Responses of subtropical seagrasses to fluctuations in salinity within an experimental facility

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Title:
Responses of subtropical seagrasses to fluctuations in salinity within an experimental facility
Physical Description:
viii, 207 leaves : ill. ; 29 cm.
Language:
English
Creator:
Chesnes, Thomas C., 1973-
Publication Date:

Subjects

Subjects / Keywords:
Seagrasses -- Effect of salt on   ( lcsh )
Seagrasses -- Physiology   ( lcsh )
Environmental Engineering Sciences thesis, Ph.D   ( lcsh )
Dissertations, Academic -- Environmental Engineering Sciences -- UF   ( lcsh )
Genre:
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Summary:
Thalassia, Halodule, Ruppia.
Thesis:
Thesis (Ph.D.)--University of Florida, 2002.
Bibliography:
Includes bibliographical references (leaves 203-206).
Statement of Responsibility:
by Thomas C. Chesnes.
General Note:
Printout.
General Note:
Vita.

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Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 028798970
oclc - 50512079
System ID:
AA00020479:00001

Full Text





















































' 'By ' '.


























This manuscript is dedicated to Rose Trivigno.
I know that you would be proud.














ACKNOWLEDGMENTS

Words cannot express my appreciation for those who supported me in this

endeavor. My supervisory committee has been without a doubt instrumental to my

success. I thank Evan Chipouras for his support from the earliest stages of this project, as

well as his ability to help me keep things in perspective. I thank Frank Nordlie for

introducing me to ecological research and mentoring my undergraduate project. Without

him, I certainly would not be in this profession. I thank Stephen Davis, whose

enthusiasm for algae is contagious and inspiring. I especially thank Thomas Crisman

who helped reintroduce me to my ecological roots. His patience and assistance were

essential in getting through a difficult period. Lastly, I thank my chairman Clay

Montague, whose mix of humor and scientific curiosity has inspired me to develop a

strong scientific ethic, an interest in the workings of the universe (on all temporal and

spatial scales), and a never-ending pursuit of truth over accepted ideas.

This study would not be possible without funding and logistical support from the

Everglades National Park Interagency Science Center in Key Largo, Florida and the

South Florida Water Management District, who also provided nutrient analysis. The

Aylesworth Foundation and Greening UF provided additional support. Special thanks to

those who assisted in data collection: Casie Regan, Christos Anastasiou, Joel Dudas,














TABLE OF CONTENTS

page

ACKNOW LEDGM ENTS................................................................................................. iv

ABSTRACT...................................................................................................................... vii

CHAPTERS

1 INTRODUCTION ............................................................................................................ 1

2 DESCRIPTION OF FACILITY DESIGNED FOR SALINITY FLUCTUATION AND
PILOT STUDY ........................................................................................................ 9

Description of Facility.................................................................................................... 9
M materials and M ethods of Pilot Study.......................................................................... 13
Results of Pilot Study ................................................................................................... 16
Discussion of Pilot Study.............................................................................................. 24














Correlations w ith Field Conditions at Collection Sites.............................................. 165

6 PRODUCTIVITY AND LEAF OSMOLALITY-RESULTS OF EXPERIMENT 8 ... 173

Introduction................................................................................................................. 173
M materials and M ethods................................................................................................ 175
D ata Analysis for Experim ent 8.................................................................................. 178
Results......................................................................................................................... 179
D iscussion................................................................................................................... 190

7 DISCU SSION ............................................................................................................... 196

Overall D iscussion...................................................................................................... 196
Conclusions................................................................................................................. 201


REFEREN CES ................................................................................................................ 203

BIOGRAPH ICAL SKETCH ........................................................................................... 207














Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
RESPONSES OF SUBTROPICAL SEAGRASSES TO FLUCTUATIONS IN
SALINITY WITHIN AN EXPERIMENTAL FACILITY

By

Thomas C. Chesnes

May 2002

Chairman: Clay L. Montague
Major Department: Environmental Engineering Sciences

The sparsity of seagrass communities within the ponds and bays of northern

Florida Bay may be due to the wide fluctuations of salinity in these habitats. Seven

experiments were performed in a facility designed for salinity fluctuation. Three seagrass

species, Thalassia testudinum, Halodule wrightii, and Ruppia maritima, were

transplanted to the facility and subjected to varying degrees of salinity fluctuation.

Treatments were varied according to salinity wave mean, amplitude, frequency, and

suddenness (slope) of change. Two experiments crossed the effects of salinity fluctuation

with methods of water circulation and reductions in available light. A final experiment,














were negatively correlated with increasing salinity wave amplitudes, frequencies, and

suddenness of change. The effect of salinity fluctuation was dampened when salinity

fluctuated within a range of higher salinities. Salinity fluctuation was more of an

influence on Thalassia survival than the reduction of light.

Halodule condition was impaired by salinity fluctuation, but not to the extent

experienced by Thalassia. Green leaf indices decreased with increases in salinity wave

amplitude, frequency, and slope. The number of turions per sprig correlated negatively

with increasing amplitude and more sudden changes in salinity. Halodule survival was

enhanced by fluctuations within a higher salinity range.

Ruppia was the most resilient of the seagrass species tested. This seagrass was

able to survive all of the salinity fluctuation treatments. Increasing the frequency of

salinity change did have a negative impact on this seagrass, resulting in lower green leaf

indices and number of leaves.

In order to survive fluctuating salinities, seagrasses must regulate their internal

osmotic concentrations in relation to their surrounding waters. Ruppia osmoregulated

more quickly than Thalassia and Halodule and may be the key to its resiliency.














CHAPTER 1
INTRODUCTION



Since 1881, human activities have disrupted the natural flow of freshwater from

the Everglades into Florida Bay (Fourqurean and Robblee 1999). The Everglades

watershed has been engineered and managed for agriculture, flood control, and water

supply for the growing population in South Florida (Light and Dineen 1994). Water

management protocols involving alterations in freshwater flow can change the regime of

salinity fluctuations in the downstream estuary. Sudden releases of flood water may

create rapid drops in salinity, whereas water held back in times of drought may amplify

salinity increases downstream (Montague and Ley 1993). Changes in community

structure will be most noticeable in the estuarine salinity fields closest to land (Estevez

2000).

Salinity related problems arise when estuaries receive too much or too little fresh

water, or water at improper times (Odum 1970). These habitats are characterized as

being harsh due to the salinity changes, especially when compared to the more static

conditions typifying marine or freshwater habitats (Deaton and Greenberg 1986).

Changes in salinity occur rapidly in the shallow basins located within the northern land

margin of Florida Bay. Periods of high freshwater inflow during the onset of the rainy

season, in tropical storms (Chesnes 1999), or water management releases can cause areas








with marine strength salinities to become fresh, in some cases within a matter of days

(Mclvor et al. 1994, Montague and Chipouras 1998).

The meteorologically driven patterns of salinity are clearly seen in the salinity

record of Little Madeira Bay, located within the northern land margin of Florida Bay

(Figure 1-1). During the course of the dry season, salinity steadily rose from 10%o

(December 1998) to above 30%o (May 1999). At the onset of the wet season (May/June

1999), salinity dropped nearly 20%o in the first week, and approximately 30%o within

three.

Acute fluctuations in salinity also occurred during this time period. During July

and August of 1998, salinity fluctuated between 1 and 18%o, with a period of

approximately 4 days between peaks and troughs. The amplitude of the fluctuation

varied over the course of the month (Figure 1-1). Acute fluctuations also occurred in

October and December of 1998, January 1999, and again in the late summer/early

autumn of 1999. The amplitude of salinity change was higher in July and August of 1999

than in 1998, when changes of over 20%o were seen over four day periods.

The pattern of salinity change during transition from high to low salinity in the

ponds and bays of the land margin of Florida Bay is more acute than during the transition

from low to high (Montague and Chipouras 1998). Increases in salinity can be caused by

evaporation during the dry season or by winds pushing saline water from Florida Bay into

the estuary. The transition to saltier conditions is thought to be more gradual, and the

loss of stenohaline freshwater macrophytes may be a more progressive process as the

salinity slowly becomes elevated. Conversely, a sharp decline in the abundance of











stenohaline marine macrophytes follows the acute exposure to low salinity at the onset of

the rainy season (Montague and Chipouras 1998).

Fluctuations in salinity correlate with decreases in submerged macrophytes and

benthic animal density (Montague and Ley 1993, Fears 1993, Jones 1999) as well as

fouling organisms (Chesnes 1999). Each individual has a range of salinity tolerance and

a narrower range of optimal salinity (Remane and Schlieper 1971). Species richness is

especially low in the salinity range between 5 and 8 %o. This paucity in flora and fauna

can be explained by the habitat instability of estuaries (Deaton and Greenberg 1986).

The salinity fluctuation hypothesis suggests that this lack of biota may be the result of

extreme salinity fluctuation (Montague and Ley 1993). Few organisms have evolved the

physiological mechanisms required for life in highly variable environments (Deaton and

Greenberg 1986).

Most studies of salinity and submerged macrophytes have focused on tolerances

to extreme high and low salinities. Few studies have looked at the effects of salinity

fluctuation on submerged aquatic vegetation (Montague and Ley 1993, Fears 1993, Jones

1999, Durako 2000). In some cases, the significance of salinity as a water quality factor

is unknown since its effect is confounded with the presence of other environmental

conditions (Twilley and Barko 1990). For example, a study by Tomasko and Hall (1999)

found that the use of field studies for estimating the lower salinity tolerances of

seagrasses might be inappropriate for those systems where water clarity is positively

correlated with salinity.

Seagrasses are a vital component of estuarine systems. If salinity fluctuates too

much, communities may not become established (Montague and Ley 1993, Montague








1996). Seagrasses provide habitat for many benthic and pelagic organisms (Doering and

Chamberlain 2000), stabilize sediments by slowing water movement and increasing

sedimentation (Ogden 1980) and can form the basis of the plant-based and detrital-based

food chains (Klug 1980). Three seagrass species, Thalassia testudinum, Halodule

(Diplanthera) wrightii, and Ruppia maritima, are commonly found within the northern

land margin of Florida Bay. Little Madeira Bay (Figure 1-1) was included in earlier

macrophytes monitoring studies (Montague and Ley 1993, Montague and Chipouras

1998). All three species inhabited these areas during these studies, though Ruppia was

not as prevalent in the earlier one when salinities were higher and did not fluctuate as

much.

The degree to which rapid and dramatic changes in salinity can influence the

distribution, abundance, and community composition of seagrasses is unknown. Its

importance should be greater at land margins where outwelling freshwater meets

saltwater pushed in by coastal tides and winds. If salinity fluctuation is important, then

changes in water delivery to the coast that is under control of water managers will be

expected to directly influence the distribution and abundance of seagrasses in ways that

could affect habitat for fish and birds. Two other physical factors that are affected by

features of freshwater discharge have received the most attention by water managers and

seagrass scientists, specifically alterations in light and nutrients. In this dissertation

attention will be given to a third and perhaps more influential environmental factor,

salinity fluctuation.

Thalassia testudinum (turtlegrass) is the dominant marine angiosperm of the

Caribbean (Patriquin 1973). It is characterized by a creeping rhizome which has often








been found branched which gives rise to erect branches bearing leaves (Phillips 1960).

This species is considered stenohaline (Jagels 1973), although it was found in habitats

spanning the entire salinity gradient from fresh to marine strength within the northern

land margin of Florida Bay (Montague and Chipouras 1998). Although not thoroughly

explored, Thalassia may have a temperature optimum near 30 C and a salinity optimum

near 30%& (Zieman 1975). Fluctuations in salinity, especially those ranging into fresher

water, may be detrimental to this species.

Halodule wrightii (shoalgrass) had a wider range of salinity tolerance than

Thalassia in experiments by McMillan and Moseley (1967). In salinity tolerance

experiments performed by McMahan (1968), Halodule survived in salinities ranging

from 9 to 52.2%o, but died in salinities of 3.5%0 and in excess of 70%0. This species was

also found in habitats spanning a salinity gradient from nearly fresh to hypersaline within

the northern land margin of Florida Bay (Montague and Chipouras 1998). Based on

these findings, Halodule is expected to be more tolerant to salinity fluctuation than

Thalassia.

Widgeongrass, Ruppia maritima, has a nearly cosmopolitan distribution and

worldwide importance as a waterfowl food (Kantrud 1991). Ruppia has the widest

known range of salinity tolerances of any genus of submerged aquatic vegetation. This

species has been found in waters ranging from 0 to 390%0 with optimum growth between

0.5 and 31%o (Durako 2000). However, a study by McMillan and Moseley (1967) found

Ruppia to be less tolerant of hypersaline conditions than Thalassia and Halodule. In the

field monitoring studies conducted by Montague and Ley (1993) and Montague and

Chipouras (1998) Ruppia was found to be common but ephemeral in ponds located alone





7

streams within the land margin of Florida Bay but rarer in the more open, saline bay

habitats. Salinity fluctuation may be detrimental to this species despite its reported wid

salinity tolerance range.

A facility designed for salinity fluctuation experiments was built in Key Largo,














acclimation rates of seagrasses subjected to salinity fluctuation.













CHAPTER 2
DESCRIPTION OF FACILITY DESIGNED FOR SALINITY FLUCTUATION ANE
PILOT STUDY



Description of Facility


A schematic diagram of the facility used for conducting salinity fluctuation

experiments is provided in Figure 2-1. The facility is located on the grounds of the

National Park Service's Key Largo Ranger Station of Everglades National Park, mile

marker 98.6 bayside Overseas Highway (Figure 2-2). A more complete description of

the facility and discussion of its design criteria, constraints, construction, and testing is

given by Anastasiou (1999). Saltwater for the facility was supplied by a well drilled 13.

meters deep into porous carbonate rock connected to eastern Florida Bay. Salinity in th<

well was approximately 36%o. Chlorinated fresh water was supplied by the Florida Key

Aqueduct Authority. The fresh water was held in a 242 m3 painted concrete reservoir

(formerly a swimming pool), which increased residence time for dechlorination.

The seagrass experiments occurred within twelve 1.1 m3 experimental tanks

(Figure 2-3). Salinities were manipulated by manually adjusting valves on a seawater-

freshwater mixing manifold (center of Figure 2-3). Up to four different salinity regimes

could be delivered simultaneously to randomly chosen replicate experimental tanks by

connection of hoses of 3.81 cm diameter to a distribution manifold. In general, water w-







IU



SActuated solenoid valve (0-60 gpm)
SBall valve, manual @ | From 60,
freshwat
Saltwater pipe fsu ppclt

Freshwater pipe Ir jtw fe
Freswaterpipe pip Freshwater Head \Freshwater Head
____unerb. Tank(2100gal Tank(2100al Water su
Salinity mixing pipe activated
sensors I
Experimental tank fill pipe Pumps tr
level drol
0*0aAa "M ON Saltwater Head Saltwater Headi max
Experimental tank drain pipe Tank (2100 gal) ank (2100 gal)
.4 aa an anaam
Main drain pipe
Experimental tank fill
Conrte sb --(S0-0pn)
0 Experimental tank drain From sa
FW iis
o Stub-up connection to mixing system FW
i---4IIsw
(14or ipe) I I Seawater Freshwater
Mixing System
Sani mix I I I
valves z- rm f '
Random connection with 1.5" hoses.
stub-up *.* ..41.~Q
connctio s
,o,+. fc t l.
to vak-es ... ......t~..


... . ............. ..
was


Amm ; 0 1 1. \
A**

mq.n pipe *uuauuugrna
% %

%


Concrete slab
149,
.<~~ ft

EXPERIMENTAL S&
FLUCTUATION FA
3/^-.tS




































IU KM lip -It

















Figure 2-2: Location of collection sites and the Key Largo Ranger Station.
(Map from the USGS)
































Figure 2-3: Photograph of Experimental Facility. Experimental tanks are in the
foreground, storage tanks for fresh and sea water are located on the hill


unless flow was ceased due to experimental design. A constant inflow facilitates water

circulation. Water level was maintained at approximately 50 cm by a stand pipe drain.

Salinity was controlled by varying the quantities of fresh and salt water delivered

through the mixing manifold to the tanks. When fresh water was delivered to a tank

containing water of a higher salinity, an extension was added to the inflow pipe to deliver

water to the bottom of the water column. This enhanced mixing and flushing of the

higher density water. Complete turnover of a 1.1 m3 tank from one extreme salinity to

another occurred within 2 or 3 hours at an inflow rate of 16 m3d"'.








Materials and Methods of Pilot Study


Seagrass Collection and Experiment Preparation

Plants used in this experiment were collected in April 1998. Sprigs of Ruppia

were collected from the northern region of Seven Palm Lake (N 25* 11.69', W 80

43.42'), and Halodule from Terrapin Bay (N 25 09.49', W 80 43.84), both areas

located in north-central Florida Bay (Figure 2-2). Thalassia sprigs were collected from a

floating mat found nearby the Key Largo Ranger Station (Figure 2-2). Twenty-four

polyethylene tubs (Rubbermaid Inc., measuring 57 X 46 cm) were filled with

approximately 22.7 kg of Quikrete Commercial Grade fine sand. Halodule and Ruppia

rhizomes were planted at a density of 40 to 60 percent coverage in separate tubs. Sprigs

were selected that had the presence of green leaves and apical meristems. Thalassia

sprigs were prepared so that each rhizome had only one shoot as well as an apical

meristem. In each Thalassia tub, five rows of three individual seagrasses were planted,

totaling fifteen. Once planted, the tubs of Ruppia, Halodule, and Thalassia were placed

in holding tanks of 1.1 m3 with salinities of 15, 25, and 36%o, respectively. The plants

remained at these salinities for approximately two months.

Eight of the facility's twelve experimental tanks were used in this experiment.

Salinity fluctuation treatments were assigned randomly to the tanks. Four tanks received

a stable salinity treatment (SST1), maintained at 18%o. Two tanks received a four day

period of salinity fluctuation (P4D) in which salinity was alternated between 0 and 36%o

every two days. Two other tanks received an eight day period of salinity fluctuation

between the same extremes (P8D). One tub of each seagrass was randomly selected from








or South) within each of the eight experimental tanks. Treatments were applied during

the period from June 30 to August 1, 1998.

Protocol of Experiment

Salinity, temperature, and amount of ambient light, light just below the water

surface and at the tank bottom were measured daily. The percentage of light reaching the

seagrass was computed using Beers Law. Light measurements were taken within two

hours of solar noon, in an unshadowed area of each tank, using a quantum photometer

(Li-Cor Inc. model LI-185 B). Salinity and temperature were measured using a

refractometer (Leica model TS) and mercury thermometer, respectively. Water inflow

rates were checked three times a week by timing the filling of a bucket of known volume.

Adjustments were made as needed to ensure that each tank was receiving a similar influx


5i.a, uiou .

ush. Notice,

r of scrubbin

Daily m(

lent, evaluati

rated using

ies 1999). T

irs were assu


pJWilu IIuunl, aiiu irom me UoDS anu

rbidity caused by the suspension of el



ag of the seagrasses involved counting

color of the leaves, and noting the pr<

ex (Table 2-1) similar to that used in g

sence of green leaves indicated a heall

indicate a physiological impairment


. wtaAI uy z

ites subsid



number o

,e of new I

Lted field t

hoot, while

ke leaf. W








reliably assessed. A grid was constructed to divide the Halodule and Ruppia seagrass

tubs into nine equal areas of 230 cm2 each. Color index ratings from Table 2-1 were

recorded for each grid region. Color ratings were converted to a percentage, based on the

mean percent within the color rating range (Table 2-1).

Complete shoot counts and color analyses of all three species were performed on

days 1, 2, 3, 15, and 31 of the experiment. On the other days, two grid regions were

randomly selected for coloration surveys and shoot counts in each tub of Ruppia and

Halodule. For Thalassia on these interim days, two of the fifteen shoots were randomly

selected in each tank for coloration analysis.



Table 2-1: Color rating scale used in pilot study.



Index Rating Percent Color Range Mean %

6 100% color 100

5 95% to less than 100% color 97.5

4 66% to less than 95% color 80

3 33% to less than 66% color 50

2 5% to less than 33% color 20

1 Greater than 0% but less than 5% color 2.5








Results of Pilot Study

isical Parameters

Average daily salinity measurements for each treatment are shown in Fig

thin the stable salinity tanks, salinity varied from the desired 18%o. Adjustme

nity of the treatment tanks caused subsequent changes in the flow rates and ho

assure in the other tanks. This adjustment, in turn, caused unintended deviation

nity of the tanks designated for stable salinity treatment. Unexpected salinity

,tuations were also caused by mechanical failure. On Days 9 and 29 the saltw


both the experimental and control tanks for an unknown pe

the total difference in range of average salinity amongst treA

ier thousand (Figure 2-4, middle panel) and the standard de'

considerably higher in the fluctuating treatments as per the dc

el).

temperatures of the treatments were similar, deviating from

C (Figure 2-5, top panel). The fraction of surface light rea

d1 a wider range amongst treatments, however (Figure 2-2, h

ae that were present primarily in the freshwater storage and

ed the turbidity over that in the seawater system. Seagrasse










OI- mbr-^

-n r77 M





0 10 20 30 40
Experiment day


Mean Salinity over Experiment (%o)
18

17-

16 ,
SST1 p8d p4d
Standard Deviation of Salinity over
Experiment (%o)
20

10-


C J











Mean Temperature over Experiment
(oC)

32 -

31

30
SST1 p8d p4d



Intensity of Light at Seagrass Depth
(uE/m2/sec)

1500 -

1300

1100
SST1 p8d p4d


Percent Light Reaching Seagrass Depth

1 -,


0.75


0.5
SST1 p8d p4d



Figure 2-5: Mean temperature (top panel), light intensity at seagrass depth (middle
panel), and percent light reaching seagrass depth (bottom panel) for treatments in pilot
study. Percent is expressed in decimal form.








eagrass Measurements

Figure 2-6 shows the average color ratings obtained from Thalassia. Ra

presented by a stacked bar for each experimental day. Green is given at the b.

ir with the other colors sequentially above from chlorotic to white on top. Sult

iried in coloration for all Thalassia treatments (Figure 2-6). It is evident from

een coloration ratings that Thalassia sprigs used in the SST treatment were in

ndition than those in the other treatments (Figure 2-6).

Daily color ratings were transformed to produce accumulations of color

ter time. At each sample day, color ratings were converted to percent colorati

recentt colorations of each daily measurement were added together and divided

timber of samples. This analysis reduced the noise caused by the subsampling.

cumulations are given for Thalassia in Figure 2-7. Color accumulations are

presented by a stacked bar for each experimental day. Green colorations are 8


nfthe hir with thEp nth.


r colors sequen


accumuiations increase only in me stable salinity treatment (Figure 2-7, top panel). No

green accumulation occurred in the fluctuating treatments over the course of the

experiment. Brown and yellow color accumulations decreased with subsequent samples

in the fluctuation treatments, replaced with increased white coloration.

Starting green coloration ratings of Halodule sprigs were similar (Figure 2-8).

Green coloration ratings oscillated around their initial values in the stable salinity

treatments, but fell (while white ratings increased) in the fluctuation treatments in

samples after ten days of experimentation. Color accumulations were similar over the

course of the stable salinity treatment (Figure 2-9, top panel). In both fluctuation


























P8D Treatment







1 6 1 1 1 6 2 1 2 6 3 1-- - * - * * - - - -




Experiment Day
8

a6 E3wtite
U brown

2 .green


1 6 11 16 21 26 31
Experiment Day


P4D Treatment





U brown
4 -- ^ -


b o yellow
2 2* ------ green
0 1 11 1111 11 11 1111 Hi ll 11 1 11 11 11 [ '', 111-1111 11-1 11 1 1 O~ e



1 6 11 16 21 26 31
Experiment Day

Figure 2-6: Color ratings for Thalassia over pilot study. (* denotes ratings deriv
average of all giants sampled)


6

i4

2

0
1


* brown
D yellow
* green










SST Treatment Color Accumulations

120 -
100- -
~80
|I brown
2 60
~40 N green
20
0
1 6 11 16 21 26 31
F -tt ftBE-!


P4D Treatment Color Accumulations

120 -
100 ---------------------------------------------
100

| 80 - - - - - - - - - - - -Ow te
U brown
~60
.2 60 - - - - - - - - - - - - - - - -
0 13 yellow
S40 w green
20


1 6 11 16 21 26 31



Figure 2-7: Coloration accumulation for Thalassia in pilot study.


120
100 ----------------------------------

80 - - -
S60 - - - -
o 40
20-
0
l l6 11 16 21 26 31
1 6 11 16 21 26 31


D white
* brown
0 yellow












8






2

0
0 . ... ..y - -| - - - - - B rv


1 6 11 16 21 26 31
Experiment Day


P8D Treatment


Figure 2-8: Color ratings for Halodule over pilot study. (* denote













SST Treatment Color Accumulations

120
100
80 -o wtite
2
2g 60 -m brown
0
S40 green

20 -

0
1 6 11 16 21 26 31


P8D Treatment Color Accumulations

120 -
100

~80 owit
2

2 60 brown
0
~40
20
0
1 6 11 16 21 26 31


P4D Treatment Color Accumulations

120 -
100

i 80 o * *

2 60 U brown
0
U 40 11 1 green
S40
20
0
1 6 11 16 21 26 31


Figure 2-9: Coloration accumulation for Halodule in nilot study.








,atments, green color accumulations in Halodule decreased, while white accur

creased.

Green coloration ratings were highest in Ruppia exposed to the stable sa]

,atment; however; green ratings in the fluctuation treatments persisted through

periment (Figure 2-10). White coloration ratings steadily increased in Ruppia

periment for all treatments, although greatest white color ratings were seen in

situation wave treatments. Ruppia sprigs exposed to the eight day fluctuation


hough green color accumulations remained high in the four day flui

*D) treatment, white color accumulations increased over the experir



Discussion of Pilot Study

The results of the pilot study demonstrate a distinct effect of sa


lent.


salinity, temperature and light) was minor and was unlikely to have measurably

influenced the results. In the three species tested, exposure to fluctuations in salinity

resulted in the replacement of healthy green leaf tissue with dead white tissue. Although

an effect of fluctuation was clear in all three species when compared with stable salinit,

an affect of period of the salinity fluctuation was not evident in the Thalassia and

Halodule experiments. In Ruppia, longer periods were more detrimental.

The method of surveillance did not include the monitoring of individual plants.

Subsampling did not allow the responses of individual sprigs to be evaluated. Repeated

Ramnleq nn the .ame nlnt. wniild hle mnrr. indiretlive nfthp. tff.r.tc nvr time








35T I reatmen


P8D Treatment

8
6 -- ----------

{4 .. -- -


2 4

0
1 6 11 16 21 26 31
Experiment Day


P4D Treatment

8 --------------------


I -


4

2

0
1


6 11 16 21 26 3
Experiment Day


average of all plants sampled) -- -- --- --- -- - -
average of all plants sampled)


* uIuwiI
* green


6 11 16 21 26 31
Experiment Day









SST Treatment Color Accumulations

120 -
100

80 white

| 60 brown
40
0 40 green

20 -

0
1 6 11 16 21 26 31



P8D Treatment Color Accumulations

120
100 -
S80 -
SDwhite
.2 60 brown
0
40- E green
* 40

20 -

0
1 6 11 16 21 26 31


P4D Treatment Color Accumulations

120 -

100 i
2 80
Owlut
0 o, IIIIIIIIIAllll//f _.t














amount of starting green coloration may have exacerbated the effects of salinity

fluctuation, giving the plants little chance of survival. Acclimation to appropriate

salinities and stricter criteria for selection in experiments may remedy this problem in

future experiments. Sparse distributions of seagrass communities in northern land

margin of Florida Bay may be influenced by the frequent changes of ambient salinity. If

seagrasses are losing photosynthetic material due to the affects of salinity fluctuation,

energy reserves may not be adequate for vegetative growth and rhizomal elongation, the

main methods of reproduction in both Thalassia and Halodule (McMillan and Mosely

1967, Phillips 1960).

Further experiments are necessary to explore the responses of seagrasses to

varying degrees of salinity fluctuation, including the amplitude, frequency, and

suddenness of change. In addition, the mean about which salinity fluctuates, light, and

nutrient interactions can be examined experimentally. With a more complete and

quantitative examination, the distributions and abundances of seagrasses may be

predicted using models that include salinity fluctuation as well as light, nutrients,

temperature and average salinity.













CHAPTER 3
MATERIALS AND METHODS FOR MAIN STUDY
(EXPERIMENTS 2 THROUGH 7)



Seagrass Collection and Acclimation

All seagrass species used in the salinity fluctuation Experiments 2 through 7 were

collected within Little Madeira Bay (N 25 11.39', W 80 38.34'), a basin located in the

northern land margin of Florida Bay (Figure 2-2). Sprigs of Thalassia testudinum,

Ruppia maritima, and Halodule wrightii were collected that consisted of a length of

rhizome with shoots and roots attached and with healthy leaves. Shoots consist of a

sheath (in Thalassia and Halodule) and at least two leaf blades. Sprigs were carefully

removed from the sediment and placed into coolers half filled with water from the

collection site. Sprigs of Halodule wrightii and Ruppia maritima were selected if they

had a minimum of three shoots and a growing rhizome tip present. Sprigs of Thalassia

testudinum had a minimum of two shoots and a growing rhizome tip. Bottom salinity of

water sampled from seagrass depth was measured at the collection site with a

refractometer. Temperature was measured in the water column with a mercury

thermometer attached to a string. In addition, salinity and temperature data from Little

Madeira Bay were obtained from the South Florida Information Access (SOFIA) website

(Patino and Hittle, unpublished) to determine field conditions in the month prior to

collection.








The seagrasses were transported to the experimental facility in coolers and

allowed to acclimate in the experimental tanks for a minimum of two weeks. During the

acclimation phase, salinities were adjusted from the salinity at the collection site to the

mean salinity of the experiments in increments less than 1 %o per day. Seagrasses were

not monitored during this time. Acclimation periods and ranges for experiments 2

through 7are given in Table 3-1.


Description of Experiments

The effects of different characteristics of salinity fluctuation were tested in a

series of six experiments (numbered 2 through 7). Amplitude, period, suddenness of

change and mean salinity were tested. A general description of the experiments is given

in Table 3-2, and a more detailed description of treatments is given in Table 3-3. The

seven column headings in Table 3-3 describe various aspects of the pattern of salinity

fluctuation. The variables tested in each experiment are designated in the shaded column.

In all but Experiment 4, fluctuating wave patterns treatments were tested against stable
eolinifxr 4"*tr, ,trf,<.Cto









Table 3-1: Acclimation periods and ranges for the facility experiments. The end date of
the acclimation period was the first day of the experiment.



Experiment Start Date End Date Salinity Range Duration at Target Salinity (18%o)


ble3-


ry of Experi


Experiment # Scope of Experiment


2 Effect of Amplitude
3 Suddenness of Change (Square vs. Pyrar
4 Effect of Mean
5 Effect of Period
6 Effect of Water Circulation Method and
Salinity Fluctuation (crossed design)
7 Effect of Light and Amplitude (crossed de,


4 2/6/99 3/3/99 16-18%o
5 4/27/99 5/19/99 30-18%o
6 6/29/99 7/13/99 18%o
7 10/4/99 10/27/99 7-18%o


i

1
If






,fer to m




Numbi
Treatrr


3
3
2
3
4


5


SuayO
days
i days
days





mber of




r of
ents P


Number of
Replicates
-r Treatmer


4
4


licates r










id Wave






ign)


3


2


3


2






















(%.) (da-
-n1


1R 11A A A


18

i around differni
Mean AmI
(NO)


4 32


od Sal. Min. Sal. Max.
(M) (%N) (i
0 18
18 36


ist of Extreme Salinity Fluctuatio
Wave Type Mean Amn


SWp8 square 18 18 0 36 0.13 100

Exp 6: Water Circulation Method and Salinity Fluctuation
Wave Type Mean Amplitude Wave Period Sal. Min. Sal. Max. Inflow Percent Sui
(%0) (%) (days) (%.) (%0) (liter / sec) (%)
SSTt stable 18 0 18 18 IN W 100
SSTb stable 18 0 18 18 100
SWt square 18 8 4 32 100
SWb square 18 8 4 32 100

Exp 7: Low and High Amplitude Fluctuation Crossed with Full and Reduced Sunlight
Wave Type Mean Amplitude Wave Period Sal. Min. Sal. Max. Inflow Percent Sui
(%.) (%.) (days) (%.) (%.) (liter I sec) (%)
SSTs stable 18 0 18 18 0 (air)
SWa7u square 18 8 11 25 0 (air)
SWa7s square 18 8 11 25 0(air)
SWa14u square 18 8 4 32 0 (air)
SWa14s square 18 8 4 32 0 (air)
















salinity max

F amphtude



I mean salinity



salinity min
I
period


Time











Figure 3-1: Characteristics of a salinity fluctuation wave. The square wave is shown in
black, the pyramid wave is gray. Frequency is the reciprocal of period.








throughflow of water versus air bubbling as a means of water circulation in the

experimental tanks was tested along with salinity fluctuation in Experiment 6. The effect

of shading was tested along with salinity fluctuation in Experiment 7.

In Table 3-3, the column titled "inflow" designates the constant inflow of water

into the experimental tanks. For Experiment 6, an air pump was installed to aerate the

saltwater head tanks and selected experimental tanks. Aeration helped reduce sulfides in

the saltwater head tanks and promoted circulation in the experimental tanks (Anastasiou

1999). Water did not flow through the bubbled experimental tanks, rather they were

filled initially with water and aerated. Evaporative losses were replaced daily with

freshwater, a task not required in flow through experimental tanks. When it was time to

change the salinity, a brief period (approximately 60 minutes) of flow through occurred

until the new salinity was achieved.

In Experiment 7, the effects of reduced sunlight were crossed with fluctuation

patterns of low and high amplitude. In this crossed design, interactions between light and

amplitude can be revealed. This was important because the freshwater at times was more

turbid than the saltwater, potentially confounding the results. Randomly selected

experimental tanks were covered by 70 % shade cloths to create reduced light conditions

(30% full sun). The treatments are designated in Table 3-3 under the column labeled

"Percent Sun". Ruppia was not tested in this experiment because there was not adequate

numbers present at the collection site and other areas of northern Florida Bay where

Ruppia has been previously found. Furthermore, an unshaded stable salinity treatment

was not included because of a lack of acclimated sprigs. An unexpected dieoffof

Thalassia and Halodule occurred during the acclimation period. The stable salinity








treatments of the five prior experiments were unshaded, therefore this treatment was not

included to ensure an adequate number of replicates for the remaining treatments tested

in this experiment.

Sprig Preparation and Planting

Immediately prior to each experiment, morphometric measurements were taken

on all seagrass samples. Sprigs with a growing rhizome tip and at least two shoots with

green leaves were randomly selected from the acclimation chamber. The number of

shoots was counted. Rhizome length and mature and immature leaf lengths were

measured to the nearest half millimeter. Sprigs were then planted into polyethylene tubs

(26.5L, Rubbermaid, Inc.), measuring 57 x 46 x 15 cm deep. Fine-grained sand

(Quikcrete brand) was used as sediment in all tubs. Two sprigs of each of the three

species were planted in each tub in random order, for a total of six sprigs per tub. Three

tubs were submerged in each experimental tank, for a total of eighteen sprigs per tank.

Sprig and Tank Monitoring and the Green-Leaf Index

During the course of Experiments 2 through 7, leaves were monitored every two

days. The total numbers of leaves were counted on each of the three youngest shoots on

the sprig, followed by a count of the number of leaves with any green coloration. Finally,

a green-leaf index was assessed for each shoot, based on the number of green leaves

present, prorated visually for partial green coloration. For this index, the number of

leaves with green coloration on a shoot was multiplied by an estimate of the fraction of

all leaves on that shoot that was green. This calculation is performed for the three
























I -- ..__^ - -

the seagrass sprigs were dried and weigh





Data and



Statistics were performed using

Associates, Inc.). For each experiment,


responses by each species to each treatr

nrnct'dire. nfwae iiaprl tn i;dpntinfA rlj;flr


'ANUVA 1


IA1 1 -


Pearson product moment corre'


to explore and quantify relationships b

resnnnmfe frnm amnnao fthi optnro Aaf c


frequency. The method of calculation for each descriptor is given in Table 3-5. Mean


TL-


A


_ ? s



















(Cluster of
leaves)

Short-Shool

4-- (Sheath)


Rhizome


Percent Green-Leaf (as a decimal):

0+0.5 +0 0.5 +0.75 1.0 + 0.5 + 1.0

Total per Shoot:

0.5 1.25 2.5

GLI for Sprig (Average of Shoots):

4.25/3 GLI = 1.42





Figure 3-2: Example of Green-Leaf Index calculation. For this example, assume black
colorations on leaves are green.









Table 3-4: Dates and durations of the six facility experiments.


2
3
4
5
6
7


salinity, standard

the salinity wavi

Suddenness giv<

the maximum sl

of this analysis,

determine the m

To aceoi

involving tempe

the stable salinity


10/28/99 11/22/99 26 da


n, and maximum amplitude describe aspects of the ai


inu meL ratC nuiU magIM uuuV Ui MIiiULy unuiiC uy quatuiiyul

occurred in the entire experiment. Due to the exploratory nal

icance threshold was set at p < 0.001 to act as a filter to

tant correlations.

y confounding effects of salinity fluctuation, correlations

ht, and water nutrient concentrations were made with plants
--d- _- 1_-. ,'1L :_L ... ...- Z',l- 1.-. -_. -- _----_ . _--.. .. 11 !-


10/25/98 11/25/98 32 di
1/4/99 2/3/99 32 di
I AIQQ MI')QOQ 9 R rit















in Salinity Mean salinity calculated from daily measurements



idard Deviation Standard deviation calculated from daily measurements
alinity


imum 1/2 (maximum minimum salinity measurement)
4litude


denness of Maximum slope of salinity wave
iity Change


iber of Changes Number of salinity changes / Number of days
Day


ificant 1/2 ((number of crossovers -1) / number of days)
juency where "crossover" occurs when salinity crosses designed mean


olute 1/2 (# of peaks + # of troughs / total days)
]uency



























een-le

ippia

ie rest

able s&


h of Taylor River in Little Madeira Bay are plotted and su

and Hittle, unpublished). The daily temperature averages

nts taken at fifteen-minute intervals. Hurricane Georges c


C il ~llli I~ll, L L1 I.IC lil ili Al llI&L1A1ill ~ VT Ol ili 11 C15* A 'l i%. "!-.J AV Ii, 1l.UlI11ilL~l

are coded as follows: 1) SST2- stable salinity treatment, 2) SWa7- square wave treatment

with an amplitude of 7%o and a period of four days, and 3) SWal4- a square wave

treatment with an amplitude of 14%o and a four day period. An indirect hit by Tropical


















































values were measured at 15- minute intervals. Gaps in the salinity record represent w
no data were reported. Temperature values are daily averages. Tabular values bottomo
































.4


Figure 4-2: Satellite Image of Hurricane Georges prior to Florida landfall. (Satellite
image from National Weather Service)









35
30 T
T25-
>20 SST2
k -SWa7
.15 SWa 14
(010-
5
0
O_ !- I-- I_ --

0 10 20 30
Experiment Day


Mean Salinity over Experiment (%@)
(Expanded Scale)
18.5 m

18-

17.5
17ALm
SST2 SWa7 SWa14


Standard Deviation of Salinity over
Experiment %o)
150



0.30
SST2 SWa7 SWa14


Figure 4-3: Salinity patterns for treatments in Experiment 2. (Coding as follows: 1)
SST2- Stable salinity treatment, 2), SWa7- Square wave with amplitude of 14%o, period
of 4 days and 3) SWa14- Square wave with amplitude of 14%o, period of 4 days)










ES was unUKely to nave oeen anectica, owing to me z 10to n

pugh the experimental tanks. Salinity was not measured uni

e constant throughflow of water into the experimental tanks

Le affect of rainfall, however. As intended, mean salinities

one-half part per thousand of 18 %96o. The standard deviation

nity fluctuation) was proportional to the amplitude of the tr

gure 4-3).

i temperatures over the experiment were nearly identical fo

Figure 4-4, top panel). Average light intensity and the fract

rass depth were slightly greater in the stable salinity treatm4

litude treatment, but not compared to the high amplitude tr

d lower panels).

i nutrient concentrations measured over the experiment froi

ment outflow and the freshwater and saltwater supplies are

im the freshwater source had considerably higher concentra

and DIN than water from the seawater source. An equal mi

nflow had intermediate concentrations of the aforemention


the freshwater source and practically none in the seawater supply.

Thalassia Measurements

The biological responses of Thalassia were negatively influenced by the high












Mean Temperature over Experiment
(C)

28
27
26
25
SST2 SWa7 SWa14


Intensity of Light at Seagrass Depth
(uEIm2/sec)
F= 3.89 (p=0.0605)
1500 -
1000-
500
0
SST2 SWa7 SWa14


Percent Light Reaching Seagrass Depth
F= 4.03 (p=0.0562)
1


0.75 -


0.5
SST2 SWa7 SWa14



Figure 4-4: Mean temperature (top panel), light intensity (middle panel) and percent ligh
reaching depth of seagrass (lower panel) for treatments in Experiment 2. Error bars are
intervals derived from Fisher's least significant difference (LSD) procedure. If the means
are not significantly different, the intervals will overlap 95% of the time. F ratios are
given when differences between means are significant. Percent is expressed in decimal
form.




















2.004 I
02.00 0 1:1 2.04
S0 0.00 0 0.01
0%. 18%. 36. 01. 18%. 36/.
Salinity of Source Salinity of Source


Total KJMldahl Nitrogen (TKN) Dissolved Inorganic Nitrogen (DIN)
1 70.00 1 25.1
-0.8 60.000. 20.1
50.00
0.6 I 40.00 0.6 1.1
0.4 E 30o.00o 0. 1 .
20.00
02 10.00 02 5.1
0 0.00 0 0.(
0%. 18%. 36%. 0o. 186%. 36%.
SalMny of Source Salinity of Source


Nitrit (NO2) Nitrate (N032)
1.40 _----0.02 60.00
1.20 0001. 6000
1.00 00.010
0.60 40.00
0.60s .0.01 ~ 30.00-
_U 000oo o
0.40 0.005 20.00
0.20 10.00
0.00 40 0,0M





46

well, but to a lesser extent. Increases in leaf and shoot number were similar between

plants in the stable and low amplitude salinity treatments, but were higher than in plants

exposed to the high amplitude treatment.

Thalassia green-leaf indices (GLI) declined in all treatments over the first 11 days

of the experiment (Figure 4-6, top panel). Plants in the stable salinity treatment however

recovered, showing a net increase in GLI over the course of the experiment (Figure 4-6,

lower panel). An increase in GLI in plants exposed to the low amplitude treatment

occurred during the last seven days of the experiment, but no recovery occurred in plants

in the high amplitude treatment.

The number of Thalassia shoots had increased by the end of the experiment in all

treatments, although this increase was smallest in the high amplitude fluctuation

treatment (Figure 4-7, top panel). Rhizome length decreased for plants in all treatments,

despite the increase in shoot number (Figure 4-7, middle panel). Belowground biomass

in Thalassia was greatest in plants exposed to the high amplitude treatment, although not

statistically different from plants in the other treatments (Figure 4-7, bottom panel).

For all treatments, Thalassia leaves were shorter after the experiment than they

were initially, however plants in either the stable salinity or the low amplitude treatments

had over 30% more leaves on average after the experiment (Figure 4-8). Those that were

in the high amplitude treatment had only 46% of original measurements. Sprigs of






47



1.5-







-U-- SWa7
0 -. -SWa14
0.5




0
0 5 10 15 20 25 30 35
Experiment Day



Before Treatment to After Treatment
Ratio of GLI
F= 15.16 (p =0.0013)
1.5 -


0.5
0"
SST2 SWa7 SWa14


Figure 4-6: Green-leaf indices for Thalassia over Experiment 2 (top panel) and before tc
after treatment ratios (bottom panel). Error bars on time series chart represent standard
error, those on ratio chart are intervals derived from Fisher's least significant difference
(LSD) procedure. If the means are not significantly different, the intervals will overlap
95% of the time.









Before Treatment to After Treatment
Ratio of the Number of Shoot
F =4.89 (p=0.0365)
1.5 -
1

0.5 -
0
SST2 SWa7 SWa14

Before Treatment to After Treatment
Ratio of Rhizome Length

1.5 -
1 __, _
0.5 -
0
SST2 SWa7 SWa14

Belowground Biomass per Rhizome
Length (glcm)

0.05 -
0.04
0.03-T
0.02 J
0.01
0
SST2 SWa7 SWa14





Figure 4-7: Before to after treatment ratios of shoot number (top panel) and rhizome
length (middle panel), and belowground biomass (bottom panel) after treatments for
Thalassia sprigs in Experiment 2. Intervals around means are based on Fisher's LSD
procedure (p < 0.05). F ratios are given when differences between means are significant.








Before Treatment to After Treatment
Ratio of Leaf Length




0.5

0 -
SST2 SWa7 SWa14

Before Treatment to After Treatment
Ratio of Percent Number of Leaves per
Shoot
F= 5.78 (p= 0.0243)
2 -
1.5 -mb

0.5
0.
SST2 SWa7 SWa14

Average Number of Leaves per Shoot
after Treatment
F= 8.09 (p= 0.0098)
2.5
2
1.5
I
0.5


SST2 SWa7 SWa14

Aboveground Biomass per Short Shoot
(g/ss)

0.3 T---------------I
0.21-
0.1
0
SST2 SWa7 SWa14

Figure 4-8: Leaf characteristics for Thalassia after Experiment 2. Intervals around means








rhizome, and leaf measurements, and the standard deviations of the measurements, are

given in Table 4-1.

Halodule Measurements

Halodule exposed to the high amplitude salinity fluctuation treatment had lower

green-leaf indices and a greater reduction in leaf length and number than plants exposed

to the other two treatments. Halodule tolerated the low amplitude treatment, having

similar responses in green-leaf index and leaf length as plants in the stable salinity

treatment.

Halodule green-leaf index declined overall under all three treatments, however

(Figure 4-9). An increase in GLI for plants in all treatments occurred during the final

seven days of the experiment, although the increase was most rapid in the stable salinity

treatment. Those in the low amplitude treatment fared the best, although not statistically

significantly better than those in the stable salinity treatment according to the ANOVA.

As with Thalassia, the high amplitude treatment resulted in the greatest decline in

Halodule green-leaf index (Figure 4-9, bottom panel).

The number of Halodule shoots increased most in the low amplitude (SWa7)

treatment and least in the stable salinity treatment (Figure 4-10, top panel). The increase

in rhizome length in the high amplitude treatment, however, was not statistically different

from that in the two other treatments (Figure 4-10, middle panel). Halodule sprig

biomass was similar among treatments (Figure 4-10, bottom panel).

Average leaf length increased in Halodule sprigs under stable salinity and low

amplitude treatments. A decrease was observed in the high amplitude treatment (Figure










igs prior to and after experimental treatments.

Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. Dev.
Shoot Number
SST2 2.92 0.83 3.67 1.27
SWa7 3.00 0.85 3.70 1.15
SWa14 3.08 0.83 3.38 1.44

Rhizome Length (cm)
SST2 22.73 11.97 19.75 10.68
SWa7 22.16 9.29 19.37 7.82
SWa14 24.64 10.79 17.15 8.93

Leaf length (cm)
SST2 9.78 2.92 2.58 2.00
SWa7 8.73 3.79 2.81 1.77
SWa14 8.47 4.03 1.24 1 A.48

Leaf Number


SWa14 1.32 0.46 0.63 0.65



1). Those in the low amplitude treatment did not change (Fi

The average number of leaves per shoot in Halodule plan

similar to those in high amplitude treatments. The low amp]

st nnmher nf leaves averagino twn leave. ner Qhnnt fPimire


LMl lliiui-sIVI IIVIll, alvc givenl 111 I IDIc +-L.

Ruppia Measurements

In contrast to Thalassia and Halodule, Ruppia fared worst in the stable salinity



























0 5 10 15 20 25 30
Experiment Day



Before Treatment to After Treatment
Ratio of GLI
F= 8.72 (p=0.0078)



0.5

0
SST2 SWa7 SWa14


Figure 4-9: Green-leaf indices for Halodule over Experiment 2 (top panel) and before to
after treatment ratios (bottom panel). Error bars on time series chart represent standard










Before Treatment to After Treatment
Ratio of the Number of Shoots
F= 6.84 (p= 0.0156)
2 -

.5 ---

0
SST2 SWa7 SWa14


Before Treatment to After Treatment
Ratio of Rhizome Length

2 S
1.5

0.5-
0
SST2 SWa7 SWa14


Total Sprig Biomass per Rhizome
Length (glcm)

1.025 -
0.02
1.015
0.01
1.005 -
0
SST2 SWa7 SWa14


are given when differences between means are significant.









Before Treatment to After Treatment
Ratio of Leaf Length
F =5.63 (p= 0.0260)
1.51


0.5 -
0
SST2 SWa7 SWa14

Before Treatment to After Treatment
Ratio of the Number of Leaves per
Shoot
F= 3.36 (p= 0.0814)
1.5
1 ,3
0.5 -
0 -
SST2 SWa7 SWa14

Average Number of Leaves per Shoot
after Treatment
F= 4.30 (p= 0.0490)
2.5-
2-
1.5 ---
I
0
SST2 SWa7 SWa14




Figure 4-11: Leaf characteristics for Halodule after Experiment 2. All percent are
expressed in decimal form. Intervals around means are based on Fisher's LSD procedure
(p < 0.05). F ratios are given when differences between means are significant.










atment (Figure 4-12, bottom panel). Declines were seen in all treatments during the

iddle period of the experiment, but these were far more dramatic in the stable and high

iplitude treatments (Figure 4-12, top panel).

Ruppia sprigs exposed to both the low and high amplitude treatment had more

oots at the conclusion of the experiment, whereas those in the stable salinity treatment

d less (Figure 4-13, top panel). Ruppia rhizome length nearly tripled (from 2.6 to 9.9

i) in the low amplitude treatment (Figure 4-13, middle panel), but no significant

Tferences were observed in total sprig biomass among treatments (Figure 4-13, bottom

nel).


erages and standard deviations of morphometrics measured
and after experimental treatments.

Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. De
mber
SST2 7.39 3.20 8.70 3.18
SWa7 6.58 2.47 10.13 3.53
SWa14 5.38 2.41 7.38 2.75


SWa14 16.99 9.43 10.79 8.44

Leaf length (cm)
SST2 5.36 1.40 6.30 2.22
SWa7 5.86 2.02 6.12 1.81
SWa14 5.42 1.57 4.40 1.66

























0 5 10 15 20 25 30 3
Experiment Day



Before Treatment to After Treatment
Ratio of GLI

1.5 -S aS a
1 -- ^ I -- e m i ---
0.5 -- 1-----------

SST2 SWa7 SWa14


Figure 4-12: Green-leaf indices (GLI) for Ruppia over Experiment 2 (top panel) and
before to after treatment ratios (bottom panel). Error bars on time series chart represent
standard error, those on percent change chart are intervals based on Fisher's least
significant difference (LSD) procedure. If the means are not significantly different, the









Before Treatment to After Treatment
Ratio of the Number of Shoots
F= 8.77 (p =0.0077)
3 ____________...__...... ________________


i ----------------
3

0-
SST2 SWa7 SWa14


Before Treatment to After Treatment
Ratio of Rhizome Length

5 -...
4


3 ---------------------
2 -

0-
SST2 SWa7 SWa14

Total Sprig Biomass per Rhizome
Length (glcm)

0.015 -
0.01

0.005
0
SST2 SWa7 SWa14



Figure 4-13: Before to after treatment ratios of shoot number (top panel) and rhizome
length (middle panel), and total sprig biomass (bottom panel) for Ruppia in Experiment
2. Intervals around means are based on Fisher's LSD procedure (p < 0.05). F ratios are
given when differences between means are significant.










ure 4-14, top panel). A slight increase (1%) occurred in 1

e number of Ruppia leaves increased in both the low and

,reas a slight decrease occurred in the stable salinity treat

el). This treatment also had the least numbers of leaves a


lausucC


cant a


were ot


gure 4-14, bottom panel). Average shoot, rhizome, and leal

rd deviations of the measurements, are given in Table 4-3.



it 3: Rate of Change of Salinity Fluctuation (Square vs. Pyr

y fluctuation was detrimental to Thalassia, regardless of the

module was in poor condition after all treatments, although

-x was slightly less in the stable salinity treatment than in tt

Wppia was most negatively affected in the pyramid wave (gr

tive the stable salinity and square wave treatments, but not

r the other two seagrasses.

physical Measurements


month prior to seagrass collection, with a mean around 5%o (Figure 4-15). Mean










f -- -- 1


I ---I

0.5
0



Be
R


1.5 --
1 -

0.5 --
0--


I" Tni


e Tn
o oft







;T2


it to
nber
hoot
2 (p=





SW.


reatr
ves


3
2
1 ------------------


0
SST2 SWa7 SWa14



Figure 4-14: Leaf characteristics for Ruppia after Experiment 2. Intervals around means
are based on Fisher's LSD procedure (p < 0.05). F ratios are given when differences
between means are significant.


~1


I MPM









able 4-3: Averages and standard deviations of morphometrics measured on Rupj
prigs prior to and after experimental treatments.


Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. Dev.
Shoot Number
SST2 5.67 1.98 4.38 2.29
SWa7 6.13 1.57 11.04 4.81
SWa14 7.00 2.83 9.48 5.96

Rhizome Length (cm)
SST2 2.06 1.66 3.54 5.21
SWa7 2.60 1.94 9.89 7.05
SWa14 3.18 3.03 5.69 4.87

Leaf length (cm)
SST2 5.75 1.43 4.08 1.37
SWa7 5.88 1.27 5.73 1.47
SWa14 5.64 1.62 4.44 0.68

Leaf Number
SST2 2.37 0.55 2.17 0.60
SWa7 2.31 0.62 2.54 0.50
SWa14 2.32 0.67 2.36 0.54



'i 1/ *-._ A I- .. A .---* - A-i_ - 1 t *- _l -- ...... *i l 1L .I_ -11 __-" __ -- .. ..r-


ajor deviations from the designed salinity pattern occurred

chanical problems involving the freshwater pump.

neratures among treatments differed less than 0.2 C (Figm


light at bottom) are statistically similar amongst treatments (Figure 4-17, middle and

bottom panels). Total phosphorus concentrations were an order of magnitude higher in

frk









Salinity prior to Collection for Exp3
14 -

12

10

8



ST1117 .8 12I1/ 1




11/17/98 12/1/98 12/16/98


Tabular values (bottom panel) are based on data collected at 15-minute intervals excepti
for data collected at time of collection).


. p +-t-$ p


~~________Salinity (X) Temperatur
Mean 4.8 25.3
Standard Deviation 3.12 1.73
Minimum 0.79 18.92
Maximum 13.2 29.6
measured at Collection 12 21




- cqI-r-I - ..._ ---J ... .^--_- / -- 11- _-_ -\ T ;.


5


IZ/U/ao











nM AA^AA SA,, AAk^










1 10 20 30

Experiment Day




Mean Salinity over Experiment (%o)
(Expanded Scale)
19 ,

18.5-
18
17.5
17
SST3 PW SW

Standard Deviation of Salinity over
Experiment (%o)

15_


Figure 4-16: Salinity patterns for treatments in Experiment 3. (Coding as follows: 1)
SST3- Stable salinity treatment, 2) PW- Pyramid wave with amplitude of 14%o, salinity
changing every 12 hours by 1.5%o, and 3) SW- Square wave with amplitude of 14%o,
period of 8 days)









Mean Temperature over Experiment
(oC)
F= 7.89 (p=0.0105)
25 -----------------
24
23
22
SST3 PW SW


Intensity of Light at Seagrass Depth
(uE/m2/sec)

600 -

300

0

SST3 PW SW


Percent Light Reaching Seagrass Depth

1 -


0.75-


0.5 -
SST3 PW SW







Figure 4-17: Mean temperature (top panel), light intensity (middle panel) and percent
light reaching depth of seagrass (bottom panel) for treatments in Experiment 3. Error
bars are intervals based on Fisher's least significant difference (LSD) procedure. If the















4
2
0
0%. 18%. 36%.
SalKinity of Source


Total KJeldahl Nitrogen (TKN)

s o


20

0fl

0%. 18 36%.
Salinity of Source



[4


).25
).2S -
3.15 -
3 .1

).05
0 0
0%. 18%. 36%.
Salinity of Source


Dissolved Inorganic Nitrogen (DIN
1.2 100.00 .-- ...-.-...
1 an nnf mi __


0.8-
0.6

0.4
0.2
0
0%. 18%. 36
SalUnity of Source



Figure 4-18: Mean nutrient concentrations means


0.15 -3
0.1 E 2
0.05 1I l
0 0

0%. 18%. 36%.
Salinity of Source


Ammonium (NH4)
-1.4 20
12 2 1 -M


0.01 50
0.008 j 40 t
0.006 30 -
0.004 20
*0.002 10 -
0 01
a 0%. 18%.
Salinity of Source



hired during Experiment 3.









assia T

Tha,

tinual, J

treatme

ber occ


if length and


ll i Uh 1111stal UsiniU U tr a1 t eAnt11;; 1 IwasUles t1l7). L L UVt1011 eILIU.UU11 111 trLatLeIns

ex in the stable salinity treatment was less than in the other treatments.


'I.1, %I O "II u ILAA I 1U N LI. U 5 '.Ju ,UJL I, I, aI %IA IL A,.%Y" W I

ed in the pyramid wave treatment (Figure 4-20, middle pan

the stable salinity treatment retained the most biomass, sig

Sthe square wave treatment (Figure 4-20, bottom panel).

;e leaf length declined during the experiment in all treatmer

e number of Thalassia leaves per shoot decreased least in t]


0.35 leaves per shoot (approximately one leaf per three shoots) after the pyramid wave

treatment, in contrast to the square wave (0.76) and stable salinity (1.01) treatments

























SIII I
0 5 10 15 20 25 30
Experiment Day





Before Treatment to After Treatment
Ratio of GLI
F= 15.92 (p= 0.0011)
1.5 -
I i-m

0.5 --
0 -" SW....
SST3 PW SW


difference (LSD) procedure. If the means are not significantly different, the intervals will
overlap 95% of the time.










Before Treatment to After Treatment
Ratio of the Number of Shoots

1 I---, I-----,----- ---


0.5

0 -
SST3 PW SW

Before Treatment to After Treatment
Ratio of Rhizome Length
F= 3.17 (p= 0.0905)
1.5 -
1 -
0.5-
0 -
SST3 PW SW

Belowground Biomass per Rhizome
Length (glcm)
F= 4.29 (p= 0.0490)
0.03 -
0.02
0.01
0~
SST3 PW SW






Figure 4-20: Before to after treatment ratios of shoot number (top panel) and rhizoi
length (middle panel), and belowground biomass (bottom panel) for Thalassia in
Experiment 3. Intervals around means are based on Fisher's LSD procedure (p < 0.
ratios are given when differences between means are significant.













0.5
0
SST3

Before Tnr
Ratio of t




0.5
0-
SST3

Average N


After
r of L
it
0.0009

|


w

eavee


Patme
es pe






rSh

er Sh<


0.5
0
SST3 PW SW

Aboveground Biomass per Short Shoot
(g/ss)

0.25-
0.2 -
0.15
0.1
0.05
0 1
SST3 PW SW
Figure 4-21: Leaf characteristics for Thalassia after Experiment 3. Intervals around
means are based on Fisher's LSD procedure (p < 0.05). F ratios are given when
i *rv -f-------------


teTore i reamnenm 0o Aner i reatmeni
Ratio of Leaf Length


I -I


"zip


SIAR


itmer
e Nur
S
= 16.9!


nber


F:



























PW 5.82 2.21 1.44 2.32
SW 6.67 2.49 3.49 3.20

Leaf Number
SST3 1.69 0.66 1.01 0.90
PW 1.67 0.45 0.35 0.52
SW 1.74 0.54 0.76 0.59



tistically significant. Average shoot, rhizome, and leaf measure

viations of the measurements, are given in Table 4-4.

measurements


--- 0 ----- ---o-------~- -^-d -------- ---_ ----- -_---- --_

fluctuation treatments.

A sharp decline in GLI occurred in Halodule by the ninth day of the experiment










2



1.5 T

0I -*- SST3
IW 1 --T-- PW

-----SW

0.5


0 ---
0 5 10 15 20 25 30 35
Experiment Day



Before Treatment to After Treatment
Ratio of GLI

1.5 -
I M
0.5
0-
SST3 PW SW




Figure 4-22: Green-leaf indices for Halodule over Experiment 3 (top panel) and before
to after treatment ratios (bottom panel). Error bars on time series chart represent standard
error, those on percent change chart are intervals based on Fisher's least significant
difference (LSD) procedure. If the means are not significantly different, the intervals will
overlap 95% of the time.










Increased more than in the stable salinity treatment (Figui

crease in rhizome length occurred in the square wave trea

in the others (Figure 4-23, middle panel). The higher Hal

nity treatment was not statistically different from the other

)m panel).

e decline in average leaf length and number of leaves per ,

:nts (Figure 4-24, top and middle panels). In addition, the

shoot after the experiment were very close, with 1.47 leave

atment versus 1.42 leaves counted in both the square and ]

(Figure 4-24, bottom panel). Average shoot, rhizome, anc

ndard deviations of the measurements, are given in Table

measurements


:or Ha

fthee

5). Al


wave treatments, although statistically significant differences occurred only in rhizome

length (top and middle panels of Figure 4-26 and 4-27). Average shoot, rhizome, and











Before Treatment to After Treatment
Ratio of the Number of Shoots
F= 3.66 (p= 0.0687)
2 -
.5 -

5 -
0
SST3 PW SW

Before Treatment to After Treatment
Ratio of Rhizome Length

.5


.5 -
0 -
SST3 PW SW

Total Sprig Biomass per Rhizome
Length (glcm)

0.01 T------------------------
.008 T
,006
.004
.002
0
SST3 PW SW


Figure 4-23: Before to after treatment ratios of shoot number (top panel), and rhizome
length (middle panel), and total sprig biomass (bottom panel) for Halodule in Experiment
3. Intervals around means are based on Fisher's LSD procedure (p < 0.05). F ratios are











Before Treatment to After Treatment
Ratio of Leaf Length

1.5 -


0.5 -
0-
SST3 PW SW

Before Treatment to After Treatment
Ratio of Number of Leaves per Shoot

1.5 -


0.5

0 S
SST3 PW SW


1119ra ghrily"1%IftV 0%9 1 fttv M^ lo -









~au -->.;.n. Vsa 4iiIU L4a1uiLLU UcVL.IUI UI IiUipiipumclrL-_ maIU-U1TCu Oun natoaute
rigs prior to and after experimental treatments.

Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. Dev.
Shoot Number
SST3 5.29 2.18 5.87 2.67
PW 4.71 2.29 6.88 2.85
SW 5.00 1.84 7.17 3.06

Rhizome Length (cm)
SST3 9.42 4.02 7.70 4.19
PW 10.29 2.88 9.90 6.15
SW 8.96 4.33 8.67 3.68

Leaf length (cm)
SST3 5.89 1.72 2.68 1.20
PW 6.18 1.74 2.81 1.12
SW 5.73 1.91 2.84 0.75


I












..T ~ ~ ~ A T \k .^ ^ -*1









0 5 10 15 20 25 30
Experiment Day




Before Treatment to After Treatment
Ratio of GLI

'1- ^ -- 4-
1.5

0.5 S--W
0 -
SST3 PW SW


S1J. I. LIJA'.,t, U r.V I ..I LJ.L'WlL X, i|CL '.. LiI IC V. 11, lIlL',. V %0lI UCUV. I .t 1 YAL'O..L 0 iI.MOIX O11ld tJI l C"tI.0 L
difference (LSD) procedure. If the means are not significantly different, the intervals wil
overlap 95% of the time.













Before Treatment to After Treatment
Ratio of Number of Shoots

1.5 -


1 -------------------
0-
SST3 PW SW

Before Treatment to After Treatment
Ratio of Rhizome Length

1.5

0.5 .--.

0 -
SST3 PW SW

Total Sprig Biomass per Length (glcm)

0.015 T----------------
0.015

0.005 -
0.005









Before Treatment to After Treatment


1.5


0.5

SST3

Before Tr
Ratio of Ni

1.5
1
0.5
0 -
SST3


0 Iatm4


Patm(
r Shi



-u


atmei
nber


Aftei
save







N


2-
1
0 -:::a
SST3 PW SW





Figure 4-27: Leaf characteristics for Ruppia after Experiment 3. Intervals around means
are based on Fisher's LSD procedure (p < 0.05). F ratios are given when differences
between means are significant.


Before Treatment to After Treatment
J m i m, .=


I


I









)rigs prior to and after experimental treatments.


SW 3.92 0.86 2.49 1.48

Leaf Number
SST3 2.69 0.45 1.94 0.96
PW 2.57 0.49 1.28 0.80
SW 2.57 0.77 1.49 0.92



Experiment 4: Salinity Fluctuation around Different Means


cited at higher salinities. Ruppia had similar responses to b

ses in leaf length and number were greater when salinity fl

range.


treatments is given in Figure 4-29. The treatments are coded as follows: 1) M9- square

wave with an eight day period, an amplitude of 9%o, oscillating around a mean of 9%o

(ranging between 0 and 18%o), and 2) M27- square wave with an eight day period, an


Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. Dev.
Shoot Number
SST3 12.54 6.17 8.96 5.45
PW 9.96 4.13 6.23 5.95
SW 12.13 5.83 6.33 5.83

Rhizome Length (cm)
SST3 13.17 6.18 7.52 5.90
PW 11.08 5.08 3.42 3.91
SW 12.13 4.88 5.79 5.82
















































1113/9 1120/Zw 1/27/W 2



~~___~___Salinity (%.) Temperature (=
Mean 13.12 22.7
Standard Deviation 2.4 2.87
Minimum 1.99 12.84
aximum 17.95 27.35
measured at Collection 16 26


Salinity prior to Collection for Exp 4

8 X








"fA
6M





0 k
4 Al-



116199 1/21/99 2/5/9


Temperature prior to Collection for Exp 4


A A A









40-
35-
30
025 -
20 --- M27
j15
C10
5
0
0 10 20 30
Experiment Day


Mean Salinity over Experiment (%.)

30 ,-,-

210

0


M9 M27


Standard Deviation of Salinity over
Experiment (%o)

12 -
8
4
0
M9 M27

Figure 4-29: Salinity patterns for treatments in Experiment 4. (Coding as follows: 1) T9-
Square wave with amplitude of 9%o, period of eight days, oscillating around 9%0, and 2)
T27- Square wave with amplitude of 9%o, period of eight days, oscillating around 27%o)










Design called for square waves with eight day periods, p


antic


ig bottom, and therefore a significantly greater intensity of

'el (Figure 4-30). The low salinity treatments received high

us, due to elevated concentrations in the freshwater supply,

alinity treatment received slightly higher concentrations of

1).

[easurements

rnity fluctuation affected Thalassia in this experiment, howe

ien salinity fluctuated around a higher mean. The number (

of leaves per shoot increased in the high salinity treatments

-n-leaf indices of Thalassia decreased over the course of th

mnte althoigrh the df.rlintp wua areatfr in the. lPce calinp- tr

Before to after treatment ratios of the number of shoots and rhizome lengths after

the experiment were slight and varied little between the treatments (Figure 4-33, top and

middle panel). The greater belowground biomass in Thalassia in the less saline treatment































Percent Light Reaching Seagrass Depth
F= 314.29 (p=0.0001)
) I
[)75


Figure 4-30: Mean temperature (top panel), light intensity (middle panel) and percent
light reaching depth of seagrass (bottom panel) for treatments in Experiment 4. Error











Total Phosphorus (TP)
0A 10,
-0.3 80.0
S 6,0
0.2
4.0
-0.1 2.0
0 0.0
0%. 180. 36%.
Sanity of Source

Total KJeoldMahl Nitrogen (TKN)
1.2 50.0
-1 40.0+


0 0.0 -
0.4 0.


otal Dissolved Phosphorus (TDP)
0.53 40
0.25
3.0
02
0.15 20
0.1 v10
0.0-L
0.05
0 0.0 -


1%. 0%. 18%. 361
Salinty of Source

Nitrite (NO2)
0.0035 12 .0
S0.003 10.0-
S*00.0025 8.0
| | |:2oSooU Io
0.002 [
0.0015 E 6.0 i1-
*0.001 4.0
0.0005 2.0
0 0.0-


S02 10.0 0.2
0.1 T 0.1
0 .0 0
0%. 18%. 36%.
SaKnitv of Source


1 1__ _ _ _ __ _ _ _ _ 1 __ _ _ __ _ _


Orthophosphate (P04)
-0.14
0.12
0.08
0.04

I. 18.. 036% 2
6 18%. 36%.


)issolved Inoi



I


Am



I


NI



I


E-4- -l


I














H--4--T









I I
0 5 10 15 20 25
Experiment Day





Before Treatment to After Treatment
Ratio of GLI
F= 11.36 (p=0.0071)
-1.5-1



0.5


Figure 4-32: Green-leaf indices for Thalassia over Experiment 4 (top panel) and before
to after treatment ratios (bottom panel). Error bars on time series chart represent standard
error, those on percent change chart are intervals based on Fisher's least significant









Before Treatment to After Treatment
Ratio of Number of Shoots

1.5 -1
1 --

0.5 -
0 -
M9 M27

Before Treatment to After Treatment
Ratio of Rhizome Length

1.5 -
1 --------,--x ----

0.5 -
0 -
M9 M27

Belowground Biomass per Rhizome
Length (g/cm)

0.025
0.02
0.015
0.01
0.005
0
M9 M27




Figure 4-33: Before to after treatment ratios of shoot number (top panel) and rhizome
length (middle panel), and belowground biomass (bottom panel) for Thalassia in
Experiment 4. Intervals around means are based on Fisher's LSD procedure (p < 0.05). F
ratios are given when differences between means are significant.








decreased less in the more saline treatment, and the number of leaves increased by a

average of over 20% (Figure 4-34, top and second panel). Thalassia sprigs in the le:

saline treatment ended with approximately 40% fewer leaves per shoot. Abovegrou

structures in the less saline treatment had more biomass, however (Figure 4-34, botti

panel). Average shoot, rhizome, and leaf measurements, and the standard deviation,

the measurements, are given in Table 4-7.

Halodule Measurements

Overall declines in Halodule GLI were also observed in both treatments (Fig

4-35). In the more saline treatment, Halodule GLI increased during the initial third

experiment. During this time the GLI of sprigs in the less saline treatment sharply

declined. By Day 15, GLI reached its lowest level in the less saline treatment, where

remained for the remainder of the experiment.

The number of Halodule shoots in the more saline treatment decreased less E

treatment than those in the lower salinity treatment (Figure 4-36, top panel). Rhizoi

length increased in the higher salinity treatment as well (Figure 4-36, middle panel).

Sprig biomass was significantly greater in the less saline treatment than those in the

saline treatment, however (Figure 4-36, bottom panel).

Leaf lengths declined by about the same amount in both treatments (Figure 4

top panel). Halodule shoots had an average of 14% more leaves after the more salir

treatment in contrast to the 32% decrease in the less saline treatment (Figure 4-37, n

panel). On average, Thalassia and Halodule had an additional leaf per shoot in the i

saline treatment (Figure 4-34, third panel, Figure 4-37, bottom panel). The average

number of leaves was statistically significant higher for Thalassia and Halodule in t








Before Treatment to After Treatment
Ratio of Leaf Length

1.5 -


0.5 -.

0 -
M9 M27

Before Treatment to After Treatment Ratio
of Number of Leaves per Shoot
F= 7.99 (p= 0.0179)
2
1.5

0.5-
0-
M9 M27

Average Number of Leaves per Shoot
after Treatment
F= 5.25 (p=0.0449)
3-
2
1

0 -
M9 M27

Aboveground Biomass per Short Shoot
(g/ss)

025 -
0.2
0.15
0.1
0.05
0 -
M9 M27

Figure 4-34: Leaf characteristics for Thalassia after Experiment 4. Intervals around
means are based on Fisher's LSD procedure (p < 0.05). F ratios are given when
differences between means are significant.


































lard deviations of the measurements, are given in Table 4-8

surements

ia varied little in GLI between the two treatments, in sharp

ecies (Figure 4-38). Green-leaf index increased in both tre<

The increase in the less saline treatment was slightly large


greater in the less saline treatment (Figure 4-39, bottom panel).

Leaf length changed little in either treatment (Figure 4-40, top panel). The


Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. De
Shoot Number
M9 4.39 1.23 4.03 1.30
M27 3.92 1.23 3.92 1.18
Rhizome Length (cm)
M9 33.11 13.52 33.43 11.21
M27 28.15 8.87 28.06 8.48
Leaf length (cm)
M9 18.27 4.50 8.19 7.42
M27 18.37 4.75 11.34 4.93
Leaf Number
M9 2.39 0.60 1.42 1.20
M27 2.33 0.86 2.53 2.06


i'rivr nnnr in m I Hiitr IPX- ExrwinnIFFItiIHI IT'EHLrInIUIIL


I I


I






























) 5 10 15 20 25
Experiment Day






Before Treatment to After Treatment
Ratio of GLI
F= 38.49 (p= 0.0001)

1.5

-I'





















Before Treatment to After Treatment
Ratio of Rhizome Length
F= 12.67 (p=0.0047)
1.5 -


0.5 -
0 -
M9 M27

Total Sprig Biomass per Rhizome
Length (glcm)
F= 5.50 (p= 0.0410)


Figure 4-36: Before to after treatment ratios of shoot number (top panel) and rhizome
length (middle panel), and total sprig biomass (bottom panel) for Halodule in Experiment
4. Intervals around means are based on Fisher's LSD procedure (p < 0.05). F ratios are


Before Treatment to After Treatment
Ratio of the Number of Shoots


1.5
1-

0.5
0


M9 M27


M9 M2Z


I r









Before Treatment to After Treatment


0.5 I
0


Before 1
Ratio o


4 _____


P1111


eatme


-=11.


Afte
r of I
.t
0.006:
O.O6


atmnei
Ds pei


1-


IVIh7 IVI& I I


after Treatment
F= 14.00 (p= 0.0038)
4
3
2
1


Elm






92


Table 4-8: Averages and standard deviations ofmorphometrics measured on Halodule
sprigs prior to and after experimental treatments.


Pre-Experiment Post-Experiment
Average Std. Dev. Average Std. Dev.
Shoot Number
M9 4.89 1.33 2.42 1.61
M27 4.19 1.09 3.75 1.90

Rhizome Length (cm)
M9 12.03 5.19 9.23 5.32
M27 10.74 4.54 10.77 4.75

Leaf length (cm)
M9 7.24 1.84 3.86 2.09
M27 8.42 2.05 5.61 0.93

Leaf Number
M9 2.25 0.50 1.53 0.97
M27 2.25 0.44 2.56 0.65



8% in the more saline treatment (Figure 4-40, middle panel). The number of Ruppia

leaves per shoot, however, was similar in both treatments (Figure 4-40, bottom panel).

Average shoot, rhizome, and leaf measurements, and the standard deviations of the

measurements, are given in Table 4-9.