of

individuals and species of benthic invertebrates were generally lower

in canal stations than in marsh and bay stations during the summer and

fall. However, the uniqueness of each canal system and its environ-

mental conditions was again emphasized. The three habitats were found

to have similar fauna during the winter and spring. Biomass comparisons

between different types of canal shorelines indicated that old bulkheads

have higher standing crops of plants and animals than do bare banks.

The old bulkheads had fewer macrophytic plants, but higher animal biomass

than did the salt marsh environment. The ichthyoplankton data, though

limited, suggested that canals are not as favorable a habitat for larval

fish as is the salt marsh.

The information reported by the University of Miami group

(Carpenter and Van de Kreeke, 1975 and Van de Kreeke and Roessler,

1975a and b) on the Marco Island, Florida development consists of

oxygen data, estimates of production and respiration, and a model to

predict oxygen levels. Their model was developed for the main flow-

through arterial channels fifteen feet in depth. The model revealed

that dissolved oxygen concentrations for Marco Island canals are sig-

nificantly dependent on the vertical mixing coefficient and the detritus-

supported respiration, and not sensitive to atmospheric transfer,

photosynthesis and respiration. For the dead-end tributary canals,





-12-


wind induced motion and diurnal density induced motion were thought to

be important factors affecting dissolved oxygen distribution.

Adkins and Bowman (1976) provide an informative review of the

impact of canal dredging in the coastal zone, as well as the results of

a two year study on canals dredged in Louisiana marshland for oil

drilling rigs. Fish, blue crab, shrimp, water chemistry, and sedi-

mentology data were presented for open, semi-open, and closed canals,

and for unaltered areas. The greatest number of animals were found in

the unaltered areas. Dissolved oxygen levels remained within tolerance

limits of marine organisms during most of the study, though fish kills

were observed in the semi-open and closed canals (one each).

Burk and Associates (1975) conducted a one day study of water

quality and biota at five stations within a 5,300 acre development off

Lake Pontchartrain, Louisiana. By evaluating the conditions of five

Florida canal developments and reviewing canal literature, Burk and

Associates made several recommendations for improving the future water

quality in the Louisiana development. Recommendations to improve flush-

ing and water circulation in the existing canals were to create flow-

through systems via culverts and saltwater wells, and to install bottom

aerators or air injection systems. Design criteria for new canals in

the area were to limit canal depths to 6 to 8 feet and canal lengths to

800 feet, to provide sloping sides and smooth bottoms in the canals, to

allow canals to be as wide as possible, and to align the canals with

the prevailing winds. Other recommendations included the construction

of grassy swales in the development, the establishment of natural

vegetation buffer zones between homes and canals,.and the spray-

irrigation of the sewage treatment plant effluent onto the local golf

course.





-13-


Thurlow (1974) examined the water quality and sediment character-

istics of four canal developments in New Jersey. He concluded that each

canal system was unique and that depth had a major influence on water

quality, particularly on the bottom water quality. Canals with sills

were "more polluted" at points remote from the entrances. Accumulations

of nutrients and heavy metals plus.anaerobic conditions were observed

in excessively deep areas. Water quality was similar in old and new

canals, even though the new canals were deeper. Canal developments

with homes utilizing septic tanks had better water quality than those

with a sewage treatment plant whose effluent was discharged into the

canals. The water quality was best in the canal system that had a

sewage treatment plant and a remote discharge point. Thurlow recommended

canal depths of 8 to 10 feet, maintenance dredging of sills, sewered

developments with remote discharge points, and the reductions of organic

inputs to the canals, in the use of lawn fertilizers, and in the sub-

stitution of stones for lawns.

Two groups of investigators at the University of Florida (Piccolo

et al., 1976 and Fox et al., 1976) jointly examined four pairs of

similar canals at different locations in Florida, on a seasonal basis.

Piccolo et al. provided the hydrography of the canals and a pollutant

dispersion model. Fox et al. reported the water and sediment chemistry,

the metabolism levels, the phytoplankton and benthic invertebrate

populations, the canal-estuary net nutrient exchanges, the benthic

oxygen demand, and the hydrocarbon levels of the canals. They concluded

that canals constitute complex and variable systems. The individual

canals within the essentially identical canal pairs (directly adjacent)

often had dissimilar attributes. Not all canals had poor water quality.





-14-


The factors responsible for the differences in water qualities were

not clear. Rankings of the canal water qualities did not simply reflect

differences in a single factor such as canal depth, age, flushing rates,

or local estuarine water quality.

No clear consensus exists in the literature for the most important

factor affecting water quality in residential canals. Excessive depths

and poor circulation and flushing are most frequently thought to lead

to poor conditions. The dead-end nature of the canals and sill forma-

tion at the canal entrances are not conducive to good mixing and flush-

ing. Local tidal dynamics and their influences on canal flushing rates

are considered important by several investigators. The water quality

of the adjoining water bodies, while not frequently mentioned by

investigators working in single locations, undoubtedly affects the

canals. In addition to canal depth, other canal characteristics such

as length, width, configuration, bottom topography, orientation to the

wind, and substrate type, are often identified as important factors.

Allochthonous sources of organic and inorganic materials and their

management, appear to be significant in some canal systems.

Many aspects of the impact of canal dredging on the coastal zone

have been discussed by the investigators cited above. Reviews of the

subject can be found in Lindall and Trent (1975), Adkins and Bowman

(1976), and Odum (1970). Possible impacts of canal dredging in the

coastal zone given by these authors and their referenced literature,

include:

1. Destruction and loss of nursery areas for coastal fisheries.

2. Biological productivity losses of dredged areas. Taylor and

Saloman (1968) estimate that $1.4 million of annual revenue is






-15-


lost from Boca Ciega Bay, Florida as a result of dredging and

filling. Douglas and Stroud (1971) concluded that 535 pounds

of fish products from the continental shelf are lost per acre

of estuary that is obliterated; Gosselink et al. (1974) value

the non-competing uses of marshland at $4,000 per acre per

year.

3. Changes in upland drainage patterns.

4. Changes in water depths and substrate types of dredged areas.

5. Harmful silt release during dredging operations and after

canal completion via resuspension.

6. Alteration of the local water currents and circulation patterns.

7. Estuarine detritus retained by canals.

8. Low dissolved oxygen concentrations and unfavorable conditions

in the canals and the resultant effects on estuarine organisms

entering the canals.

9. Possible spill-over of accumulated sludge and poisonous wastes

from canals to estuaries (Barada and Partington, 1972).

10. Saltwater intrusion into shallow freshwater aquifers and

former freshwater areas.

11. Deleterious effects of an active dredging operation on local

residents and wildlife.














CHAPTER 3
SITE DESCRIPTIONS



Thirty-three canals at twelve locations throughout the State of

Florida (Figure 1) were sampled over a twenty month period. The indi-

vidual canals and sampling stations are shown in Figures 2 through 13.

Several canals were sampled more than once, resulting in a total of

sixty-one canal observations. In addition, data for thirteen canals

were obtained from the Environmental Protection Agency and have been

included in some analyses.

Canal geometries (length, width, mean depth, water surface area,

water volume, sill height), canal age, percent of shoreline bulkheaded,

canal water minimum residence time, and some of the canal development's

attributes (presence or absence of curbed streets and sewer systems,

percent development) are shown in Table 1 for each canal observation.

The levels of solar insolation, tidal ranges, and cumulated tidal

amplitudes on the sampling days are also given in Table 1. Additional

information and distinguishing features of each canal site are given

below.

Punta Gorda (PG. Figure 2). The three canals at this location

are part of the Punta Gorda Isles development. The developer made an

effort to design this rather new canal system so that circulation and

flushing were maximized by dredging to uniform depths and leaving

sloping banks. Management of the canal system includes regulations

against the discharge of grass clippings and fish heads into the canals.


-16-






-17-


Figure 1. Sampling sites within Florida.
















Table 1. Canal and sampling day physical characteristics.

Units: LENGTH, WIDTH, MDEPTH, SILL, TIDE, CUMTIDE -- meters
AREA -- square meters
VOLUME -- cubic meters
DEVEL, AGE -- percent
AGE -- YEARS
CURBS, SEWERS -- 1 present, 0 absent
MINRES (Minimum residence time) -- days
SUN -- langleys/day
DAYL (Daylength) -- hours

See Table 2 for more complete identification of the parameters.









OBS CANAL MONTH DAY YEAR LENGTH WIDTH MDEPTH


PG6
PG3
PC3
PC6
P83
P86
LX3
LX6
PG6
PG3
PC3
PC6
PB3
PB6
LX6
L X3
PG3
PG6
PG9


747
652
b75
018
732
732
631
521
747
652
575
618
732
732
521
631
652
747
3650


2.8
2.2
3.2
2.7
3. C
3.2
1.8
1 6
2.8
2.2
3.2
2.7
3.0
3.2
1.6
1.8
2.2
2.8
3.0


22400
19000
19000
20400
16800
15400
13900
8860
22400
18300
19000
20400
16800
15400
8860
13900
18300
22400
480000


62700
60700
60700
55100
50500
49200
25000
14200
62700
40200
60700
55100
50500
49200
14200
25000
40200
62700
1440000


0.0
0.2
1.1
0.8
1.1
0.8
0.6
1.2
0.2
0.0
0.5
0.8
1.1
0.8
1.2
0.6
0.2
0.0
0.0


08S DEVEL AGE BULK CURbS SEWERS


30
50
100
100
100
98
0
0
30
50
100
100
100
98
0
0
50
30
50


100
100
100
100
100
100
80
0
100
100
100
100
100
100
0
80
100
100
100


MINRES TIDE CUMTIDE SUN DAYL


2.9
2.7
5.0
4.0
2.0
2.1
1.2
1.2
3.6
2.9
4,2
3.6
1.8
1.9
1.4
1.4
2.2
2.7
2.7


0.58
0 58
0.58
0.58
1. 10
1 10
0.70
0.70
0.55
0.55
0C73
0.73
1.01
1.01
0.52
0.52
0.64
0.64
0,64


0.83
0.83
0.77
0.77
2. 14
7. 14
1.15
1.15
0 74
0.74
0.83
0.83
1.77
1.77
1.24
1. 24
1.10
1.10
1. 10


602
602
642
642
488
488
434
434
650
650
676
676
342
342
378
378
426
426
*


12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
13.5
13.5
13.5
13.5
13.5
13.5
13.5
13.5
12.3
12.3
12.3


AREA VOLUME SILL








OBS CANAL MONTH DAY YEAR LENGTH WIDTH MDEPTH AREA VOLUME SILL


Table 1. (Continued)


20 PC3 9
21 PC6 9
22 PC9 9
23 P83 9
24 PB6 9
25 LX3 9
26 LX6 9
27 PG6 11
28 PG3 11
29 PG9 11
30 PC3 11
31 PC6 11
32 PC9 11
33 P86 11
34 P9 11
35 P83 11
36 LX3 11
37 LX6 11
38 MIl 3

OBS DEVEL AGE

20 100 16
21 100 16
22 75 14
23 10C 23
24 98 23
25 0 16
26 0 16
27 30 9
28 5C 9
29 50 11
30 100 16
31 100 16
32 75 14
33 98 23
34 100 20
35 100 23
36 0 16
37 0 16
38 50 10


9 75
9 75
9 75
7 75
7 75
12 75
12 75
21 75
21 75
21 75
23 75
23 75
23 75
14 75
14 75
14 75
16 75
16 75
24 76


575 33
618 33
1350 30
732 23
732 21
631 22
521 17
747 30
652 28
3650 30
575 33
618 33
1350 30
732 21
738 23
732 23
631 22
521 17
2837 30


BULK CUR6S SEwERS

100 0 1
100 0 1
90 0 1
100 0 0
100 0 0
80 0 0
0 0 0
100 0 1
100 0 1
100 0 1
100 0 1
100 0 1
90 0 1
100 0 0
100 0 0
100 0 0
80 0 0
0 0 0
100 0 1


3.2
2.7
2.5
3.0
3.2
1.8
1.6
2.8
2.2
3.0
3.2
2.7
2.5
3.2
2.5
3.0
1.8
1.6
2.7


19000 60700 0.5
20400 55100 0.8
182000 455000 1.5
16800 50500 1.1
15400 492C0 0.8
13900 25000 0.6
8860 14200 1.2
22400 62700 0.0
18300 40200 0.2
480000 1440000 0.0
19000 60700 0.5
20400 55100 0.8
182000 455000 1.5
15400 49200 0.8
70000 175000 1.0
16800 505C0 1.1
13900 25000 0.6
8860 14200 1.2
312000 842000 0.0


MINRES TIDE CUMTIDE SUN DAYL


4.4 0.57
3.8 C.57
3.1 0.57
1.8 0.98
2.0 0.98
1.5 0.64
1.6 0.64
2.5 0.74
1.9 0.74
2.9 0.74
3.6 0.80
2.9 0.80
3.0 0.80
2.4 0.73
2.1 0.73
2.3 0.73
1.2 0.63
1.2 0.63
3.3 0.67


0.81
0.81
0.81
1.67
1.67
Is 14
1.02
1* 02
1.02
1.02
0.83
0.83
0.83
1.17
1.17
1.17
1.37
1.37
0.81


446 12.3
446 12.3
23 12.3
238 12.3
238 12.3
296 12.3
296 12.3
296 11.0
296 11.0
1.0
334 11.0
334 11.0
11.0
352 11.0
11.0
352 12.3
204 11.0
204 11.0
520 12.0









08S CANAL MONTH DAY YEAR LENGTH WIDTH MDEPTH AREA VOLUME SILL


Table 1. (Continued)


MI2
MI3
8C1
8C2
BC3
HI I
HI2
HI3
FL1
FL 2
FL3
API
AP2
AP3
G81
GB2
GB3
KC1
KC2


OBS DEVEL AGE BULK CURdS SEWERS


3 24
3 24
4 20
4 20
4 20
5 19
5 19
5 19
6 12
6 12
6 12
7 14
7 14
7 14
7 31
7 31
7 31
8 18
8 18


76 397 30
76 040 30
76 1320 53
76 984 48
76 1310 30
76 3370 30
76 3370 30
76 690 30
76 520 21
76 450 24
76 800 24
76 3910 46
76 1140 52
76 2710 38
76 264 25
76 173 25
76 427 20
76 730 29
76 730 29


MINRES TIDE CUMTIDE SUN DAYL


0.67 0.81
0.67 0.81
0.67 0.67
0.67 0.67
0.67 0.67
0.82 1. 50
0.82 1.50
0.82 1.50
0.31 0.47
0.31 0.47
0.31 0. 47
0.72 0.95
0.72 0.95
0.72 0.95
0.21 0.30
0.21 0.30
0.21 0.30
0.41 0.59
0.41 0.59


520 12 0
520 12.0
571 12.5
571 12.5
571 12.5
515 13.0
515 13.0
515 13.0
504 13.5
504 13.5
504 13.5
506 13.5
506 13.5
506 13.5
554 13.5
554 13.5
554 13.5
72 13.0
72 13.0


2.6
2.7
4.0
3.0
4.0
1.5
2.0
2.9
2.8
3.1
4.9
2.6
2.7
2.0
1.1
1.7
1.2
3.8
4.1


12700 33000 0.5
41100 111000 0.0
184000 736000 1.1
46800 140000 2.3
122000 488000 1.4
385000 577000 0.0
385000 770000 0.0
36000 1040CO 0.8
11000 30800 0.9
11000 34100 1.4
50000 145000 1.2
402000 1040000 2.7
56000 151000 1.5
238000 476000 0.
9200 10000 0.6
4300 7300 1.2
22000 26000 0.3
21200 80400 2.1
21200 86900 0.3


25
10
75
100
100
100
100
100
20
40
80
50
10
45
60
80
30
50
80


7 100
8 100
20 100
20 100
20 100
18 100
18 100
18 100
11 20
15 40
20 50
19 75
i9 10
19 50
7 10
15 100
5 5
16 50
16 80


3.2
3.3
6.0
4.5
6.0
1.0
1.3
1.9
9.0
10.0
9.4
2.7
2.8
2.1
3.7
5.7
4.0
6.4
6.9









OBS CANAL MONTH DAY YEAR LENGTH WIDTH DEPTH AREA VOLUME SILL


Table 1. (Continued)


KC3
NMI
NM2
NM3
PE1
PE2
BP3
8P4
SA8
A83
A65
MIH
MIJ
MIL
MIM
MIM
MIN


18 76
26 76
27 76
28 76
14 74
14 74
19 74
19 74
23 74
17 74
17 74
8 75
10 75
6 75
6 75
8 75
7 75


08S OEVEL AGE BULK CURBS SEWERS

58 20 16 40 0 1
59 50 20 50 0 1
60 50 20 50 0 1
61 50 20 50 0 1
62 0 19 0 0
63 30 19 0 0
64 0 15 0 0
65 30 15 0 0
66 0 0 0
67 75 0 0
68 40 0 0
69 80 10 100 0 1
70 10 100 0 1
71 10 100 0 1
72 50 10 100 0 1
73 50 10 100 0 1
74 8 80 0 1


730 29
624 31
624 31
624 31
762 30
610 25
457 12
163 9
873 26
671 43
488 30
1267 30
458 30
660 30
2837 30
2837 30
4463 30


3.9
6.2
6.2
6.2
2.1
2.1
2.7
2.4
5.4
3.3
3.6
3.1
2.0
3.4
2.7
2.7
2.2


MINRES TIDE CUMTIDE SUN DAYL


6.6
7.8
8.7
8.7
2.6
2.6
3.9
3.5
11.5
2.2
2.4
1.7
1.3
2.1
3.3
3.3
1.2


0.41 0.59
0.80 1.42
0.71 1.36
0.71 1.23
0. 70 0. 80
0.70 0.80
0.31 0.69
0.31 0.69
0.31 0.47
0.91 1.52
0.91 1.52
1 08 1.81
0.82 1.49
1.02 1.61
1.02 1.62
0.95 1.62
1.03 1.79


72 13.0
316 11.5
346 11.5
183 11.5
13.0
& 13.0
13.0
S 13.0
13.0
12.3
S 12.3
13.0
S 13.0
S13.0
13.0
S13.0
S 13.0


21200 82700 0.8
38500 238000 2.9
38500 238000 2.9
38500 238000 2.9
22900 48000 1.2
15200 32000 0.6
5480 15000 0.0
1650 3950 0.0
52400 263000 3.1
28900 95200 1.2
14600 52700 0.6
120000 373000
13800 27600
63000 214000
312000 842000 0.0
312000 842000 0.0
613000 1350000






-23-


Canals and sampling stations at the Punta Gorda site.


Figure 2.






-24-


Floating debris is regularly removed from the canals. Limited boating

activity was observed. Canals 3 and 6 were sampled four times during

1975, while Canal 9 was sampled twice. Local tidal dynamics are quite

irregular in amplitude and frequency. The adjoining Peace River has high

phosphorus levels as a result of phosphate mines in its drainage basin,

and experiences lowered salinities during the rainy summer season.

Port Charlotte (PC. Figure 3). The three canals in the Port

Charlotte development are across the Peace River estuary from the Punta

Gorda canals, but are older and more developed than Punta Gorda Isles.

A sand bar (exposed at low tides) separates the dredged channel along

the development from the river. Southerly winds in the spring and

summer tend to hold floating debris in the canals. A secondary sewage

treatment plant in Port Charlotte enters the end of a 4,000-foot canal

whose entrance to the Peace River is approximately 2,000 feet east of

the canals. Canals 3 and 6 were sampled four times during 1975. Canal

9 was sampled twice.

Pompano Beach (PB. Figure 4). The three canals sampled at the

Pompano Beach location are representative of many canals in that area.

Extending off the Intracoastal Waterway, the canals are old, narrow,

and completely developed with homes using septic tanks (until 1975).

Considerable boating activity exists along the Intracoastal Waterway

and within the canals. Tides in the area are uniform and semi-diurnal.

The nearest oceanic inlet (Hillsboro Inlet) is approximately six

kilometers north.

Loxahatchee River (LX. Figure 5). Dredged and abandoned about

1960, the two canals at this site are approximately seven kilometers

up the Loxahatchee River from Jupiter Inlet. One of the canals (LX3)





-25-


:-I .Ii ,: ^] -'"

j2 l . *:'.. .... ..

22 ../ 23

S )rt Charlot e .








2 26 _
I s *

SScal .e i


'c
Figure 3. Canals and sampling stations at the Port Charlotte site.
A . .







I Point'',
... ..






S- PC 9 PC --6 PC3









500 m









Figure 3. Canals and sampling stations at the Port Charlotte site.






-26-


Figure 4. Canals and sampling stations at the Pompano Beach site.






-27-


Canals and sampling stations at the Loxahatchee River site.


Figure 5.





-28-


has concrete bulkheading, while the other (LX6) has sloping sides up to

the dredge spoils on one side and to a mangrove community on theother

side. The unbulkheaded canal has a landfill site at the dead end. The

Loxahatchee River in this vicinity is about one meter deep, is lined

with mangrove trees, experiences uniform semi-diurnal tides, and'is

strongly influenced by freshwater inputs during the wet season.

Marco Island (MI. Figure 6). This large and complex development,

constructed by the Deltona Corporation, is an island separated from the

mainland by the Marco River. Canal MI1 is large, extensively branched,

and borders a golf course that is spray-irrigated with the development's

sewage treatment plant effluent. The MI3 canal had received maintenance

dredging the year prior to sampling, as part of a canal design experi-

ment by the Marco Island Applied Marine Ecology Station. At the time

,of sampling (March) the water in the area was more turbid than during

most of the year due to strong westerly winds that kept the Gulf .of

Mexico turbulent. Some of the Environmental Protection Agency's data

from Marco Island has been incorporated into this study (canals MIH,

MIJ, MIL, MIM, MIN).

Boca Ciega Bay (BC. Figure 7). Located in the southeast section

of Boca Ciega Bay, this site was the only one that had curbed streets

in the development. The stormwater enters directly into the canals via

drain pipes. A large boat marina operates at the end of BC3 canal

(station BC32). Westerly winds from the Gulf of Mexico during the

spring and summer afternoons keep Boca Ciega Bay and the canal entrances

turbulent. Tides in the area have irregular amplitudes and frequencies.

On the sampling day the tidal cycle was diurnal, i.e., one high slack

and one low slack tide in 24 hours.






-29-


Figure 6. Canals and sampling stations at the Marco Island site.




-30-


Pier


CANALS


BC1-

BC 2-

:BC 3-


IC '


I -


Scale
1:24000


500 m
t-. I


Figure 7. Canals and sampling stations at the Boca Ciega Bay site.


''





-31-


Hillsboro Inlet (HI. Figure 8). The three canals sampled near

Hillsboro Inlet are part of Lighthouse Point Township. Canals HI1 and

.HI2 form a single complex canal system with two entrances. Both the

HI2 and HI3 canal entrances are approximately 500 meters from the

Hillsboro Inlet. Yet, the influence of the oceanic inlet is quite dif-

ferent for each canal. More of the ocean water that passed through the

inlet during flood tide seemed to be flowing north, rather than south

along the Intracoastal Waterway, during the sampling period. As a

result the turbidity and color at the HI2 canal entrance was noticably

less than at the HI3 entrance. Different volumes of freshwater flow

into the respective Intracoastal Waterway sections from upland drainage

were assumed to be affecting the movement of the seawater entering the

inlet. Boat traffic along the Intracoastal Waterway results in much

wave activity at the canal entrances. The large homes in the develop-

ment tend to shelter the canal branches from the wind. A sewer system

was installed in the development during the year prior to sampling.

Flagler Beach (FL. Figure 9). The three canals sampled at Flagler

Beach extend off the Intracoastal Waterway about 15 kilometers south of

Matanzas Inlet. This section of Florida's coastline is not extensively

developed. Mangroves and marshland surround most of the Intracoastal

Waterway in the area. The water was quite colored (ca. 200 cpu) at the

time of sampling, and did not have much tidal activity.

Apollo Beach (AP. Figure 10). The Apollo Beach development,

located on the eastern shore of Tampa Bay, is approximately 10 kilo-

meters from a phosphate processing plant. One large canal was

sampled as three canal observations. Canal API was taken as the

entire canal. Canals AP2 and AP3 were the major branches of the system.






-32-


-Scale

1:24000

500 m
t- -


8


Figure 8. Canals and sampling stations at the Hillsboro Inlet site.





-33-


\ -,, .
-- -- - -- --._ .-- .- - -
'.VJV........ -.................. ........ .. :

ATL.
'2 ... . 5, ', i' x ,V', \\ O n





'" '219
,' . :"' : \ ., -.. \ 1 .\

I '," Iv ,, ' . :\ \

IFL
.. .. C.I A L 2"
7Z\IBM


S0 *, .* i
o.... :, "




S ..



I
1


Scale
1:24000


J ...' ,,o o, \ .
FL 3




1,8MI ,



S, Flagler Beach
I-




] "" 'V '"


' .I ' \ \ (
, ,, ,,-
.. .- .' I ', ..







^ 'B. -
S -- ----0

", ,K,. \ \ '13 K
14 \








'2


Figure 9. Canals and sampling stations at the Flagler Beach site.


ANTIC


SN\
1M


-N


tI


\BM
i'











**,
!\
.-.A
.. '*'>~



'' '
*...
\
.







)





,/'
/;-






i//.
/j


---


'Ei






-34-





-35-


A shallow culvert connects sections of AP2 and AP3, but the interaction

between the two canals is limited to the surface water. The canal

system was dredged in a former mangrove community, had several deep

holes, and had varying widths. Onshore winds were strong (ca. 20 mph)

throughout the sampling period.

Goose Bayou (GB. Figure 11). The three canals sampled on Upper

Goose Bayou, located off North Bay near Panama City, were the most

recently dredged of the canals examined. These canals were also

shallowest and experienced the least tidal fluctuations. Marshland

and sparsely populated shorelines predominate in this estuary.

Key Colony (KC. Figure 12). The three canals in Key Colony

Beach are located on Fat Deer Key, about midway down the Florida Keys.

The substrate is limestone and fossilized sand. A sewer system serves

the development. However, the outfall from the treatment plant enters

an embayment about 400 meters north of canal KC1. A tropical depres-

sion with high winds, heavy rains, and little solar insolation, was

over the area during the sampling period, making conditions rather

uncharacteristic of the Keys.

North Miami (NM. Figure 13).' One branched canal in North Miami

Beach was sampled for three consecutive days. Each 24 hour period was

considered a canal observation. This canal was the deepest (6 m) of the

canals examined. An anoxic water layer existed below the two meter

depth throughout the three days. A cold weather front came through the

area during the sampling period, bringing cloudiness, shifting winds,

and rain. The development and the adjacent Maule Lake were mangrove

communities before dredging and filling.





-36-


Little Oyster Bar Point .- '
/4 I I :
SI - .Light.
\. Light .. '0 '

', '' U S MILITARYm RESERVATION /-
r-. V -',-- ---i- -- 1J
7 "


GB 1
.* -i" :. ",,
CANALS GB 2
GB3


"*, +- - i f

-- -- -



City) site.
'.- 17 \ _
/7 / .i- % '--. -- '
, . - '-*. .- Ii


\ ^ --<, ---J-: '* '-- .--- --7 .,- --- ----- -
SGoose Island' -- '"-

Go Scale" "'... ,- - -"



1 : 24000 F'. rNNU' Nt J-, R po -- ... -.O
** ^ --^ ^^ 1" //-- -^


i ^ ,\"< .:' *r/h 9i / - 2 --, +



I 500 m I "> "-" "^ "




Figure 11. Canals and sampling stations at the Goose Bayou (Panama
City) site.






-37-


9


.1


I \
1\




Scale

1:24000


500 m


Figure 12. Canals and sampling stations at the Key Colony site.


(l~






-38-


I'"



It -...-r I uzzZZZIL



itli


-.-- '"'



\h I




Ala u~Lae drrey`
/ ..(- I


Light l


4,\


CANAL NM 1,2,3 ...

[ East" I,,
3reynolds. \ *--- \\\
Fark, .. .. ,;'* : -".




S NORTIP MIAMI BEACH

:. : i (part of) '
,,. -: ,. .


\ I ,'* :-- : i .




\ \ .- 1 .


Scale

1:24000


500 m I
I I 'j--


Figure 13. Canals'and sampling stations at the North Miami site.


[i..
* -.? *C*


__


II


s-:

"~~ "' "~"
::





-39-


Environmental Protection Agency Data. Observations 62-74 were

obtained from the Environmental Protection Agency. Descriptions of

their Punta Gorda (PG), Big Pine Key (BP), Marathon (SA), and Atlantic

Beach, North Carolina (AB) canal studies can be found in their report

(E.P.A., 1975). Their Marco Island data (MIH, MIJ, MIL, MIM, MIN) has

not been published.















CHAPTER 4
MATERIALS AND METHODS



Metabolism


The oxygen metabolism rates for the total canal communities and

the planktonic components were determined for each canal, except Punta

Gorda 9, Port Charlotte 9, and Pompano Beach 9.

Community metabolism was estimated by the free-water diurnal oxygen

method (Odum and Hoskins, 1958, see also Slack et al., 1973 for a

detailed outline). This technique assumes that the dissolved oxygen

change from sunrise to sunset in a volume of water can be attributed to

either net oxygen production of the biotic community in contact with the

water, or to oxygen diffusion across the air-water interface. Similar-

ly, any change in dissolved oxygen levels from sunset to sunrise is

assumed to be due to either community respiration or to diffusion. By

neglecting or adjusting for oxygen diffusion, estimates of daytime net

production and nighttime respiration are obtained. By further assuming

that the daytime respiration rate equals the nighttime respiration rate,

the total gross primary production and respiration levels for a 24 hour

period can be calculated.

For the first two sampling trips in 1975 (March and June), dis-

solved oxygen profiles were taken every three hours for 24 hours at

four stations along each canal (32 stations on 8 canals). Oxygen values

were determined by Winkler titrations. Mean values for the water column


-40-






-41-


at each sampling interval were used to compute the community metabolism.

Oxygen stratification generally was present. Oxygen diffusion across

the air-water interface was neglected, since the mean values for the

water column and not the surface values were used in the computations.

Ignoring diffusion leads to underestimates of metabolism, but was not

felt to be a serious source of error due to the generally quiescent

nature of the canal water.

After the first two sampling trips, oxygen profiles were taken at

every station for a sunrise-sunset-sunrise or a sunset-sunrise-sunset

sequence. The resulting three mean values for the water columns were

used to compute the daytime net production rates and the nighttime

respiration rates. The total community gross primary production and

total respiration were estimated on an areal (m 2) basis from the two

rates, allowing for daylength on the sampling day and for water depth.

The planktonic contribution to the total community oxygen metabolism

was determined by light-dark bottle 24 hour in situ incubations at one

or more stations per canal. Pairs of light and dark bottles were sus-

pended at one meter intervals throughout the water column. The changes

in dissolved oxygen levels were determined by Winkler titrations. To

obtain metabolism estimates on an areal (m 2) basis, the values at the

discrete depths were integrated over the depth of the water column.

The production:respiration ratios for the total community and

plankton component were calculated from the respective 24 hour gross

primary production and respiration values (m 2). The extent of plankton

dominance of the community primary production was calculated as the

ratio of the plankton GPP to the community gross primary production

values (canal means). The amount of solar insolation on the sampling





-42-


days was measured with a Belfort pyrheliometer.



Nutrient Exchange and Water Quality


The net exchanges of total carbon, inorganic carbon, total organic

carbon, total phosphorus, ortho-phosphorus, total organic phosphorus,

ammonia, turbidity, color, and conductivity across the canal entrances

were estimated by determining the total mass of each material entering

and leaving the canals during 24 hour periods. The concentrations/

values of these parameters were measured in surface water samples taken

periodically at the canal entrances. The volume and direction of water

flow across the canal mouths were determined from a recording tide

gauge and the canal water surface area. By summing the products of

the concentrations and volumes of flow for each sampling interval, the

total mass exchange for each material and each tidal phase was obtained.

Since the ebb and flood tidal phase volumes were not always equal, the

total mass exchange for each tidal phase was divided by the respective

total flow volume, to obtain weighted-average concentrations of each

material. The difference between the weighted-average concentrations

(flood-ebb) yield the net exchanges in concentration units. The mass

exchange values are not shown in the Results section but can be obtained

for each material by multiplying the weighted-average exchange concen-

trations (Table 7) by the canal surface area (AREA) and the cumulated

24 hr tidal range (CUMTIDE) in Table 1.

Several assumptions were included in this approach to estimating

net exchanges. The water samples collected and the concentrations

measured were assumed to represent the average concentrations of the

water transported during the sampling intervals. The water surface was





-43-


assumed to have zero slope and have constant area, so that changes in

water level were proportional to the flow volumes.

During the first two sampling periods at the Punta Gorda, Port

Charlotte, Pompano Beach, and Loxahatchee River canals, surface and two

meter depth water samples were taken from the center of the canal

entrance (ca. 50 meters inside). For the remaining exchange observa-

tions, hourly surface water samples were taken near the canal shoreline

by Serco Model NW3-8 Automatic Samplers. All water samples were

preserved with a solution of saturated mercuric chloride (1 ml/1) and

kept on ice until returned to the laboratory for analysis.

Total carbon and total inorganic carbon concentrations were deter-

mined with a Beckman Model 915 Total Carbon Analyser. Total organic

carbon concentrations were then determined by subtracting the inorganic

carbon concentrations from the total carbon concentrations. Total

phosphorus concentrations were determined by persulfate digestion and

the Murphy-Riley single reagent method (APHA, 1971). Ortho-phosphorus

concentrations were also determined by the Murphy-Riley technique. Total

organic phosphorus concentrations were obtained by subtracting the

ortho-phosphorus value from the total phosphorus value. Ammonia analyses

were performed with an AutoAnalyzer using the indophenol method (E.P.A.,

1974). Turbidity levels were determined with a Hach Model 2100A

Analytical Nephelometer. Apparent-color was measured at a 420 nm

wavelength on a Bausch and Lomb Spectronic 88 spectrophotometer.

Specific conductance (25 OC) values were obtained with a Beckman Model

RC 16B2 Conductivity Bridge.





-44-


Canal/Sampling Day Characteristics


The canal geometries and tidal exchange information for the Punta

Gorda, Port Charlotte, Pompano Beach, and Loxahatchee River sites, were

provided by B.A. Christensen, Hydraulics Laboratory, Department of Civil

Engineering, University of Florida. For the remaining canal sites, this

information was obtained from scaled maps, tide recordings and depth

profiles.

The recorded canal lengths were the distances along the canals from

the entrances to the most distant points. The mean centerline depths

and entrance-sill heights were determined from depth recordings. The

canal water surface areas were obtained from scaled maps. The canals

were assumed to be rectangular channels to that canal volumes were taken

as the product of the surface areas and mean depths. Canal ages were

obtained from local residents or estimated from comparisons of aerial

photographs and maps. The canal-water minimum residence times were

calculated as the ratios, mean depth:cumulated tidal amplitude, where

the cumulated tidal amplitude was the sum of the tidal ranges during

the 24 hour period.



Statistical Analyses


Descriptive statistics, principal components analyses, canonical

correlation analyses, and stepwise multiple regression analyses were

performed by an IBM 370 computer using the Statistical Analysis System

(Barr et al., 1976) package. Brief conceptual descriptions of the

multivariatemethods and references for each are given in Chapter 4.














CHAPTER 5
RESULTS



As stated in the introduction, the data for this study were

collected in two phases. The first phase (1975 data) was done in con-

junction with a more extensive team study (see Fox et al., 1976 and

Piccolo et al., 1976) wherein pairs of similar canals at four locations

(Punta Gorda, Port Charlotte, Pompano Beach, Loxahatchee River) were

examined four times. The second phase consisted of single sampling

trips to eight other locations. At seven of these locations, data were

collected for three canals over single 24 hour periods. At the eighth

location (North Miami), data were collected for one canal over three

consecutive 24 hour periods.

Four types of data were collected for each canal: 1) metabolism

levels, 2) nutrient/water quality net-exchanges between the canals and

adjacent estuaries, 3) several basic water quality parameters, and

4) canal and the sampling day physical characteristics (shown in Site

Description section).

Analysis of the data has been done in four steps. The first step

is a presentation of the raw data, frequency distributions, and descrip-

tive statistics for the metabolism, exchange, and water quality

responses. The second step is an attempt to evaluate the structure

of the data and to reduce the number of variables to a more manageable

figure without loss of information. The third step is an examination

of the association or correlations between the four data types, and the


-45-





-46-


final step is the generation of descriptive models that relate the

responses of the dependent variables to the levels of the independent

variables.

Sixty-four variables appear in the metabolism, exchange, water

quality, and physical characteristics data sets. The nomenclature for

the variables is shown in Table 2.



Metabolism


Combined Data


The metabolism results for the individual stations are included in

the Appendix. The mean values for the individual canals are presented

in Table 3. The frequency distributions and descriptive statistics

for the metabolic parameters are shown in Figures 14-20.

The mean value of total community gross primary production was
2
8.59 g 02/m -day for the 56 individual canal observations, with a

standard deviation of 5.87 g 02/m2-day. These two values lead to a

coefficient of variation (C.V.) of 66 percent. The frequency distri-

bution and range (0.0 to 24.9 g 02/m -day) of the 56 observations are

shown in Figure 14.

The planktonic component of the total community had a mean gross

primary production of 4.91 g 02/m2-day and a standard deviation of

3.91 g 02/m2-day. The range of values (0.40 to 23.9 g 02/m2-day) and

the frequency distribution are shown in Figure 15. The coefficient

of variation (80 percent) suggests that plankton production is

relatively more variable in the canals than is the total community

gross primary production (C.V. = 66 percent). The frequency distribution





-47-


Table 2. Nomenclature for the variables.


METABOLISM

TGPP Total community gross primary production (g 02/m2-day)


2
TR Total community respiration (g 02/m2-day)

PGPPM2 Plankton gross primary production (g 0 /m -day)

PRM2 Plankton respiration (g 02/m2-day)
3_
PGPPM3 Plankton surface gross primary production (g 02/m -day)

PPRM3 Plankton surface respiration (g 02/m3-day)

TPR Community production:respiration ratio (TGPP/TR)

PPR Plankton production:respiration ratio (PGPPM2/PRM2)

PDOMIN Plankton dominance of community production (PGPPM2/TGPP)

SUN Solar insolation (langleys/day)


EXCHANGE

TC Total carbon concentration (mg/l as C)

TIC Total inorganic carbon concentration (mg/l as C)

TOC Total organic carbon concentration (mg/l as C)

TP Total phosphorus concentration (mg/l as P)

OP Ortho-phosphorus concentration (mg/l as P)

TOP Total organic phosphorus concentration (mg/l, TP-OP)

NH3 Ammonia concentration (mg/l as N)

TURB Turbidity (NTU)

COLOR Apparent color (CPU)

COND Conductivity (micromhos/cm 100)

F-prefix Weighted-average flood tidal phase concentration

E-prefix Weighted-average ebb tidal phase concentration






-48-


Table 2. (Continued)


D-prefix Difference between flood and ebb concentrations (Flood Ebb)

Sign convention -- minus sign (-) indicates Flood value was less than

Ebb value

positive sign (+) indicates Ebb value was less than

Flood value


WATER QUALITY

AVGDO Average dissolved oxygen concentration (mg/l)

MAXDO Maximum dissolved oxygen concentration (mg/1)

MINDO Minimum dissolved oxygen concentration (mg/1)

SECCHI Secchi depth (meters)

TEMP Water temperature (OC)

E-prefix Nutrient and water quality parameters from Exchange data


CANAL/SAMPLING DAY CHARACTERISTICS

LENGTH Centerline length, entrance to most distant point (meters)

WIDTH Average canal width (meters)

MDEPTH Average canal depth (meters)

AREA Canal water-surface area, total (meters)

VOLUME Water volume in canal at mean water level (cubic meters,
MDEPTH AREA)

SILL Sill height (meters)

AGE Canal age (years)

BULK Percent bulkheaded, canal sides

CURBS Presence or absence of curbs and gutters in development
(1 or 0, respectively)

SEWERS Presence or absence of a sewer system in development
(1 or 0, respectively)


I





-49-



Table 2. (Continued)


MINRES Minimum residence time of canal water (days, MDEPTH/CUMTIDE)

CUMTIDE Cumulated tidal amplitude in 24 hr period (meters)

TIDE Maximum tidal amplitude in 24 hr period (meters)

DAYL Hours of daylight on sampling day

SUN Solar insolation (langleys/day)














Table 3. Metabolism results averaged by canal (1 to 5 stations
per canal) for each sampling day.

Nomenclature and units as in Table 2






-51-


OBS CANAL MONTH LDA YrtAk FPf' T PGPPM2

1 PG6 3 l1 75 b.1t 3.28 1.64
2 PG3 J 21 7s 1.15 .06 2.10
3 PC3 3 2 75 b.44 10.12 9.19
4 PCO 3 -1 75 5.57 6.03 5.79
5 Pu3 3 20 75 7.64 8.85 7.01
6 Pb6 3 jo 75 5.Ob 5.9 8 7.58
7 LX3 3 25 75 /.37 6.14 '2.89
8 LXo 3 2 75 t. 8t o.06 2. o
I Pub 6 1 75 6.5o 5.51 2.39
10 PG3 6 14 75 7.91 6.13 2.62
S1 PC3 O 1b 75 11.07 '9.61 3.90
12 PCo 6 1b 75 7.63 10.22 6.50
13 P63 6 19 75 10.25 13.01 7.51
14 POb 6 19 75 v. .2d 14.15 6.45
15 LXc 6 1l 75 6.88 9.46 2.07
16 LXJ 6 lo 75 4.d2 4.64 3.72
17 PG3 9 6 75 0.00 0.00 0.4d
18 PG6 9 o 75 0.00 0.00 0.61
19 PG9 9 b 75
20 PC3 9 9 75 20.73 18.15 3.29
21 PC6 9 9 75 7 3.95 23.51 5.93
L2 PC Y 9 9 75
23 P83 9 7 7z 17.o0 20.13 7.56
24 Pu6 9 7 75 *14.15 14.05 10.04
25 LXJ 9 1. .7b 8.8a 6.47 3.67
26 LX6 9 i7 75 11.47 8.87 7.12
27 PG6 11 1- 75 6.10 3.25 2.80
2d PG3 11 21 75 e.02 5.84 2.73

L S PRM2 POPPM 3 PPMt3 T PPk POOMIN SUN

1 2.03 2.47 O.ou 0.97 0.7o 0.52 602
2 2.05 2.2j 1.07 0.06 3.21 1.00 602
3 5.9c5 .91 2. O0.oj 3.61 i.09 642
4 3.20 3.57 L. : 0. 9 1 .e1l 1.04 642
5 2.32 1.J36 l.lo 0.b9 j.O0 0.89 488
6 2.63 1"2.ob 0.b 0.95 2 .6 1.00 488
7 0.66 ,.73 O0.u 1.20 4. r0 0.39 434
8 1.75 2.00 0.6/ 1.lo 1.7. 0.49 434
9 2.C5 2.13 0.71 1.19 1.18 0.36 650
1 01.6 3 0.o 1.29 1.56 0.3-; 650
11 4.57 4.34 2.00 1 .b O.0o 0.35 o76
.17 7.98 3.99 1.73 0.7 0.90 O.j3 75
13 6.46 9.55 J.Jb 0.7- 1.lu 0.7J 342
14 o.33 9.50 4.o O.oo0 1.08 0.69 342
15 2.87 4.55 1.44 0.73 0.72 0.30 370
16 1.95 4.52 0.96 1.04 1.90 0.77 378
17 0.75 0.77 0.51 1.20 426
18 0.49 1.06 0.O c 2.92 426
19
20 3.77 5.66 2.04 1.1:, 0.93 0.16 446
21 6.03 8.68 3.c0 1.02 0.96 0.25 446
22 .
23 2.74 11.69 2.0o 0.td 3.5v 0.43 238
24+ 3.17 13.72 1.9' 1.01 J.41 0. 71 23d
25 1.96 3. 76 1.0 1 7 1 7 0.41 296
20 4.72 6.02 2.b4 1.2y 1.49 0.62 290
27 0.79 3.7o 0.o2 1.8 4.24 0.46 296
28 1.37 4.41 2.10 ,.89 1.97 0.47 290






-52-


Table 3. (Continued)
OBS CANAL MONTH DAY YEAR TGPP TR PGPPM2

29 PG9 11 21 75 .
30 PC3 11 23 75 9.33 9.91 2.04
31 PC6 11 23 75 8.49 4.52 3.48
32 PC9 11 23 75
33 PB6 11 14 75 3.39 3.06 3.45
34 P89 11 14 75
35 P83 11 14 75 3.45 3.09 2.96
36 LX3 11 16 75 5.09 4.60 2.87
37 LX6 11 16 75 3.42 3.67 3.03
38 MI1 3 24 76 5.86 5.72 5.64
39 MI2 3 24 76 7.11 7.20 3.46
40 M13 3 24 76 9.79 11.19 3.94
41 bC1 4 20 76 24.89 18.65 8.04
42 BC2 4 20 76 16.30 14.30 8.61
43 BC3 4 20 76 15.40 14.19 13.50
44 HI1 5 19 76 7.65 2.66 6.46
45 HI2 5 19 76 7.53 2.55 7.43
46 HI3 5 19 76 14.79 5.65 23.90
47 FL1 6 1L 76 8.34 8.63 3.19
48 FL2 6 12 76 12.69 12.69 2.91
49 FL3 6 12 76 8.66 11.22 4.12
50 API 7 14 76 21.84 19.89 4.00
51 AP2 7 14 76 15.22 16.34 7.71
52 AP3 7 14 76 10.83 10.82 3.30
53 GB1 7 31 76 1.56 2.86 1.20
54 G82 7 31 76 2.27 3.57 0.77
55 GB3 7 31 76 1.95 2.15 0.96
56 KC1 8 18 76 5.53 9.39 1.39

OBS PRM2 PGPPM3 PPRM3 TPR PPR PDOMIN SUN

29 .
30 0.74 2.01 0.56 0. 4 1.98 0.22 334
31 0.53 2.93 0.06 1.88 5.02 0.41 334
32 .
33 1.92 1.39 1.51 1.11 1:79 1.02 352
34
35 1.96 2.71 1.57 0:90 1:76 0.47 352
36 0.92 2.96 0.70 1.11 3.45 0.56 204
37 1.49 3.10 0.93 1 13 2.04 0.78 204
38 3.67 6.38 1.49 1.02 1.54 0.96 520
39 2.91 2.99 1.27 0.99 1.19 0.49 520
40 4.91 3.40 1.56 0.87 0.80 0.40 520
41 4.35 4.81 1.54 1.33 1 84 0.32 571
42 3.20 4.41 1.37 1.14 2.69 0.53 571
43 5.24 6.02 1.88 1.08 2.58 0.88 571
44 2.47 5.55 1.76 2.87 3.76 0.84 515
45 2.99 5.15 1.93 2.95 2.48 0.99 515
46 6.16 18.00 3.10 2.62 3.81 1.00 515
47 3.92 3.26 2.17 0.97 0.81 0.38 504
48 4.98 1.77 1.75 1.00 0.58 0.23 504
49 3.48 3.25 1.01 0.77 1.18 0.48 504
50 3.94 3.96 2.40 1.10 1.02 0.18 506
51 3.75 10.64 2.86 0.93 2.05 0.51 506
52 2.95 4.22 2.04 1.00 1.12 0.30 506
53 1.45 1.67 1.62 0.55 0.83 0.77 554
54 0.74 1.18 1.12 0.64 1.04 0.34 554
55 0.46 1.34 0.21 0.91 2.09 0.49 554
56 2.01 0.87 0.86 0.59 0.69 0.25 72






-53-


Table 3. (Continued)
OBS CANAL MONTH DAY YEAR TGPP TR PGPPM2

57 KC2 8 18 76 5.51 6.37 1.53
58 KC3 8 .18 76 1.76 5.63 0.40
59 NM1 10 26 76 1.88 1.96 9.06
60 NM2 10 27 76 11.10 4.15 10 71
61 NM3 10 26 76 15.01 12.10 6.40
62 PE1 8 14 74
63 PE2 8 14 74
64 8P3 8 19 74
65 BP4 8 19 74
b6 SA8 8 23 74
67 AB3 9 17 74
68 AB5 9 17 74
69 MIH 8 6 75
70 MIJ 8 10 75
71 NIL 8 6 75
72 MIM 8 6 75
73 MIM 8 8 75
74 MIN 8 7 75

UBS PRM2 PGPPM3 PPRM3 TPR PPR PDOMIN SUN

57 2.09 0.43 0.56 0.86 0.73 0.28 72
58 1.36 0.38 0.60 0.31 0.29 0.23 72
59 5.02 3.81 3.10 0.96 .O0 1.00 316
60 6.06 6.26 1.45 2.68 1 77 0.96 346
61 2.62 4.37 175 1.24 1.64 0.43 183
62
63 .
64 .
65
66
67 .
68
69
70 .
71 .
72 .
73
74 .





-54-


u15
o
o.* ___



g 02/m-day
0 -H





0 - - -

0 2 4 6 8 10 12 14 16 18 20 22 24 26

g 0 2/m -day

N = 56 Mean = 8.59 Std. Dev. = 5.87 Range 0.00 to 24.9
C.V.% = 66


Figure 14.


m15
0

o
10

S5


Frequency distribution and descriptive statistics for
total community gross primary production (g 02/m2-day),
averaged by canal. Values are rounded to nearest integer.


Ii I I I I I I
1 2 3 4 5 6 7 8 9 10

g 02/m -day


N = 56 Mean = 4.91 Std.


13 24 r
13 24


Dev. = 3.91 Range 0.40 to 23.9


C.V.% = 80


Figure 15.


Frequency distribution and descriptive statistics for
planktonic gross primary production (g O2/m2-day), averaged
by canal. Values are rounded to nearest integer.


Ir I I~rl I





-55-


histogram suggests that a bimodal distribution was observed for

planktonic production. No canal actually exhibited the mean value of

5 g 02/m2-day (values were rounded to nearest integer to construct

the histograms). The plankton production for these canals tended to

occur in two levels; a low range of 1-4 g 02/m2-day, and a higher range

of 6-10 g 0 2/m2-day.

The distribution and descriptive statistics of the community and

plank-tonic respiration are shown in Figure 16 and 17, respectively.

Community respiration had a mean value of 8.20 g 0 /m2-day for the 56

canal observations, compared to 3.01 g 02/m2-day for the plankton. The

standard deviation and range of the community respiration responses

(5.45 and 0.0 to 23.5 g 02/m2-day) were greater than those of the

planktonic component (1.83 and 0.46 to 7.98 g 02/m -day). The relative

variabilities of respiration are comparable for the total community

and plankton (C.V. = 66 and C.V. = 61, respectively).

The frequency distributions and descriptive statistics for the

primary production:respiration ratios of the total community and

planktonic component, are presented in Figures 18 and 19. The mean

value (1.16) of the 56 community observations suggests that these

systems tend to be balanced or slightly autotrophic. However, the

range of values (0.31 to 2.95) indicate that canals can exhibit both

heterotrophic and autotrophic characteristics. The range of P:R ratios

(0.29 to 5.02) for the planktonic component of the total canal com-

munities also indicates that both heterotrophic and autotrophic behavior

exists for the plankton. The mean value for plankton P:R ratio (1.93)

indicates greater autotrophy in the water column than for the entire

canal. From a trophic standpoint the planktonic component is relatively






-56-


SJ15

J 10

c 5n 5


0
0 2 4 6 8 10 12 14 16 18 20 22 24

g 02/m2-day


N = 56 Mean = 8.20 Std. Dev, =
C.V.% = 66


Figure 16.















n 15
o 0
0 -H
4J 10

zao
P) 5
o0
0


5.45 Range 0 to 23.5


Frequency distribution and descriptive statistics for
total community respiration (g 02/m2-day), averaged
by canal.


0 1 2 3 4 5 6 7 8
02/m day
g 02/m -day


N = 56 Mean = 3.01


Std. Dev. =
C.V.% = 61


1.83


Range 0.46 to 7.98


Figure 17.


Frequency distribution and descriptive statistics for
planktonic respiration (g 02/m2-day), averaged by canal.






-57-


O i
)l



4) > 5


O I I I I I I I I
o1 0 P i-\ !F-----, -o--


0.3 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.9 2.6 2.9

TGPP/TR

N = 56 Mean = 1.16 Std. Dev. = 0.59 Range 0.31 to 2.95
C.V.% = 50


Figure 18.















Uo
44 o
LO
0 -r4




0
0


Frequency distribution and descriptive
total community production:respiration
by canal.


0 1-
0.0


N = 56 Mean = 1.93


statistics for
ratio, averaged


.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

PGPPM2/PPM2


5.0


Std. Dev. = 1.14 Range 0.29 to 5.02
C.V.% = 59


Figure 19.


Frequency distribution and descriptive statistics for
planktonic production:respiration ratio, averaged by
canal.


I





-58-


more variable than the total canal community (C.V. = 59 and 50,

respectively).

Figure 20 shows the frequency distribution and descriptive

statistics for the degree of plankton dominance of the total community

gross primary production for the 56 canal observations. The distri-

bution seems to be somewhat bimodal with plankton production accounting

for 50 percent or less of the total community production in 31 of the

54 observations. In other words, some canals were plankton dominated

on the day sampled but others were not. The range of values (PGPPM2/

TGPP) was 0.16 to 1.0. The mean value (0.60) for all the observations

may be misleading since few of the responses were this value.



1975 Data


Thirty-two of the fifty-six metabolism observations were obtained

during 1975 in a study for the Florida Department of Environmental

Regulation (see Fox et al., 1976). The design of the project consisted

of four locations (Punta Gorda, Port Charlotte, Loxahatchee River, and

Pompano Beach) with two similar canals per location, four stations per

canal (bay, mouth, middle, and'back), and four sampling seasons (March,

June, September, and November).

This design allowed the factors of location, season, and distance

along the canals to be evaluated for significant effects on the

metabolic levels. In addition to making possible the assessment of

the seasonal and distance variabilities, the unexplained or inherent

variability between canals that appeared identical could be determined

using analysis of variance.

The canal mean metabolic levels from this 1975 work are included






-59-


o 10


5
zm
o0 *
z o ,

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

PGPPM2/TGPP

N = 54 Mean = 0.60 Std. Dev. = 0.28 Range 0.16 to 1.0
C.V.% = 101


Figure 20. Frequency distribution and descriptive statistics for
plankton domination of community production.






-60-


in Table 3 for the eight canals and four seasons. The individual

station results are presented in the Appendix. The results of the

analyses of variance on the data are shown in Table 4.

The analyses indicate that there are significant differences in

the levels of community production and respiration with the season of

the year, with the location of the canal, and with distance up a canal.

This three way interaction indicates that the spatial and temporal

distribution of metabolic levels in these residential canals is a

non-additive function of the distance, location and season factors.

The seasonal changes have different effects on community metabolism

depending on the canal location and on the distance up the canal. The

lack of simple trends for any of the three factors can be illustrated

by the fact that the highest community metabolism levels occurred

during September for all locations except Punta Gorda, where the level

was the lowest recorded for the year.

The sources of variation listed in Table 4 account for 88 and 87

percent (R2 value) of the community production and respiration vari-

ability, respectively. The remaining 12 percent of the variability

is composed of the error involved with the determinations of the

metabolic levels and with the difference in metabolism levels of the

individual canals within the pairs, which were treated as replicate

observations; the latter source of residual variance could be a result

of factors such as plankton patchiness, water circulation patterns, and

nutrient inputs. This small amount of unexplained variability indicates

that the individual canals within the pairs of canals do not differ

appreciably in the patterns and levels of metabolic activity, relative

to the total variability for all locations, seasons, and distances.





-61-


Table 4. Results of the analyses of variance for the total community
and planktonic metabolism data (1975).


Community Plankton
Source of
Variation Per Square Meter Per Square Meter Surface

GPP* R* P/R* GPP R P/R GPP R


Location NS NS

Distance NS NS NS NS

Month NS

Location x Distance NS NS NS NS ** NS

Location x Month NS ** ** NS ** **

Distance x Month NS NS NS ** NS NS

Location x Distance ** ** NS NS NS NS NS NS
x Month

Mean 7.80 7.49 1.36 4.01 2.56 2.30 4.71 1.47

S.D. (adjusted) 2.95 3.30 1.80 1.69 1.64 1.52 1.68 0.91

C.V. % 37 44 132 42 64 65 35 62

R2 0.88 0.87 0.50 0.83 0.77 0.77 0.92 0.77

Unadjusted S.D. 6.22 6.49 1.77 2.63 2.20 2.01


GPP gross primary production; R respiration;
P/R production : respiration ratio (GPP/R)

** Indicates the term is a significant source of variation

NS Indicates the term is not a significant source of variation

Blank indicates that an exact test for the term cannot be made

Units- g 02/m2-day or g 02/m3-day


I






-62-


The community production:respiration ratio analysis does not

yield the same.pattern as the production and respiration results. No

significant differences were found for the 64 combinations of location,

distance and month factors. The mean value for all observations was

1.36 with a coefficient of variation equal to 132 percent. This para-

meter was relatively more variable than production and respiration for

the replicate canals, resulting in the inability to detect differences

among the means.

Analysis of the planktonic metabolism data yields inferences some-

what different from those of the whole community metabolism. The level

of planktonic gross primary production and respiration on a square

meter basis depends on the season and the location. No significant

differences in the levels of planktonic production and respiration for

the entire water column could be detected along the lengths of the

canals.

There were significant differences among the means of the plank-

tonic P:R ratio. The changes in the P:R ratio with season varied

depending on the distance up the canals.. No significant differences in

the patterns of planktonic P:R ratios was detected for the four

locations.

The results of the analysis of variance for the surface values of

planktonic metabolism were similar to those for the entire water columns.

The effect of distance and season varied with canal location for the

surface plankton production, whereas only the effect of season varied

with location for the entire water column. In fact, no effect of

distance up the canal could be detected for the planktonic metabolic

levels on a square meter basis, for these canals.





-63-


The variability or standard deviation remaining after the re-

sponses were adjusted for the three factors and their interactions is

also shown in Table 4. These unexplained variances represent the

dissimilarity between canals that appear identical, for the individual

parameters. For example, the community gross primary production values

had a standard deviation of 6.22 g 02/m2-day before adjustment.for the

factor effects, and 2.95 g 02/m2-day after adjustment. The latter

value indicates the variability of community production estimates once

the canal location, the season of the year, and the distance along the

canal have been specified. The corresponding unexplained variability

for the plankton production data is 1.69 g 02/m2-day.

While the analyses of variance for the metabolic parameters in-

dicated that no consistent trends existed for all the locations and

sampling periods, the mean values (Table 5) computed by location, by

season, and by distance for all the data show the average pattern for

these different factors.

Community gross primary production was lowest in March (5.13
2
g 02/m -day), increased through June, peaked in September (11.2 g

02/m2-day), and then declined in November. The production:respiration

ratio for the total communities increased each sampling season to a

peak in November (mean P:R = 2.34), whereas the planktonic P:R ratio

was highest in the fall and lowest in June.

The mean values of the metabolic parameters with distance along

the canal (Table 5) suggest that the community and plankton production

tends to increase from the adjacent estuary (Bay) to the middle and

back of the canals. It would be tempting to conclude that these canals

were more productive than the adjacent estuaries. However, the





-64-


2
Table 5. Community and plankton gross primary production (g 0 /m -day)
means for the four locations sampled in 1975, averaged by
location, by season, and by distance along canal.


TGPP PGPPM2 TPR PPR


PG

PC

PB

LX

Std. Dev.


March

June

September

November

Std. Dev.


3.74

10.5

8.48

6.15


2.92


5.13

6.63

11.2

5.53

2.79


Means by Location

1.85

4.87

6.43

3.46


1.96


Means by Month

4.78

4.16

4.47

2.89

0.83


2.11


1.56

1.71

0.98

1.18


2.35

2.39

2.44


0.34


0.15


0.94

0.98

1.32

2.34

0.65


2.55

1.21

1.92

3.40

0.93


5.33

6.68

8.2.8

8.20

1.40


Means by Distance Along Canal

2.53 1.29

3.96 1.11


4.40

0.98


1.16

1.87

0.35


3.23

2.27


2.07

0.62


Grand Mean 7.18 3.98 1.36 2.31


Nomenclature as in Table 2
Units g 02/m2-day


Bay

Frong

Middle

Back

Std. Dev.





-65-


analysis of variance detected no significant differences for plankton

production between the bay and canal stations, and indicated that the

effect of distance on community metabolism depended on the location

and month. No significant differences for community production:

respiration ratio could be detected for distance, season, or location,

though the highest mean value was found at the backs of the canals.

For the planktonic P:R ratio the lowest mean value occurred at the

backs of the canals; the highest mean value occurred in the bay, but

again this cannot be considered a consistent pattern since the analysis

of variance found that the effect of distance depended on the month of

sampling.



Daily Variability in One Canal


One canal (North Miami site) was sampled for three consecutive

days to obtain an estimate of the day-to-day variability for one canal;

the metabolism results are shown in Table 6.

The estimates of planktonic primary production were quite repro-

ducible when the level of solar insolation is considered. The planktonic

production:respiration ratios were also consistent (mean = 1.74,

C.V. % = 5) for the three days. The community metabolism results,

however, were not as uniform (mean TGPP = 9.33 g 0 /m -day, C.V. % =

72). The changes of community primary production, community respiration

and the community production:respiration ratio estimates did not

parallel those of the plankton for the three day period.

The most likely explanation of the seemingly sporadic total com-

munity results for the three consecutive days at the North Miami site,

is the limitation of the estimation technique. The free-water diurnal





-66-


Table 6. Metabolism results for three consecutive
one canal (North Miami site).


days of sampling on


Date TGPP TR PGPPM2 PRM2 PGPPM3 PPRM3


26 Oct 76 1.88 1.96 9.06 5.02 3.81 3.10

27 Oct 76 11.10 4.15 10.7 6.06 6.26 1.45

28 Oct 76 15.0 12.1 6.40 2.62 4.37 1.75

Mean 9.33 6.07 8.72 4.57 4.81 2.10

Std. Dev. 6.73 5.33 2.17 1.76 1.28 0.88

C.V. % 72 88 25 39 27 42



Date TPR PPR PDOMIN SUN


26 Oct 76 0.96 1.80 4.82 316

27 Oct 76 2.68 1.72 0.96 346

28 Oct 76 1.24 1.64 0.43 183

Mean 1.63 1.74 2.07 281

Std. Dev. 0.92 0.08 2.40 87

C.V. % 57 5 1.16 31


Nomenclature as in Table 2

Units g 02/m2-day or g


02/m -day






-67-


method requires a homogeneous water column, to be reasonably accurate

and precise. The North Miami canals were approximately six meters deep

and were anaerobic below the two meter depth throughout the three days.

The chemical oxygen demand of the hydrogen sulfide (strong odor present)

in the large anoxic layer could remove varying amounts of oxygen from

the surface layer. The weather conditions during the three day study

in October were also not conducive to uniform conditions within the

canal (a cold front was passing through the area, producing colder air

and strong shifting winds). The deep stratified North Miami canal

during a period of water column overturn, was inappropriate for appli-

cation of this technique. The only other occasion when a canal with

anoxic bottom water was sampled during a period of overturn was Port

Charlotte (Canal PC1) in November 1975.



Nutrient Exchange


Combined Data


The weighted-average flood concentrations, the difference between

the flood and ebb concentrations for the nutrient/water quality para-

meters determined for each canal observation during this study, plus

those obtained from the Environmental Protection Agency, are shown in

Table 7. The frequency distributions and descriptive statistics for

the weighted-average ebb concentrations and net changes of the carbon

forms, phosphorus forms, ammonia, and turbidity are presented in

Figures 21-28. A positive (+) sign with the net exchange values in-

dicates a net retention or sink type of activity. Conversely a negative

(-) sign indicates a net export or source type of activity.














Table 7. Canal-estuary exchange results for the nutrient and water
quality parameters.

Nomenclature and units as in Table 2






-69-


C M
A 0 Y i
U N ND t F UE T1 T F G F
13 A T A A r T I I I U T T O
b L H Y C C L C C C P P P

1 PG6 3 21 75 20.6 -0.6 10.2 0.5 1o.3 -1.2 0.441 0.005 0.377
2 PG3 3 21 75 20.3 -1.4 9 -2.4 17.1 1.2 0.460 -0.068 0.369
3 PC3 3 22 75 27.5 0.ti .2 1.3 lo.3 -1.0 0.547 0.069 0.423
4 PC6 3 22 75 26.8 -0.1 0.7 0.9 10.1 -1.0 0.500 0.063 0.401
5 P83 3 26 73 31. 0 l .t [ 17.4 0.219 0.189
6 Pbb 3 26 75 32.2 1 l.7 0.222 '0.203
7 LX3 3 25 75 37.9 1.7 b.4 0.7 12.6 0.6 0.04 0.c005 0.027
8 LX6 3 25 75 37.7 1.0 2..7 -0.4 13.1 1.1 0.053 0.004 0.029
9 PG6 6 14 75 29.7 -2.4. 168. -0.3 10.6 -2.1 0.479 0.011 0.533
10 PG3 6 14 75 29.8 -0.o 19.2 0.6 10.6 0.3 0.500 0.043 0.547
11 PC3 6 15 75 28.3 0.0 lo.6 0.0 9.7 0.9 0.53d -0.007 0.583
12 PC6 6 15 75 30.5 -1.0o 1.9 1.4 11.4 -3.4 0.518 0.003 0.600
13 Pb3 6 19 75 41.4 -1.3 9.5b -0.j 11.9 -1.1 0.221 0.000 0.180
14 Pb6 6 19 75 41.7 -1.4,+ 9.o 0.3 11.9 -1.7 0.225 0.013 0.179
lb LX6 6 18 75 46.4 1.7 4.b 2.1 11.8 -0.4 0.067 -0.001 0.024
o1 LXJ 6 18 75 47.3 2. .t .2 2.1 11.1 0.4 0.086 0.002 0.028
17 PGJ 9 6 73 33.2 0.0 1t,.5 -0.4 16.7 2.1 0.511 0..028 0.405
18 PG.6 9 6 75 29.2 -3.7 14.3 -2.4 14.9 -1.3 0.449 -0.029 0.447
19 PG9 9 6 75 35.0 1.9 Ib..~ -1.0 19.o 3.c 0.550 0.067 0.503
20 PC3 9 9 75 34.1 0.7 it.5 -0.1 17.6 0.9 0.535 -0.017 0.4bb
e1 PC6 9 9 75 36.3 1.1 15.9 0.1 2.' 1.0 0.4 76 -0.066 0.470
22 PC9 9 9 75 34.5 -1.1 lo.1 0.1 lo.4 -1.2 0.bol 0.026 0.463
23 PU3 9 7 75 38.2 -0.9 -o .o -1.7 11.4 -0.5 0.243 -0.004 0.207

F D
F L C C F D
F L F U T T L U C C
O O T T N N U U L L 0 O
a O U 0 H -R R 0 U N N
S P- P P 3 J u u K P O O

1 0.039 0.OoO -0.03o 0.0- 0.00 4.6 0.1 .
2 O.OOC 0.099 -0.C69 0.0, 0.01 b.J -1. .
J 0.045 0.144 0.029 0.05 0.04 7.2 2.1 .
S 0.0 3 0.100 0.042 0.01 -0.02 7.c 3.3 .
5 0.030 C. 1 4.0 .
6 0.019 0.10 J. .
7 -0.001 0.022 0.006, 0.01 C.0 3. 0.3 .
8 -0.008 0.C24 0.012 0.01 0.00 3.j 0.2 .
9 0.055 -0.044 O.Cb 0.00 0.9 -0.0 53 -1J
10 0.037 -0.012 0.07 -0.02 0.1 -0.6 05 8
11 0.002 -0.009 0.0 -0.01 1.0 0.0 41 10
12 0.030 -0.027 0.04 -0.OJ 1.0 0.0 39 34 .
1J 0.010 0.041 -0.008 0.09 0.00 2.2 0.0 104 12
14 0.002 0.036 -0.002 0.07 -0.01 2.4, 0.2 113 12
15 0.004 0.044 -0.005 0.0 u.0 3.0 -0.3 140 16
16 0.001 0.0 8 0.010 0.0z 0.01 3.4 -0.9 1 38 1J .
17 0.030 0.046 -0.002 0.21 0.02 J.1 -1.3 239 -14
18 -0.006 002 -0.023 C.2 -6.04 3.0 0.b 232 -13
I1 0.009 C.O" -0.003 0.17 -0.01 2.9 0.1 20 39
20 -0.014 0.077 -0.004 0..4 0.06 4.2 -0.5 222 8 .
21 -0.017 0.CO -0.049 C.lo 0.04 10.0 5.0 233 13
22 0.005 0.090 0.021 0.11 0.01 0.b c.0. 223 d
23 0.007 0.CJo -0.011 0.00 -0.C4 3.1 0.9 j 17






-70-


Table 7. (Continued)

C M
A O Y F D
O N N D E F D F D T T F D F
SA T A A T T I I U 0 T T 0
SL H YR C C C C C C P P P

24 P86 9 7 75 41.3 -0.4 26 6 -1.9 15.0 1.5 0 254 -0.016 0.206
25 LX3 9 12 75 50.1 -0.3 32.7 0.8 17.4 -1.L 0.051 -0.002 0.063
26 LX6 9 12 75 49.1 -0.1 33.1 0.4 16.0 -0.4 0.048 -0.009 0.058
27 PG6 11 21 75 33.2 -0.9 18.5 -0.4 14.7 -0.5 0.296 -0.030 0.257
28 PG3 11 21 75 .
29 PG9 11 21 75 34.0 -0.4 15:6 -0.9 18.4 0.7 0.382 0.012 0.356
30 PC3 11 23 75 34.4 1.2 21.5 0.4 12.7 0.6 0.349 0.007 0.303
31 PC6 11 23 75 35.1 0.0 18.0 0.0 17.1 0.0 0.332 0.022 0.296
32 PC9 11 23 75 34.3 -1.1 19.9 0.5 14.4 -1.6 0.346 -0.011 0.283
33 P86 11 14 75 57.8 -0.1 41.5 1.J 10.2 -1.5 0.236 -0.014 0.203
34 PB9 11 14 75 57.0 0.7 42.1 -0.5 14.9 1.2 0.224 -0.012 0.196
35 P83 11 14 75
36 LX3 11 16 75 49.4 6.2 34.0 1.5 15.4 4.6 0.057 0.003 0.016
37 LX6 11 16 75 .
38 MI1 3 24 76 39.0 -5.4 23.3 05 15.6 -5.9 0.067 -0.016 0.043
39 M12 3 24 76 36.9 -1.6 22.1 -0.9 14.7 -0.7 0.064 0.004 0.043
40 MI3 3 24 76 39.8 -0.4 24.2 0.3 15.5 -0.7 0.082 0.029 0.044
41 BC1 4 20 76 36.4 0.9 13.7 1.2 22.7 -0.4 0.193 -0 004 0.158
42 bC2 4 20 75 38.1 0.9 12.7 -0.1 25.3 0.9 0.210 0.008 0.166
43 BC3 4 20 76 37.5 2.4 12.1 -2.2 25.4 4.8 0.184 -0.010 3.159
44 HI1 5 19 76 49.9 1.8 21.1 0.5 28.9 1.4 0.063 0.011 0.044
45 HI2 5 19 76 42.0 -0.6 1 .4 -1.0 2J.6 0.2 0.041 0.002 0.025
46 HI3 5 19 76 47.8 2.5 22.4 0.3 25.4 2.1 0.120 -0.003 0.104

F D
F D C C F D
F 0 F U T T U O C C
SD T T N N U U L L O O
6 0 0 U H H R R O 0 N N
S P P P 3 3 b 8 R R 0 D

24 -0.012 0.048 -0.004 0.08 -0.18 4.2 0.7 112 7 .
25 -0.01C 0.000 0.000 0.00 0.03 4.5 -0.3 124 3
26 -0.009 0.000 0.000 0.02 -0.03 4.1 0.2 115 18
27 -0.031 0.038 0.001 0.07 -0.02 .
28 .
29 C.014 0.026 -0.002 0.01 -0.07 .
30 0.003 0.045 0.003 0.21 0.01 .
31 0.019 0036 0004 00 -0.10
32 -0.029 0.064 C.019 0.04 0.04 .
33 -0.002 0.031 -0.014 0.23 0.00 .
34 -0 007 0.028 -0.005 0.23 0.02 .
35 .. : .
36 0.004 0.041 0.000 0.05 0.01
37 .
38 -0.013 0.025 -0.003 0.10 -0.01 5.7 09 35 2 345 -2
39 0.002 0.021 0.002 0.06 0.01 3.0 -0.1 14 -12 343 -8
40 0.011 0.037 0.017 0.05 0.02 4.1 0.4 26 -13 337 -14
41 -0.007 0.034 0.003 0.09 0.02 3.1 -2.1 21 -7 260 -20
42 -0.002 0.044 0.010 0.15 0.00 5.4 0.8 21 5 274 9
43 -0.009 0.C25 -0.005 0.10 -0.03 2.6 -0.5 12 -8 268 9
44 0.011 0.019 0.000 0.14 0.04 1.0 0.0 52 -2 307 -23
45 0.002 0.C16 0.000 0.12 0.03 0.5 -0.2 25 -18 376 21
46 -0.003 0.016 0.000 0.11 -0.02 1.2 0 1 69 4 294 -5





-71-


Table 7. (Continued)

C M
A O Y F D
O N N D E F F D T T F 0
B A T A A T T I I O O T T
S L H Y R C C C C C C P P

47 FL1 6 12 76 41.0 1.1 22.6 -0.3 18.4 1.4 0.090 0.004
48 FL2 6 12 76 40.3 1.1 2348 1.0 16.5 0.1 0.092 0.009
49 FL3 6 12 76 41.3 2.0 22.5 1.2 18.9 1.0 0.095 0.007
50 API 7 14 76 37.6 -1.i 13.1 0.5 22.9 -2.5 0.842 -0.025
51 AP2 7 14 76 44.6 7.5 16.8 -2.5 27.7 10.0 0.807 0.020
52 AP3 7 14 76 40.3 0.0 13.6 -1.5 26.7 1.7 0.842 0.006
53 GB1 7 31 76 32.7 1.6 14.4 -0.9 18.3 2.5 0.021 -0.001
54 G82 7 31 76 28.0 -0.1 15.9 0.2 12.1 -0.3 0.023 0.001
55 663 7 31 76 30.1 -2.5 16.2 0.0 13.9 -2.5 0.030 -0.007
56 KC1 8 18 76 34.9 1.7 25.4 0.0 9.5 1.7 0.021 0.002
57 KC2 8 18 76 32.4 0.5 25.0 0.4. 7.3 0.0 0.018 0.001
58 KC3 8 18 76 30.6 0.2 24.9 0.1 5.7 0.1 0.014 0.000
59 NM1 10 26 76 54.8 -0.4 12.6 0.6 42.2 -1.0 0.065 0.000
60 NM2 10 27 76 56.7 1.1 1J.6 -C04 42.0 0.4 0.066 0.004
61 NM3 10 28 76 53.0 0.3 12.6 -0.4 40.6 0.7 0.054 -0.001
62 PE1 8 14 74 15.6 -0.2 0.310 -0.020
63 PE2 8 14 74 e 15.3 0.6 0.200 -0.020
64 BP3 8 19 74 1.8 -0.1 0.040 0.000
65 BP4 8 19 74 1.9 0.0 0.030 -0.010
66 SA8 8 23 74 1.0 0.0 0.030 0.000
67 A83 9 17 74 a 3.3 -0.1 0.030
68 A85 9 17 74 2.6 0.2 C0040 -0.010
69 MIH 8 8 75 a 9 7.0 -1.2 0.179 0.029

F D
F D C CF D
F 0 F D T T O 0 C C
O F D T T N NU U L L 0 0
S0 0 0 H H R R O O N N
S P P P P 3 38 8 R D D

47 0.037 0.004 0.053 C.000 0.09 0.01 4.5 0.8 236 43 341 -2
48 0.035 0.002 0.059 0.008 0.05 0.01 4.7 0.6 219 43 337 -5
49 0.038 -0.001 0.057 0.009 0.08 0.02 4.8 1.3 170 44 335 -4
50 0.692 -0,028 0.151 0.003 0.04 0.01 J.9 -0.9 107 -6 274 3
51 0.747 0.025 0.076 0.001 0.06 0.00 5.0 -0.3 109 -6 275 1
52 0.731 0.027 0.111 0.004 0.06 0.02 6.0 0.4 126 1 268 1
53 0.015 0.001 0.003 -0.001 0.07 0.00 2.8 -0.4 112 0 266 -3
54 0.016 0.000 0.007 0.001 0.09 0,02 2.8 -0.3 93 -7 269 4
55 0.019 -0.005 0.011 -0.002 0.07 0.00 4.8 0.2 140 -12 285 0
56 0.003 -0.003 0.018 0.005 0.07 -0.04 1.8 -0.2 26 -3 448 0
57 0.004 0.001 0.014 0.001 0.03 -0.01 2.4 0.4 37 6 446 3
58 0.004 0.000 0.010 0.001 0.01 0.00 1.8 -0.1 20 -5 443 -4
59 0.034 -0.002 0.029 0.000 0.04 0.01 3.0 0.0 85 3 260 2
60 0.032 0.003 0.032 0.001 0.04 0.03 3.4 0.1 91 7 259 -4
61 0.025 0.000 0.028 -0001 0.02 -0.03 3.4 0.1 85 -3 265 -4
62 .* 0.12 -0.01 .
63 0.10 -0.04 .
64 .* 0.06 0.00 .
65 e. 0.08 -0'.02 .
66 .* 0.04 -0.01 .
67 0.09 0.00 .
68 * 0.08 -0.02 .
69 .* 0.02 0.00 .






-72-


Table 7. (Continued)


0
N D
T A
H Y


F U F D
T T I I
C C C C


70 MIJ 8 10 75 10*7 1.7 0.257
71 MIL 8 6 75 6.2 -0.1 0.072
72 MIM 8 6 75 6.6 0.3 0.090
73 MIM 8 8 75 6.2 0.1 0.095
74 MIN 8 7 75 8.4 -0.2 0.095


F 0
F D T T
0 0 0 0
P P P P


F 0
F 0 C C F D
D T T C C C C
N U U L L 0 0
H R R 0 0 N N
3 B B R R D D


70 0.093 *
71 0.004
72 0.006 .
73 0.010 *
74 0.003 .


S 0.03 0.01
* 0.01 -0.01 .
* 0.01 0.00 .
* 0.03 0.01 .
* 0.03 0.01 .


* .
* .
* .
* .
. .





-73-


The total mass exchange of each material is not shown in Table 7

but can be calculated for each canal observation from the net change in

concentrations (weighted-average flood concentration minus weighted-

average ebb concentration) in Table 7 and the information in Table 1.

The product of the cumulated 24 hr tidal amplitude (CUMTIDE, Table 1)

and canal surface area (AREA, Table 1) for a particular canal observa-

tion yields the tidal exchange volume (m ) for the sampling day. The

product of the exchange volume and the net changes in concentration from

flood to ebb tidal phases (D values in Table 7, mg/l or g/m 3) gives

the net mass transport (g/day) of each material.

The average total carbon concentrations (Figure 21) ranged from

24.1 mg/1 to 57.9 mg/l, with a mean of 38.0 mg/l. The estimates of

net exchange of total carbon ranged from a net export of 5.4 mg/l of

exchanged water, to a net retention of 7.5 mg/l of exchanged water.

The mean value for net exchange was a net retention of 0.2 mg/l, with

a standard deviation of 2.0 mg/l. The distribution of net exchange

responses indicates that all canals do not exhibit the same type of

behavior. About equal numbers of these canals were found to be sources

of carbon to the adjacent estuaries, as were found to be sinks for

carbon from the estuaries.

The average inorganic carbon concentration (Figure 22) was 20.6

mg/l, with a standard deviation of 7.6 mg/l and a range of 7.8 to 42.6

mg/l. The mean value for inorganic carbon exchange was a net export of

0.1 mg/l of exchanged water, with a standard deviation of 1.1 mg/1 and

a range of -3.4 to +2.1 mg/l.

The mean total organic carbon concentration (Figure 23) was 15.5

mg/1, with a standard deviation of 8.3 mg/l and a range of 1.0 to 43.2





-74-


a. Average ebb concentration of total C.


24 27 30 33 36 39 42 45 48 51 54


N = 58 Mean = 38.0


mg/1

Std. Dev. = 8.0


Range 24.1 to 57.9


b. Net change (flood-ebb) of total C.


'4- 0 10
0 *H




0




N = 56 Mean = +0.2 Std. Dev. 2.05 Range -5.4 to +7.5




Figure 21. Frequency distribution and descriptive statistics for
(a) weighted-average ebb total carbon concentration (mg/1),
and (b) the net changes from average flood concentrations.


o
0
4 10


M 5
0






-75-


a. Average ebb concentration of inorganic C.


8.0 11 14 17 20 23 26 29 32 35 38 41

mg/1


N = 58 Mean = 20.6 Std. Dev. = 7.6


Range 7.8 to 42.6


b. Net exchange (flood-ebb) of inorganic C.


15
0
' 10
nd


o-
0

-3.4


-2.7 -2.2-1.7 -1.2 -0.7-0.2 +0.2 +0.7+1.2 +1.7 +2.2


mg/1

N = 56 Mean = -0.1 Std. Dev. = 1.1 Range -3.4 to +2.1



Figure 22. Frequency distributions and descriptive statistics for
(a) weighted-average ebb inorganic carbon concentrations
(mg/1), and (b) the net changes from average flood con-
centrations.


15

o
10



0





-76-


a. Average ebb concentration of organic C.


o15
4J
S10

4 5
0
C


N = 71


1.0 4.0 7.0 10 13 16 19 22 25 28 31 40 43

mg/l

Mean = 15.5 Std. Dev. = 8.3 Range 1.0 to 43.2


b. Net change (flood-ebb) of organic C.


S15
0

10 10

0 5


-0 3. -7 +0'.2 +1.2-,
-5.9 -2.7 -1.7-1.2 -0.2 +0.7 +1.7+2.2+2.7 4.7 10.0
3.6
mg/1

N = 69 Mean = +0.2 Std. Dev. = 2.0 Range -5.9 to +10.0








Figure 23. Frequency distributions and descriptive statistics for
(a) weighted-average ebb total organic carbon concentrations
(mg/1), and (b) the net changes from average flood con-
centrations.





-77-


mg/l. The mean value for net organic carbon exchange was a net reten-

tion of 0.2 mg/l of exchanged water, with a standard deviation of 2.0

mg/1. The values ranged from a net export of 5.9 mg/l at Marco Island

canal Mil, to a net retention of 10 mg/l at Apollo Beach 2. The most

frequent response, however, was no significant change in the organic

carbon concentration between estuarine water entering and that leaving

the canals.

The range of total phosphorus concentrations (Figure 24) in these

canals was large, reflecting the presence of phosphate mining in the

vicinity of some of the canals. The highest values observed (ca. 0.8

mg/1) were at the Apollo Beach site. The higher values make the mean

value (0.231 mg/1) somewhat misleading, considering that nearly half

of the observations had values less than 0.1 mg/l. The net changes in

total phosphorus concentrations from flood to ebb tides had a mean

value of +0.003 mg/1, with a standard deviation of 0.020 mg/l and a

range of -0.067 to +0.093 mg/1. As in the case of total carbon, these

canals differ in the phosphorus mass transport activities, but most

frequently have little or no effect on the phosphorus loads of the

exchanged water.

The frequency distributions and descriptive statistics for the

ortho-phosphate levels and exchange responses of these canals are

presented in Figure 25. The ortho-phosphate distribution follows a

pattern similar to that of total phosphorus. The range of net exchange

responses (-0.031 to +0.069 mg/1) indicates that some canals can be

sources of ortho-phosphate to the estuaries, while other canals can be

sinks. The most frequent response was essentially no effect on the

ortho-phosphate concentrations, whereas the mean value (+0.005 mg/1)





-78-


a. Average ebb concentration (ppm) of total P.


15
0
-H
4-1



.. 5
o


.00 .05 .10 .15 .20 .25 .30 .35 .40 .45 .50 .55 .79 .84.87

mg/1

N = 71 Mean = 0.231 Std. Dev. = 0.226 Range 0.014 to 0.867












b. Net change (flood-ebb) of total P.


'15
O -H









-.032
mg/1
mg/1


.012 .022 .032 .063
.007 .017 .027 .043 .093


N = 68 Mean = +0.003 Std. Dev. = 0.030 Range -0.067 to +0.093



Figure 24. Frequency distributions and descriptive statistics for
(a) weighted-average total phosphorus concentrations (mg/1),
and (b) the net changes from average flood concentrations.





-79-


a. Average ebb concentration of ortho-P.


20 -

o 15
o
O *.r
P a 10-
3
ze 5
0

0


.00 .05 .1


I I I I I I I
0 .15 .20 .25 .30 .35 .40 .45 .50
mg/l


Unr


.55 .60 .71


N = 58 Mean = 0.221 Std. Dev. = 0.29 Range = 0.003 to 0.722











b. Net change (flood-ebb) of ortho-P.


20

S15
04-1
o

K 10
oJ>

zo 5
0

0


-.031-.017 -.007 .002 .012
-.028 -.012 -.002 .007

mg/l


.022 .032 .045 .069
.017 .027 .039 .055
.057


N = 56 Mean = +0.005 Std. Dev. = 0.024 Range -0.031 to +0.069


Figure 25.


Frequency distributions and descriptive statistics for
(a) weighted-average ebb ortho-phosphate concentrations
(mg/1), and (b) the net changes from average flood con-
centrations.





-80-


suggests a slight retention of inorganic phosphate by the canals.

Figure 26 shows the frequency distributions and descriptive

statistics for the total organic phosphorus (TP-OP) concentrations and

net exchanges. The organic phosphorus concentrations are.more normally

distributed around the mean value (0.043 mg/l) than are the total and

ortho-phosphorus concentrations. The net organic phosphorus exchange

estimates also exhibit a wide range of values (-0.069 to +0.042 mg/1),

and a mode of essentially zero effect on the organic phosphorus levels

of the estuarine water entering the canals. The mean value (-0.002

mg/l), though, suggests that a net export of organic phosphorus took

place.

The frequency distribution and descriptive statistics for the ebb

concentrations and net exchanges of ammonia for these canals are shown

in Figure 27. The ranges of concentration (0.00 to 0.26 mg N/l) and of

net exchange (-0.18 to +0.08 mg N/1) are wide. The mean value of ammonia

exchange (0.00 mg/l) indicates that the "average canal" has no effect

on the ammonia levels of the estuarine water. The distribution of the

exchange responses shows that some canals are sources of ammonia to

the estuary, whereas other canals are sinks.

The distributions of the average ebb turbidity levels and the net

changes in turbidity levels from ebb to flood tide for these.canals

(Figure 28), show the ranges of values and of effects on the flooding

waters. The mean net change value (+0.2 NTU) suggests that the "average

canal" lowers the turbidity level of the estuary. But the range of

values (-2.1 to +5.0 NTU) show that canals can either decrease or

increase the turbidity levels of the entering water.






-81-


a. Average ebb concentration of organic P.


0
4 10


u 5
o
0


.00 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10

mg/l


N = 54 Mean = 0.043


.11 .15 .17


Std. Dev. = 0.033 Range 0.000 to 0.168


b. Net change (flood-ebb) of organic P.


020


Q)
cl5

010
144
0
o '-- ____
S5 -

| 0 T,. r- ,
-.069 -.044 -.023 -.012 -.002 .007
-.049 -.038 -.017 -.007 +.002 .012


.017
.022


.029


.042


-.027
mg/1

N = 56 Mean = 0.002 Std. Dev. = 0.017 Range -0.069 to +0.042

Figure 26. Frequency distributions and descriptive statistics for
(a) weighted-average ebb total organic phosphorus con-
centrations (mg/1) and (b) the net changes from average
flood concentrations.





-82-


a. Average ebb concentration.


.00 .02 .04 .06 .08 .10 .12 .14 .16 .18 .20 .22 .24

mg N/1


N = 71 Mean = 0.08 Std. Dev. = 0.06


Range 0.00 to 0.24


b. Net change (flood-ebb).


-.18 -.10-.07-.04 -.03-.02 -.01 .00 +.01 .02 .03 .04 .08

mg N/1

N = 69 Mean = 0.00 Std. Dev. = 0.03 Range -0.18 to +0.08


Figure 27. Frequency distributions and descriptive statistics for
(a) weighted-average ebb ammonia concentrations (mg/1) and
(b) the net changes from average flood concentrations.


0
t 10

S5
o
0


S15
0


0
" 5






-83-


a. Average ebb value of turbidity.


0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

NTU


N = 50 Mean = 3.4 Std. Dev. = 1.4


Range 0.7 to 6.9


b. Net change (flood-ebb) of turbidity.


0

CO

5
o


-2.2 -1.7 -1.2 -0.7 -0.2+0.2 0.7 1.2 1.7 2.3

NTU

N = 48 Mean = +0.2 Std. Dev. = 1.1 Range -2.1 to +5.0


Figure 28.


Frequency distributions and descriptive statistics for
(a) weighted-average ebb turbidity levels (NTU) and (b) the
net changes from average flood concentrations.


14
0



z
-


0
' 10

5

0
,x9
o






-84-


Diurnal Cycle of Nutrient Concentrations


A diurnal cycle of nutrient concentrations in the canal and bay

waters could influence the estimates of the net direction and magnitude

of exchange. If a diurnal cycle were superimposed on the tidal cycle,

a bias in the estimate would result, particularly for those canals

where essentially only one ebb and one flood tidal phase occurred

during the 24 hour period. For example if planktonic primary production

during the daylight hours raises the levels of organic carbon in the bay

and canal waters, and if water continually floods into a canal during

the day, the rising levels of organic carbon would be recorded as

increasing flood phase concentrations. Then as photosynthesis stopped,

the tide reversed, and respiration continued, a decreasing organic

carbon concentration would be recorded for the ebb tidal phase. That

canal would be labelled a sink for organic carbon. Conversely a canal

could mistakenly be labelled a sink for organic carbon, when in fact

only a diurnal cycle was observed, superimposed on a tidal cycle having

predominantly ebb phase during daylight.

To determine whether diurnal cycles were occurring for the exchange

parameters that could bias the results, the mean concentrations of the

response parameters for all observations were regressed against the

hour of the day, transformed with a sine function. The transformation

(sin (0.2618 (Time 12))) was used so that a sunusoidal function with

a period of 24 hours, the minimum value at 0600 hours, and the maximum

value at 1800 hours, would result and would coincide with the diurnal

cycle. The results of these regressions are summarized in Table 8.

The only parameter observed to have a significant diurnal component





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Table 8. Regression coefficients for the change in nutrient concen-
trations versus time of day (transformed). Model y =
Intercept + Slope (NTIME).

,t 2
Parameters Number of Intercent Slope Probability R
y Observations Slope # 0

Total carbon 1105 38.77 -0.035 0.92 0.00

Inorganic carbon 1103 20.80 -0.24 0.45 0.00

Total organic carbon 1101 17.97 0.19 0.60 0.00

Total phosphorus 1108 0..253 -0.0010 0.91 0.00

Ortho-phosphorus 1102 0.214 -0.0018 0.84 0.00

Total organic P 1065 0.043 0.0007 0.68 0.00

NH3 1107 0.086 -0.012 0.0005 0.01

Turbidity 951 3.61 0.16 0.16 0.00

Color 850 104. 3.1 0.36 0.00

Conductivity 532 31.7 0.69 0.86 0.00



aTransformation: NTIME = sin (0.2618 (Time 12)), Time 0-24 hours

Units: as in Table 2





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to the mean concentrations was ammonia. The rate of change of ammonia

concentration per unit transformed time is -0.012 mg/l (non-linear on

an hourly basis). The transformed values of the hour of the day ranged

from -1.0 at 0600 hours to +1.0 at 1800 hours. Therefore by stustituting

these values into the linear equation (Table 8), it can be seen that

the mean ammonia concentration tends to be 0.012 mg/l greater at sun-

rise than at noon, and 0.012 less at sunset than at noon. This results

in an expected change in ammonia concentration of 0.024 mg/1 from

sunrise to sunset, attributable to a diurnal cycle.

The lack of a significant diurnal effect on nutrient concentra-

tions, except for ammonia, suggests that a serious bias is not intro-

duced by neglecting the time of day for tidal phases. The possible

bias associated with a diurnal ammonia cycle and the estimated net

movements of .ammonia across the canal mouths is limited to Gulf Coast

canal observations that met the conditions given above. The Atlantic

canal systems generally experience semi-diurnal tides.



1975 Data


The nutrient exchange results obtained during the first phase of

this study, wherein four pairs of canals (PG, PC, LX, and PB) were

sampled on four occasions, provide information on the seasonal changes

and on the variabilities between canals that appear identical. The

two-way design (4 locations x 4 seasons, with replication) of this phase

of the study allowed analyses of variance to be performed on the data

in order to test for significant location and season effects. The

nutrient exchange data from the 1975 work are included in Table 7.





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The mean net changes of total organic carbon, total organic phosphorus,

and ammonia concentrations for the four locations (PG9, PC9, and PB9

not included) and four sampling periods are shown in Table 9. The

descriptive statistics and significant factor effects (as determined

by analyses of variance) for the 1975 data are presented in Table 10.

No significant location or season effect was detected for total

organic carbon and ammonia exchange levels for these four locations

(Table 9). It may actually be that there were organic carbon and

ammonia exchange differences between these locations and seasons, but

the large amount of variability within the pairs of canals and the small

sample size (2 canals per location) prevent the detection of small dif-

ferences in mean values.

For the total organic phosphorus (TP-OP) exchange data, there were

significant differences between the mean values. The significant month

x location interaction effect indicates that both location and season

did affect the organic phosphorus exchange activities, but that the

effect of season depended on location. The organic phosphorus exchanges

between canals and estuaries did change with season, but the magnitude

or direction change varied with canal location. For example, the

mean net export of organic phosphorus from the Pompano Beach canals

increased from 0.008 mg/l in September to 0.010 mg/l in November,

whereas a mean net export (0.011 mg/l) or organic phosphorus from the

Port Charlotte canals in September, had shifted to a net import of

0.009 mg/l in November.

Even though differences between the organic phosphorus exchange

activities among these canals were detected, the variability within

the pairs of similar canals was rather large. The mean value for these




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