• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Introduction
 Methods
 Data assembled from other phases...
 Results
 Discussion
 Appendix
 Explanation of the energy symbols...
 Graphical analyses of diurnal studies...
 Initial and maximum values of stocks...
 Initial and maximum values of stocks...
 Initial and maximum values of stocks...
 Documentation of data used in summary...
 Literature cited
 Bibliographical sketch
 Copyright






Title: Productivity measurements and simulation models of a shallow estuarine ecosystem receiving a thermal plume at Crystal River, Florida
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Permanent Link: http://ufdc.ufl.edu/UF00084178/00001
 Material Information
Title: Productivity measurements and simulation models of a shallow estuarine ecosystem receiving a thermal plume at Crystal River, Florida
Physical Description: xx, 426 leaves : ill. ; 28 cm.
Language: English
Creator: Smith, Wade Hampton Barnes, 1944-
Publication Date: 1976
 Subjects
Subject: Estuarine ecology -- Florida -- Crystal River   ( lcsh )
Thermal pollution of rivers, lakes, etc   ( lcsh )
Crystal River, Fla   ( lcsh )
Environmental Engineering Sciences thesis Ph. D
Dissertations, Academic -- Environmental Engineering Sciences -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 414-425.
Statement of Responsibility: by Wade Hampton Barnes Smith.
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00084178
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000178072
oclc - 03105860
notis - AAU4575

Table of Contents
    Title Page
        i
    Acknowledgement
        Page ii
        Page iii
    Table of Contents
        Page iv
        Page v
        Page vi
    List of Tables
        Page vii
        Page viii
        Page ix
    List of Figures
        Page x
        Page xi
        Page xii
        Page xiii
        Page xiv
        Page xv
        Page xvi
    Abstract
        Page xvii
        Page xviii
        Page xix
        Page xx
    Introduction
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    Methods
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    Data assembled from other phases of the crystal river project and elsewhere
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    Results
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    Discussion
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    Appendix
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    Explanation of the energy symbols used in this study
        Page 257
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    Graphical analyses of diurnal studies of community metabolism in the inner bay affected by the thermal discharge plume and in the fort island and hodges island areas away from the influence of the thermal discharge
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    Initial and maximum values of stocks and flows, heat budget calculations, calculation of transfer coefficients, scaled equations, potentiometer settings, function generator set-up, and analog computer patching diagram for diurnal simulation of inner bay
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    Initial and maximum values of stocks and flows, heat budget calculations, calculation of transfer coefficients, scaled equations, potentiometer settings, function generator set-up, and analog computer patching diagram for diurnal simulation model of the inner bay
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    Initial and maximum values of stocks and flows, calculation of transfer coefficients, scaled equations, potentiometric settings, function generator set-up, and analog computer patching diagram for seasonal simulation model of the inner bay
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    Documentation of data used in summary diagrams of summer stocks and flows for the inner discharge bay and south intake area
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    Literature cited
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    Bibliographical sketch
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    Copyright
        Copyright
Full Text












PRODUCTIVITY MEASUREMENTS AND SIMULATION MODELS
OF A SHALLOW ESTUARINE ECOSYSTEM
RECEIVING A THERMAL PLUME
AT CRYSTAL RIVER, FLORIDA










By

WADE HAMPTON BARNES SMITH


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





UNIVERSITY OF FLORIDA


1976














ACKNOWLEDGEMENTS


Many of the ideas presented here were shaped in

discussions among the entire systems ecology group of

the Department of Environmental Engineering Sciences.

Special acknowledgements go to major professor H. T.

Odum for his stimulation, guidance, and the distinct

privilege of participating in this program. My super-

visory committee included P. L. Brezonik, T. Bullock,

J. Ewel, and S. C. Snedaker.

This work was supported, by contract No. GEC 159,

918-200-188.19 (Models and Measurements for Determining

the Role of the Power Plants and Cooling Alternatives

at Crystal River, Florida) between the Florida Power

Corporation and the University of Florida Systems Ecology

Program, Department of Environmental Engineering Sciences,

H. T. Odum, principal investigator.

Many people helped in the field and with data

workup: J. Bevis, N. Black, W. Boynton, C. High, D.

Hinck, M. Homer, M. Kemp, M. Lehman, H. McKellar, A.

Merriam, F. Ramsey, and D. Young. Analog computers used

in this study were maintained by A. Copsey, and J. Murphey,

who also provided programming assistance. Progress in









this study was much facilitated by K. Garrison, J. Johnson,

D. McMullin, and W. Trowell of the Florida Power Corpora-

tion.

Use of the R. V. Susio was provided by the State

University System Institute of Oceanography.


iii















TABLE'OF CONTENTS


Page



ACKNOWLEDGEMENTS . . . . ii

LIST OF TABLES . . . ... vii

LIST OF FIGURES . . . . x

ABSTRACT . . . . . xvii

INTRODUCTION . . . . 1

System Adaptation, Environmental Impact,
and Thermal Loading of the Estuary at
Crystal River, Florida . . 5

Models for Gaining an Overview of the
Estuary and Power Plant at Crystal
River . . 9

Previous Studies of Thermally Affected
Aquatic Ecosystems . .. .... 16

Description of Study Area at Crystal
River . . . . 21

Other Studies of the Crystal River
Region . . . . 31

Previous Simulation Models of Marine Eco-
systems, Diurnal Oxygen Dynamics,
Temperature, and the Effects of Power
Plants on Ecosystems . . 33

Plan of Study . . 39












METHODS . . . . .

Metabolic Measurements . . .

Other Field Measurements . .

DATA ASSEMBLED FROM OTHER PHASES OF THE CRYSTAL
RIVER PROJECT AND ELSEWHERE . .

Energy Sources and Inflows Affecting the
Inner Bay . . . .

Stocks of the Inner Bay . .


RESULTS












DISCUSS


Metabolism Measurements . . .

Model Diagrams for Comparing Ecosystems
Affected and Unaffected by the
Discharge Plume . . .

Simulation Model of Diurnal Properties
of the Inner Bay Ecosystem . .

Simulation Model of Seasonal Properties
of the Inner Bay Ecosystem . .

ON . . . . .

Seasonal Patterns of the Ecosystems at
Crystal River . . .

Comparisons of the Ecosystems at Crystal
River and Adaptation to the Thermal
Discharge . . . .

Predictions of the Effect of the Operation
of Unit Three at Crystal River ..

Energy Costs of Alternatives to Estuarine
Cooling of the Thermal Discharge at
Crystal River . . .


Page


41

41

62


69


69

78

116

116



149


154


201

223


223



239


252



253









Page


APPENDICES . . . . . 256

A EXPLANATION OF THE ENERGY SYMBOLS
USED IN THIS STUDY . ... .257

B GRAPHICAL ANALYSES OF DIURNAL STUDIES
OF COMMUNITY METABOLISM IN THE INNER
BAY AFFECTED BY THE THERMAL DISCHARGE
PLUME AND IN THE FORT ISLAND AND
HODGES ISLAND AREAS AWAY FROM THE
INFLUENCE OF THE THERMAL DISCHARGE 262

C INITIAL AND MAXIMUM VALUES OF STOCKS AND
FLOWS, HEAT BUDGET CALCULATIONS, CAL-
CULATION OF TRANSFER COEFFICIENTS,
SCALED EQUATIONS, POTENTIOMETER SET-
TINGS, FUNCTION GENERATOR SET-UP,
AND ANALOG COMPUTER PATCHING DIAGRAM
FOR DIURNAL SIMULATION MODEL OF
INNER BAY . . ... 311

D INITIAL AND MAXIMUM VALUES OF STOCKS
AND FLOWS, CALCULATION OF TRANSFER
COEFFICIENTS, SCALED EQUATIONS,
POTENTIOMETRIC SETTINGS, FUNCTION
GENERATOR SET-UP, AND ANALOG COM-
PUTER PATCHING DIAGRAM FOR SEASONAL
SIMULATION MODEL OF THE INNER BAY 356

E DOCUMENTATION OF DATA USED IN SUMMARY
DIAGRAMS OF SUMMER STOCKS AND FLOWS
FOR THE INNER DISCHARGE BAY AND
SOUTH INTAKE AREA . . .. 407

LITERATURE CITED . . . . 414

BIOGRAPHICAL SKETCH . . . ... 426














LIST OF TABLES


Table Page


1 Results of a technique test of the
Winkler method to determine the effect
of the presence or absence of acid in
fixed bottles which have been stored
for eight hours before titration. 44

2 Seasonal comparison of average wind speed
at Crystal River site. 75

3 Record of metabolism for the inner dis-
charge bay as measured by diurnal free
water oxygen changes and light and dark
bottles. 117

4 Record of metabolism for the Fort Island
and Hodges Island areas away from the
influence of the power plant discharge as
measured by diurnal free water oxygen
changes and light and dark bottles. 121

5 Diffusion rates measured in the power
plant discharge and Fort Island study
areas. 146

6 Average extinction coefficients for light
penetration of water on the inner dis-
charge bay affected by the power plant
discharge plume and unaffected areas to
the north and south. 148

7 Differential equations for diurnal model
of inner bay given in Figure 40. 157


vii









Table Page


8 Differential equations for seasonal
model of inner bay system given in
Figure 55. 202

9 Comparison of gross primary produc-
tion and total respiration measured
at Crystal River with some values from
other areas in Florida and similar
systems elsewhere. 225

C-1 Documentation of values used for forcing
functions, standing stocks, and exchange
rates in the diurnal simulation model of
the inner bay. 312

C-2 Initial and maximum values of storage
for diurnal simulation model of inner
bay. 329

C-3 Initial and maximum values of forcing
functions for simulation model of inner
bay. 330

C-4 Calculation of radioactive, evaporative,
and convective heat losses for use in
diurnal simulation model of inner bay. 331

C-5 Calculation of transfer coefficients for
diurnal simulation model of inner bay. 333

C-6 Equations of Table 7 scaled for simulation
of diurnal model of the inner bay given
in Figure 40. 339

C-7 Scaling of terms associated with photo-
synthesis in equations in Table 10 for
diurnal simulation model of the inner bay. 347

C-8 Potentiometer settings for initial run
of diurnal simulation model of inner bay. 349

C-9 Potentiometer settings for the EAI 580
variable diode function generator used to
produce the tidal volume exchange function
given in Figure 42 for the diurnal model
of the inner bay. 352


viii









Table Page


D-1 Documentation of values used for stand-
ing stocks and exchange rates in the
seasonal model of the inner bay. 356

D-2 Initial and maximum values of forcing
functions and storage for seasonal
simulation model of inner bay. 376

D-3 Calculation of transfer coefficients for
seasonal simulation model of inner bay. 377

D-4 Equations of Table 11 scaled for simula-
tion of seasonal model of the inner bay
given in Figure 54. 387

D-5 Scaling of terms associated with photo-
synthesis in equations in Table 8 for
seasonal simulation model of the inner
bay. 398

D-6 Potentiometer settings for initial run
of simulation of the seasonal model of
the inner bay. 402

D-7 Potentiometer settings for EAI 580 vari-
able diode function generator used to
produce the seasonal cycle of sunlight
given in Figure 55 for the simulation
of the seasonal model of the inner bay. 404

E-1 Documentation of numbers appearing on
Figure 38 of the inner discharge bay
ecosystem affected by the thermal dis-
charge of the power plant. 408

E-2 Documentation of numbers appearing on
Figure 38 of the south intake area eco-
system unaffected by the thermal plume of
the power plant. 411















LIST OF FIGURES


Figure Pag


1 Location of Florida Power Corporation's
power plants near Crystal River, Florida,
in relation to the major features of the
regional coastline. 3

2 Energy diagrams of producer and consumer
modules indicating the push-pull effects
of temperature on internal processes. 8

3 Aggregated energy diagram of the main
features believed important in the eco-
system of the inner discharge bay at
Crystal River. 12

4 Energy diagram of the ecosystem of the
inner discharge bay, which includes much
of the complexity omitted from Figure 3. 15

5 Bathymetry of power plant discharge area
at Crystal River. 23

6 Thermally affected area showing location
of the shallow inner bay system dominated
by the seagrass, Halodule wrightii, and
the deeper outer bay system. 27

7 Typical daily tidal cycle at Crystal River
site indicating unequal high and low tides. 29

8 Model of factors affecting oxygen dynamics
in water. 46

9 Example of graphical format for calculation
of community metabolism at Fort Island, 24-25
August, 1973, using full diurnal curve of
oxygen. 50









Figure Page


10 Graphical format for calculation of
community metabolism using dawn-dusk-
dawn data. 57

11 Comparison of community metabolism
estimates obtained from complete
diurnal measurements of oxygen versus
estimates obtained from dawn-dusk-
dawn calculations made using the same
data. 60

12 Example of two experiments to determine
oxygen diffusion coefficients by measur-
ing the rate of return of oxygen into a
nitrogen-filled dome floating on the
water's surface. 65

13 Examples of submarine photometer measure-
ments of light penetration through the
water column taken at Fort Island away
from the influence of the power plant
discharge plume and in the inner bay
influenced by the plume. 68

14 Average daily insolation by month at
Tampa, Florida. 71

15 Wind direction by season at Crystal River
site. 74

16 Monthly mean air temperature at Tampa,
Florida. 77

17 Monthly mean precipitation at Tampa,
Florida. 80

18 Weekly averages of surface water temper-
atures for the plume-affected inner dis-
charge bay and ambient water of the south
intake area. 83

19 Weekly average of electricity generated by
power units at Crystal River, and weekly
average intake and discharge water temper-
ature for unit 1. 86









Figure Page


20 Average diel water temperatures meas-
ured during community metabolism studies
of the inner discharge bay and the Fort
Island and Hodges Island control areas. 88

21 Diurnal patterns of electricity generated,
water temperatures at three locations,
and tidal stage in the discharge area of
May 24-27, 1974. 91

22 Average salinities measured on the inner
discharge bay and Fort Island and Hodges
Island study areas during the community
metabolism studies. 94

23 Seasonal patterns of benthic macrophytes
in the thermally affected inner bay and
inshore portion of the south intake area. 97

24 Map of summer standing crop of attached
macrophytic plants in the region near the
Crystal River power plants. 100

25 Seasonal diversity of benthic macrophytes
in the inner discharge bay and the south
intake area. 102

26 Seasonal record of biomass of benthic
macroinvertebrates in the inner discharge
bay and south intake areas. 105

27 Seasonal record of biomass of fish caught
with drop nets in the inner discharge bays
and south intake areas. 107

28 Carbon, nitrogen, and phosphorus measure-
ments at the mouth of the discharge canal
and a station in the south intake area. 110

29 Measurements of live chlorophyll-a and
phytoplankton biomass at a station in the
south intake area and at the mouth of the
discharge canal. 114


xii









Figure Page


30 Daytime net photosynthesis and night
respiration in the inner discharge bay
affected by the thermal plume and the
Fort Island and Hodges Island area
away from the influence of the power
plant. 125

31 Daytime net photosynthesis plus night
respiration as a measure of gross
primary production in the inner dis-
charge bay affected by the thermal plume
and the Fort Island and Hodges Island
areas away from the influence of the
thermal plume. 127

32 All daytime net photosynthesis and night
respiration values from Tables 6 and 7
and Figure 30 plotted on 12-month graph. 129

33 All daytime net photosynthesis plus night
respiration values from Tables 6 and 7
and Figure 31 plotted on 12-month graph. 131

34 Average oxygen values from all summertime
diurnal measurements taken in the inner
discharge bay and Fort Island control bay. 135

35 Seasonal averages of daytime net photo-
synthesis and night respiration in the
inner discharge bay and control areas. 138

36 Seasonal averages of daytime net photo-
synthesis plus night respiration as a
measure of gross primary production for
plume-affected inner bay discharge area
and unaffected control areas. 141

37 Seasonal trends of the ratio of daytime
net photosynthesis divided by night
respiration for plume-affected inner bay
area and unaffected Fort Island and Hodges
Island areas. 144

38 Summary energy diagram of summer stocks and
flows for the inner discharge bay. 151


xiii









Figure Page

39 Summary energy diagram of summer stocks of
biomass or material and flows of energy
and organic matter for the south intake
area away from the influence of the power
plant discharge. 153

40 Energy diagram for simulation model of
inner discharge bay emphasizing the
diurnal properties of the system. 156

41 Computer plots of forcing functions of
tidal volume exchange, depth, offshore
oxygen, and offshore water temperature
used in the diurnal simulation model. 163

42 Simulation results of diurnal model of
inner bay with coefficients set as
originally scaled. 166

43 Data gathered from the inner bay during
the community metabolism study of June
21-22, 1973, against which the simulation
of the model of Figure 20 was compared. 170

44 Solar insolation for June 21, 1973, as
recorded by a pyranometer located at the
Crystal River power plant site. Total
radiation received is indicated. 172

45 Simulation results of diurnal model of
inner bay with original scaling, but
sunlight reduced to a daily total
similar to June 21-22, 1973. 174

46 Simulation results of diurnal model of
inner bay with equal amounts of canal
and offshore water contributed to the
inner bay on a rising tide. 178

47 Simulation results of diurnal model of
the inner bay with two parts canal water
to one part offshore water contributed to
the inner bay on a rising tide.

48 Simulation results of diurnal model of
inner bay with canal water alone being
contributed to the inner bay on a rising
tide. 182


xiv








Figure Page


49 Simulation results of diurnal model
of the inner bay with a 7C dif-
ferential of discharge canal water
over ambient water and a mixing ratio
on a rising tide of one part canal
water to one part offshore water. 185

50 Simulation results of diurnal model of
the inner bay with a 7C differential
of discharge canal water over ambient
water and a mixing ratio of 2 parts
canal water to 1 part offshore water
on a rising tide. 187

51 Simulation results of diurnal model of
the inner bay with a 70C differential
of discharge canal water over ambient
water and with canal water alone flow-
ing onto the inner bay on a rising tide. 192

52 Simulation results of diurnal model of
the inner bay with no discharge of
cooling water from the power plant dis-
charge canal and original scaling of
insolation. 194

53 Simulation results of diurnal model of the
inner bay with no discharge from the
power plant discharge canal and insolation
reduced to one-half original scaling. 196

54 Simulation results of diurnal model with
timing of occurrence of high and low tide
reversed from previous runs. 198

55 Energy diagram of simulated model of
inner discharge bay emphasizing seasonal
properties of the ecosystem. 200

56 Seasonal patterns of insolation and tempera-
ture used as forcing functions in the
seasonal model of the inner bay ecosystem. 200

57 Simulation results with initial scaling
of seasonal model of the inner bay. 210









Figure Page


58 Simulation results of seasonal model
of the inner bay with seasonal pattern
of temperature increased 3C. 214

59 Response of seasonal simulation model
of the inner bay to increased tempera-
ture and turbidity. 217

60 Response of seasonal simulation model
of the inner bay to decreased turbidity
and a seasonal temperature range as
originally scaled. 220

61 Response of seasonal simulation model
of inner bay to decreased turbidity
and a seasonal temperature range of
180C 36C. 222

62 Energy diagram and analog computer patch-
ing diagram of simulation model of
producer module with temperature affec-
ting both photosynthetic and respiratory
pathways. 231

63 Simulation results of model of producer
module in Figure 62 with seasonally vary-
ing light and temperature. 233

64 Simulation response of seasonal model of
the inner discharge bay to the addition
of pathways of exchange of fish and fish
larvae with offshore waters. 237

65 Simulation results of seasonal model of
inner bay as modified in Figure 64 with
larger photosynthetic coefficient added
in winter. 241

C-1 Analog computer patching diagram of
scaled equations given in Tables C-6 and
C-7 for the diurnal simulation model of
the inner bay. 354

D-1 Analog computer diagram of scaled equa-
tions given in Tables D-4 and D-5 for the
seasonal simulation model of the inner
bay. 406


xvi










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


PRODUCTIVITY MEASUREMENTS AND SIMULATION MODELS
OF A SHALLOW ESTUARINE ECOSYSTEM
RECEIVING A THERMAL PLUME
AT CRYSTAL RIVER, FLORIDA


By

Wade Hampton Barnes Smith

August, 1976


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


The effects of the heated discharge of two power

plants on the receiving estuarine ecosystem near Crystal

River on the west coast of Florida were investigated with

measurements and simulation models to help understand

relationships and predict the consequence of a third

power plant under construction. Energy circuit models

emphasizing diurnal and seasonal aspects of ecosystem

responses were used to assess the effect of power plant

operation on estuarine ecosystems. Field measurements

were taken in the discharge-affected and -unaffected

areas nearby.

Benthic populations dominated total metabolism

in both systems. Community gross primary production

varied seasonally in.the unaffected areas from a winter


xvi









low of 3.3 g 02/m2.day to a spring high of 8.8 g 02/m2-day.

In the discharge area it was relatively constant, remain-
2
ing about 4 g 02/m -day in all seasons. Phytoplankton

production normally was about 5 percent of total produc-

tion in the unaffected areas and about 23 percent in the

discharge area. In the spring its contribution increased

greatly to 25 percent in the unaffected area and 70 per-

cent in the discharge area.

Total biomass was less in the discharge than

in unaffected areas. Lower standing stock of primary

producers and benthic invertebrates in the discharge

area accounted for almost all the difference.

Diversity was lower in the discharge bay than in

the unaffected area. Mixed macroalgae and seagrasses

were the dominant benthic producers in the unaffected

areas, while the seagrass Halodule wrightii was virtually

the only species in the discharge bay. Species diversity

was lower for oyster reef organisms, and fewer species

of fish were caught in drop nets in the discharge bay

than in the unaffected bay.

A shift toward more cycling of material and energy

through the phytoplankton and filter feeders and away

from the benthic components of the system may have

occurred in the discharge area as an adaptation to the

thermal plume.


xviii









Simulation of the model of diurnal system proper-

ties with coefficients representing those for discharge

conditions gave patterns similar to those measured in the

discharge bay. The model was relatively insensitive to

adjustments in water temperature within the range expected

in the future at Crystal River. A change in the quantity

of daily insolation produced a larger change in model

response.

The simulation model of seasonal system proper-

ties was also more sensitive to light than to water

temperature. Increasing temperature alone increased

primary production and total respiration somewhat, espe-

cially in the spring. Fish and invertebrate biomass

remained the same, while detrital storage declined,

perhaps indicating their importance as an energy source

for offsetting increased respiratory drains on consumers

because of increased temperature. Increases in light

alone greatly increased system storage and flows, sug-

gesting the importance of turbidity in controlling

metabolism in the discharge area. Increasing temperature

but decreasing light lowered metabolism.

Adjustments to the seasonal model tested the

theory that systems with prominent seasonal pulses may

be exploited by populations that move in during the period

of plenty, experience rapid exponential growth, and then


xix










move away. With some migration the fish stock could main-

tain itself in a stable oscillating yearly pattern.

Results of other adjustments to the seasonal model

suggested that seasonal substitution of species of primary

producers may be the most effective way to make maximum

use of available energies at all times of the year.
















INTRODUCTION


This is a study of shallow, benthic-dominated

estuarine ecosystems on the Florida west coast, one of

which received a thermal discharge from two electric

generating stations of the Florida Power Corporation.

Water was drawn from the deeper offshore Gulf of Mexico,

passed through the power plant condenser system, where

its temperature was increased about 5C, and discharged

onto the shallow inshore coastal area (Figure 1). This

study was made to increase understanding of the structure

and function of estuarine ecosystems, the relationship of

individual parts to the functioning of the total pattern

as an integrated unit, and the effects of temperature

change. Specifically investigated was the nature of an

estuarine system which had been receiving thermal effluent

for six years. How does an entire ecosystem adjust and

adapt to these new energy conditions imposed on it? How

does the new system serve as an interface between the

economy of man and that of nature?

Energy diagrams were drawn to organize, summarize

and synthesize data in models, and as a conceptual tool




















Figure 1. Location of Florida Power Corporation's power plants near Crystal
River, Florida, in relation to the major features of the regional
coastline. Oyster bars are indicated by dotted outlines.








for illustrating ideas about the ecosystem at Crystal River

and the role of thermal loading in shaping its pattern.

Total metabolism, including photosynthetic production and

total respiration, was measured as the primary indicator

of the main system functions. Using simpler models, com-

puter simulations of seasonal and diurnal trends were run

and compared with measured data. This study was part of

a much larger project funded by the Florida Power Corpora-

tion evaluating questions related to the impact of its

power plants at Crystal River on the adjacent estuarine

ecosystems. As required by our contract, efforts were made

to summarize data from other studies in developing an over-

view of the ecosystem.

As fossil fuels for powering man's economy become

scarcer and more expensive, the need increases for recognizing,

utilizing, and protecting the important work contributions

of nature in support of man's economy, and establishing

effective feedback pathways from man to protect his life

support system. A regional system of man and nature which

allows its natural components to contribute work services

in support of the overall pattern may avoid unnecessary

technological constructions and be most successful in

utilizing all available energies when use of the environ-

ment constitutes more useful work than is lost by environ-

mental impact. For example, should coastal and estuarine

waters be used for cooling of the thermal effluent from









electric generating stations, or is it necessary to build

technological alternatives such as cooling towers for this

purpose?



System Adaptation, Environmental Impact,
and Thermal Loading of the Estuary at
Crystal River, Florida


At Crystal River, and wherever thermal effluents

flow into an ecosystem, potential energy is carried with

it. This energy, like all other energy sources impinging

there, is available for doing work in the environment,

although its exact way of doing work may not be known

(Odum, 1974b).

Other changes besides thermal loading are caused

by power plant installations. At Crystal River the con-

struction of dikes and the pumping of cooling water through

the canal system (see Figure 1) may modify the current

and flushing characteristics of the surrounding waters.

Turbidity in the discharge area may have increased because

of scouring of the discharge canal and from sediments

carried through the power plant from the intake canal

where they had been stirred up by barge traffic. Canal

construction caused changes in drainage patterns and mor-

phology of adjacent salt marshes.

The most important impact, however, may be the

effect of higher temperature on biological processes.










Adaptation and acclimation of metabolism of individual

organisms to offset temperature changes is well estab-

lished (Bullock, 1955). Much less is known about the re-

sponse of whole ecosystems to changed thermal regimes.

How does system structure adapt so that the new pattern

that emerges is best coupled to the changed thermal

regime? What is the nature of this new system linked to

man's technology? These questions may begin to be answered

by observing such system properties as total community

metabolism, species diversity, and seasonal patterns.

4The effect of thermal loading on biological pro-

cesses may be important at both the level of individual

organisms and the ecosystem (Kelley, 1971; Odum, 1974b;

McKellar, 1975). Since all processes are stimulated equally

below the threshold of rapid thermal enzyme destruction,

temperature acts to increase processes building structure

as well as those degrading it (Figure 2). "For a plant

(Figure 2a), the dark reactions of photosynthesis may be

stimulated as much as respiratory pathways, so that the

overall effect on biomass may be neutral. However, if

photosynthesis is limited by energy and material shortages

so that respiratory losses are not offset, biomass may

decline. The same holds true for a consumer (Figure 2b).

If the metabolic pathways of digestion and rebuilding of

structural animal biomass are affected at the same rate

as those degrading this biomass, metabolism increases but




















Figure 2. Energy diagrams of producer and consumer
modules indicating the push-pull effects of
temperature on internal processes. See
Appendix A for meaning of symbols.

(a) Producer module with temperature acting
on both photosynthetic primary produc-
tion and respiration processes.

(b) Consumer module with temperature acting
on processes of biomass formation through
food gathering, digestion, and assimila-
tion as well as the respiratory degrada-
tion of biomass.























































(b)


















FOOD
SOURCE


I


~__ _I_


_-








the amount of biomass is unaffected. However, if food is

limited the population loses mass because it cannot compen-

sate for respiratory losses.

For the ecosystem, if it is to compete at the new

steady state, respiration degrading structure induced by

higher temperatures must be compensated for by the larger

push of increased rates of production of system structure.

-Can accelerated cycling of nutrients from increased res-

piration offset nutrient limitations to primary production?

Is this increased production enough to supply energy demands

of larger consumers?



Models for Gaining an Overview of the
Estuary and Power Plant at Crystal River


Proposed in Figures 3 and 4 are the energy circuit

models at different levels of complexity of the system of

estuary and power plants at Crystal River. Their purpose

is to organize in overview concepts of system structure,

processes, pathways, interactions, and relationships.

Inherent in the diagrams are patterns important on both

daily and seasonal time scales. An explanation of symbols

used in this dissertation is given in Appendix A. More

complete discussions and additional symbols are given by

Odum (1971, 1972, 1974a, 1975).









Simplified Model of the Inner Bay


Given in Figure 3 is a model diagram of the inner

bay ecosystem from which details have been eliminated

leaving only the basic system structure of water storage,

benthic macrophytes, consumer populations and tidal ex-

changes with the saltmarsh, offshore, and canal ecosystems.

On a rising tide surface water from the power plant dis-

charge canal is forced onto the inner bay by the damming

effect of water flowing on from offshore and the increasing

height of head of the approaching wave of the tide. On

a falling tide canal water flows directly down the channel

beside the inner bay, where it receives water flowing off

the bay. Diffusive oxygen exchange with the atmosphere

occurs driven largely by turbulence induced by tidal

exchange. Gains of heat result from solar insolation

and atmospheric longwave radiation. Heat losses occur

from conduction, back radiation, and evaporation.

Primary production occurs in the phytoplankton

and the benthic macrophytes, which take up nutrients and

oxygen from the water column while returning oxygen and

organic matter to it. Storages of organic matter are in

the water column and sediments, which are consumed by

populations of microbes. Two classes of consumers are

shown. In the water column are free living animals feed-

ing on detritus, phytoplankton, benthic invertebrates, and





















Figure 3. Aggregated energy diagram of the main fea-
tures believed important in the ecosystem
of the inner discharge bay at Crystal
River. Details within the compartments
have been omitted to emphasize basic sys-
tem structure and function in overview.

Symbol shown as T indicates a connection

from heat sinks (- ). See Appendix A for

definition of symbols.










S SALT MARSH
S SUBSYSTEM I


EVAPORATION


EXCHANGE WITH
CANAL ONLY ON
RISING TIDE


INNER BAY I
WATER COLUMN
CONTAINING HEAT,
NUTRIENTS, TURBIDITY,
ORGANIC MATTER,
OXYGEN, AND
PHYTOPLANKTON


BENTHIC
MACROPHYTES
AND EPIPHYTES









each other. Many of the larger members of this compart-

ment migrate seasonally to and from the offshore regions.

Benthic invertebrates and oysters feed largely on detritus

and phytoplankton. Nutrients are regenerated into the

water column from all respiratory pathways.


Detailed Model of the Inner Bay


In Figure 4, more of the complexity of detail

within the compartments has been added to the model of

Figure 3. Sunlight penetrating the water column of the

inner bay is attenuated by turbidity, shading of phyto-

plankton biomass, and the natural extinction properties

of water. Primary production utilizes the remaining

light, and is concentrated in the benthic macrophytes

and their associated epiphytes with a smaller contribution

from the phytoplankton. This production moves to the higher

trophic levels primarily through a storage of detritus and

its associated microbes in the sediments. A much smaller

amount is stored in the water column. A small amount is

transferred by direct grazing of epiphytes. Larger con-

sumer populations are represented by benthic inverte-

brates and oysters, zooplankton and larval forms, shrimps

and crabs, and resident and migratory fish. Seasonal

migratory movements of shrimps, crabs, and migratory fish

stocks are indicated. All respiratory pathways are shown

returning nutrients into the water column storage. Various


























Figure 4. Energy diagram of the ecosystem of the inner
discharge bay, which includes much of the
complexity omitted from Figure 3. Pathways
of oxygen uptake and temperature effects
have been abbreviated for clarity. Pathways
from storage of heat and oxygen labeled T
and 0, respectively, are assumed to be con-
nected with similarly labeled pathways on
work gates and consumer modules. Pathway

marked as T indicates a connection from

heat sink symbols ( ).









exchanges with the adjacent saltmarsh, power plant canal,

and immediate offshore ecosystems occur with the rise and

fall of the tide.

Heat in the water is lost and gained through physi-

cal processes as well as advective exchanges. Gains occur

from solar insolation, atmospheric longwave radiation, and

heat generated from all biological processes. Losses re-

sult from back radiation and evaporation. Conduction is

a gain or loss depending on the direction of the gradient

between air and water. Oxygen has a diffusive exchange

with the air driven largely by water turbulence.

In summary, this detailed model serves to emphasize

issues related to the interactions of power plants with

estuaries, helps the reader visualize the system studied

at Crystal River, summarizes initial understanding of its

characteristics, helps to plan the research program, and

provides a basis for simpler models for simulation.



Previous Studies of Thermally Affected
Aquatic Ecosystems


Most work on the effect of temperature on life

processes has been at the level of the whole organism

or at smaller (e. g. subcellular) levels; less work has

been concerned with its effect on whole ecosystems.

Perhaps because of their simplicity the most thoroughly

studied ecosystems to date have been thermal spring








ecosystems. System structure has been discussed by most

authors (Brock, 1967a, 1967b, 1969; Brock and Brock, 1969;

Kullberg, 1966; Stockner, 1967, 1968; Wiegert and Fraleigh,

1972). Zonation of algal or bacterial mat communities

associated with temperature gradients, both down and across

spring runs, with a vertical zonation of structure at any

given point were the main characteristics of these eco-

systems. Filamentous bacteria were dominant in the hotest

portion of the stream, being replaced by blue-green algae

as the water cooled. Green algae, in turn, replaced the

blue-green at still lower temperature cooling. Species

diversity was very low overall, tending to increase down

the temperature gradient.

Community metabolism in thermal springs has also

been measured (Brock, 1967b; Duke, 1967; Phinney and

Mclntire, 1965; Stockner, 1968; Wiegert and Fraleigh, 1972).

Values measured generally fell within ranges reported

for many other types of aquatic ecosystems. Brock (1970)

reviewed work on high temperature systems.

The work reported above is mostly on springs with

temperatures in excess of 45C, which is generally above.

the thermal limits for enzyme destruction of most organisms.

Available work on thermally affected systems within temper-

ature ranges more normally encountered in nature has mostly

involved microcosm studies. Allen and Brock (1968) re-

ported that microcosms held at a range of temperatures







from 20C to 75C and all seeded alike from a wide variety

of sources; each developed its own characteristic combina-

tion of species. Beyers (1962) found only small responses

in community metabolism to 36-hour increases in temperature.

Davis (1971), studying experimental estuarine ecosystems

contained in large plastic swimming pools, found increased

gross community primary production and respiration during

spring, summer, and fall in those heated 4-60C above con-

trols. Kelley (1971) studied high-nutrient freshwater micro-

cosms subject to constant low, constant high, and fluctuat-

ing temperature regimes. Mean values of net production

and night respiration over the study period were higher in

those microcosms which had higher mean temperatures. Vari-

ous aspects of the biology of Par Pond, a freshwater reactor-

cooling pond at the Savannah River Plant, South Carolina,

have been studied for a number of years by investigators

at the Savannah River Ecology Laboratory of the University

of Georgia (Gibbons and Sharitz, 1974b).

A general assessment of research related to the

environmental effects of the operation of power plants

is difficult because much of it is contained in reports

to Federal agencies concerned with licensing, and is gen-

erally unavailable for review. Zieman (1970) has reported

on the early effects of the operation of power plants at

Turkey Point on Biscayne Bay, near Miami, Florida. Condi-

tions of flow rate and temperature rise of the cooling water

were very similar to those at Crystal River. The receiving









ecosystem was dominated by a mixture of macroalgae and sea-

grasses (mostly Thallassia testudinum). By the end of the

second summer of operation 50-60 acres of bay bottom adja-

cent to the mouth of the discharge canal had been denuded

of this community and replaced by a blue-green algal mat

community. An additional 70-75 acres had some Thallassia,

but were still devoid of macrophytic algae, while 160-170

more acres exhibited some stress to the existing macro-

algae populations.

Other available power plant data have dealt with

more northern situations involving phytoplankton.-dominated

ecosystems. The effects of increased temperature on pri-

mary production were usually measured by the uptake of

carbon-14, often in bottles held in illuminated light

boxes. Results have been mixed. Several studies in-

volving both estuarine and freshwater cooling systems

have found stimulation of photosynthesis in the cooler

months and a depressing effect in the warmest months

(Morgan and Stross, 1969; Smith et al., 1974). Tilly

(1974), using carbon-14 measurements incubated in situ

in Par Pond, South Carolina, found primary production to be

somewhat greater in the surface water at the warmer station.

This tendency was more pronounced during the warm months of

the year. Gurtz and Weiss (1974), also using carbon-14

methods, found inhibition of photosynthesis at all times

of the year. A trend toward greater inhibition at higher

ambient water temperatures was suggested by the data.









Only several reports appear to be available on

aspects of ecosystems which have been adapting to power

plant discharges for a number of years. North (1968)

studied the discharge area affected since 1957 at Morro

Bay, California. He found abundance and diversity of

plants and animals to be reduced in a transitional

region over a distance of approximately 200 m from the

end of the discharge canal. Recovery to conditions

typical of the area occurred in a relatively short hori-

zontal distance of 10 m at the end of the transitional

region. J. R. Adams et al. (1974) could find no differ-

ence in intertidal sandy beach populations located near

the discharge versus ones further away.

Few power plant studies appear to have synthesized

the diverse data into an overview of the ecosystem respond-

ing as an integrated unit to the new set of environmental

forcing functions. Emphasis has generally been placed

on individual aspects of power plant operation, such as

entrainment through the condenser cooling system and

entrapment on the screens protecting the cooling water

intake pumps (Jensen, 1974c), or on individual species

or components of the ecosystem. Typical studies might

examine mortality of phytoplankton from passage through

the condenser system, diversity and biomass of benthic

organisms and fish in the discharge area, or primary

production of the phytoplankton component of the ecosystem.









Often these studies have been done in the laboratory.

Chesapeake Science, volume 10 (1969), and proceedings of

symposia edited by Gibbons and Sharitz (1974a) and Esch

(in press) contain many papers of this type.

Several studies have been published which contain

most research results for a particular power plant in one

volume (Jensen, 1974a, 1974b; Central Electricity Generat-

ing Board). Discussion of results, however, is by sub-

systems with little attempt to synthesize the findings

with text, diagrams, or simulation models into a picture

of the functioning of the whole ecosystem.



Description of Study Area at Crystal River


The power plant site in Citrus County (Figure 1)

is on the low wave energy portion of the Florida west

coast as defined by Tanner (1960). The shallow sloping

bottom (46 km to the 5 fathom contour) is part of the

drowned karst topography of this portion of west central

Florida. The topography of the immediate offshore region

is a series of shallow basins separated by oyster reefs

(Figure 5). Freshwater sources influencing the area are

the Crystal River 4.8 km to the south (mean flow 1500

m /min; 400,000 gpm), and the Withlacoochee River and

Cross Florida Barge Canal 6.4 and 5.8 km to the north,

respectively, with a combined flow of 2150 m /min

(570,000 gpm).





















Figure 5. Bathymetry of power plant discharge area at Crystal River. Location
of inner bay has been circled. Contour interval is 1.0 feet. Datum
based on mean sea level. (Adapted from Rodgers et al., 1974)
























5 4-.45 INNER
-' ,_ H















~~ DISCHARGEE

5 5
49














N I4 M7 A

NAUTICAL MILE RODGERS, eF C/,i 1974)








The power plants are on the landward edge of a

tidal saltmarsh dominated by Juncus roemerianas bordered

on the seaward edge by a narrow fringe of Spartina

alterniflora. Two units were in operation during this

study--unit 1 since July, 1966, and unit 2 since November,

1969--giving a combined total output of 897 megawatts

electrical (MWe). A nuclear powered unit of 885 MWe

output was under construction. The two operating units

cycle water for once-through cooling at a combined flow

of 2430 m3/min (640,000 gpm) through canals dredged

across the shallow offshore region and saltmarsh.

Maximum condenser temperature rise is 6.10C.

The power plant intake canal extends approxi-

mately 4.8 km into the Gulf with an average depth of

6-7 m and a width of about 75 m, serving also as the

passageway for delivery of fuel oil in barges by large

ocean-going tow boats. Cooling water passes down the

canal at about 8 cm/sec before being pumped through

the power plant condensers, where its temperature rises

5-60C. The discharge canal is about 1.6 km long with

an average depth and width of about 4.5 m and 50 m,

respectively. The smaller cross-sectional area causes

the stream velocity to be about twice that in the intake

canal. The residence time of water masses in the canal

system is about 20 hours for the intake canal and about

3.5 hours for the discharge canal.








Two types of bay systems are affected by the

thermal plume (Figure 6). Immediately adjacent to the

saltmarsh is the shallow bay of this study averaging

about 1 m in depth, composed of a mixture of bottom

covered with seagrass, some oyster reef associations,

and areas of sand and mud. Seaward of a row of oyster

bars is a deeper outer basin of about 2 m average depth

in which the plankton and reef ecosystems become impor-

tant. The "bays" referred to here are actually the

immediate landward edge of the Gulf of Mexico.

The plume-affected inner bay of this study is

a shallow benthic seagrass-dominated system composed

almost exclusively of Halodule (Diplanthera) wrightii

during the warm months, while in the winter of 1972-73

mixed Ectocarpaceae proliferated and covered much of the

bottom area. It did not return during the milder winter

of 1973-74. The unequal semi-diurnal tide (see Figure

7) has an average tidal amplitude of about one meter

exposing much of the bay bottom on the lowest of the

two daily low tides, and draining the entire bay on

the lowest spring tides. In addition, strong northerly

winds associated with passages of cold fronts in winter

occasionally push the regional water mass offshore and

drain the bay and the nearby coastal area for several

days. With normal weather and tides, the heated plume

moves back and forth across portions of the bay in



























Figure 6.


Thermally affected area showing location of
the shallow inner bay system dominated by the
seagrass, Halodule wrightii, and the deeper
outer bay system. Lettered dots indicate
inner bay locations of remote telemetry
buoys maintained by Florida Power Corporation
for recording water temperatures. Location
lettering is as designated by the Florida
Power Corporation.




















0 0.5
KILOMETERS


a
o
o ra,,' '


OUTER


B BAY


\Le :/
O


O



























Figure 7. Typical daily tidal cycle at Crystal River site
indicating unequal high and low tides. Ampli-
tude changes were taken from tide tables (U. S.
Department of Commerce, 1972) for June 12,
1973.














2.0





E

F1.0
a






O
0


TIME OF DAY


0600 1200 1800









response to the tidal cycle. The shallow areas near

the power plant which were unaffected by the thermal

plume were dominated by a diverse mixture of benthic

macroalgae and seagrasses.

Areas away from the influence of the power plant

discharge at Fort Island, Hodges Island, and in the south

intake area (Figure 1) were used as comparison areas.

The south intake area was located immediately south

of the southern intake canal dike. Measurements taken

there by others included stocks of fish, benthic inverte-

brates, benthic macrophytes, zooplankton, sediment organic

content, and nutrient concentrations. The benthic macro-

phytic producers were a diverse mixture of macroalgae

and seagrasses.

Total metabolism measurements were made at Fort

Island and Hodges Island. Most measurements were made

in a funnel-shaped bay south of Fort Island. This area,

which was somewhat deeper than the inner discharge bay

area, was characterized by a benthic flora similar to

the south intake area. The extreme clarity of the water

influenced by the nearby Crystal River allowed much

greater light penetration to the bottom as measured with

a submarine photometer than in the power plant discharge

area. Hodges Island to the north of the Withlacoochee

River (Figure 1) was away from freshwater influences.

This bay had more turbid water with little growth of

benthic macrophytic plants.










Other Studies of the Crystal River Region


Little work is available on the Crystal River

region prior to power plant construction. Dawson (1955)

provided data on oyster populations and hydrography,

including measurements at stations now well within the

influence of the power plant.

After construction and operation of the plants

were initiated, many studies were made as part of the

larger research program undertaken by Florida Power

Corporation. Benthic seagrasses and algae were inven-

toried by Steidinger and Van Breedveld (1971), while

quantitative measurements of biomass were made by Van

Tyne (1974). Benthic invertebrates were inventoried

by Lyons et al. (1971) and measured quantitatively by

Evink and Green (1974).

Trawl samples of fish were reported by Grimes

(1971), Grimes and Mountain (1971), and Mountain (1972).

C. A. Adams (1974) analyzed data on fish caught in

dropnets from the shallow inshore areas, while Carr and

Adams (1973) discussed the food habits of juvenile fish

in the beds of benthic seagrasses and macrophytes.

Homer (1975) studied seasonal patterns of tidal creek

fishes.

Trace metal content of oysters from the intake

and discharge canals was reported by Grimes (1971) and









Mountain (1972). Biomass, diversity, and metabolism of

oyster bars were measured by Lehman (1974a, 1974b).

Blue crab movements in the intake canal area

were monitored by Adams, Oesterling, and Snedaker (1974).

Nutrients, chlorophyll, and phytoplankton numbers and

diversity were measured by Gibson (1975). Zooplankton

biomass and diversity were studied by Maturo (1974).

Fish and other organisms trapped on the screens

protecting the condenser water intake pumps were monitored

by Adams, Bilgere, and Snedaker (1974). Entrainment of

larval fish and zooplankton through the condenser system

was measured by Maturo (1974) and Snedaker and Johnson

(1975).

Total community metabolism was measured and

studied with simulation models for the saltmarsh by

Young (1974), for the oyster reefs by Lehman (1974a,

1974b), for the deeper outer bays by McKellar (1974, 1975),

and for the power plant canals by Kemp (1974). A larger

scale analysis of the energetic costs associated with

estuarine cooling compared to technological alternatives

was done by Odum (1974b), Odum et al. (1974), and Kemp

et al. (1975).

Physical measurements of the hydrography of the

area were reviewed by Carder (1975). These were used

by Klausewitz (1973) for verification of a computer

simulation model of the behavior of the thermal discharge









plume. Bedient (1972) simulated the flushing of water

from the discharge canal as it related to dispersion of

radioactive wastes in the discharge water. Swindler

(1973) examined the sedimentology of the region between

the Crystal River and Withlacoochee River. Cottrell

(1974) studied sediment composition and sedimentation

rates in the more immediate plant area.



Previous Simulation Models of Marine Ecosystems,
Diurnal Oxygen Dynamics, Temperature, and the
Effects of Power Plants on Ecosystems


Several previous attempts at modeling marine

ecosystems have appeared in the literature. Chen and

Orlob (1972) developed an extensive simulation of the

San Francisco Bay and Delta region incorporating spacial

as well as temporal elements. The geographical region

was divided into a network of nodes and connecting path-

ways. Mass balance equations were used to transfer

materials between nodes with tidal dynamics as the

forcing function. Up to 22 parameters could be con-

sidered: dissolved oxygen, biochemical oxygen demand,

alkalinity, pH, temperature, nitrogen (three forms),

phosphorus, suspended sediment, three types of algae,

zooplankton, three types of fish, and benthic animals.

For conservative elements, only terms for diffusion,

advection, input, and output were included in the mass








balance. For biological elements, appropriate terms

for rates of growth, respiration, mortality, and chemical

transformations were added. Temperature linearly affected

respiratory pathways of fish and zooplankton, and affected

both photosynthesis and respiration of algae. Growth rate

coefficients were based on Michaelis-Mention kinetics.

Model calibration to real data was presented for only

several parameters with fit being quite good. Subsequent

runs evaluated the effect on the bay of proposed regional

sewage treatment and water diversion alternatives.

Steele (1974) simulated a simple model of the

North Sea using storage of nutrients, phytoplankton,

zooplankton weight, and zooplankton numbers. Sunlight

was considered nonlimiting and was omitted as a forcing

function, so that changes in phytoplankton biomass were

a function only of nutrients, mixing below the thermo-

cline, and zooplankton grazing. Nutrient cycling was

included as excretion by zooplankton respiration.

Equation terms for nutrient uptake and zooplankton

grazing were derived from observed experimental data

and were given the form of Michaelis-Menton kinetics.

Brylinsky (1972) performed a sensitivity analysis

on a model of the English channel, which included storage

of phytoplankton, zooplankton, benthic fauna, pelagic

fish, demersal fish, and bacteria. Photosynthesis was

considered a constant external input. Pathways of


I









exchange between compartments were linear and controlled

solely by the donor compartment. Since nutrients were

not included as a variable, cycling was not a model fea-

ture. It was stated that the model was not intended to

be realistic, but, instead, to illustrate the applica-

tion and usefulness of the tool of sensitivity analysis.

An early attempt to simulate diurnal oxygen

dynamics of an ecosystem was made by Odum, Beyers, and

Armstrong (1963) using a passive analog circuit. Results

supported the theoretical discussion of the effect of

a small organic storage capacity in the nannoplankton

on the measurement of primary production in tropical

seas.

Several authors have obtained very good fit

for data from microcosms to relatively simple models

of their diurnal properties. Sollins (1970), studying

a blue-green algal mat, followed oxygen through compart-

ments of producers, consumers, detritus, dissolved oxy-

gen, CO2 (total in solution), atmospheric oxygen, and

water. All flows between compartments were controlled

by the upstream compartment only (donor control). Using

a square-wave regime of light input, the model produced

simulated curves of oxygen very similar to measured

curves and their rates of change.

Kelley (1971) included only storage of carbon

dioxide and labile and structural organic matter in his







simulation of a nutrient-rich freshwater microcosm of

mixed plankton. Since his study was partially concerned

with the effects of temperature, it was included in a

push-pull fashion as an action on every pathway. Rates

of flow between compartments were otherwise controlled

only by the donor compartments, as in the model by

Sollins. Excellent fit was obtained to the measured

oxygen data.

Nixon and Odum (1970) considered only storage

of organic material and nutrients in a model of hyper-

saline algal mat community. Transient responses of this

very simple model were compatible with those observed

in the microcosm.

Simulations based on the more variable data

gathered from open ecosystems in nature have been

carried out. A model of Bissel Cove, Rhode Island

(Nixon and Oviatt, 1973) was basically an oxygen balance

consisting of a single storage of oxygen with inputs

from primary production of plankton, macroalgae, and

benthic microflora. Respiratory oxygen losses occurred

to producers, sediments, detritus, shrimp, and fish.

Diffusion exchange with the atmosphere and tidal exchange

with a constant oxygen source were losses or gains

depending on the saturation level of the water and the

stage of the tide. Rates of oxygen losses or gains for

each pathway were empirically derived from regression









equations calculated from observed data. No feedback

or cycling pathways were included. Model response fit

reasonably well to observed diurnal curves of oxygen.

Boynton (1975) simulated a river-dominated

estuary to examine issues of river discharge schedules

and potential effects of human development on nearby

lands and its relation to an oyster fishery existing

in the bay. Using a simplified energy symbol model,

diurnal curves of oxygen very similar to data measured

in the area were obtained.

Several simulations have included temperature

actions. An early one emphasizing the effect of temper-

ature as an exponential function on zooplankton popula-

tions of the North Sea was done by Riley (1946, 1947).

Odum (1975) translated these equations into models

using the energy circuit language.

Hall (1974) briefly reported on a simulation

model of the effect of power plants on the striped

bass fishery of the Hudson River. Details of the model

were not given.

Odum (1974b) discussed some general principles

regarding temperature and system responses, including

the push-pull effect on both ordering and disordering

processes. Examples were given of simulations of equa-

tions proposed by Eyring and Eyring (1963) and Morowitz

(1968) which incorporated the push-pull feature of

temperature action.




38


Nixon and Oviatt (1973) included temperature

actions only on respiratory pathways in their simula-

tion model of Bissel Cove. As a result, a decline in

oxygen was predicted as the effect of the action of a

hypothetical power plant on the cove.

Miller (1974) simulated the effect of maintain-

ing mangrove vegetation in power plant canals to aid in

cooling the water before recirculation through the power

plant. Increased, but not severely detrimental, water

stress was predicted for the trees.

Several simulation models of other ecosystems

at Crystal River have been run. Young (1974) observed

increased photosynthesis, respiration, and live and dead

standing crop in simulations of the effect of elevated

water temperatures on the fringing Spartina saltmarshes.

Lehman (1974b) simulated the intertidal oyster reefs.

i Model responses included faster turnover rates for

plume-affected conditions. Simulations of effects of

adding thermal waters of another power plant suggested

reduced seasonal variation of reef standing stocks.

Kemp (1974), in a preliminary simulation of the com-

munity of fish, plankton, and benthos of the power plant

intake canal, found fish stocks to be most sensitive to

water flow rates and immigration. Plankton was rela-

tively insensitive to most parameters, being controlled

principally by concentrations carried in from outside








the canal. McKellar (1975) simulated the outer bay of

the discharge area (see Figure 6). Raising the water

temperature to that measured in the discharge area

produced only small increases in total metabolism and

some component storage. Water exchanges were shown to

be a stabilizing influence by dampening large fluctua-

tions in zooplankton, phosphorus, and detritus. Simula-

tion of the conditions expected with future power plants

produced no large changes in total community metabolism.



Plan of Study

The structure and function of the thermally

affected inner bay ecosystem at Crystal River and

unaffected areas to the north and south were determined

from field measurements of biomass of organisms and

system metabolism, and from the behavior of ecosystem

simulation models evaluated with these and other data.

The conceptual model shown in Figure 4 was developed as

an overview to show the relation of the main energy

exchanges with the outside, and of the main storage

of the inner bay ecosystem among themselves. Simpler

models which aggregated the main stocks and processes

were simulated on an analog computer.

Total community metabolism was determined from

diurnal changes in free-water oxygen concentrations

and was used as an indication of the ability of the









ecosystem to process the energies available to it.

Comparison of metabolism of the thermally affected

area with areas away from the influence of the power

plants indicated the degree to which these processing

abilities had been altered. Measurements were taken

from June, 1972 through May, 1974 representing all

seasons and establishing general seasonal trends of

metabolism.

Efforts using bottle experiments were made to

partition total metabolism between its planktonic and

benthic components. Measurements were made of penetra-

tion of light through the water column.

Models were evaluated with data obtained in this

study and gathered concurrently by other researchers,

with other supporting measurements, information from

the literature, and some necessary calculations and

assumptions. These models were translated directly into

a set of differential equations, which were programmed

for analog computer simulation. Simulation runs were

made with coefficients set for conditions with and without

the influence of the power plant. Results were compared

to the observed data. Sensitivity of the models was

examined with respect to changes in water temperature

and ratios of discharge canal water to offshore water

mixing on the inner bay. Finally, simulations were run

with conditions expected when the new power plant begins

operation.















METHODS


Metabolic Measurements


Community metabolism was measured with diurnal

sampling of oxygen following Odum and Hoskins (1958),

Odum and Wilson (1962), and Odum (1967), and an abbrevi-

ated method using dawn-dusk-dawn oxygen samples (McConnell,

1962). Oxygen was measured by the azide modification of

the Winkler technique (Amer. Publ. Health Assoc., 1971),

but adapted for use with smaller sample collection

bottles.


Mini-Winkler Field Kit and Winkler Method
Modification


Because of the large number of samples to be

processed and the need for compactness, a mini-Winkler

field kit developed at the University of Texas Institute

of Marine Sciences was used in this study. Standard

flat-topped 125-ml reagent bottles were used for sample

collection in place of 300-ml BOD bottles. Samples were

fixed with 0.5 ml of manganous sulfate and azide reagent

carried in dropping bottles in the field kit. After








acidification with 0.5 ml concentrated sulfuric acid,

100-ml subsamples were titrated with 0.012 N sodium

thiosulfate. This normality allowed direct reading of

milliliters of titrant as mg/l of oxygen.

Variability between replicate pairs of oxygen

samples could have arisen from many sources. Since the

small reagent bottles used were inexpensive, variation

in their individual volumes was expected. A test of a

54-bottle subsample of those in use gave an average

volume of 122.8 ml with a standard error of 0.22.

Because each bottle was filled from a separate sample

of bay water taken 30 seconds to one minute apart, vari-

ations due to water mass differences could also have

occurred. Other sources of variation could have included

differences in reagent volumes added and differences in

sample volumes titrated.

Actual differences in titrant volume encountered

between replicate pairs of samples were small, however.

Based on a subsample of 486 replicate pairs, 72.6 percent

differed by 2 drops (0.1 ml) or less. Since titrant

volume was generally in the range of 4-8 ml, this gave

an average error of 1.3-2.5 percent. Loss of accuracy

due to increased sources of variability was, therefore,

considered minimal, and was far outweighed by convenience

in handling in the field. More samples could be processed,

permitting better estimates for the whole bay.









Significance of Delay in Fixing Winkler Bottles
with Acid


A test was made of the effect of an eight-hour

delay in adding acid to the sample bottles in the Winkler

analysis of oxygen. Thirty bottles were filled with

thoroughly mixed salt water from a bucket, and immediately

fixed with the manganous sulfate and azide reagents. Ten

bottles were picked at random, acidified, and titrated

within 30 minutes. The remaining bottles were split

into two groups, one group of 10 bottles receiving acid,

while the other did not. Both groups were stored in the

dark for eight hours. At the end of that time, acid was

added to the bottles which had not received it earlier,

and both groups were titrated. Table 1 gives the results

of the three treatments. Differences between treatments

were significant (95% level), but were considered too

small to have any significant effect on the measurements.


Complete Diurnal Sampling of Oxygen


The calculation of total community primary pro-

duction and respiration from free-water measurements

of oxygen is based on the model given in Figure 8.

As indicated, the oxygen concentration in the water

column at any moment and changes in concentration with

time are a function primarily of the production of oxygen

during photosynthesis, its consumption in respiratory















Table 1.


Results of a technique test of the Winkler
method to determine the effect of the
presence or absence of acid in fixed bottles
which have been stored for eight hours before
titration. Each treatment contained 10
bottles. Results are given in milliliters
of titrant.


Bottles fixed, Bottles fixed and Bottles fixed
acidified, and acidified immedi- immediately;
titrated ately; titrated acidified and
immediately 8 hours later titrated 8 hours
later

Average 5.45 5.43 5.48


Std. Error 0.02 0.01 0.01






























Figure 8. Model of factors affecting oxygen dynamics
in water.





























SATURATION


--- ADVECTIVE
---- EXCHANGE


PHOTOSYNTHESIS


RESPIRATION


I ________









processes, gains or losses because of advective exchange

with adjacent water masses, and diffusive exchanges with

the atmosphere. The contribution to oxygen dynamics of

the nonbiological processes of advection and diffusion

may be corrected for if their magnitudes are known or can

be estimated. Subtracting their effect allows a calcu-

lation of changes resulting only from the biological

processes of photosynthesis and respiration, and, thus,

a calculation of production and respiration.

After correcting for diffusion and advection,

any gain in oxygen concentration during daylight hours

would be a consequence of the greater production of oxygen

in photosynthesis than its concurrent use in respiration,

thereby providing a measure of net primary production.

At night, when there would be no production of oxygen

by photosynthesis, the rate of oxygen decline would be

an estimate of community respiration. By assuming a

similar respiration rate for daylight hours (which would

be a conservative assumption), an estimate of the rate

of gross primary production may be obtained by adding

daytime photosynthesis and night respiration.

Stations were sampled approximately every three

hours over a 24-hour period. Two buckets of surface

water were collected 30 seconds to one minute apart at

each station, and sample bottles were filled from the

bottom by siphoning through rubber tubing. Late night









samples were sometimes stored without acidification for

titration the following morning (see above for effect

on Winkler analysis). Time, temperature, salinity, and

depth were noted at each station.

Because of the large tidal flushing, advection

of water masses from outside areas was at first thought

to be important. In order to assess this effect on the

diurnal oxygen curve in the study areas, four or five

stations were sampled in the early part of the project.

Analysis indicated a general similarity in the daily

increase and decrease of oxygen at all stations, sug-

gesting that advection was from areas of similar metabo-

lism. Thus, errors introduced by advection were thought

to be small, and the number of stations was usually re-

duced to two or three to meet field schedules.

Diurnal metabolism graphs were constructed using

a standard format (Figure 9) to allow easy visual com-

parison among all diurnal samples taken at Crystal River

as well as with others in the literature (Odum and

Hoskins, 1958). The data were analyzed several different

ways as the study progressed. At first, a graph for each

station was plotted and analyzed separately. Later, all

points from separate stations were plotted on one graph,

but only the mean curve was analyzed (Figure 9). Each

oxygen point was the average of duplicate Winkler

analyses. Oxygen per square meter (Figure 9c) was












Figure 9. Example of graphical format for calculation of
community metabolism at Fort Island, 24-25
August, 1973, using full diurnal curve of oxy-
gen. Open circles represent average of measure-
ments at four stations, each of which are shown
as solid points. (See text for detailed dis-
cussion of [g] and [h].)

(a) Oxygen concentration.

(b) Depth.

(c) Areal oxygen obtained by multiplying (a)
and (b).

(d) Temperature.

(e) Salinity.

(f) Percent saturation of oxygen calculated
using oxygen values in (a).

(g) Rate-of-change of oxygen. Dotted line is
rate-of-change of (c). Solid line with
solid dots ( -- ) is rate-of-change cor-
rected for depth changes. Solid line with
open circles (o--o) is rate-of-change
curve corrected for diffusion using coef-
ficient values given across the top of the
diagram. Units of diffusion coefficients
are g02/m2/hr./l00% deficit.

(h) Rate-of-change of oxygen. Solid line with
solid dots ( -- ) is rate-of-change of
(a) multiplied by average depth at each
hour. Solid line with open circles
(o---o) is curve corrected for diffu-
sion using same coefficients as in (g).










z


I-

0
o
u


Go

0 o


000 1200 1800
TIME OF DAY


-( C)


(d)





















Il "- L % I I IIVIL
o (g) HOTOSYT
o I
+0.5



n- o
0 E 77-


z -0.5 -_
wI

x I
o -1.0 V
I NIGHT RESPIRATIC


1.5
+1.0 I I
(h)
w
0 DAYTIME NET
z PHOTOSYNTHESIS
< + 0.5-


o E
I77


I 0.5-
x
o NIGHT RESPIRATION-

1.0 I I I
0600 1200 1800
TIME OF DAY


Figure 9 continued









obtained by multiplying oxygen concentration (Figure 9a)

by depth at that time. Percent saturation (Figure 9f)

was calculated for the temperature and salinity at each

time using the formula of Truesdale et al. (1955). The

divergence of Truesdale's saturation values from those

presented in Standard Methods (Amer. Publ. Health Assoc.,

1955) was reviewed by Churchill et al. (1962), who showed

deviations at temperatures less than 250C. Maximum

deviations, however, were less than 5% of the values

from Standard Methods, so the errors incurred in this

study by using Truesdale's values were considered small.

An oxygen rate-of-change curve (Figure 9g) was

constructed from the graph of average oxygen per square

meter. The amount of change of oxygen during each hour

was measured and plotted on the half hour. This raw

curve reflected changes in oxygen concentration under

one square meter due to changing depth from tidal exchange

and diffusive exchange with the atmosphere, as well as

photosynthesis and respiration. The effect of changing

depth was eliminated by multiplying the incremental depth

change for each hour by the average oxygen concentration

during that hour. This value was added to the rate

curve if the tide was falling or subtracted if the tide

was rising.

The final adjustment to the rate-of-change curve

was for oxygen lost or gained by diffusion between the









water and atmosphere (see more complete discussion on

page 62). In general, in the discharge bay only a falling

tide from a high high to a low low stage had a sufficient

current producing a diffusion rate large enough to make

an appreciable correction in the metabolism calculation.

Both rising and falling tidal current velocities were

greater in the control areas making diffusion corrections

more important at all tidal stages. For daytime net

photosynthesis the average difference between the area

under the curves adjusted and unadjusted for diffusion

in the inner bay was 8 percent. At the Fort Island

control area it was 24 percent, while at Hodges Island

(only two measurements) it was 2 percent. Any diffusion

estimate that was incorrect for the discharge bay would

have a relatively small effect on the metabolism calcu-

lation. At Fort Island the effect would be only somewhat

larger.

This laborious method was later modified; average

oxygen concentration, temperature, depth, salinity, and

percent saturation were plotted as before, but the

area-based oxygen curve was not calculated. The rate-

of-change curve (Figure 9h) was obtained by multiplying

the hourly rate-of-change of oxygen concentration by the

average depth at that hour giving the rate-of-change

on an areal basis. The adjustment for diffusion was

made as before.









In all methods the final rate-of-change graph

showed the rise of oxygen resulting from net photosyn-

thesis during the day, and decrease because of respira-

tion at night. Net daytime photosynthesis was taken as

the area under the rate-of-change curve above the zero

rate-of-change line. Nighttime respiration was taken

as the area under the rate-of-change curve below the

zero rate-of-change curve (Figure 9g and 9h).


Dawn-Dusk-Dawn Measurements


In order to gain more data as a check on day-

to-day variability of total metabolism and to reduce

the amount of field labor involved, the dawn-dusk-dawn

method (McConnell, 1962) was used after the first year.

The low point of oxygen at dawn, the high point at dusk,

and the low point the following dawn were measured as

a short-cut method of approximating the true diurnal

curve. Experience in the field showed that the time

of the minimum and maximum was not always at dawn or

dusk. Clouds in the east at sunrise tended to delay

the onset of rising oxygen by an hour or more. Simi-

larly, afternoon thunderstorms often caused the downturn

of oxygen well before dusk. Even on clear days full

diurnal curves showed that oxygen concentration often

would not increase any more in the last two hours before

sunset. The times of dawn and dusk sampling, then, were









often adjusted to the prevailing conditions. Dawn

samples were delayed if the morning was cloudy in the

east. Dusk samples were generally taken about 1-1/2

hours before dusk.

Water samples were drawn, fixed, and titrated

as described before. Diurnal graphs of averaged data

were drawn in the same way as for full diurnals (Figure

10) but, of course, used only three points. Straight

lines were used to connect points for oxygen, tempera-

ture, and percent saturation. Because depth was impor-

tant to the metabolism calculation, the actual daily

pattern was estimated from the observed measurements

and the expected tidal amplitudes for the Crystal River

area published in the U. S. Department of Commerce

tide tables. Because the daily pattern of salinity

change was complex, no attempt was made to extrapolate

between the measured values.

With the three-point dawn-dusk-dawn method,

net production and/or night respiration would be under-

estimated if the minimum and maximum points of oxygen

were not sampled when they occurred. The method also

used fewer replications so that any one unusual measure-

ment would have a greater effect on the calculation of

metabolism. McKellar (1975) gives a more complete

discussion of errors associated with the method.



























Figure 10. Graphical format for calculation of community
metabolism using dawn-dusk-dawn data. Open
circles are the average of measurements at
individual stations indicated by solid dots.
Numbers across top of the rate-of-change
graph are diffusion coefficients.











Z E
(\
>- cJ
XO
0


I
E 2.0
0 1.0


W
ar

FU


0E
W
I-





I--









z


I-






Lir
2




I -

cr0




x
0


36 -

34-


+0.5




0.0



-0.5


1200 1800


I


I I I


0
0 -


0600









An analysis of the difference in metabolism

estimates calculated by the dawn-dusk-dawn and full

diurnal curve methods is given in Figure 11. Data points

were read from a subsample of the graphs of full diurnal

curves of oxygen as if that day had been sampled by the

dawn-dusk-dawn method,and daytime net photosynthesis

and night respiration were calculated. Daytime net

photosynthesis would have been underestimated by the

dawn-dusk-dawn method three times in the inner bay by

an average of 33 percent and overestimated twice by a

small amount. Agreement was better at Fort Island and

Hodges Island but would have been over- or underestimated

by up to 25 percent.

Night respiration by the dawn-dusk-dawn method

was only an average of 58 percent of that calculated

by the full diurnal curve method in the inner discharge

bay. At Fort Island the three-point method was only

75 percent of the full curve method on three occasions,

while the full curve value was only 88 percent of the

three-point value two times.

McKellar (1975) for the outer discharge and

control bays at Crystal River found the dawn-dusk-dawn

method to underestimate gross production values (daytime

net production plus night respiration) usually by less

than 10 percent. The average difference between the

two methods was not significant at the 0.05 level.



























Figure 11. Comparison of community metabolism estimates
obtained from complete diurnal measurements
of oxygen versus estimates obtained from
dawn-dusk-dawn calculations made using the
same data.

(a) Daytime net photosynthesis.

(b) Night respiration.











-o
LI'

N
01



0



-j
z
UJ
>



Q:
'3
0
-J






0
2
*0
N














,I
Q
-J







>
0


DAWN-DUSK-DAWN,


6 8

g 02/m2day



/N












CHARGE BAY
-AND .
ISLAND
'
6 8
g 02/m -day


DAWN- DUSK-DAWN,








Eley (1970) found that dawn-dusk-dawn estimates averaged

91 percent of gross production and 87 percent of total

respiration in eight laboratory microcosms and 71 percent

of gross production and 52 percent of total respiration

in Keystone Reservoir, Oklahoma when compared to the full

diurnal curve analysis. In this study 61 percent of the

metabolism measurements from the inner bay and 68 percent

from the outer bay were made with the dawn-dusk-dawn

method. Since the apparent underestimation was largest

in the inner bay, these values may be conservative esti-

mates.


Effects of Advection on Calculation of Metabolism


If an increase in oxygen occurred at night because

of advection, an artifact in the rate-of-change curve

was produced which made it appear as if photosynthesis

was occurring. Net production would be overestimated

because the nighttime gain in oxygen would be added to

the actual net production occurring during daylight hours.

Night respiration would be underestimated because the

area of positive oxygen gain would not be counted in the

calculation of respiration. By measuring this omitted

area, night respiration was found to be underestimated

by an average of 1.5 g/m2.day on the full diurnal curves

from the inner bay.









Light and Dark Bottle Measurements


Light and dark bottle studies were made in the

later stages of the project to estimate metabolic com-

ponents of the water column as apart from the metabolism

of the sediments and larger consumer organisms. Bottles

(300 ml, BOD) were suspended at about 0.5 m depth by

small chains secured to a four-foot length of 3/4-inch

PVC pipe floated at each end by a plastic milk carton.

Generally, five replicates each of both light and dark

bottles were put out as soon as the dawn diurnal run

was completed, and picked up at the same time the follow-

ing day. Fixation and titration were as in American Public

Health Association (1971), except that only a 100-ml sub-

sample was titrated because of the 0.0125 N thiosulfate

used. The increase in the light bottle was taken as 24-

hour net production, the decrease in the dark bottle was

taken as 24-hour respiration, and the sum of the oxygen

gained plus that used up was taken as gross photosynthesis.


Other Field Measurements


Diffusion Measurements


At Crystal River the rate of diffusion of oxygen

into and out of the water column tended to be largely

a function of tidal current velocity. Diffusion was

measured at various stages of the tidal cycle using a









small nitrogen-filled plastic dome, which floated on the

water surface (Hall, 1970, based on original work of

Copeland and Duffer, 1964). An oxygen probe measured

the return of oxygen into the dome from the water under

the normal conditions of underwater circulation. A

linear regression was calculated from the raw data.

Although the increase in oxygen in the dome is not

linear, the early response approximates a straight line.

The diffusion rate as g/m2/hr/100 percent deficit was

calculated from the linear regression, area of water

surface covered, volume of the dome, and the observed

saturation value of dissolved oxygen in the water. This

was the maximum rate of diffusion into oxygen-free water

or out of water 200 percent saturated with oxygen.

Figure 12 shows a typical diffusion measurement.

Because of the small number of measurements

taken, assigning diffusion rates to time periods on

the graph was a combination of actual measured values

and estimates based on field experience with the general

magnitudes of tidal currents at different stages of the

tidal cycle in the study areas. The actual diffusion

correction for each hour was calculated by multiplying

the maximum rate selected for that hour by the actual

saturation deficit during that hour.




























Figure 12.


Example of two experiments to determine oxygen
diffusion coefficients by measuring the rate
of return of oxygen into a nitrogen-filled
dome floating on the water's surface. Line
through points was obtained by calculating
a linear regression. Meter was calibrated
to give a reading of 10 in air. Data obtained
at Fort Island study area.












30


LU
-j
<0
c) JUNE 25, 1973
.J FALLING TIDE (HIGH HIGH
I TO LOW LOW )
: y = 0.175 + 0.021 x
U- 2 r2= 0.998
LL 20
--
0

z





Z 10
LU
CL






Sy=0.139+ 0.0 85 x
2= 0.988
30 60 90 120
TIME FROM START, MINUTES
U- '0 60 90 LTIM FRO STARITIN MINUTESWLO








Light Penetration of the Water Column


Light penetration through the water column was
measured with a submarine photometer (Tsurumi Precision

Instrument Co., S/N 88130). Light intensity was mea-

sured at 0.1-meter depth intervals from the surface

to the bottom and compared to a deck cell reading insola-

tion incident to the water surface. Results were graphed

on semi-log paper (Figure 13). The extinction coefficient

was calculated was


ln (11/12)
K = I
Z2 Z1


where I1 was light intensity at the shallower depth

(Z1) and 12 was light intensity at the deeper depth

(Z2). K was in units of meter- .



























Figure 13.


Examples of submarine photometer measurements
of light penetration through the water column
taken at Fort Island away from the influence
of the power plant discharge plume and in
the inner bay influenced by the plume. Lines
through points were fitted by eye. k, extinc-
tion coefficient.












PERCENT


10
O -


OF SURFACE LIGHT INTENSITY

50 100














DATA ASSEMBLED FROM OTHER PHASES OF THE
CRYSTAL RIVER PROJECT AND ELSEWHERE



One of the major objectives of the overall

research program at Crystal River was to synthesize

the knowledge of the forcing functions outside of the

system and the storage and process operating within

the system. To this end, records of many of these

variables from other phases of the project and elsewhere

are included here to provide a total view of the estuarine

ecosystem. These data are used for obtaining values for

the model simulations and in determining if the simula-

tion results are reasonable.


Energy Sources and Inflows
Affecting the Inner Bay


Seasonal and diurnal patterns of some of the

external factors shown in Figure 4 are given below.


Sunlight


In Figure 14 is the average daily insolation by

month measured at Tampa, Florida, 97 km to the south of

Crystal River (Water Information Center, Inc., 1974).






























Figure 14. Average daily insolation by month at Tampa,
Florida (Water Information Center, Inc.,
1974).




















8000






0
cu

^ 6000




0 4000







.J
0
0
C( 0


I. --


I I I I I I I i I





















I I I I I I


J F M AM J JY A S O N D


I


I









Peak insolation months (about 6000 Kcal/m2-day) were

April and May at the very end of the winter-spring dry

season. Daily summer values were lower due to frequent

cloudiness from convective storms.


Wind Direction and Speed


Wind rose diagrams by season are given in Figure

15 (Fla. Power Corp., 1972). Summer winds were pre-

dominantly westerly and easterly as influenced by the

large-scale circulation about the shifting position of

the subtropical high-pressure system and by the more

local regional land-sea breeze system. With the change

in the fall and winter to weather patterns dominated by

frontal systems, the predominant wind direction shifted

to northerly directions. Average wind speed as given

in Table 2 (Fla. Power Corp., 1972) was lowest in the

summer and highest in fall and winter due to the strong

winds associated with frontal passages.


Ambient Air Temperature


In Figure 16 are monthly mean, mean maximum,

and mean minimum daily temperatures at Tampa, Florida

(Fla. Power Corp., 1972). Diurnal variation was smallest

during the summer months when the climate was primarily

under the influence of the subtropical high pressure

system, and frontal systems usually remained well north




























Figure 15. Wind direction by season at Crystal River site.
Bars are percent of readings occurring from
each compass bearing (Florida Power Corpora-
tion, 1972).































DEC., JAN., FEB. MAR. ,APR., MAY


JUN.,JUL., AUG.


SEP!,OCT., NOV.












Table 2. Seasonal comparison of average wind speed at
Crystal River site (Fla. Power Corp., 1972)


Average wind speed, mph


11.1


9.5


12.0


12.0


Annual average


Season


Spring


Summer


Autumn


Winter


11 .4





























Figure 16. Monthly mean air temperature at Tampa,
Florida (Water Information Center, Inc.,
1974).




77














100
100. i i -- i -- -j,...l...L ,j -- 1 1
EXTREME HIGH,.-'' AVERAGE DAILY MAXIMUM --.-
MONTHLY MEAN
80
SL- AVERAGE DAILY MINIMUM
o .. --- -.,

cr 60
.. / .__

J 40-
CL
/ 1



20 EXTREME LOW

O JFM I i J I J I
J F M A M J JYA S 0 N D









of the area. Minimum temperatures dropped sharply in

October as cold fronts began penetrating into Florida,

and remained low through the winter when the climate was

characterized by cold air advection following frequent

frontal passages.


Precipitation


Monthly mean precipitation at Tampa is presented

in Figure 17 (Fla. Power Corp., 1972). About 60 percent

of the yearly rainfall occurred from June through Sep-

tember and was associated with showers and thunderstorms

in tropical air masses. During the extensive eight-month

dry period extending through May, precipitation was mainly

associated with frontal systems.



Stocks of the Inner Bay


Assembled below are data on stocks of organisms

and other quantities important within the inner bay

system.


Water Temperatures


Weekly average water temperatures at various

locations in the discharge canal, discharge study area,

and intake area during the course of this study are given

in Figure 18. Buoy locations are given in Figure 6.

Weekly average electricity generated by units 1 and 2





























Figure 17. Monthly mean precipitation at Tampa,
Florida (Water Information Center, Inc.,
1974).





















15 --- --
.)
<:
C
o

". 10 -

O
t-





0. L L J J L. I J._

J F M A M J JYA S O N D




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