Oyster reefs at Crystal River, Florida and their adaptation to thermal plumes

UNIVERSITY

OF FLORIDA

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ENGINEERING AND PHYSICS
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OYSTER REEFS AT CRYSTAL RIVER, FLORIDA
AND THEIR ADAPTATION TO THERMAL PLUMES

By

MELVIN Eo LEHMAN

THESIS PRESENTED TO THE GRADUATE COUNCIL OF THE
UNIVERSITY OF FLORIDA
N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

1974

ACKNOWLEDGEMENTS

Dr. Ho T. Odum deserves foremost appreciation as committee chair-

man and advisor. The support and guidance of such a stimulating and

erudite individual was truly a unique experience.

Dr. W. E. Bolch and Dr. P. L. Brezonik made special contributions

as members of my committee. The contribution of Dr. H. A. Bevis

during final review of the thesis was greatly appreciated.

Dr. F. J. Maturo, Mr. Mike Osterling, and Mr. Clay Adams indenti-

fied reef animals. Maury Sell assisted with modeling and the analog

computer. Lance Gunderson, helped in the field and with drafting of

figures, and Don Young, Dan Hinck, Mark Homer, and Walt Boynton provided

commentary and field help.

Special thanks go to my wife, Amalia, for her native impatience,

which provided extraordinary incentive.

This work was supported under Florida Power Corporation contract

# GEC-159, 918-200-188.19, entitled "Models and Measurements for

Determining the Role of the Power Plants and Cooling Alternatives at

Crystal River, Florida", H. To Odum, principal investigator.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS ............................................... ii

LIST OF TABLES ........... ........................................ iv

LIST OF FIGURES ......................................... ..... v

ABSTRACT .......................... ..................... o ....... ix

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

Previous Studies of Consumer Reefs .......................... 2
Oyster Reefs in the Crystal River Estuary ................. 3
Oysters and Effects of Temperature .......................... 10
Conceptual Model of Reefs at Crystal River, Florida ........... 12

METHODS ... 0 ....... 0 0......... .. ....... ............. .... ......00. 22

Biomass and Numbers ..................................... 22
Diversity ..................... .................... 23
Larval Setting ....................................... .. 23
Metabolism .. ....................................... ...... ... 26
Exposed reefs with CO2 gas exchange .................... 26
Underwater with artificial channels ...................... 32
Total reef metabolism .................................... 40
Development of Models, Simulation, and Energy Calculations .... 40

RESULTS ............. ... .... ... ..... ......... .................. 44

Biomass and Numbers ........................................ 44
Larval Setting .............. ... ............ .... 0......... 53
Diversity ................... ......... ............. ...... 65
Metabolism ........ .......... ........... ................... 65
Underwater with artificial channels ..................... 65
Exposed reefs with CO2 gas exchange ......... ......... 82
Total reef metabolism ................................. 82
Simulation of Seasonal and Temperature Effects ........... 93

DISCUSSION .............................o .......... ......... 149

Seasonal Pattern ................ ..................... ....149
Metabolism, Current, and Temperature ..................... 150
Diversity and Temperature ................................... 150
Turnover and Temperature ....................................151
Comparison of Thermally-Affected and Unaffected Reefs ........ 152

Comparisons with Reefs Elsewhere ............................ 153
Role in the Estuary ..........o.......................o..... 154
Adaptation and Power Plants ................................ 155

APPENDICES

A Details of Analog Simulations ................................ 157

B Data ............................ .................. .... ....166

BIBLIOGRAPHY ...... .......... ................................... 190

BIOGRAPHICAL SKETCH ................................................ 197

LIST OF TABLES

Table Page

1 Dry Weights of Oyster Reef Organisms in the Discharge Bay ..... 45

2 Dry Weights of Oyster Reef Organisms in the Control Area ..... 47

3 Numbers of Organisms per 0.25 m2 in the Discharge Bay......... 49

4 Numbers of Organisms per 0.25 m2 in the Control Area..........o 50

5 Ratios of Dry Weight to Wet Weight as Percentages for
Selected Organisms in Discharge and Control Areas ............. 60

6 Area-Weighted Estimates of Biomass.......................o.. 61

7 Oyster Reef Set Count Data. Set Cage Count in Discharge
Bay .......... *.................00. .000............. .....oo.... 62

8 Oyster Reef Set Count Data. Set Cage Count in Control
Area ...o... .. .... ..o .... ..... o .. ..... ... . .. ....... 63

9 Spat Count Data from Biomass Samples. Discharge and
Control Areas........................................... 68

10 Diversity Indices. Discharge Bay............................. 70

11 Diversity Indices. Control Area7............................ 72

12 List of Common Marine Animals Collected from Oyster Reefs
at Crystal River, Florida, 1973-1974.....o..................o. 74

13 Simulation Results, Thermally-Affected Oyster Reef Model .o... 96

14 Sources, Storages and Rates for Thermally-Affected Oyster
Reef Model0............................o.................. 98

15 Simulation Results0 Control Area Oyster Reef Model......o.....21

16 Sources, Storages and Rates for Control Area Oyster Reef
Model............... ................... ....................123

LIST OF FIGURES

Figure Page

1 Site of Florida Power Corporation Electrical Generating
Power Plants at Crystal River, Florida..................... 5

2 Crystal River Oyster Reef Sampling Sites in Discharge Bay.... 7

3 Oyster Reef Sampling Sites in Control Area.................. 9

4 Model Used to Conceptualize the Oyster Reef,................ 14

5 Symbols Used in Model Diagrams..............................o 16

6 Reefs at Crystal River Showing Spat Cages, July 20, 1973 ..... 25

7 Measurement of CO2 Exchange with Gas Analysis................... 28

8 Channel Used to Measure Underwater Metabolism ....o........... 34

9 Artificial Channel with Floating Diffusion Dome............. 38

10 Oyster Reef Model Evaluated with Field Data and Used for
Simulation .o...,............ ......... ....... ... ............ 42

11 Height-Frenquency Distribution Curves for Oysters., .......... 52

12 Relationship of Whole Wet (Blotted) Weight to Shell Height
for Crassostrea virginica in Discharge Bay, July 30, 1973,
Reef 6........... ....................... ...... ............ 55

13 Relationship of Whole Wet (Blotted) Weight to Shell Height
for Crassostrea virginica in Control Area, August 6, 1973,
Reef 5.,............................. o ................... 57

14 Relationship of Wet (Blotted) Meat Weight to Shell Height for
Crassostrea virginica in Control Area, January 10, 1973,
Reef 4.......... ... ................ o..... ..................... 59

15 Seasonal Larval Setting Rates of Oysters....................67

16 Upstream-Downstream Data Using Plastic Channels for One
Hourly Measurement, October 8, 1973, in Discharge Bay,
Reef 6.7.... ...... ..... ... ... .o........... ..... 79

17 Composite of Upstream-Downstream Oxygen Changes in Plastic
Channels in Discharge Bay Over Three Tidal Cycles, Reef 6....81

vi

Figure Page

18 Composite of Upstream-Downstream Oxygen Changes in Plastic
Channels in Control Area Over Three Tidal Cycles, Reef l..... 84

19 Respiration Versus Current ................................o.. 86

20 Respiration Rates of Exposed Oyster Reef Assemblage, July
30, 1973, in Discharge Bay, Reef 2a.......................... 88

21 Respiration Rates of Exposed Oyster Reef Assemblage, July
30, 1973, in Discharge Bay, Reef 2b, with corresponding Tide
and Solar Insolation Data.................................... 90

22 Respiration Rates of Exposed Oyster Reef Assemblage, August
7, 1973, in Control Area, Reef 4, with Corresponding Tide
and Solar Insolation Data............................ ....... o. 92

23 Evaluated Oyster Reef Diagram for Thermally-Affected Area..o. 95

24 Simulation Data Versus Field Data. Thermally-Affected
Oyster Reef Model......... ....... ..........*....... ..o o 0..105

25 Simulation Graphs. Temperature Effects on Thermally-Affected
Oyster Reef Model .......0...................... ..... ........ 107

26 Simulation Graphs. Changes in Respiration (Current Effect).
Thermally-Affected Oyster Reef Model.................. .......111

27 Simulation Graphs. Changes in Reef Standing Stocks (Harvest
Effect). Thermally-Affected Oyster Reef Model............... 113

28 Simulation Graphs. Changes in Food Supply. Thermally-
Affected Oyster Reef Model .......o ............................115

29 Simulation Graphs. Changes in Spawning Temperature0
Thermally-Affected Oyster Reef Model ....................... 117

30 Evaluated Oyster Reef Diagram for Control Area...............120

31 Simulation Data Versus Field Data. Control Area Model....... 130

32 Simulation Graphs. Temperature Effects on Control Area
Model ................ ....... o.. .... .............. .... o. .132

33 Simulation Graphs. Changes in Respiration (Current Effect).
Control Area Model ................... ..................... 000.136

34 Simulation Graphs. Changes in Reef Standing Stocks (Harvest
Effect)o Control Area Model.................................o o138

35 Simulation Graphs, Changes in Food Supply. Control Area
Model...o. ............. ....... .. o ....... .... .. ... .. .... 40

36 Simulation Graphs. Changes in Spawning Temperature. Control
Area Model. ........................................... 142

vii

Figure Page

37 Food Chain Diagram. Discharge Bay..........................146

38 Food Chain Diagram. Control Area........................... 148

Abstract of Thesis Presented to the Graduate Council
of the University of Florida in Partial Fullfillment of the Requirements
for the Degree of Master of Science

OYSTER REEFS AT CRYSTAL RIVER, FLORIDA
AND THEIR ADAPTATION TO THERMAL PLUMES

By

Melvin Earl Lehman

December 1974

Chairman: H. T. Odum
Major Department: Environmental Engineering Sciences

Intertidal oyster reefs receiving thermal effluent from power

plants were compared with those unaffected nearby. Field measurements

of biomass gave area-weighted estimates of 253 g/m2 (dry meat weight)

for the thermal area, and 256 g/m2 for the control area. The American

oyster, Crassostrea virginica, comprised 78% of the total consumer

biomass in the thermal area, and 47% in the control area. Lower species

diversity in the thermally-affected area may reflect the greater oyster

dominance. Oyster spat setting rates were similar in both areas with

less seasonal variation in the plume-warmed waters. Total community

respiration of reefs in the thermal plume was 20.9 g 02/m2/day. Respi-

ration of reefs not in the thermal plume was 15.7 g 02/m2/day. Under-

water metabolic rates of thermally-affected reefs were six times greater

than rates during exposed periods at low tides. The underwater rate

was three times the exposed rate for reefs not receiving thermal

effluent.

Simple models evaluated and simulated to help understand reef

function showed higher turnover rates with the thermal plume model.

Simulation of effects of adding thermal waters of another power plant

suggested reduced seasonal variation of reef standing stocks0 When

ix

temperatures were increased 40C, reef stocks were decreased by 20%.

Simularities of reef system structure and function, and comparable

energy budgets, of thermally-affected and unaffected reefs, suggests

successful adaptation of reefs at Crystal River to thermal plumes.

Food chain diagrams indicated the organic budget of oyster reefs

to be as high as 46% of the total organic matter in the water column

of the Crystal River estuary,

INTRODUCTION

This is a study of oyster reef ecosystems (mainly Crassostrea

virginica) at Crystal River, Florida where some have adapted to a

thermal plume from power plants operating approximately seven years.

Measurements of the structure and function of oyster reefs in and out

of the thermal plume were made to characterize their over-all proper-

ties of mass, metabolism, and diversity as an ecological unit. Simple

models were evaluated and simulated to help understand present eco-

systems and to suggest the response and adaptation of the oyster reef

with additional power plant effluents. For ecological perspective and

for use in impact studies, the organic budget of oyster reefs in the

estuary was estimated.

As a subsystem of the estuary, oyster reefs may perform functions

for the larger system in exchange for organizational services in supply

of food. For example, the estuary sends energy via food-bearing

currents to the oyster reef and receives back nutrients. This feed-

back loop may stabilize the relationship of parts to the whole. In

new situations feedback stabilization loops may' develop as mechanisms

of self-desigh that help a system maximize its power by improving the

exchange among its components. Such changes as increased heat may

require adjustments by the species. Adjustments are made by the natural

selection process or by mechanisms of adaptation selected previously.

This study considers the long-term ecological adaptation that develops

between power plants and oyster reefs after the first period of rapid

transition is over.

Previous Studies of Consumer Reefs

Early studies of oysters and their associations were summarized

by Churchill (1919), Galtsoff (1964), and Mackin and Hopkins (1961).

Most work concerned biology and physiology of the oyster.

In Florida, field measurements by Ingle and Dawson (1952) on the

growth (shell length) of the American oyster, and a later study by

Dawson (1955) included reef distribution at Crystal River. Copeland

and Hoese (Texas, 1966) evaluated reef biomass and production on an

area (g/m2) basis. Studies of distribution and growth preceded

holistic reef investigation and concentrated on the economic harvest

of oysters.

Hedgepeth (1953) characterized oyster reefs as important biotic

aggregations, and described the predominant physical factors and

species character of some in the Gulf of Mexico. Chestnut (1967, 1974)

summarized properties of the oyster reef in a review of literature.

The concept of the oyster reef as an animal city (Odum et al., 1967-

1974, and Odum, 1971b) suggests concentrated metabolism and a wide

variety of organisms, a functional unit, not one of independent parts.

Documentation of some properties of a consumer reef was done by Nixon

et al. (1971) in Rhode Island. Measurements of community metabolism

and biomass on beds of the mussel, Mytilus edulis, showed importance of

outside forcing functions such as current.

A recent estimate of a gross energy budget for the American oyster

was given by Day et al. (1973). The gross energy budget for the

Pacific oyster, Crassostrea gigas was calculated by Bernard (1974).

These calculations are necessary for reef system model simulations

and energy value determinations.

Oyster Reefs in the Crystal River Estuary

The majority of the power plants in operation and under construc-

tion in the state of Florida are sited in coastal areas. Florida

Power Corporation has operated power plants at Crystal River on the

west coast of Florida for several years (Fig. 1). Unit one operation

(387 megawatt) started in July, 1966 and unit two (510 megawatt)

started in Novi mber, 1969 (Directorate of Licensing, AEC, 1973). A

nuclear plant (885 megawatt) is under construction and is scheduled to

add effluent in 1975 or 1976.

A once-through cooling process introduces thermal effluent into a

shallow bay and estuarine system from two oil-fueled generating plants

at this site. The combined temperature change (AT) across the conden-

sers of the two units is about 6.4C. Oyster reefs as subsystems of

the receiving estuary are subject to a thermal bath consistently 40C

warmer than surrounding natural waters. Of more than 260 hectares of

estuary predominantly influenced, oyster reefs comprise about 3%.

Measurements were taken in two areas. The thermally impacted area

north of the power plant discharge channel and the control area south

of the intake canal shown in Fig. 2 and Fig. 3, respectively. Six

reefs in the discharge bay and five reefs in the control area were

chosen.

Figure Io Site of Florida Power Corporation Electrical Generating Power Plants at
Crystal River, Florida.

'' Bay
I j- o

oRiver
Kilometers "::' :. v : .,i -
-. ..

0 0.5 1 :: "
r For

Nautical Mile Fort o:.
Island ;y
(J
-J~ti
r' .N

0~ I 2

Nautica Mile-a

3 ':'c l

Figure 2o Crystal River Oyster Reef Sampling Sites in Discharge Bayo
Note reefs 1 through 6.

Ni MIE ^ "" /"

DRUM -
ISLAND C A

0 -0. 2 PE AT .-OUTER BAYK

: JINNER BAY
I------I------ KILOMETERS
0 0.5
S--I-- NAUTICAL MILES N DISCHARGE CANAL
0 0.25 POWER PLANT 2.1 KM

Figure 3. Oyster Reef Sampling Sites in Control Area

I T E C A LP W R L- -
I POWER PLANT 2 KM
INITAKE CANAL

I --------I KILOMETERS
0 0.5

I I ---- -- NAUTICAL MILES
0 0.25

6

6

i2

CRYSTAL RIVER ENTRANCE
CHANNEL

t 0.73 KM

~1

'"''

Oysters and Effects of Temperature

Temperature has been designated as one of the most important

single factors in the environment of the estuarine organism,

Crassostrea virginica by Gunter (1957). However, effects of tempera-

ture on isolated examples of indigenous reef species may not be the

same as when all energy flows, interactions, and species are considered

together.

Temperature and Metabolism

Galtsoff (1928), Nelson (1935) and Loosanoff (1958) found that

increasing temperature from 40C to 340C increased pumping rates by as

much as a factor of 20. Beyond 340C, increased temperature caused a

drastic reduction in pumping, Kennedy and Mihursky (1971, 1972) showed

temperature-increased metabolic rates in some bivalves could lead to

starvation under adverse food conditions rather than thermal death,

Studies by Semper (18. ), Mayer (1914) and Gunter (1957) indicated that

thermal death points for marine animals vary throughout their latitu-

dinal ranges, but concurred that normal activity of the American

oyster is almost completely stopped above 420C.

Quick (1971) found some internal temperatures of 44 490C in

oysters exposed for three-hour periods during low tides in Tampa Bay,

Florida; air temperature was 370Co He offered this as evidence of

recooperative ability, since oysters held at constant temperatures of

these magnitudes generally do not survive.

Temperature, Growth, and Production

Owen (1953) found that a season of low oyster production in

Louisiana followed a previous year of high temperatures and low rain-

fall. Butler (1965) noted increases in meat weight of thermally

acclimated oysters, but found no shell growth. Tinsman and Maurer

(1973) measured a net annual meat growth of Delaware oysters held in

thermal effluent, and attributed increased shell growth to an exten-

sion of the normal growing season. They found seasonal levels of

biomass (glycogen content) to be highest during late fall, winter, and

early spring (November through March). Engle (1957) described seasonal

biomass (percent solids) levels on commercial oyster reefs as highest

in late fall and spring with a summer low following spawning, and a

second low in mid-winter attributed to a period of hybernation. Data

from Hawaii showed lowest biomass (condition index) levels from May

through October, when seasonal temperatures were high and highest

levels during the period from November to June when temperatures were

lower (Sakuda, 1966a).

Temperature and Spawning

In 1881, Semper suggested that some tropical organisms may have

continuous breeding seasons. Thorson (1946) found larval stocks of

some tropical marine animals throughout the year; oysters in Hawaii

(Sakuda, 1966b) released spawn primarily March through October, but

started as early as February and continued into November. Spawning in

temperate and higher latitudes is usually associated with the warmer

seasons of the year with a spring spawning peak (Loosanoff, 1966)o

Hopkins (1931) stated that a long warm season may induce two spawning

peaks; a spring peak and a smaller fall peak. The larger spawning

peak was found to be in the fall for some estuarine bivalves (Kennedy

and Mihursky, 1971). Gunter (1957) stated successful spawnings may be

four years apart in extreme northern ranges. He cited oyster spawning

in Long Island Sound at 160C while southern oysters require 200C.

Menzel (1974, personal communication) indicated temperatures up to 240C

may be necessary to induce spawning in Florida waters. Preliminary

indications by Gennette and Morey (1971) were that periodic high

temperatures (350C) did not grossly interupt the spawning cycle of

oysters in Tampa Bay, Florida.

Diversity and Temperature

A compilation of world-wide taxonomic diversity data for bivalves

(Stehli et al., 1967) showed a consistent poleward decrease in number

of species. According to Wade (1972), species diversity in a tropical

estuary was inversely related to environmental stress levels; the

greater the stress the lower the diversity.

Conceptual Model of the Reefs at Crystal River, Florida

It is possible to simplify and summarize one's view of an ecologi-

cal system through the use of models. One model used to conceptualize

the oyster reefs at Crystal River (Fig. 4) incorporates a pictoral and

mathematical representation of process pathways, storage, and forcing

functions, using energy language developed by H, To Odum (1971 and 1972).

Symbols used in the models in this thesis are described in Fig. 5.

In this model, the energy sources considered important were

larvae, salinity variation, food, current, tide, and heat. It is

through the interaction with current that food and larvae reach the

reef, and thermal effluent and varying salinity become major factors.

Most of these interactions are possible only when the water level is

sufficient to cover the reef. Tidal exchange was simulated by a

comparator-switch mechanism programmed with a mean tidal level to switch

Figure 4o Model Used to Conceptualize the Oyster Reef.

*pert

Figure 5. Symbols Used in Model Diagrams.

Forcing Function. Outside source of
energy or materials: such as sun, fossil
fuel, heat, tide, water, or food.

Pathway of energy or materials. Arrow
designates flow in either direction or flow
against a backforceo Flow, J, is proportional
to population of active forces, N.

J2

kS

Adding Junction. Intersection of two flows
capable of adding. J1 + J2 = J3

Heat Sink by which potential energies entering
the system leave in degraded form according to
the second law of thermodynamics. Outflow is -kS.

Passive Storage of energy or materials in which
no new potential energy is generated. Work
must be done in moving the potential energy in
and out of the storage. This is called a
state variable with the sum of the inputs and
outputs being dQ/dt = J kQ.

Figure 5. (continued)

kJIJ2

Workgate. Intersection at which one flow
makes possible another. In this case one
flow affects the conductivity of the other
to produce a multiplier output, kJ1J2.

Workgate. Special case of the above where
temperature is used as a linear input.
Output is kJT.

Rate Sensor monitors flow rate and controls
input of another flow in proportion to
monitored flow.

Self-Maintaining Consumer uses its own
stored potential energy to do work on the
processing and work of the unit. An auto-
catalytic response through combination of
passive storage, workgate; can symbolize
an animal, city, industry, oyster reef
system, etc.

Special Case of self-maintenance that
adjusts inflow to depreciation.

Figure 5. (continued)

Flow a Squared Function from a passive
storage. Represents loss of potential
energy: eg, stress function such as
disease, or high energy cost of information
storage. Output is kQ2.

Logic Comparator with a critical threshold,
T; logic on or off control depends on which
input (+ or -) is larger

On-Off Switch to a flow.

Comparator-Switch Mechanism combines above
two components for switching action of flows
that control other flows: eg, switching
off flows of food, larvae, and salinity
when tide is out, on when it is in,

General Symbol for switching functions

the flow from the forcing functions off or on as water level changed.

Standing stocks included larvae biomass, oyster biomass, reef

structure, biomass of all organisms other than oysters, and diversity.

The shell portion of reef organisms is stored as reef structure, the

majority of which is oyster shell. Diversity is an information

storage of species per thousand individuals. Transfer of energy

between the forcing functions and the state variables occur along the

connecting pathways. Important natural processes such as a disease,

harvest, and feces and pseudofeces deposition are included in the

export pathways.

Increased temperatures accelerate respiration and stimulate food

flow through a workgate-sensor combination on the respiratory pathway.

This push-pull effect increases turnover times of storage and subse-

quently affects all other flows and processes in the system. Because

the temperature range at Crystal River is small, a linear temperature

action was used as an approximation,

METHODS

Field measurements were made of reef organism numbers and biomass,

reef metabolism and diversity, and "set" of oyster larvae

Biomass and Numbers

Measurements of biomass of oyster reef organisms from samples in

the discharge bay and control area were made during two seasons of the

year. A total of six biomass samples were collected in each area;

four summer samples and two winter samples. Duplicate samples were

taken from one reef in each area to check sampling variability.

Samples were selected from zones of highest organism density by a

random toss of a quarter meter square quadrant. One control sample

was taken from a lower density zone on a reef fringe. All organisms

and structure within the quadrant were removed to a depth of 10 cm,

transported to the laboratory and frozen consolidated. Samples from

which relationships of oyster weight and height were determined were

processed fresh. All conspicuous organisms from these samples were

counted, identified and weighed. Dry weights of organisms were taken

after one week at 105 C. Area-weighted values of oyster reef standing

crop calculated for each bay were used in the simulation models

Diversity

Number of species per thousand individuals as an indicator of

community diversity was determined by counting the first 1000 organisms

encountered on each oyster reef. The species diversity of the

macroinvertebrate community was measured by this method for six reefs

in the thermal discharge area and five reefs in the control area over

the summer and winter seasons. Duplicate counts were made during the

summer. Data on species per thousand were translated into several

other diversity indices.

Representatives of each species encountered on the reef were

collected, preserved, and identified. A species list contrasted

organisms collected in the thermally-affected area with those in the

control area.

Larval Set

Estimates of larval setting rates were made for oyster larvae by

two methods. Spat in biomass samples were counted and weighed to

determine differences in standing stocks with season. In the second

method counts were made of set on shell placed on the reef. Wire

"cages" were attached to the reef substrate (Fig. 6). Each cage con-

tained a quarter square meter of oyster reef structure loosened from

the reef and placed inside the anchored cage. Set were removed,

counted, and weighed from four spat cages in each area for three

periods of the year; May-June, June-December, and December-May.

Figure 6. Reefs at Crystal River Showing Spat Cages, July 20,
1973.
a. Discharge area, reef 5.
b. Control area, reef 4.

25

b.

I _

Metabolism

Reef metabolism was measured by two methods. One when reefs were

exposed to air, and another when reefs were underwater.

Exposed Reefs with CO2 Gas Exchange

Changes in carbon dioxide concentration in the air flowing over

plant and animal ecosystems have been sensed by using infrared gas

analyzers (IRGA) as measures of metabolism of the communities During

the summer of 1973, an IRGA unit was operated in the salt marshes

bordering on the discharge bay and control area (Young, 1974b).

Proximity of the oyster reefs to the marshes afforded an opportunity

to investigate metabolism of oyster reefs during periods of low tides.

Two quarter-meter square samples were removed from reefs in the dis-

charge bay and transported to the gas metabolism unit. Each sample

was placed inside a gas metabolism chamber (Fig. 7) at its approximate

reef elevation, and hourly carbon dioxide changes were measured over a

24-hour period. Similar measurements were made for a reef sample in

the control area.

Calculations of diurnal rates of respiration and photosynthesis

and details of the complete sampling apparatus have been described by

Odum (1970), Lugo (1969), and Young (1974). A basic equation used for

CO2 calculations

Sg C/2 hr (diff.) (flow) 273. P 12 g C/mole 60 min/hr
was: g C/m hr, = T( ) ()(g g/mole 0)
(area) -T 760 22.4 k/mole 06

where diff. = difference in ambient CO2 concentration and chamber CO2

concentration calibrated to some standard gas such as 300

gas (300 ppm CO2)o

Figure 7. Measurement of CO? Exchange with Gas Analysis.
a. Plastic bag with oyster.
b. Schematic view of the infrared gas analyzer unit.

28

_

Figure 7o (continued)

Ambient air
supplied at

Strip Chart
Recorder

Temperature _
,Thermocouples
Exhaust Flowmeters
-Air Sample IR Gas
7;s^^/ A ^ Ambient Analyzer
-Exhaust Air
Thermocouple
iGas Recorder

< Continuous Pumps
Air Samples Thermocouple

.92m Leads
LBlower

Chamber
Enclosure
Mud Seal--

D.92m m li"
dia.
(a.) (b.)

flow = air flow rate through chamber, liters/mino

area = area of reef, square meters

T = absolute temperature, Kelvin.

P = atmospheric pressure, mm Hg

One of the calculations made from field data is offered as an example

(Control Area, August 7, 1973);

Time Flow Press. TempoC CO2chamber CO2ambient
1824 1361i/min 760 mm Hg 31.7 280.5 ppm 278.5 ppm

Rate = (278.5 280.5 ppm) (1361) /min.) 2730K 760
0.2500 m2 304o70Kd 760

12 g C/mole) 60 min/hr
S22.4/mole 109ppm

= 30.85 x 10-2 = -0.31 g C/m2/hr (negative sign implies respira-
tion)

A total of seventeen hourly respiration measurements were obtained for

each sample in the discharge bay; eighteen in the control bay. The

difference in number of measurements and hours sampled reflects periods

of high tide when the reef communities in the chambers were submerged

and no significant changes in CO2 concentration were recorded.

Rate-of-change curves plotted for each diurnal measurement were

integrated to obtain respiration values in units of g C/m2/day for the

bay. After each metabolism measurement biomass of chamber samples was

determined by methods previously described, and respiration values of

g C/g dry wt/day calculated.

Underwater with Artificial Channels

Upstream-downstream changes in flowing waters have been used to

measure community metabolism for a variety of ecosystems; coral reefs

(Odum and Odum, 1955), turtle grass beds and freshwater springs (Odum,

1956, 1957), streams (Hall, 1971) and mussel beds (Nixon et al., 1971).

The methods described by these authors were adopted to measure under-

water respiration of the oyster consumer community on two reefs, one

thermally-affected and the other natural.

Review of the main metabolic processes in the tidal stream flowing

over the reefs indicated that the observed upstream-downstream change

in oxygen would be the algebraic sum of the primary production, the

respiration, the diffusion into or out of the water, and advection

into the sides of the tidal stream. A channel of polyacetate sheets

and steel posts was constructed parallel to current flow across the

reef to remove lateral advection and diffusion effects (Fig. 8).

Diffusion (reaeration) measurements were made using a floating plastic

dome at the midpoint of the channel stream (Fig. 9) following methods

by Hall (1971) based on the earlier work of Copeland and Duffer (1964),

Diffusion rates were calculated as g/m2/hr/100% saturation deficit for

seventeen measurements over a tidal cycle. From these measurements, a

multiple regression equation was calculated relating diffusion, currency

speed, and depth. This graph (Appendix B) was used to estimate diffu-

sion rates for sampling periods when no diffusion data were taken.

Oxygen concentration was measured at the upstream and downstream ends

of the channel by analysis of quadruplicate water samples using azide

modification of theWinkler method (Standard Methods, 1971) adapted for

125 ml collection bottles. Measurements of temperature, salinity,

current speed fluoresceinn dye), and depth were also made with each set

of samples.

Channel Used to Measure Underwater Metabolism.
. and b. Photographs of reef 6, discharge bay,
July 7, 1974, at low tide.
Co and d. Photographs of reef 4, control area,
July 4, 1974, at high tide.
Note power plants in background,

Figure 8.

34

b.

a.

Figure 8. (continued)

36

d.

___

Figure 9. Artificial Channel with Floating Diffusion Dome.
Photograph at reef 6, discharge bay, July 7, 1974.

38

Fe 1w
-j^' L r* ' T^-
w^ " T' ~ -25C
S&. ___ ' ^

'i~ S2^ --"' '"'-"^"TB^

Underwater community metabolism with artificial channels was

followed hourly and sometimes on the half hour over three consecutive

tidal cycles during July, 1974. This effort included 23 measures of

metabolism in the discharge bay, and 17 in the control area. Calcula-

tion of one of these metabolic rates is illustrated:

g 02/m2/hr = [(Ag 02/m3)
S02/m2/hr = [g 02 ) (depth)] (diffusion correction)
(res. time)

where, (Ag 02/m3) =

res.

diff. corre

difference between upstream and downstream,

plus (+) implies downstream greater than

upstream and minus (-) implies downstream

less than upstream.

time = time difference between upstream and down-

stream station based on current speed;

residence time (in channel) of water volume

sampled.

depth = average depth of water flowing over reef

during sample.

action = diffusion rate x saturation deficit (for

conditions of current, depth, temperature

and salinity during sample). The degree of

saturation of water column determines sign:

(-) undersaturation, (+) oversaturation.

(Discharge Bay, July 7, 1974)

Time Current Ag 02/m3 Res. time Depth % Sat. Diffusion
183- 0.214 m/sec -0.11 0.026 hr 0.71 m 117.68% 3.59 g/m2/hr/l00%
sat, def.

Rate = [(-0.ii g 02/3 ) (0o71m)] [(+0.18 sat. def.) (3.59 g 02/m2/hr/l.O
(0026 hr) sat. defo)]

= [(-4/23 g 02/m3/hr) (0.71 m)] + (0.64 g 0 /m2/hr)

= -3.00 g 02/m2/hr) + (0.64 g 02/m2/hr)

= -2.36 g 02/m2/hr (neg. sign implies respiration)

Intergation of the rate of change curves of hourly rates over the

entire sampling period gave total respiration values that could be

interpreted on a g/m2/day basis.

Total reef community

Total reef metabolism was the sum of the exposed value (low tide)

and the underwater value (high tide), based on the assumption that

each tidal stage was twelve hours per day.

Development of Models, Simulations
and Energy Calculations

Two models of the oyster reef system were developed. A more

detailed model was used for conceptualization (Fig. 4), and a simpli-

fied model for simulation using data from field measurements (Fig. 10)o

Three basic groups of symbols used in the oyster reef diagrams

were forcing functions (circles), storage (tanks), and flows (lines).

Reference to the model diagram shows the outside energy sources

(forcing functions) considered important to be larvae, salinity

variation, food,current, tide, and heat. Transfer of energy between

forcing functions and storage occur along the connecting pathways.

Stored properties are larvae biomass, oyster biomass, reef structure,

biomass of all organisms other than oyster, and diversity.

Figure 10. Oyster Reef Model Evaluated with Field Data and Used for

Simulation, For explanation of symbols see Fig. 5o

Equations are given below.

a. Biomass:

B = K' D + k23JrBH + K15 L k8 B k7 B k B

k20 B k24 BH k9 BS,

b. Diversity:

D = kll BS k D2

c. Structure:

S = k8 B k10 ES k12 S

do Set:

L = k18 L k16 L k15 L + k25 JrBH

e. J remainder (Jr):

Jr = k2P / (l+k21BH)

,...=----

S\l | DIVERSITY kllBS STRUCTURE 1
/ SPECIAL I D
S FOOD CA I

krI B kB.
BIOMASS
I I w U 5
I FOOD 1k2 k2JrBH I k.

SSET- k

,N
l hkl6L T

k24BH H
%-.

43

The effect of temperature, both natural and man-induced, was

diagramed to operate on two pathways simultaneously; pulling on the

respiration pathways and pushing on the food uptake pathways.

Energy values of the forcing functions, storage, and flows of

both models were calculated and put on diagrams. Model simulation was

performed on two EAI MiniAc analog computers slaved to function as one

unit.

RESULTS

Biomass and Numbers

Biomass data are given in Tables 1 and 2, and numbers data are in

Tables 3 and 4, for the discharge bay and control area respectively.

T-tests for differences in mean values of biomass and numbers between

the discharge and control areas gave the following results at the 95%

confidence levels: (1) no significant biomass differences were found

for oysters, reef structure or larval set (spat), (2) significantly

larger biomass was found for all other organisms in the control area,

(3) oyster numbers were not significantly different, but (4) numbers

of spat were larger in warmer waters, and (5) other organisms were less

numerous in the discharge area.

Seasonal differences in the discharge bay oyster biomass proved

significant. T-tests at the 95% confidence level showed no significant

seasonal fluctuations in other stocks such as reef structure, other

organisms biomass and larval set. Significant seasonal differences

were found for other organisms, but trends indicated essentially no

changes in oyster biomass in the control area. A sharp seasonal change

in larval stocks might be inferred from control data in Table 2.

Height-frequency distribution curves of oysters are given in Fig.

11 for both areas. The peaks of the curves are similar, but large

oysters were missing in the discharge area.

Relationship of whole blotted wet weight to shell height for

oysters in the discharge and control areas was determined for two

44

Table 1

Dry Weights of Oyster Reef Organisms and Structure per Quarter-Meter Square.
Crystal River, Florida Discharge Bay

Reef Date Total Reef Total Reef Whole Weight Meat Weight
Number Sampled Weight incl. Structure of of
all organisms g Oystersa Oysters
g _g g

1 July 19, 1973

6 July 30, 1973

2a July 31, 1973

2b July 31, 1973

2a Dec. 07, 1973

25053.2

39137ol

7494.0

8542.6

9668.0

23331.9

35167.6

6699.1

7873.3

8719.7

2120.7

4764.8

837.8

950.3

2030.6

25.3

65.1

6.8

6.9

26.6

2b Dec. 07, 1973 9339.2 8765.0 2115.6 25.1
-----------------------------------------------------------------------------
e 32095.2c 29249.8c 2136.6 26.0
8761.0d 8014.3d

-

S. E,.

577.7

8.7

Table 1 (continued)

Reef Date Whole Weight Whole Weight Whole Weight Whole Weight
Number Sampled of Crabs of of of
g Barnacles Mussels Spat
g g g

1 July 19, 1973 13.8 -

6 July 30, 1973 38.7 7.2 250.8

2a July 31, 1973 9.6 6.7 25.1

2b July 21, 1973 15o7 9.5 0.2 102.2

2a Dec0 07, 1973 7.0 0.4 9.6

2b Dec. 07, 1973 3.7 10.3 31.6

x 148 6.7 3.7 83.9

So E. 5.1 2.2 44.7

a Blotted wet weight in this column only

b T-tests indicate significant difference at 95% confidence level in data in these
columns taken at different sample depths. Reefs 1 and 6 sampled to 20 cm. Reefs
3 and 4 sampled to 10 cm.

c Mean of values from reefs 1 and 6

d Mean of values from reefs 2a and 2b

e x = mean

f So Eo = one standard error about the mean, x

Table 2

Dry Weights of Oyster Reef Organisms and Structure per Quarter-Meter Square.
Crystal River, Florida Control Area

Reef Date Total Reef Weight Total Reef Whole Weight Meat Weight
Number Sampled inclo all organisms Structureb of of
g g Oysters Oysters
_gg

July 20, 1973

Aug, 06, 1973

Aug. 06, 1973

Aug. 06, 1973

Jan. 10, 1974

23826.0

38010.9

12480.4

8552.2

11259.6

17826.9

33486.2

10605,5

6448.9

9014o4

3196,7

2891.0

1647.3

2139.5

1346.5

32.5

39.2

21o6

20.6

20.1

4 fringe Jan. 10, 1974 4830.0 2869.4 284,8 4.0
---------------------------------------------------------------------------------------
x (does not include 30918.4c 25656.6C 2244.2 26.8
fringe sample) 10516o3d 8527.2d

353.4

3.9

SQ Ea

Table 2 (continued)

Reef Date Whole Weight Whole Weight Whole Weight Whole Weight Whole Weight
Number Sampled of of of of of
Crabs Barnacles Mussels g g
g g .g

1 July 20, 1973 33.2 38.7

5 Aug. 06, 1973 27.7 239.4 141.4 82.2 232,8

3 Aug. 06, 1973 11.4 23.7 39.4

4 Aug. 06, 1973 20.7 30.9 38.4 75.2 30.3

4 Jan. 10, 1974 35.0 45,6 59.4 128.1

4 fringe Jan. 10, 1974 3,2 16.6 28.1 70.6
-----------------------------------------------------------------------------------------------------
x (does not include 25.6 105.3 55.0 81,2
fringe sample)

S. E 4.3 67.2 19.7. 18.2

a Blotted wet weight in this column only.

b T-tests indicate significant differences at 95% confidence level in data in these columns taken at
different sample depths. Reefs 1 and 5 sampled to 20 cm. Reefs 3 and 4 sampled to 10 cm.

c Mean of values from reefs 1 and 5

d Mean of values from reefs 3 and 4

e Fringe refers to sample collected in low organism density area on oyster reef

Table 3

Numbers of Organisms per 0.25 m2 Discharge Area

Organism July 19, 1973 July 30, 1973 July 31, 1973 Dec. 7, 1973 x S. Eo
Reef Reef Reef Reef Numbers/
1 6 2a 2b 2a 2b 0O25 m2

Oysters 110 132 150 237 207 207 174 20

Spat 198 425 22 106 39 94 147 61

Crabs 63 179 182 208 111 89 139 24

Mussels 77 2 3 27 25

Barnacles -- 51 154 6 33 61 32

Worms 98 1 -

Amphipods 20 -

Anemones 59 -

Table 4

Numbers of Organisms per 0.25 m2 Control Area

Organism July 20, 1973 Aug. 6, 1973 Jan. 10, 1973 So Eo
Reef Reef Reef Numbers/
1 5 3 4 4 Fringe 0.25 m2

Oyster 411 61 342 228 199 49 248 60

Spat 450 646 360 978 1037 626 696 135

Crabs 136 439 210 281 939 204 401 144

Mussels 391 1025 480 555 1010 410 692 135

Barnacles 6 477 695 159 393 203

Worms 17 42 103 54 26

Starfish 1

Amphipods 36 93 -

Anemones 1 367 -

Conches 2 1 -

Clams 22 -

Figure 11i Height-Frequency Distribution Curves for Oysters.
ao Discharge bay.
b. Control area.

40- DISCHARGE

3o
P

20--

-I 10

0 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10

HEIGHT, cm

CONTROL
S-40

30-

5 20-

= 10
z
a

0 1-2 2-3

8-9 9-10 10-11

HEIGHT, cm

biomass samples (Fig. 12 and Fig. 13). The curves were similar. One

curve of (wet) meat weight and shell length was made for a control

area sample (Fig. 14).

Ratios of dry weight to wet weight are given in Table 5. Those

for the discharge bay were slightly higher for oysters, set, and crabs,

when compared with ratios for the control area.

Area-weighted estimates of biomass based on distribution of mass

relative to each reef and each reef as a percentage of the total reef

system are given in Table 6. The area-weighted values indicated a

higher oyster biomass in the discharge bay. The biomass of all other

organisms was higher in the control area.

Larval Setting

Spat cage setting rates were similar in both areas (Table 7 and

8). T-tests showed the June setting rate peak in the control area to

be significantly higher (95% confidence level) than the March and

September rates. No significant differences were found among rates in

the discharge bay. Annual mean setting rates of 4.6 spat/0.25 m2/day

for the discharge area and 5.3 spat/0.25 m2/day were not significantly

different.

The mean level of 317 spat/0.25 m2 in the discharge area did not

test significantly different from the 280 spat/0.25 m2 in the control.

Larval numbers appeared higher at certain periods of the year; however,

no significant difference could be found between high and low variations.

Differences at the 95% confidence level did exist between some reefs

within the discharge and control areas. Numbers of larvae on reefs

5 and 6 tested significantly different from those on reef 2 in the

Figure 12. Relationship of Whole Wet (Blotted) Weight to Shell Height
for Crassostrea virginica in Discharge Bay, July 30, 1973,
Reef 6.

Y =0.103 x 25

R =0.8785

** .
1010oo

ca

LJ
3-

1 --

1 10 100

SHELL HEIGHT, mm

Figure 13.

Relationship of Whole Wet (Blotted) Weight to Shell
Height for Crassostrea virginica in Control Area,
August 6, 1973, Reef 5.

1.58
Y =0.036 x

R =0.8955

* a

I. a. -

I r *
*w j *-

S. * a

L.

1+ / *'."***
S* * *.

.. a

1 10 1a0

SHELL HEIGHT, mm

*.'.

Figure 14. Relationship of Wet (Blotted) Meat Weight to Shell
Height for Crassostrea virginica in Control Area,
January 10, 1973, Reef 4.

Y =0.00013 x2.43

R =0.9018

*. .14

0.14-

SHELL HEIGHT, mm

10-r

.. / .

Table 5

Ratios of Dry Weight to Wet Weight as Percentages for Selected Organisms in
Discharge and Control Areas.

Area Organism
Oyster Set Crabs Barnacles Mussels Drills Starfish
Meat (incl. shell) (inclo shell) (incl. shell) (inclo shell) (inclo shell)

Discharge 13.4 % 72.7 % 35.6 % 62.9 % --- -----

Control 11o4 % 70,9 % 27.2 % 64.3 % 63.6 % 77.8 % 3700 %

Table 6

Area-Weighted Estimates of Biomassa

Organism Discharge Bay Control Area

Structure Dry meat weight Structure Dry meat weight
(all shell) g/m2 (all shell) g/m2
g/m2 g/m2

Oysters 49,979.2 196o4 35,449ol 119o5

Setb 694.2 36.8 274.9 14o5

Other
organisms 106.2 56.8 748.7 135ol

Total 50,779.8 290o0 36,472.7 269ol

a Area-weighted estimates based on distribution of mass relative to each reef and
each reef as a percentage of the total reef system.

b Spat and juveniles

Table 7

Oyster Reef Set Count Data Set Cage Count.
Number Spat per 0.25 m2,
Discharge Bay.

Reef Number Date Sampled Number Counted Time period Rate, Number/ 0.25 m2/day

May 12, 1973

It it t
IT VT II

Int. count

i1i

IT T;
I1 II

2 June 20, 1973 119 41 days 2.9

II 1T 1T

11 T1 T1

11 11

It II
IT IT

17.3

12.0

2 Dec. 18, 1973 110 181 days 0o6

TI 11 t1

TI TI IT

1t 11

II 11
IT TI

TI II

2 June 1, 1974 21 165 days 0o13

IT TI 11i

I It 11i

11 11

TI TI

S. E.

2.0

Table 8

Oyster Reef Set Count Data Set Cage Count.
Number Spat per 0.25 m2,
Control Area

Reef Number Date Sampled Number Counted Time Period Rate, Number/ 0.25 m 2/day

1 May 13, 1973 560 Initial count

3 t?" "i 159 "

4 2i t 2i43

5 298 "

1 June 22, 597 42 days 14,2

3 519 12o4

4 516 12.3

5 347 8.3

1 Dec0 17, 812 180 days 4o5

3 472 i" 2.6

4 It" "i 388 it" 2.2

5 11" "I 170 i" "i 0.9

1 May 29, 1974 332 163 days 2.0

3 it" "I 357 I" "t 2.2

Table 8 (continued)

Reef Number Date Sampled Number Counted Time Period Rate, Number/ 0O25 m2/day

4 May 29, 1974 197 163 days 1.2

5 t" "it 113 0O7

X 380 5.3

So .E 47 1.5

discharge, while reef 1 differed significantly from reef 5 in the

control (Fig. 15).

Spat count data from biomass samples are given in Table 9.

Accumulations of spat reflected in standing stocks in each area are

different.

Diversity

Results of species per thousand counts are given in Table 10 and

11o Species per thousand data was translated into various other

diversities indices of interest. Mean values of species/thousand were

significantly different between discharge and control areas. Variation

in seasonal values was significantly different in the thermally-

affected area but not in the control area.

Marine organisms collected and identified from oyster reefs are

listed in Table 12.

Metabolism

Underwater with artificial channels

Fig. 16 shows an hourly measurement of the rate of change of

oxygen in a tidal cycle. Rate of change of oxygen over three tidal

cycles is shown in Fig. 17 for the thermally-affected bay. Total

observed change was 36.57 g 02/m2/23 hrso At an average rate of 1.59 g

02/m /hr, and assumed tidal inundation of 12 hours, the underwater

community metabolism rate was calculated to be 17.84 g 02/m2/day.

Correlated with biomass data, this gave a rate of

0,062 g 02
go dry wto

Figure 15. Seasonal Larval Setting Rates of Oysters.
a. Three reefs in discharge bay.
b. Four reefs in control area.

1000

DISCHARGE

REEF 6

500 .

REEF 2

J J A S O N D J F M A M
MONTHS
a.

1000 r

CONTROL

,, 500
SREEF 3 4

U

J J A S N D J F M A M

MONTHS
b.

Table 9

Spat Count Data from Biomass Samples Discharge Bay

Reef Number Date Sampled Number Dry Weight Weight/Individual, g
g (whole)

1 July 19, 1973 198 --

6 30, 425 250.8 0.59

2a 31, 22 110 0.50

2b 106 102o2 1.0

2a Dec. 7, 39 9.6 0.2

2b 94 31.6 0.3

S147 83.9 0.64

S. E. 66 44.7 0o18

Table 9 (continued) Control Area

Reef Number Date Sampled Number Dry Weight Weight/Individual, g
g (whole)

1 July 20, 1973 460

5 Aug. 6, 646 82.2 0o13

3 359 39.4 0.08

4 987 75.2 0.08

4 Jan. 10, 1974 1037 128.1 0o12

4 fringe 619 70o6 0oll

x 698 79.1 0o10

S. E. 136 21.3 0.02

Table 10

Diversity Indices Discharge Bay

Date Reef Number Number Species/ Margalefb Menhinickc Pieloud Shannon-e Simpsonf
Number Indi- Species 1,000a Weaver Dominance
viduals

March: 1 404 8 11 0.81 0,40 0,12 1.03 0,68

2 1057 13 13 1,19 0,40 0.15 1.53 0,43

3 1000 14 14 1.30 0,44 0.21 2.06 0.36

4 1005 13 13 1.20 0.41 0,19 1.93 0.51

5 1004 16 16 1.50 0,50 0.18 1.83 0,48

6 1013 13 13 1,20 0,41 0.17 1.73 0,49

So E. 13.3 +0o7 1.20 0.09 0.43 0.02 0,17 0o01 1,o68 0ol5 0,49 0.04

June: 1 1166 11 11 0,99 0.33 0.20 1.99 0,36

2 1102 11 11 0.99 0.33 0.17 1,o72 0,43

3 1163 12 12 0,98 0.34 0.15 1,46 0.56

4 1175 13 13 1,17 0.38 0,19 1,94 0.36

5 1166 12 12 1o03 0,34 0,16 1,71 0.44

6 1134 13 13 1.19 0,37 0,20 2,02 0.35

So Eo 11.8 0.3 1,06 0.03 0,34 0.01 0.18 0.01 1.81 0.09 0,42 0.03

71

Footnotes to Table 10

a) Odum, Cantlon and Kornicker: number species/1000 individuals

b) Margalef: number species -1 / log2 number of individuals

c) Menhinick: number species / N; N = number of individuals

d) Pielou: Shannon-Weaver / log2 number of species

e) Shannon-Weaver: ni/N) log2ni/N; N = number of individuals, ni
number of individuals/species

f) Simpson: (ni/N)2

Table 11

Diversity Indices Control Area

Date Reef Number Number Species/ Margalefb Menhinickc Pieloud Shannon-e Simpsonf
Number Indi- Species 1,000a Weaver
viduals

Feb.: 1 1060 12 12 1o09 0.37 0.22 2.20 0.32

2 513 10 12 1o00 0.44 0o18 1.63 0.47

3 1061 15 15 1.39 0.46 0,24 2.36 0.30

4 1043 19 19 1.80 0.59 0.23 2.29 0o31

5 1106 13 13 1.19 0.39 0.24 2.33 0.29

S. E. 14o2 1.3 1.29 0.14 0.45 0.04 0.22 0.01 2.18 0ol4 0.34 003

June: 1 1160 16 15 1.42 0o46 0.19 0o94 0.41

2 1132 14 14 1o28 0.42 0.18 1o78 0.47

3 1158 14 14 1.23 0.40 0.18 1.90 0o44

4 1228 17 17 1o56 0o48 0.20 2.06 0.38

5 1194 14 14 1.22 0.39 0.20 2.04 0.37

So E. 14.7 0.5 1.34 0.05 0.43 0.01 0o17 0.02 1.94 0.06 0o41 0.02

73

Footnotes to Table 11

a) Odum, Cantlon, and Kornicker: number species / 100 individuals

b) Margalef: number species 1 / log2 number of individuals

c) Menhinick: number species / N ; N = number of individuals

d) Pielou: Shannon-Weaver / log2 number of species

e) Shannon-Weaver: (ni/N) log2 ni/N

f) Simpson: (ni/N)2

List of Common Marine Animals Collected From

able 12

Oyster Reefs at Crystal River, Florida, 1973-1974

Phylum Common Name Scientific Name Discharge Bay Control Area

Annelida
Class Polychaeta

nereid worm

mud worm

calcareous tube worm

Nereis succinea

Polydora websteri

Eupomatus dianthus

Porifera
Class Demospongiae

boring sponge

encrusting sponge

Cliona spo

Haliclona spo

Cnidaria
Class Anthozoa

Anthropoda
Class Crustacea

sea anemone

barnacle

fiddler crab

fiddler crab, juvenile

flat mud crab

(cf. Aiptasiomorpha)

Balanus improvisus

Balanus eberneus

Uca pugilator

Uca sp.

Eurypanopeus depressus

porcelain crab Petrolisthes -rmatus

+ +

Table 12 (continued)

Phylum Common Name Scientific Name Discharge Bay Control Area

mud fiddler crab

little xanthid crab

common mud crab

blue crab

spider craba

hermit craba

Stone crab

burrowing shrimp

snapping shrimp

unidentified amphipods

Uca minax

Eurypanopeus abbreviatus

Panopeus herbstii

Callinectes sapidus

Libinia dubia

Paguras annulipes

Menippe mercenaria

Upogebia affinis

Alpheus armalatus

Class Insecta

Class Onychophora

Mollusca
Class Gastropoda

springtail

dwarf spider

small snail

oyster drill

Anurida martima

Erigone teniupalpus

Bittium varium

Polinices duplicatus

Table 12 (continued)

Phylum CommonName Scientific Name Discharge Bay Control Area

crown conch

mud snail

banded tulip shell

ark shell

Class Pelecypoda

Echinodermata
Class Asteroidea

Chordata
Urochordata
Class Molgula

cross-barred venus

calico shrimp

small clam

mussel

American oyster

common starfish

sea squirt

Melongena corona

Busycon spo

Urosalpinx tampaensis

Nassarius vibex

Fasciolaria distans

Area reticulata

Chione cancellata

Pecten gibbus

Tellina lineata

Brachiodontus exustus

Crassostrea virginica

Echinaster spinulosus

Molgula sp.
(cfo manhattensis)

Table 12 (continued)

Phylum Common Name Scientific Name Discharge Bay Control Area

Vertebrata
Class Chondrichtyes scrawled cowfisha Lactophyrys quadricornis +

skillet fish Gobiesox strumosus +

toad fish Opsanus beta +

Observe once only,

Adams, 1974.

Figure 16o Upstream-Downstream Data Using Plastic Channels for One Hourly Measurement, October 8,
1973, in Discharge Bay, Reef 6.
ao Change in oxygen concentration.
bo Water depth in channel.
c. Schematic of channel across reef; numbers represent approximate sampling points.

5.2-

0 5 10 15 20 25 3

CHANNEL DISTANCE, meters

0.8.
S
S
E
0
I. 0.4
UJ
Q

* CURRENT

cUrreDpt

re
r

O
O 0-I ~tcc
__

0 5 10 15 20 25 30

CHANNEL DISTANCE meters

Figure 17. Composite of Upstream-Downstream Oxygen Changes in
Plastic Channels in Discharge Bay Over Three Tidal
Cycles, Reef 6.
Each point is based on quadruplicate samples.

- respiration
4- production

0400

TIME OF DAY

-10

-6-

Ne
e"

+-6-

4-10

I

I,,

- respiration
-- production

0400

TIME OF DAY

- 16-1

-12+

-8-

=
N
oc
(M
N
0M

1200

2000

I
I
I
I 1

1200

2000

_

_ _

\1

m -mmR m

-2-

0 --J

,,,,

Ilrr~~

For the unaffected bay, total observed change shown in Fig. 18 was 22.34

g 02/m2/24 hrs. This gave an average rate of 0.93 g 02/m2/hro, calcu-

lated to be 11.17 g 02/m2/day underwater. On a gram per gram basis

this was

0.042 g 02
/ day
g. dry wt.

Apparent differences in slopes of plots of respiration and current

(Fig. 19) indicated higher respiration in the discharge bay for any

given current speed.

Exposed reefs with CO2 gas exchange

CO2 gas metabolism results are given in Figo 20, 21, and 22 with

corresponding light and tide data. Exposed reef metabolism was 31. g

02/m2/day and 4.5 g 02/m 2/day in the discharge bay and control area,

respectively. The gram of 02 per gram dry body weight rates were

0.035 g 02
/ day
g. dry wt.

in the control area, and

0.039 g 02
/ day
g. dry wto

in the discharge bay.

Total reef metabolism

Total metabolism of the oyster reef community determined on the

basis of a half day at each rate (exposed and submerged) was 20.94 g

02/m2/day in the thermally-affected bay and 15.67 g 02/m /day in the

unaffected bay. This represents a difference of about 27%. Based on

Figure 18. Composite of Upstream-Downstream Oxygen Changes in
Plastic Channels in Control Area Over Three Tidal
Cycles, Reef 1.
Each point is based on quadruplicate samples.

./--/---\--.-
respiration
production

1200
TIME OF DAY

1200
TIME OF DAY

E

mc
N^~
CS

2000

0400

'J

0400

2000

Z I

Figure 19. Respiration Versus Current.

Control Area
July 4,1974
-1 Reef 1
Step = 270C

CURRENT, m/sec

0
0

0 0

o Discharge Bay
July 7, 1974
Reef 6

SX temp E- 330C
I I I I ,

CURRENT, m/sec

Figure 20. Respiration Rates of Exposed Oyster Reef Assemblage,
July 30, 1973, in Discharge Bay, Reef 2a.

1.2-

1.0-

0.8-

0.6-

0.4-

0.2

0

TIME OF DAY

0400 1200 2000

	Front Cover
	Title Page
	Acknowledgement
	Table of Contents
	List of Tables
	List of Figures
	Abstract
	Introduction
	Methods
	Results
	Discussion
	Appendix A: Details of analog...
	Appendix B: Data
	Bibliography
	Biographical sketch
	Back Matter
	Back Cover
	Spine

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