Factors affecting accelerated eutrophication of Florida lakes

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Factors affecting accelerated eutrophication of Florida lakes
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Putnam, Hugh D.
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Research Project Technical Completion Report


"FACTORS AFFECTING ACCELERATED
EUTROPHICATION OF FLORIDA LAKES"

OWRR Project No. A-002-FLA







TO:

U. S. Department of the Interior
Office of Water Resources Research
Washington, D.C. 20240


Hugh D. Putnam, Principal Investigator
Environmental Engineering Department
University of Florida
Gainesville
August 29, 1968






NOTE: This report, after final correction and editing, will be published
by the Florida Engineering and Industrial Experiment Station, College of
Engineering, University of Florida, as Technical Progress Report Number 16
and Florida Water Resources Research Center Publication Number 5.












TABLE OF CONTENTS


Page

Research Staff ...................................... II

Introduction ........................................ 1

The Process of Eutrophication ....................... 4

Rate of Nutrient Addition to Anderson-Cue Lake ...... 12

Physical Characteristics of the Research Lakes
and Drainage Basins ............................ 18

Routine Chemical Studies ............................ 27

B iology ............................................. 43

Analysis of Environmental Factors Affecting
Primary Production ............................. 90

Trophic State of Lakes in North Central Florida ..... 106

Models of the Eutrophication Process ................ 118



List of References ................................. 121













Members of Research Team and Assistants

Dr. Hugh D. Putnam

Dr. Patrick L. Brezonik

Dr. William H. Morgan

Dr. James B. Lackey

Professor A. L. Danis

Mrs. Zena Hodor

Mr. Roger Yorton

Mr. Thomas Salmon

Mr. H. A. Blalock

Mr. Earl Shannon

Mr. Michael Long

Mr. Gary Ashley

Mr. Larry Seymour

Mr. Howard Crown

Mr. Samuel Richardson

Mr. Glen Brasington

Mrs. Jeanne Dorsey

Mr. T. L. Tang

Mrs. Carol Harper











Section 1


Introduction


Florida has a vast and valuable resource of fresh water consid-
ering the springs and nearly 30,000 lakes found within the state. Prac-
tically all of these surface waters are useful in a recreational sense
and for this reason Florida appeals greatly to tourists everywhere with-
in this country and Canada. Fishing, beating, and various contact water
sports are enjoyed by both residents and out of state visitors through-
out the year. Therefore, the conservation of this fresh water resource
is most important to the state's economy.

However, since water is so intimately involved in the total
well being of the environment, impairment of aquatic systems in varying
degrees will affect all the biota including man within a particular
ecosystem. Essentially, the water quality of lakes and other fresh
water resources mirrors the status of the total environment.

Over the years, Florida lakes have been enriched gradually
with nutrient salts from the land. Encroaching urbanization and in-
tensive agricultural practices have, however, increased nutrient addi-
tions to lakes on an unprecedented scale in recent years. This enrich-
ment has accelerated the eutrophication of surface water thereby short-
ening the lives of lakes and generally impairing the quality of the
water.

This problem, which can be reflected nationally, is acute
in Florida. The shallow lake basins, long hours of sunlight and mild
winter temperatures are some of the factors which make surface water
particularly susceptible to the effects of enrichment and lead to
sustained algal blooms throughout the year. The most classic example
in Florida is Lake Apopka near Orlando. This is a 30,000 acre lake
which has been extensively enriched by fertilizers from bordering citrus
and winter vegetable farms, municipalities, and citrus processing plants.
A hyacinth erradication program by chemical sprays over the last 20 years
has left a flocculant bottom layer of undecomposed plant residues. The
lake bottom is anaerobic. At all times during the year soupy algal
growths are found in the surface water over the entire lake.

A similar process is occurring in many other lakes within the
state. Although the visible effects of eutrophication are well documented
very little real knowledge exists regarding the interplay of environmental
parameters during lake enrichment. Ultimately management systems must be
devised to include whole drainage basins if the eutrophication problem is
to be dealt with effectively. First, however, it is necessary to under-
stand in quantitative terms what eutrophication is; what are the most
effective combinations of enriching substances and how these relate, for











example, to the physical environment of lake morphology, climate and
various edaphic factors. To accomplish these objectives and ultimately
offer the maximum use of a lake to those living within the basin we
must know what enrichment stress can be placed on surface water without
measurably impairing its quality.

This can be brought about only by long term research. Projects
such as that described in this report, using whole lakes as experimental
units, are few in this country. More are needed especially in varying
geographic locations if we are to understand completely the eutrophication
process.

The site for this study was selected in the sandy, scrub-oak
terrain near Melrose, Florida, about 30 miles east of Gainesville. Nu-
merous lakes are located in this area, and two lakes located on private
property were selected through the cooperation of the owners. The isola-
ted location of these lakes assures freedom from outside interference
and urban or agricultural influences. Considerable effort was exerted
in 1966 to establish a field station at the lake site and to install
appropriate instrumentation. Background data on the chemistry and
biology of the lakes was obtained in order to be certain of their similar-
ity and original trophic status. It became apparent, however, that the
lake originally selected for nutrient enrichment, Berry Pond (see Figure
1-1), was not similar in biological and chemical characteristics to the
lake selected as the control, Anderson-Cue Lake (see Figures 1-1 and 4-1).
It was then decided to use Anderson-Cue Lake as the experimental unit and
to attempt its controlled eutrophication. A nearby lake, McCloud,
similar to Anderson-Cue Lake in size and physical characteristics, was
selected finally as the control in late 1966. McCloud Lake is located
approximately one-half mile north east of Anderson-Cue Lake.

















































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Section 2


The Process of Eutrophication


It is axiomatic that a problem must be clearly defined before
solutions can be developed. The problem of lake eutrophication has long
suffered because the process, its causes, and effects have lacked clear
definition. While the phenomenon of eutrophication has many ramifica-
tions the problem itself is basically two-fold. Eutrophication itself
is simply the process of nutrient enrichment of natural waters. Previous
workers have defined the process only qualitatively and quantitative
loading rates do not necessarily specify a particular rate of eutrophica-
tion. The second aspect of the eutrophication problem is definition of
its effects on the trophic state of a lake. Eutrophy or the eutrophic
condition is a state of a lake defined by a variety of biological and
chemical conditions. Eutrophy is of course a result of eutrophication
but unfortunately there are no well defined units or quantitative meas-
ures of a trophic state. Thus it has been heretofore impossible to
quantitatively relate the process of nutrient enrichment (that is eu-
trophication) to the effects on trophic state (that is the degree of
eutrophy). In many cases it is actually the rate of eutrophication
which is of primary interest. Aquatic scientists are primarily con-
cerned with the manifestations of eutrophication on the trophic state of
a lake. This implies that they are actually concerned with the rate of
change in trophic state or eutrophy or the rate of change in the effects
of nutrient enrichment.

Stewart and Rohlich (1967) recently published a comprehensive
review of the eutrophication problem. According to their review the term
eutrophication has been used and defined rather loosely by different
workers. However, Naumann (1931) originally defined eutrophication as
"an increase of the nutritional standard (of a lake) especially with
respect to nitrogen and phosphorus." There is general agreement among
present workers that eutrophication is the process of nutrient enrich-
ment.

Most previous workers have cited nitrogen and phosphorus as the
main eutrophying elements. There is no general agreement among author-
ities concerning the relative importance of nitrogen and phosphorus as
limiting elements. Cases can be made for both elements, and bioassay
methods have found both limiting primary production in different lakes.
Many other elements and compounds (e.g., trace metals and vitamins) are
essential for algal growth. However, little is known about their role in
the eutrophication process. There are reasons -- based on geochemical
and biological considerations -- to believe that lakes generally are
limited by their nitrogen and phosphorus inputs, but unambiguous proof
would be nearly impossible. It is also likely that input of minor
essential nutrients is highly correlated with one or both of the major
limiting elements.











One of the objects of the present research project is to clarify
the factors involved in eutrophication and trophic state and to relate
them quantitatively to each other. The factors affecting nutrient enrich-
ment of lakes are largely geological and cultural, as indicated in Table
2-1. The nutrient load imposed on a lake is a function of the geochem-
istry of its drainage basin, the hydrology of the region, climate and
other natural factors. Superimposed on these natural factors are a vari-
ety of human factors, e.g., urban and agricultural runoff and the amount
of domestic sewage disposed into the lake. It should also be noted that
human factors can affect some of the natural forces. For example, mining
operations may change the geochemistry and hydrology of the basin, and
air pollution may increase the nutrient content of rainfall. For a given
total nutrient influx, net enrichment may vary depending on the temporal
variations in the input (whether it is a periodic slug or steady addition)
(Brezonik, 1965).

The effects of nutrient enrichment on the trophic state of a
lake are controlled by numerous physical and chemical factors; these are
summarized in Table 2-2. Limnologists have long realized that lake pro-
ductivity is influenced by factors besides the concentrations of nutrients.
This is apparent when it is realized that lakes of similar chemical com-
position may vary significantly in productivity. The other factors in-
fluence lake productivity primarily by affecting the distribution, avail-
ability and utilization of nutrients. Thus they influence productivity
only indirectly, and because of this it is much more difficult to assess
their individual importance. Similar statements can be made with regard
to the factors affecting trophic state in general. Brezonik (1965) re-
viewed the effects of physical factors such as morphology and climate on
lake productivity. Morphology has a dominant influence on the avail-
ability and distribution of nutrients in a lake and thus profoundly
affects productivity and trophic status. A number of morphological param-
eters are important in this regard, including mean depth, steepness of
bottom contour, percent littoral area, shore line irregularity and mean
depth/surface area ratio. Rawson (1955 and earlier papers) considered
mean depth of fundamental importance with regard to lake productivity.
He found a hyperbolic relation between mean depth and long-term fish
production in the five great Lakes and seven large western Canadian lakes,
indicating a rapid increase in fish production as mean depth decreased
below 25 meters and a slow decrease in production as mean depth increased
beyond 25 meters. Similar results were obtained by relating phytoplankton
and bottom fauna standing crop to mean depth of lakes, and Rawson con-
cluded that a mean depth of 20-25 meters is the dividing point between
oligotrophic and eutrophic lakes. Reasons for the dominant effect of
mean depth on lake productivity are several but mostly relate to the
possibility of nutrient replenishment from the underlying sediments in
shallow unstratified lakes. This factor has special significance for
eutrophication in Florida since most of its lakes are shallow and not
stratified. Climatic factors include temperature, insolation, and wind,
as it affects circulation patterns in the lake. Effects of chemical
composition of the water on the availability of nutrients are also noted



















Table 2-1


Factors Affecting Nutrient Enrichment
Rates (Eutrophication) of Lakes


Human Factors


Geochemistry of the basin
(Composition of underlying
rock structures)

Soil types
Hydrology
Size of drainage basin
Short-circuiting
Detention time in lake
Groundwater composition

Climate
Precipitation
Thermal structure


Domestic sewage
Agricultural runoff
Type of farming
Fertilization practices
and extent
Soil retentive capacity

Mining operations
Industrial wastes
Urban runoff
(Auto exhaust, lawn and
garden fertilizing
leaves, etc.)

Nutrient leaching from
drained marshes and
from garbage dumps


Natural Factors























Table 2-2


Physical and Chemical Factors Controlling the
Effects of Nutrient Enrichment on Trophic Status



Chemical


Mean depth
Steepness of bottom contour
Shoreline irregularity
Percent littoral area
Mean depth/surface area ratio
Wind protection by surrounding
terrain
Temperature
Insolation
Circulation which affects
sedimentation rates


pH
Balance of all nutrients
needed for production
Suspended solids (as
affecting transparency)
Nutrient concentrations
Dissolved oxygen


Physical











in Table 2-2. The temporal distribution of the nutrient input to a lake
(whether continuous or highly seasonal) may also control the effects of
nutrient enrichment on trophic state.

The trophic state or degree of eutrophy of a lake may be con-
sidered to be a function of the amount of eutrophication or nutrient en-
richment as modified by the edaphic factors given in Table 2-2. Trophic
state is defined by many factors and cannot be adequately measured by any
single parameter. The physical, chemical and biological criteria commonly
used to indicate trophic state are shown in Table 2-3. Many of the param-
eters are only qualitative indicators. While some of the parameters are
highly correlated and dependent on each other, others are at least quasi-
independent. The problem of defining trophic state is a serious one for
if progress is to be made in relating the process of eutrophication to its
effects criteria for trophic state will have to be well defined and
quantified. Fruh et al. (1966) and Stewart and Rohlich (1967) have re-
viewed the parameters used to measure trophic state in detail and have
discussed their assets and limitations. On a qualitative level the crite-
ria appear to present no problems. Oligotrophic lakes are low in nutrients,
have low chlorophyll and primary production levels, high transparency, are
generally deep, and have few numbers of organisms but large numbers of
species. Eutrophic lakes are generally the antithesis. They have high
nutrient and chlorophyll levels, high primary production, low transpar-
encies, are usually shallow, and have high algal populations distributed
among few species. However, the criteria do not generally lend themselves
to quantitative measures of eutrophy; i.e., using these criteria it is
impossible to state how much more eutrophic one lake is compared to
another. The various indicators sometimes present conflicting values for
the trophic state of a given lake. Beeton (1965) reported such anomalies
for some of the Great Lakes. While all criteria indicate Lake Erie to
be a eutrophic lake, some biological and chemical criteria indicate that
Lake Ontario is eutrophic and other chemical and physical criteria indicate
the lake is oligotrophic.

Most previous studies on trophic state indicators have been con-
cerned with temperate lakes. Subtropical lakes, such as those in Florida,
have considerably different characteristics, however, and the indicators
of trophic state in northern lakes may not be altogether applicable in
these situations. Some differences between temperate and subtropical
lakes are summarized in Table 2-4. In their natural states, some Florida
lakes simultaneously have characteristics of oligotrophic, eutrophic, and
dystrophic temperate lakes, which implies that parameters used to define
these northern lake types are not always useable in subtropical situations.
Nearly all Florida lakes are shallow; and considerable water fluctuations
occur between dry and rainy periods. Water level fluctuations of plus or
minus five feet in lakes with normal maximum depths of only 20 feet are
not infrequent, and many lakes dry up completely (or nearly so) in periods
of prolonged drought. Change in water level implies a moving shore line.
In Florida lakes there is often no distinctive land-lake interface, and
the shore areas of lakes are often submerged land. The littoral vegeta-
tion in Florida lakes is composed of emergent and submergent aquatic
species as in northern lakes, but because of the changing shore, terres-
trial species are also found in the littoral area. Extended growth periods

























Table 2-3


Indicators of Trophic Status


Chemical


Biological


Transparency

(Secchi disc reading)

Morphology

(mean depth, etc.)


Sediment type
Oxygen supersaturation
in epilimnion
Hypolimnetic
Oxygen deficit
Conductivity
Dissolved solids
Nutrient concentrations
(at spring maximum)
Chlorophyll level


Algal bloom frequency
Algal species variety
Characteristic algal
group
Littoral vegetation
Fish species and biomass
Characteristic zoo-
plankton
Bottom fauna
Primary production


Physical



















Table 2-4


Differences in North Temperate and Semitropical Lakes
Which May Bear on Eutrophication Process


Northern Lakes


Semitropical Florida Lakes


1. Defined shore line usually
with beach

2. Thermally stratified, usually
dimictic

3. Usually calcareous

4. Ice covered

5. Runoff from meltwater

6. Winter solar radiation and
temperature limit primary production


1. Shore-water interface
ill-defined

2. Little or no thermal
stratification

3. Soft, acid water

4. Always ice free

5. No spring runoff

6. Low temperature and solar
energy not evident; longer periods
for optimum plant growth. Sus-
tained yields of standing crop
throughout year.











lead to large standing crops throughout the year under subtropical con-
ditions compared to highly seasonal crops in north temperate lakes. In
general, seasonal changes in subtropical lakes are less evident than in
northern lakes. Temperature structuring is less pronounced, and because
of their shallowness few Florida lakes exhibit stable thermal stratifica-
tion. The general chemical compositions of temperate and subtropical
lakes differ considerably. Typical temperate lakes are calcareous, have
pH values above 7, and moderate to high alkalinities. Florida lakes
typically have soft acid waters and very low alkalinities. Organic
color is a more common constituent in Florida lakes than in temperate
lakes. Because of the difference in chemical composition, species of
plankton in Florida lakes tend to differ from those in temperate lakes.
Desmids are common in soft, acid waters of Florida, and diatoms are often
sparse. However, blooms of blue-green algae, such as Microcystis,
Anabaena, and Aphanizomenon occur in fertilized Florida lakes as in their
northern counterparts. The problem of adequate criteria for trophic
state will be further discussed in a later section on models of eutrophica-
tion.











Section 3


Rate of Nutrient Addition to Anderson-Cue Lake


One approach to studying eutrophication is to artificially enrich
(eutrophy) a lake at a controlled rate and measure all the parameters which
define trophic state. The problem then becomes a matter of relating the
response of a lake (in terms of trophic structure) to the degree and rate
of nutrient enrichment. The lake thus serves as a model for the process
in general; this approach has been used in the present study. Intentional
fertilization of lakes for scientific purposes is not a new concept.
Stewart and Rohlich (1967) recently reviewed previous experiments on lake
fertilization. Einsele (1941) reported one of the first experiments on
lake fertilization. He applied slug doses of super phosphate to a small
German lake in 1937 and 1938. Temporary increases in the phytoplankton
of the lake were found but the lake soon returned to normal. A number
of investigators (e.g. Ball, 1948a, b; Langford, 1948; Hooper and Ball,
1964) have attempted to increase the productivity of fish ponds by adding
fertilizer. These attempts have had only moderate success. In most
fertilization experiments nutrients have been added as slug applications
rather than continuously. While temporary effects have been noted the
ponds or lakes returned to their original condition in short periods of
time. Because of the nature and purpose of previous fertilization efforts,
the results from these studies are not directly applicable to the problem
of cultural eutrophication. Man induced eutrophication is characterized
by a more or less continuous addition of nutrients to a lake from such
sources as sewage, effluent and urban and agricultural runoff, while most
previous fertilization attempts have used sporadic or one time applications
of fertilizer. Generally sufficient background data was not obtained to
describe the trophic state of a lake in its natural temporal variations.
The study reported here is viewed as a long term effort to follow the
effects of a controlled nutrient input on a lake's trophic state. Two
small lakes are involved; one lake is serving as a control and the other
lake is being artificially eutrophied by continuous and controlled addi-
tion of nutrients. A variety of routine chemical and biological data
is being collected on these lakes along with routine physical and climatic
data in order to delineate the factors affecting the rate and severity of
eutrophication.

Chemical and biological measurements during 1966 and early 1967
established the oligotrophic nature of Anderson-Cue Lake. In March, 1967,
nutrient additions were started into the lake. It was decided to add
sufficient nitrogen to raise the total N content of the water 0.50 mg
N/1 over a period of a year (assuming all nitrogen would stay in solution).
This is equivalent to 500 mg/m3 -yr. or about 10 mg/m3 -week. The volume
of Anderson-Cue Lake was estimated to be 248,000m Thus a weekly loading
of 2.48 kg N was desired. This was achieved by adding 21.2 pounds of
ammonium chloride to 300 gallons of sewage effluent, which was trucked out











to the lake site and fed into the lake with a chemical feed pump at a
rate of 1.8 gallons per hour. The nutrient outfall is located 2 feet
below the surface and 200 feet off the south shore of the lake in about
10 feet of water.

It was decided to increase the total phosphorus content of the
lake by 0.0427 mg P/1 in one year. This is equivalent to 42.7 mg/m3-yr.
or 0.854 mg/m3-week. For the whole lake a loading rate of 0.212 kg P/week
is indicated. This was achieved by adding 2.47 lb. of Na3PO4 to the
sewage effluent each week.

Originally it was planned to add only sewage effluent to the
experimental lake. This would have been feasible if Berry Pond (1 acre
surface, maximum depth, 13 feet) had been used as originally planned, but
the trophic characteristics of this lake rendered that impossible. With
the larger Anderson-Cue Lake as the experimental lake, nearly a million
gallons of sewage effluent would have to be transported to the lake site
annually for the desired nutrient loading rate. Logistics thus precluded
the use of sewage effluent alone, and it became necessary to enrich
effluent with nitrogen and phosphorus compounds.

The above nutrient addition rates compare closely with those
estimated for the nutrient budget of Lake Mendota, Wisconsin, by Lee
et al., (1966). This eutrophic lake receives a heavy influx of nutrients
from agricultural drainage, but ground water and atmospheric precipitation
also make important contributions. The nitrogen load ng of Lake Mendota
was estimated to be 556,000 lb. per year, or 534 mg/m -yr. Of this
quantity, Brezonik and Lee (1968) have estimated that two-thirds or
360,000 pounds remains in the lake and is deposited in the sediments,
while the remainder is lost through the outlet and by denitrification.
The phosphorus budget for Lake Mendota was estimated to be 44,900 lb.
per year or 42.7 mg P/m3-year.

Relatively few other lake nutrient budgets have been established.
Mortimer (1939) constructed a nitrogen balance for Lake Windermere
(England). He found a close balance between input and output -- 326 and
318 metric tons, respectively. Hutchinson (1957) felt that nutrient in-
flow and outflow normally would balance closely in oligotrophic lakes,
but not in eutrophic lakes. Rohlich and Lea (1949) reported an extensive
nutrient balance on Lake Mendota, Wisconsin. Of the estimated 156 metric
tons of nitrogen entering the lake annually, only 41 tons left through
the surface outlet. Corresponding values for phosphate were 16.4 and
11.6 metric tons. Partial nutrient budgets were determined for the lower
Madison lakes by Sawyer et al. (1945). However, only soluble phosphorus
and inorganic nitrogen inputs were measured rather than total values, and
the usefulness of the results are thus lessened. Aside from the nutrient
balances on Lake Tahoe (McGauhey et al., 1963) and Lake Washington
(Edmondson, 1966) no other definitive nutrient budgets are known. Cer-
tain aspects of nitrogen and phosphorus budgets and sources have been
treated by various workers. Brezonik (1968), Feth (1966), and Fruh
(1967) have reviewed these studies in considerable detail.











Table 3-1 lists the most common nutrient sources and sinks for
lakes. Only some of these are applicable to the study lakes. Artificial
enrichment represents the most significant nutrient source for Anderson-
Cue Lake. The possible natural sources of nitrogen are biological fix-
ation, atmospheric precipitation, airborne particulates and surface and
subsurface runoff. Preliminary results indicate the rainfall directly
on the lake surface is the most important natural source. Nitrogen fix-
ation has not yet been measured in the lake, but the near absence of blue-
green algae in the biota of the lake implies that it does not occur. While
bacterial fixation is possible, available carbon substrates are low and
indicate the source is probably negligible. Contributions from runoff
also appear to be small. The amount of runoff draining into the lake is
apparently low, and the soil is so nutrient depleted that rainfall runoff
would pick up little or no additional nutrients in passing through and
over the soil.

Measurements of the nutrient content of the rainfall were made
periodically in 1967 and 1968. A summary of the results are shown in
Table 3-2. The nitrogen content of rainfall appears to be quite variable.
However, these results can be combined with the rainfall amounts (see
Section 4, Table 4-1) to yield an estimate of the total nitrogen con-
tribution of rainfall to Anderson-Cue Lake. For 1967, 49.4 kg nitrogen
was added to the lake by rainfall directly on the lake surface. This
compares to about 124 kg N added in the nutrient mixture. Actually a
greater disparity between these two sources exists than is indicated
by the magnitude of the two numbers. The rainfall contribution is
diluted in a large volume of water, whereas the nutrient mixture is
highly concentrated and contributes an insignificant amount of water to
the lake. No phosphate analyses are available for 1967; results from
1968 indicate a wide range of phosphatein rain water -- from about 1 to
25 pg P/1 with a mean content of 10 ug/l. Assuming this mean represents
the average phosphorus content of rainfall in 1967, 1.05 kg P was con-
tributed by rainfall in 1967. This compares with 10.6 kg added to the
lake in the nutrient mixture. These results are summarized as a nutrient
budget for Anderson-Cue Lake in Table 3-3.











Table 3-1


Sources and Sinks for the Nutrient Budget of a Lake


Sources


Sinks


1. Airborne
Rainwater
Aerosols and dust
Leaves and miscellaneous
debris

2. Surface
Agricultural runoff and
drainage
Urban storm water runoff
Marsh drainage
Runoff and drainage from
uncultivated land
Domestic waste effluents
Industrial waste effluents
Wastes from boating activities

3. Underground
Natural groundwater
Subsurface agricultural and
urban drainage
Subsurface drainage from
septic tanks near lake
shore

4. In situ
Nitrogen fixation
Sediment leaching


Effluent loss
Groundwater recharge
Fish caught or removed
Weed harvesting
Insect emergence
Evaporation (aerosol form-
ation from surface foam)
Denitrification
Sediment deposition of
detrital particles
Inorganic precipitation (for
calcium phosphate, and some
trace metals) and
deposition into sediments.











Table 3-2


Nutrient Content of Rain at Anderson-Cue Lake


NH3 (1)


2/7
2/14
5/9
6/6
6/13
6/27
7/11
8/22
9/6
10/10
11/2
11/16
12/19


1/8
2/5
3/4
5/27
6/24
7/22


0.10
0.04
0.54

0.11
0.74
0.08
0.15
0.25
0.40
0.51
0.61
0.06


0.65
0.71
0.80
0.02
0.02
0.01


N03-


TR


0.005
0.002
0.002



0.004


0.003


0.006
0.016

0.002
0.003
0.003


0.07

0.04
0.04
0.03
0.05
0.12
0.06
0.21


0.67
0.05


0.17
0.81
0.27
0.05
0.14
0.08


(1) Values in mg N/i
(2)
Values in mg P/1


-3(2)
PO4 j


Date

1967:

1/31
2/7
5/2
5/30
6/6
6/13
6/27
8/15
8/31
10/3
10/26
11/9
12/12


1968:


1/1
1/29
2/26
5/20
6/17
7/15


<0.001
0.007
0.025
0.009
0.009
0.008


NO2-











Table 3-3


Annual Nutrient Budget for Anderson-Cue Lake(1)


Nitrogen


Sewage and nutrient mixture
Rainfall on lake surface

Total


kg mg/i of lake water

124 0.50
49 0.20


173


0.70


Other sources not yet completely evaluated are nitrogen fixation,
ground water seepage, subsurface runoff, and airborne particulates, in-
cluding leaves and miscellaneous debris. Contributions from these
sources are thought to be relatively small.


Phosphorus


Sewage and nutrient mixture
Rainfall on lake surface

Total


kg mg/l of lake water

10.60 0.043
1.05 0.004


11.65


0.047


Other phosphorus sources are groundwater, subsurface runoff and
airborne particulates. Contributions from these sources are thought
to be small.










Rainfall based on 1967 calendar year; nutrient mixture contribution
based on year from April 1, 1967 to March 31, 1968; nutrient addi-
tion was started in March, 1967.
(2)
This is the concentration which would result if the amount of the

nutrient shown in column 1 were diluted to the volume of the lake
(approximately 248,000 m3 during 1967).










Section 4


Physical Characteristics of the Research Lakes
and Drainage Basins


General

Anderson-Cue and McCloud Lakes are located in a region of high
sand hills with many circular to elliptical basins which have resulted
from solution of the underlying limestone. Both lakes have small drainage
basins with no influent or effluent streams.

The tops of many of the surrounding hills reach elevations of
190 to 220 feet, MSL. Westward at Melrose the terrain changes from sand
hills to the Okefeenokee Terrace, a poorly drained terrace 140 to 160
feet, MSL. Eastward, beyond Baywood, the sand hills are bound by lower
marine terraces. The immediate area of the research lakes is the Trail
Ridge portion of the Central Highlands.

Three hydrographic surveys of Anderson-Cue Lake have been made
since the fall of 1965. Echo soundings were made in November 1965; a
stadia survey was made in July-August 1967; and echo soundings were again
made in March 1968. A hydrographic map of the lake was prepared using
these data and is shown in Figure 4-1. The highest level shown on the
map was the shoreline which stood at 125.78 feet, MSL, in March 1966 at
which time the lake had a surface area of 19.3 acres and a volume of
approximately 201 acre feet. When it was decided to use McCloud Lake
instead of Berry Pond as the control body of water in late 1966 the
volume of water in McCloud Lake exceeded that in Anderson-Cue Lake by
approximately 15 per cent. This information was obtained by stadia
survey.

Yearly excess precipitation over evaporation (30 year record)
is 12 to 18 inches in the xeric hills surrounding Anderson-Cue Lake1.
The excess precipitation and runoff percolate downward through breaks in
the sands and clays of an aquifuge that overlies the Floridan aquifer.
The influent drainage has resulted in a subsidence karst landscape which
forms a principal recharge area in North Florida for the Floridan artesian
system. Analysis of the water level data for Anderson-Cue Lake, the
surrounding water table data, and the rainfall and evaporation records
indicates that there is very little contribution from surface and sub-
surface runoff to the lake. Sands covering the basin are porous. Down-
ward seepage rates are high and surface runoff is exceedingly low. The
relatively small water level fluctuation (except during periods of drought)

These data are not applicable to the research lake itself.





.-7'. e 4-1


0
WELL NO. 4


0 WELL NO.


HYDROGRAPHY
ANDERSON-CUE LAKE


0 100 290
FEET


390 4900


Contours Referenced To MSL


7/31/68
19











further indicates that the lake bottom, although originally hydrologically
connected with the Floridan aquifer, is effectively sealed by organic de-
posits.


Geology

Materials exposed in the sand hills are largely of two types:
very fine surface sands and the underlying kaolinitic gravels, sands and
sandy clays. These sediments are known as the Citronelle Formation. Well
borings show an aquifuge of from 80 to 100 feet of phosphatic sands, sandy
clays and clays lies below the surface. These materials are known as the
Hawthorne Formation of Lower and Middle Miocene Age. Underlying the
Hawthorne Formation is the Floridan aquifer, the upper portion of which
is the Ocala Limestone of Eocene Age.

The piezometric surface of the water in the Floridan aquifer is
approximately 90 feet above MSL in the vicinity of Anderson-Cue Lake.
The porous sand and gravel of the Citronelle Formation contains a perched
water table above the aquifuge -- the Hawthorne Formation. Anderson-Cue
Lake is itself a perched lake. The lake level is the result of a balance
between percipitation, evaporation and outflow into the water table aquifer
and Floridan aquifer.

The vegetation in both lake basins is sparse and primarily scrub
oak, indicative of poor nutrient conditions. There is no human habitation
in either basin. The major source of nutrients for the lakes in their
natural states appears to be from the atmosphere via precipitation and air-
borne particulates.


Instrumentation

A Gurley water level recorder with staff gage and a recording
rain gage were installed at Anderson-Cue Lake in February 1966.

In September 1967 an Aerovane wind recorder and Foxboro hygro-
thermograph were installed. The transmitter for the wind recorder was
mounted on a pole approximately 150 feet from the south shore of the lake
and three feet above the water surface. Examples of some of the instrumen-
tation are shown in Figure 4-2.


Meteorological and Hydrological Phenomena

Anderson-Cue Lake lies in a shallow valley oriented in a NNE --
SSW direction and is surrounded by scrub oak and pine trees. These
characteristics have a marked effect on the air-flow over the water
surface. The air speed in general is calm to light (0-7 mph). The
prevailing winds are from 30 to 60 degrees (NNE to NE) and from 210 to
240 degrees (SSW to SW). When a tropical storm or frontal system passes









Figure 4-2


' .v '. .* *- ,- --- L ." ..

':,'," -.- "- --o o' :,- I' -- .,
.- i ; : .., -. ,


- ~-, .- t


View of Anderson-Cue Lake
Looking Northwest


". '.. Rain Gage at Lake Site


I.

'it ...i
r


Unloading Sewage Effluent
into Storage Tank


Checking Hygrothermograph
at Lake Site


j .
I. *


' .r .











over or close to NE Florida the wind direction is influenced by such
phenomena and higher wind speeds are recorded. A wind rose for the
period October 1967 -- June 1968 is shown in Figure 4-3.

The only significant currents in shallow Anderson-Cue Lake are
wind currents. A NE wind causes the surface water to flow toward the
SW and a SW wind causes the surface water to flow toward the NE. In
bodies of water larger than Anderson-Cue Lake such surface water currents
flow to the right of the wind and set up a clockwise circulation. In
Anderson-Cue Lake, however, these currents cause a pile-up of water on
the leeward shore which is returned by fan-outs in both clockwise and
counter-clockwise directions. Due to long periods of calm and very light
and variable winds the lake is considered to be in an equilibrium state
throughout its mass.

Many factors must be considered in attempting to explain the
fluctuations of the lake level and the water table in the research area.
These include evaporation, precipitation, and flow to the water table
aquifer and Floridan aquifer. The most complex of these factors is
evaporation. The question arises as to what per cent of time in a
certain period was the variation of dewpoint temperature with height such
as to lead to condensation on or evaporation from the lake surface. An
inversion of the dewpoint will develop if the surface acts as a heat sink
to remove water vapor. This condition can be expected during clear
nights when there is strong radiation from the ground; during times of
high relative humidity; and during times of the build-up of surface
inversions which occur frequently in the Anderson-Cue Lake area. In
fact, about 50 per cent of the time the water vapor flux is directed
downward. This reversal of evaporation is evident during non-daylight
hours when winds are persistently less than 7 mph and relative humidity
greater than 90 per cent.

It is interesting to note from the rain gage records of the
past year that during the periods when the vapor flux is directed up-
ward (generally from 0800 hours to 1800 hours) approximately 0.12 to
0.15 of an inch of water is evaporated daily. This indicates the large
amount of evaporation from the lake surface that can be expected unless
the amount of precipitation plus condensation received when the lake
acts as a heat sink can overcome the evaporation losses and losses to
the water table aquifer and Floridan aquifer.

Water in the water-table aquifer is unconfined so that its
surface is free to rise and fall with the variance in rainfall2. As
may be deduced from Figure 4-4 (refer to Figure 4-1 for location of test
wells) the water table slopes toward the lake on the western side and

2 Rainfall on the Anderson-Cue Lake basin for the period March 28, 1966
through June 30, 1968 was deficient by 13.85 inches (the closest "depar-
ture from normal" data are accumulated at Gainesville, approximately
20 miles to the west). For the period November 2, 1967 through June 30,
1968 the deficiency was 8.56 inches.





Figure 4-3


ANDERSON CUE LAKE WIND ROSE

October 1, 1967 June 30, 1968


SCALE: Imm = 3 HOURS


Calm
1-3 MPH


4-7 MPH
I->7 MPH





































w
>
0


LU
U.
-I I
PM
PM


NOTE: The initial plotting point for Well No. 2 should have been 123.27 feet, MSL.











away from the lake on the eastern side. Because the piezometric surface
of the Floridan aquifer is below the level of the lake, water cannot move
from the Floridan aquifer to the lake. The net ground water flow during
the period of study has been composed only of out-flow to the water-table
aquifer and out-flow to the Floridan aquifer. During the period of drought
experienced since March 1966, it may be assumed that the greatest ground
water loss from the lake has moved eastward into the water-table aquifer.

As shown in Table 4-1, for the period March 28, 1966 through
June 30, 1968, evaporation losses exceeded rainfall by 24.09 inches and
approximately 64 acre feet of lake water was lost to the aquifers.







Table 4-1


ANDERSON-CUE LAKE

Hydrological Data


Dates


From 3/28/66
To 4/26/66
5/25/66
6/22/66
7/21/66
8/18/66
9/13/66
10/11/66
11/08/66
12/06/66
1/03/67
3/28/67
5/02/67
5/31/67
6/27/67
8/01/67
9/06/67
10/03/67
11/02/67
12/03/67
1/04/68
1/31/68
2/29/68
3/31/68
4/30/68
5/31/68
6/30/68


(1)
Lake Evaporation
(in.)


4.73
4.89
6.04
6.48
6.25
4.84
3.87
3.17
2.53
2.12
9.53
7.18
7.58
5.35
6.24
5.77
5.24
4.19
3.11
2.37
2.10
2.59
4.14
6.63
6.95
6.09
129.98


(2)
Rainfall
(in.)


1.42
3.99
5.96
2.45
8.70
5.00
5.45
1.56
0.05
2.67
9.15
1.65
7.92
7.66
8.12
10.91
1.38
1.32
0.00
5.60
0.24
1.35
1.42
0.45
6.09
5.38
105.89


(3)
Lake Level
(ft.--MSL)

125.78
125.33
125.04
124.69
124.25
124.43
124.41
124.51
124.21
123.75
123.61
123.61
122.99
122.83
123.07
123.33
123.81
123.66
123.46
122.99
123.07
122.63
122.17
121.59
120.83
120.49
120.02
-(69.12 in.)


Summary: 129.98 (1)
-105.89 (2)
24.09 in.


69.12 (3)
-24.09
45.03 in. or
feet


approximately 64 acre
lost to aquifers


Note: Lake evaporation is computed from data collected at the U. S.
Weather Bureau evaporation station at Gainesville, Florida.
Pan coefficients are those used for Lake Okeechobee, Florida:
Kohler, M.A., 1954, Lake and Pan Evaporation in Water Loss
Investigations -- Lake Hefner Studies, Technical Report: U.S.
Geological Survey Prof. Paper 269, p. 128.










Section 5


Routine Chemical Studies


The trophic state of the lake is manifested in a variety of chemical
and biological parameters. This section will summarize the routine chemical
data obtained; biological results will be presented in the following section.
Results for Anderson Cue Lake, the experimental lake, extend for a period of
nearly three years-from 1966 to the present. McCloud Lake, the control, has
been sampled routinely since the beginning of 1967. During 1966 and 1967
sampling was approximately biweekly, especially for the important nutrient
parameters. Since January 1, 1968, sampling has been on a monthly basis
because rather minor variations were noted in more frequent sampling. This
sampling schedule has allowed more time for a variety of other special studies
to be conducted. Parameters measured routinely (biweekly or monthly) include
dissolved oxygen, pH, conductivity, acidity, dissolved and suspended solids,
ortho and total phosphate, total and particulate organic nitrogen, ammonia,
nitrite, and nitrate. In addition, data has been routinely collected on
physical conditions such as water temperature and Secchi disc transparency.
Other major and minor chemical constituents have been determined less
frequently. These include chloride, sulfate, calcium, magnesium, sodium,
potassium, silica, iron, manganese, chemical oxygen demand and biochemical
oxygen demand. Chemical characterization of lake sediments has included
determination of percent volatile solids, total organic nitrogen, ammonia,
total phosphate, iron, and manganese.

Three permanent sampling stations were located in Anderson Cue
Lake. Stations 4 and 7 are in the centers of the lake's two basins, and
Station 8 is on the south shore in about 3 feet of water. The location of
these stations is shown in Figure4-1. Two permanent stations are located
in McCloud Lake, Station 11 in about 21 feet of water near the center of
the lake and Station 12 near the north shore in 3 feet of water.


The two lakes are typical of the small lakes in the Trail Ridge
portion of the Central Highlands. Table 5-1 summarizes the chemical char-
acteristics of the lakes. Few significant changes in gross chemical
composition have been noted during the period of record. Both lakes are
colorless, low in dissolved solids and extremely soft. The waters are acidic,
with typical pH values ranging between 4.6 and 5.5. The waters have little
buffer capacity and essentially no alkalinity. Consequently, acidity
titrations have been used to estimate total CO2. Specific conductance has
increased in Anderson Cue Lake from about 25 mho cm-1 to about 38 V mho cm-1
over the last 18 months. Corresponding increases in McCloud Lake have been
less from 30 to 35 jLmho cm-1. Some of the increase would seem to be the
result of excess evaporation over precipitation during the period nutrient
additions were probably responsible in part for the increase in the
experimental lake.











Table 5-1 Chemical Composition of Anderson-Cue
amd McCloud Lakes and Rainwaterl


Constituent

Spec. Conductance

pH

Acidity as CaCO3

Cl -

S0=

Na+

K+

Ca+2

Mg+2

Total Org. N

Particulate Org. N

NH3-N

NO2-N

NO3-N

Total Phosphate

Ortho Phosphate

Silica


Anderson-Cue Lake

25-38

4.5-5.2

1.0-4.0

5.1-7.5

4.0-6.0

2.3-2.9

0.4-0.5

0.5-0.8

0.5-0.6

0.3-0.4

0.1-0.4

0.03-0.4

0.001-0.002

0.04-0.2

0.00-0.04

0.00-0.02

0.1-0.2


McCloud Lake

28-35

4.5-5.5

1.0-4.0

5.0-7.0

3.5-7.0

2.5-3.2

0.1-0.3

0.3-0.7

0.5-0.6

0.3-0.4

0.1-0.3

0.02-0.2

0.001-0.002

0.01-0.2

0.00-0.03

0.00-0.01

0.1-0.2


Rainwater

10-15

5.3-6.8



1.2-3.0



2.2-2.5

0.1-0.4

1.4-3.1

0.3-0.4






0.1-0.5

0.001-0.002

0.05-0.5



0.01-0.03


Values represent normal range but do not include some extremes.
All concentrations in mg/l; specific conductance as mho-cm-1.

































D!5. Oz


TEMR


tI I I


JAN. Fe, MAR. APR. MAY J Ju t JuLy A uG. SEPT OCT.


Nov. DEC.


Fv~u~c ~ ~ *rr"'-'c ~ ~'i~ ~ "2~~ I p _


2.


a6 -


22. 1






14


I4-


(-





0
6
LU

i/1











The low dissolved solids and ionic content of the lakes are
indicative of the waters' origin, i.e. atmospheric precipitation. Table 5-1
lists some comparative values for the chemical composition of rain water at
the lake site. Concentration of major ions compare rather closely for the
lakes and rain water. While concentrations of major ions are not likely to
limit primary production in either lake, the paucity of several is likely to
select against certain types of organisms. Low silica probably is a
contributor to the small diatom populations; low calcium and magnesium
indicate the waters are unsuitable for macrophytes like Chara and some
algae which prefer hard water.

Neither lake shows much evidence of stable thermal stratification
at any time of the year. Temperature profiles are usually within one degree
Celsius from top to bottom. Somewhat larger differentials (30C) were some-
times found in McCloud Lake during periods of high water, but the thermocline
occurred in the bottom few feet in these cases, and most of the lake was freely
circulating. During periods of intense warming and calm weather, temporary
stratification may occur in either lake, but this has no significance with
regard to the present study. Water temperatures range from about 120C in winter
to about 320C in mid summer. Dissolved oxygen profiles also show little change
with depth; top and bottom values are usually within one mg/l. There is no
evidence for oxygen depletion in the bottom water of either lake, but consider-
ing the lack of thermal stratification and the oligotrophic conditions, this
is not surprising. Seasonal variations in dissolved oxygen largely reflect
changes in solubility with temperature. Figure 5-1 shows the surface temper-
ature and dissolved oxygen values for 1967 in Anderson-Cue Lake; the results
for McCloud Lake and for other years are similar. Values are generally near
saturation, but a slight tendency toward undersaturation has been noted.
The rates of photosynthesis in the lakes are too low to markedly influence
dissolved oxygen, but slight diurnal variations in dissolved oxygen have been
noted.

Greatest attention in the chemical analyses has been focused on
nitrogen and phosphorus compounds, which presumably are most critical in
eutrophication. Both lakes were extremely depleted in nitrogen and phosphorus
before enrichment began. Ammonia ranged between 0.02 and 0.06 mg N/l; nitrate
was less than 0.04 mg N/l; and total organic nitrogen averaged about 0.3 mg N/l.
Ortho phosphate was often undetectable and averaged less than 5 ,JLP/l. Total
phosphate showed similarly low concentrations. Nutrient addition to Anderson-
Cue Lake began in March of 1967. Figures 5-2 to 5-6 show the temporal
variations in total organic nitrogen, ammonia, nitrate, total phosphate
and orthophosphate, respectively, in the 18 months from January, 1967, to
June, 1968. The points on each plot represent mean values for all sampling
stations in each lake. The effects of nutrient enrichment are most clearly
shown in the ammonia, nitrate and total phosphate graphs.

Increases have been noted in both lakes during this period, but
average values are consistently higher in Anderson-Cue Lake. There are
several possible explanations for the increases in McCloud Lake. Water levels
have fallen considerably in the lakes, especially since fall of 1967, because








Figure 5-2 Total Organic Nitrogen, mg N/1I 1/3/67 6/24/68




.- -- A:nderson-Cue


1,-- W 1\tcCl0udt
tot




1. 0 -- -- -----------.-.--



0.9 -
t I


0 8 ]-1_1





0II6II'I
tot
SL
-4. M c... .. .. .. ..














0. 7 I I .. ____..
07
t1, I I t,
6 '1 ~_ 7.!", .



















Months
....... 4 --- 4 1 i '
0 .... 3- -- -. ---- -- --- -- --,N


o ., ------ -- "--- -- .-i ..; .. :
Ti' i I L T ; :
L. 7t_ . .: : ,m




J F Mk A M J J A S 0 N D J F MV A h4 J J
Mvlonths





Figure 5-3 Free Ammonia, mg N/1


' /


1/3/67 6/24/68


I I

I'





I.






I

I,
II
II


'I
'I
'I


. 0 I I I I 1 I
J F MA M J


I I I I I I
A S 0 N D J
Months


I I I I I
F M A M J


Ande rson-Cue


l IIcCload
\ 4


I














SF----- -4r- -- -6/




h---_ ___-__ -......__._..... .... :
4 --
Tr






t- t.4 -+ i I I I I I




-i- I-- I
I l l iI-I-


____K__ V2__ 1Q1.111LJ


/


I,
I~i


- + I 4---- ----- -- -- -' -


~1


- I1


I I


!-
A +
__ __J_ L
l' T i1'


K


I







I
- --
. ... i + _- .
+ / +/







-/-- --
. .


Ii ~
/ .'


/
I


~~>4


-I


I.- --- -.-- ---- -- -..
--- 1-------
| |-


I T 1 ~ 4 -~--~ 4 1 i-~- 4-4-4 -r 4'- I -~---r 4 -i----
N.


-I


Mt (


Aloud


-L4-L--
II ltiii 14


F M A


1~~


M J J A


ri


Ii


S 0 N D J
Months


-1


I I I


A M J


-* -
.0__

. C_-_


SO(b
. Oi- --
. O07__
. OCR -

. 0I-
.0--


.002





.00.


.
CID- -
I \tt ^-]tli


,~ ,


, J I


, ,


1/3/67 6/24/68


Figure 5-4Nitrate, mg N/1


In


004 ___--


L"Ll


- -- i


i 01- C


- I I --- I I
ffI I





Figure 5-5 Total Phosphate, mg P/I


7~:


.0,
.00
.00

.00

. 00

.00


S00<



.003


\ /
\


!

'I
'I
*I

II
II /







I
0 I
II









'I
,



I





\* i
II
1I













\ i
*
II
1I


//
1I
\ 1
11I
,1.1


.00


I
I




0 'i J ; -1 J
.00 II t tf I I I: I 1 I
J F MA M J J A S O N D J F MA M J
Months


Anderson-Cue


N IcC loud
1


1/3/67 6/24/68







Figure 5-6 Ortho Phosphate, Ag P/I


1/3/68 6/24/68


H i ..


1 + n i in n -V: ;


1*1 .1 1 i~- I ii -I I


i -( And erson-CL e


? 7 --__ __ d


21
20
19
18
17
16
151
a14
1 3
12
11
10



6

8


m


1-


;--
.... ...... -- -- : : f: t -
-- --- ... .. .



\



.- . .. .. \ \ ..





_, .... / ... .. .- ---- -___
-. "- -..i ..

a/ \ /




J F M A M J J A S 0 N D J F M
Month s


, -
f







A M J


tT^S


- .^.,










of a deficiency in rainfall over evaporation and ground water seepage. Concen-
tration resulting from evaporation may have had some effect, but other changes
resulting from the lower lake levels may be more important. One possibility
is increased sediment-water exchange of nutrients in the now shallower lakes.
The nutrient rich sediments from the lake centers are now closer to the
shallower shore areas. Another possibility is that the newly exposed land
(previously submerged littoral zone) may have contributed nutrients to the
lake from dying aquatic macrophytes. Other possible explanations for the
increases are changes in analytical procedures during this study and the
natural variability of nutrient concentrations in lakes of this type. It
will be interesting to follow the nutrient levels in McCloud Lake as the
water levels return to normal. The appearance of seasonal trends are less
obvious in the nutrient results than is typical for temperate lakes, but
most changes can be explained by seasonal and biological factors.

During the first year of nutrient enrichment (March, 1967 to
March, 1968) approximately 124 kg nitrogen and 10.6 kg phosphorus, mostly
as ammonia and ortho-phosphate, were added to the experimental lake through
the nutrient outfall. This was sufficient to increase the N and P levels
in the lake by 0.5 and 0.047 mg/l, respectively, at the lake's volume in
1967, if all the nutrient material remained in the lake. Inspection of
Figures 5-2 to 5-6 shows this clearly was not the case. Increases in total
N and P concentrations do not approach these levels and much of the added
nutrient evidently was deposited in the sediments or was lost through
ground water seepage. This has been found to be the case in other lakes
where nutrient budgets have been constructed (see Section 3). This would
seem to imply an important role for sediment regeneration of nutrients in the
eutrophication process. Possibly the onset of deleterious conditions in the
eutrophication process is contingent upon exhaustion of the sediment's
capacity to retain nutrients.

Several studies have shown that the lakes are well-mixed and nearly
homogeneous chemical. Table 5-2 shows mean values for pH, acidity and
dissolved oxygen in the surface water of the different stations. The results
also show the chemical similarity of the two lakes. A detailed


Table 5-2 Mean Values for Some Chemical
Parameters at the Permanent
Sampling Stations

Station Acidity pH Dissolved Oxygen

4 3.1 4.61 7.8
7 2.8 4.65 8.0
8 3.0 4.62 8.0
11 3.4 4.88 8.2
12 3.0 4.75 8.2











study of the lateral variations in ammonia, and othophosphate gave further
evidence of the experimental lake's comparative homogeneity. This is
not to say that there are no differences at all. Figure 5-7 shows a slight
trend for higher ammonia near the southern shore. In general ortho phosphate
was higher in shore areas than in the lake center (Figure 5-8), but values
for the southern shore were the lowest in the lake. The high ortho phosphate
values in the northwest portion of the lake probably represent a minor source
of pollution from cattle grazing in this area during this period. The results
indicate that the routine stations are representative of the conditions through-
out the lakes within the limits of accuracy desired for this project. The
studies also imply rapid mixing in Anderson-Cue Lake since no concentration
gradients resulting from the nutrient outfall were detected.

Because of the probable importance of sediments in eutrophication,
considerable effort has been directed toward delineation of their role as a
nutrient source and sink. As a first step the chemical characteristics and
variations in sediment types have been determined for both lakes. Representa-
tive results for Anderson-Cue Lake are shown in Figure 5-9 to 5-11.

Several sediment types are evident in Anderson-Cue Lake: near shore
the bottom is sand covered detritus and viable organisms. In parts of the deep
regions brown peat-like sediments are evident with much fibrous and undecom-
posed plant material. In other areas the sediments are darker and finer
grained, more like the ooze or Schlamm of alkaline lakes. The sediments of
McCloud Lake have not been as well characterized, but peat-like sediments
are less in evidence there. The results indicate that the lake's sediments
are actually higher in nitrogen and phosphorus than sediments from some
eutrophic lakes. For example, sediments from Lake Mendota, Wisconsin, have
from 200 to 1200 ppm phosphorus and 2000 to 14,000 ppm total organic nitrogen
(Hasler, 1963). The sediments in this alkaline lake are over 30 percent
precipitated calcium carbonate, whereas those in the lakes of this study are
composed largely of organic matter. The sediments in Anderson-Cue Lake are
enriched in nitrogen and phosphorus compared to the overlying water and
represent a potential nutrient source. Leaching and incubation studies with
the sediments are underway, the results of which should indicate the role of
the sediments in nutrient storage and release in lakes.














.18 .19


.17 .17 .18


22 .19 .18 .20


.21 19.21.2:


.21 .24 .19 .20 .21


.21 .21 .20 .21 .21 .21 .20 .20


Sewage
0
Outfall
.27 .19 .20


Figure 5-7


.21 .21 .24 .24 .19.21


Lateral Variations of Ammonia
in Anderson-Cue Lake, January,
1968. Concentrations in mg N/l.
















5 7 4 3


3 4 4 3


3 4 2


6 6


3 3


4 5


6 4 3 2 4 3 4


Sewage
0
Out fall
5 3 2


3 2 2


2 2 1


1 ,?


Figure 5-8 Lateral Variations of
in Anderson-Cue Lake,
Concentrations in /pg


Ortho-Phosphate
January, 1968.
P/l.-


MY








































































Figure 5-9


Nitrogen in Anderson-Cue Sediments.
Top number is ammonia; bottom number is total
organic nitrogen. Values in mg -N/g dry wt. of
sediment.















6.3 9.6
730 I.:.

L19


8.0
800


9.5
730


1.6
530


6.7
550


Figure 5-10


1.3
330


2.0
1050
4.5


1240 4.6 1 7 710



Phosphate in Anderson-Cue Sediments.
Top number is ortho phosphate, bottom
number is total phosphate values in
pAg P/g dry wt. of sediments.


10.4
1540


7.4
3070


3.3
470


4.6
100


17.0
80


3.9
.270


7.2
1080


5.1
170


2.2
870















58 67
64 .60
Ea


30
1.24


68
1.49


52
2.94


56
1.58


74
1.95


56
1.95


39 6
3.16 --


Figure 5-11


Percent Volatile Solids (Top Number)
and Total Iron (Bottom Number) in
Anderson-Cue Sediments. Iron values
in mg Fe/g dry wt. of sediment.


49'
1.35












Section 6


BIOLOGY



Introduction

The biological effects of lake enrichment have been followed in
Anderson-Cue Lake during the period of this project in order to gain a
better understanding of the eutrophication process. Both routine and
specially designed experimental procedures have been employed for this
purpose. These have included the assessment of phytoplankton systematics,
accession of species, and primary productivity. Standing crop measurements
have been made by chlorophyll determinations. Littoral plant growth has
been estimated by periodic cropping of square-meter plots. Horizontal
distribution of bacterial species have been made quarterly. Nutrients
limiting algal growth have been determined by bioassay techniques.

The last part of this section is devoted to the microbiotic
ecology of Anderson-Cue Lake (experimental) and McCloud Lake (control).

Primary Productivity

Figure 6-1 shows that primary productivity in Anderson-Cue Lake
in 1968 has been from two to twelve times that in McCloud Lake. No attempt
has been made to quantitate the relationship between nutrient addition and
enhancement of primary productivity, but use of a pure-culture indicator
strain in the C-14 uptake technique may soon make this possible. Peaks
in diurnal variations in photosynthesis occur at mid-morning and mid-
afternoon during August suggesting an inhibitory effect of intense sun-
light on the upper layer of water. (Note that times on the graph are
Eastern Daylight-saving Time which runs approximately one hour ahead of
sun time.)

Tables 6-1 and 6-2 show that at the ten-foot level there has been
a sharp decrease in fixation rate in Anderson-Cue Lake while no such change
has been observed at the same level in the rate of fixation in McCloud
Lake. This suggests increased turbidity in the water of Anderson-Cue Lake.
In fact, water samples taken at or near the surface are visibly more
turbid than corresponding samples from McCloud Lake. Findenegg (1964)
has used productivity profiles to characterize the degree of eutrophica-
tion in lakes. He raises the point that there is a limit in the degree
to which eutrophication raises production due to the decrease in light
transmission concomitant with increase in phytoplankton per unit volume.

Chlorophyll

Figures 6-2, 6-3 and 6-4 show that the chlorophyll content of
Anderson-Cue Lake water in 1968 increased two to three times over that of
the past year. Predictably, values rise as hours of sunlight per day






Figure 6-1
Diurnal Variation of Primary Productivity in Anderson-Cue & McCloud Lakes


- ii. .. ..i .. .. .- -4

1. ,I, I ,i, 1 [ 1 I ,. , ,i,, ,,j. i,, ,t : !


"--- Ik



: ..


20-

"13
0
'-i

0
15 o





10 -- -


5-





0 70I :0
7:00


9:00


11:00


I- -t I I I'







I __ -.
I -


'N

- I


Andrsbon-4Cue Lakd
w-- June -1, "968" ,


_.__ Andersion-Cu.e Lak
Februa'rvy 27, 1968

McCloLtd Lake
June 18, 1968

- ---4-- de rson C-ueL ---
Aueust 15, 1967


' I




I I


V-'
.- N-
\


-
McCloud Lake
august 1, 1967





I-

McC oud L ake
February i2, 1 8


1:00


3:00


--',- ..... ----








: t::; i II


7:00


9:00


5:00


TIME (o clock)


25


J


I \


_T__


















Table 6-1
Cue Lake Primary Productivity
(mg C fixed/day/m3)


Langlevs/dav


9.21
9.39
9.23
6.24
14.60
25.60
32.40
14.00
27.50
27.20
47.70
57.50
98.10
66.70
14.40
15.04
51.30
21.70
18.40
31.80
16.67
47.35
59.60
109.57


12.30
9.70
6.91
13.24
5.90
21.80
22.00
7.33
8.62
23.70
10.30
42.80
70.30
33.50
6.80
35.60
43.50
15.80
6.93
48.50
5.23
1.46
9.32
8.05


Date


Surface


1/24/67
1/31/67
2/28/67
3/14/67
3/28/67
4/11/67
4/25/67
5/9/67
5/23/67
6/6/67
6/20/67
7/7/67
7/19/67
8/1/67
9/12/67
9/26/67
10/11/67
11/28/67
1/9/68
2/21/68
3/19/68
4/29/68
5/16/68
6/18/68


7.18
2.30
19.70
20.80
7.47
34.80
47.30
9.53
28.90
31.60
68.40
96.00
127.50
33.80
40.10
31.90
22.70
17.0
17.4
33.10
24.52
42.69
105.63
196.00


402
382

375
203
540
652
703
400
461
483
456
607
504
225
560
573
461
294
426
499
574
600
560


















Table 6-2
McCloud Lake Primary Productivity
(mg C fixed/day/m3)



Date Surface 5' 10' Langleys/day

2/7/67 8.28 15.50 7.14 278
2/14/67 3.27 3.53 3.77 452
2/28/67 13.80 13.90 7.07 ---
3/14/67 5.21 16.34 13.17 375
3/28/67 24.92 13.64 36.62 203
4/11/67 24.90 30.16 23.33 540
4/25/67 2.00 13.26 6.37 652
5/9/67 10.50 17.34 23.58 703
5/23/67 30.86 31.33 22.44 400
6/6/67 59.5 43.72 67.20 461
6/20/67 59.56 96.23 169.06 483
7/7/67 32.69 49.90 37.00 456
8/1/67 68.03 45.48 19.07 504
8/29/67 6.49 14.43 7.55 575
9/12/67 53.78 29.33 13.21 225
9/26/67 109.59 150.57 37.41 560
1/9/68 7.70 18.44 15.10 294
2/22/68 2.10 5.60 4.81 320
3/19/68 3.37 4.25 4.01 499
4/29/68 29.26 30.06 27.55 574
6/18/68 120.02 74.27 35.58 560






Figure 6-2
Chlbro phyll a -alues for 1967, 196C in Anderson-Cue Lake. (Samples taken between S:00 10:00 a.m .)
|1 -7 7 g I_

T. --_, 1- g- -.- --- -... ,' ...I.... I -_. ,._j
SII


I --- -- ---



94- -- ----
.. ._ _. ...... : .. ._i -- i I l I [ I I I .. ... ....--. I- I l I




8 1,- i ---- i ; 7 7 T 7 r r -..
1 0 .. : -- : ... I Ii I I __ m .. I r ; I i
Si \.- .... .. . .. .



S I- :-I I _" : - _
: 2 i I I f / / I I I | -- I I i I _
(I II I I
1 ,I --_ "- '- .I -- I.-I I


1 "


V :: I







Figure 6-3
Diurnal Variation of Chloroohvll a Anril


.968


II p71 .~7 II
____ 11


-.- : -.. ...... .. ..-- H- -. tl i- Q_ g '.'^--e i .-







77 -7-7
-M- CDlO-aoud Lake -







S .7 7 : : 7: 7*; *- 7 :::: : :: 2 ..:: ......
7- r 1









T~ -4





. . .










7:00 9:00 11:00 1:00 3:00 5:00 7:00 9:00


A.M.


P.M.


' ,'.' .. .i '. '. j


TIME (o'clock)







Figure 6-4


-Cue ake
uia~e I~:


/ ..~

.411




I III Lr i I
-t I
I I -
...-r
I


3:00


TIME (o'clock)


-1- -4-


10





5-


P.M.


A.M.










increase until a peak is reached in late spring or early summer. There-
after, there is a decrease in surface levels, probably due to temperature/
actinic effects as discussed by Meyers in Burlew (1953).

Data obtained in a ten-day diurnal study of samples taken from
one station (Station 7) (Figures 6-5, 6-6 and 6-7) show that diurnal
variation is of greater absolute magnitude than weekly variation. This
is significant in planning long-term experiments as it calls for great
care in setting up sampling schedules. This relatively large short-term
variation, taken together with the nonuniform horizontal distribution,
may indicate that wind and current movement are important in determining
chlorophyll levels. Surface level peaks accompanied by drops at lower
levels suggest sampling local concentrations of motile organisms attracted
to the surface by rain as the cause. Following May 11, 1968, surface
chlorophyll concentration dropped. This is probably due to greater sun-
light intensity.

Figures 6-8, 6-9 and 6-10 show the horizontal distribution of
chlorophyll a on three days from February to April 1968. The data shows
that phytoplankton as measured by pigment concentration is not uniformly
distributed in surface water. The unequal distribution of organisms is
probably due to wind effects, local nutrient enrichment by animal wastes,
and other undefined effects such as regeneration of nutrients from sediments.
The figures show a general trend toward higher chlorophyll levels where the
lake is deeper and water temperatures lower. There is, however, one area
at the southernmost end of the lake which consistently shows chlorophyll a
levels of 10 mg/m3 and higher. We cannot at this time account for the
high chlorophyll levels in this isolated area.

Population makeup, response to irradiation and temperature
levels most likely account for the non-linear relationships observed with
diurnal and monthly variations in sunlight and water temperature.

Biomass

The harvest of peripheral plant growth with respect to dry plant
weight has remained constant at both lakes, as shown in the comparison of
the spring cutting of 1967 with the spring cutting of 1968. However, an
approximate 7 per cent decrease in per cent organic matter has resulted
(See Table 6-3).

Since this area in Florida experienced an extended drought during
the winter and early spring months of the past year both lakes have dropped
considerably, exposing former submerged stations and those stations out of
water were not cut in December. A second problem encountered was that of
migrant cows feeding on these areas. Adequate fencing now prevents this
from occurring. Although May and June brought heavy rains the lakes have
not risen (See Section 4). Therefore, the marginal plants collected for
biomass studies have been terrestial rather than aquatic growth.

Bacteriological Distribution

The northeastern section of Anderson-Cue Lake shows higher plate
counts than the main body of the lake. Peripheral areas are subject to






Figure 6-5
10-Day Field Study Anderson-Cue Lake


5/6/68 5/16/68

; I


4 -


-I


I I


300


200


100


7 7 I
I_____________
* I I i_





I* &0
.... . 4, -,, i ,,

'[ I I I *I i t I 1


700





.. 500


4. 400


i 7 1







'Figure 6-6


Sl ::i i! : Noon Sap-ipes ,



II .] _5'__'_ .. --

Sunlight
o I : : : i: I- e ; t-
-u ght I




. . . .. . . . . .


--- 700


-I N


-


N
N,
I I
N


S------ 600


.- 500


-t


400


- 300


100


DATE


15 -







Figure 6-7
10-Day Field Study Anderson-Cue Lake


5/6/68 5/16/68


I I t


-- 700


--l 600

-------------------------------------------------------------------------------------.0


-__ 400


300


200


bo
-c-I
'1 00

a7^
A-v-
U:


-Aft rnoon. Samples

4-Surface -----------

t Stilg11 --


', i


20


iCO



4-3

--I
_ 700bo
1(1)


.1


7









































>10 Mg/M


LI,,,,


5 10 Mg/M3

0 5 Mg/M


Figure 6-8
Horizontal Distribution of Chlorophyll a
Anderson Cue Lake, 2/15/68














































>10. 6 Mg/M-

9. 5 10. 5 N


8. 1 9. 4 M


7. 8. 0 M


g/M




g/M3
g/M3


Figure 6-9
Horizontal Distribution of Chlorophyll a
Anderson Cue Lake, 3/12/68









































> 15 Mg/M3


0 *L 10. 1 15 Mg/M3

4. 1 10 Mg/M3

S0 4 Mg/M3

Figure 6-10
Horizontal Distribution of Chlorophyll a
Anderson-Cue Lake, 4/9/68








Table 6-3
Standing Crop Estimates of
Cue and McCloud Lakes


March May, 1967


Organic Matter


Organic Matter


13.4367
11.4776
14.5065
39.1172
3.9631


11.2179
47.6368
29.4393


76.4
93.4
76.7
88.2
75.1


93.7
85.9
94.8


June August, 1967


36.6874
22.0299
19.3535
105.7579
39.8170


21.3215
27.0365
50.8171


McCloud
1
2
3


October December, 1967


Cue


0.6651
5.0363
7.7053
10.1398


3.6714


McCloud
1


January March, 1968


Cue


1.3599
2.8250
2.0906
5.9957
0.7454
2.2399


Plant
Dry Wt./R


Station


Cue
1
3
5
6
7


17.5749
12.2894
18.9235
44.3655
5.2773


11.9673
55.4363
31.0443


Plant
Ash Wt./R


4.1382
0.8118
4.4170
5.2483
1.3142


0.7494
7.7995
1.6050


McCloud
1
2
3


3.9242
2.0512
2.5064
6.6955
2.3864


2.8341
1.2425
3.9842


32.7632
19.9787
16.8471
99.0624
37.4306


18.4874
25.7940
46.8329


89.3
90.7
87.0
93.7
94.0


86.7
95.4
92.0


0.0773
0.7867
2.0148
2.0935


0.6179


0.5878
4.2496
5.6905
8.0463


3.0535


88.4
84.4
73.8
79.4


83.2


0.2388
0.6043
0.2597
1.0297
0.1124
0.2808


1.1211
2.2207
1.8309
4.9662
0.6330
1.9591


82.4
78.6
87.6
82.8
84.9
87.5











Table 6-3 (Continued)


Organic Matter


Organic Matter


January March, 1968


McCloud
1
2
3


1.7174
1.9834
1.2515


April June, 1968


Cue


McCloud
1
2
3


44.5779
24.8772
21.4956
83.6573
36.9836
38.1837


43.7322
23.5226
41.6614


Summary March


Cue
1
2
3
5
6
7


McCloud
1
2
3


1967 March 1968


56.2873
29.8912
41.4388
130.6771
55.2507
47.3342


38.6776
84.4562
83.1129


Station


Plant
Dry Wt./g


Plant
Ash Wt./g


0.3277
0.1669
0.1402


1.3897
1.8165
1.1113


80.9
91.6
88.8


9.0419
6.4809
4.8200
9.7295
12.0098
13.8765


5.9879
3.7630
8.6337


35.5360
18.3963
16.6756
73.9278
24.9738
24.3072


37.7443
19.7596
33.0277


79.7
74.0
77.6
88.4
67.5
63.7


86.3
84.0
79.3


8.3785
3.4422
5.5927
12.1422
7.4542
3.9814


4.5291
9.2089
5.7294


47.9088
26.4490
35.8461
118.5351
47.7965
43.3528


34.1485
75.2473
77.3835


85.1
88.5
86.5
90.7
86.5
91.6


88.3
89.1
93.1










widely fluctuating levels of coliforms, probably as a result of local
fauna. There seems no generalized pattern of bacterial growth which
would result from physical factors. A comparison of values for January
and July does not show significant seasonal variation (See Table 6-4
and Figure 6-11).

Bioassay

The bioassay for limiting growth substances has been carried
out by the isotopic carbon method first reported by Goldman. The results
as shown in Table 6-5, although qualitative, show clearly that phosphorus
was the only consistently limiting factor of algal growth in Anderson-Cue
Lake. The seasonal pattern is the same through the year regarding the
demand of phosphorus by the phytoplankton. At no time was phosphorus at
a level to satisfy the growth requirements of the lake phytoplankton.

Sulfur was limiting during the early spring of 1967 in the
experimental lake and in the late summer in the control lake. Since a
sulfur deficiency has not been noted since that time, no special signifi-
cance is given these results.

A special study to relate the uptake of phosphorus (as indicated
by C-14 fixation) with time showed a near linear response up to 72 hours
following phosphorus addition. The results show that algal growth as a
response to phosphorus can be estimated at between 24 and 72 hours. The
lag in growth as measured by C-14 uptake before 24 hours of incubation may
reflect the lag in phosphorus transfer from the medium into the cell
(See Figure 6-12).

Microbiotic Ecology of Anderson-Cue and McCloud Lakes

The original microbiotic work on Anderson-Cue and McCloud Lakes
concentrated on learning what organisms were found in the lakes; which
ones were found on the marginal shallow bottom and among the vegetation
in this area, to a depth of two feet, as compared with the kinds and
numbers in the open surface waters, and with those in the waters near the
sediment water interface where the lakes attained their greatest depths.

This original work was finished, insofar as general information
is concerned, in 1965, 1966 and early 1967. A portion enough to give
the general picture is presented in Table 6-6.. The data is too
voluminous for all of it to be presented, but it is expected that at the
conclusion of the project a complete list of species found in each lake,
together with such changes in biotic composition as may have occurred,
will be given.

The second phase of the work is concerned with such changes,
especially those due to the addition of nutrients to Anderson-Cue Lake,
and a comparison of the two lakes. This work is underway.

The qualitative aspects of this work were largely attained and
reported by Lackey and Lackey (1967), but the statement was made that con-
tinued examination would probably greatly increase the numbers of species








Table 6-4
Bacteriological Data


No./Station I


1/A7
2/A2
3/A3
4/B1
5/B2
6/B3
7/Cl
8/C2
9/C3
10/C4
11/C5
12/C6
o 13/C7
14/DI
15/D2
16/D3
17/D4
18/D5
19/D6
20/D7
21/D8
22/D9
23/El
24/E2
25/E3
26/E4
27/E5
28/F1
29/F2


1/23/68
MPN
Coliforms


1/23/68
MPN
Fecal
Coliforms


1/23/68
MPN
Enterococci


1/23/68
Total
SPC


~1* 4 ~. 4 --


8.0
23.0
2.0
5.0
5.0
49.0
5.0
5.0
5.0
2.0
<2.0
2.0
<2.0
5.0
<2.0
2.0
<2.0
8.0
<2.0
2.0
2.0
<2.0
49
2.0
2.0
2.0
<2.0
>1609
8.0


<2.0
<2.0
2.0
2.0
<2.0
4.0
<2.0
5.0
5.0
<2.0
<2.0
<2.0
<2.0
<2.0
<2.0
2.0
<2.0

<2.0
<2.0
2.0
<2.0
14
2.0
<2.0
<2.0
<2.0
>1609
<2.0


2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2


1500
130
230
180
150
140
600
140
100
180
120
360
100
790
83
140
130
150
120
76
87
50
870
610
338
83
168
340
360


7/8/68
MPN
Coliforms


7.0
<2.0
9.2
5.1
<2.2
13.0
<2.2
9.2
5.1
5.1
5.1
2.0
9.2
9.2
2.2
17
2.2
2.2
<2.2
9.2
2.2
2.2
5.0


7/8/68
MPN
Fecal
Coliforms


7.0
<2.0
9.2
2.2
<2.2
13.0
2.2
9.2
2.2
2.2
5.1
2.0
2.2
9.2
2.2
7.0
<2.2
<2.2
<2.2
5.1
2.2
2.2
5.0


7/8/68
MPN
Enterococci


<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2


7/8/68
Total
SPC


340
130
110
170
130
130
440
610
150
180
330
490
350
100
97
120
470
230
260
150
78
620
130


,








Table 6-4 (Continued)


No./Station


30/F3
31/F4
32/F5
33/G1
34/G2
35/Hl
36/H2
37/H3
38/H4
39/H5
40/11
41/12
42/I3
43/14
44/J1
45/J2
46/J3
47/KI
48/K2
49
50


1/23/68
MPN
Coliforms


1/23/68
MPN
Fecal
Coliforms


1/23/68
MPN
Enterococci


1/23/68
Total
SPC


7/8/68
MPN
Coliforms


t '1- I' 4 I.


2.0
2.0
918
33.0
79.0
4.0
7.0
<2.0
2.0
2.0
2.0
2.0
17.0
70.0
13.0
8.0
8.0
<2.0
<2.0
<2.0
2.0


2.0
<2.0
918
5.0
33.0
<2.0
2.0
<2.0
2.0
<2.0
<2.0
<2.0
11.0
23.0
<2.0
5.0
2.0
<2.0
<2.0
<2.0
<2.0


5.0
<2.2
23.0
2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
13.0
<2.2
13.0
<2.0
<2.0
<2.0
<2.2
<2.2


1500
24
170
170
68
65
69
52
63
110
84
27
65
300
600
610
830
21
140
17
110


16.0
5.0
2.0
9.0
7.0
17.0
5.0
5.0
2.0
5.0
11.0
8.0
2.0
5.0

14.0

4.0
8.0
2.0
7.0


7/8/68
MPN
Fecal
Coliforms


2.2
<2.0
<2.0
9.0
7.0
13.0
5.0
5.0
2.0
2.0
11.0
5.0
<2.0
2.0

8.0

<2.0
2.0
<2.0
<2.0


7/8/68
MPN
Enterococci


<2.2
<2.2
<2.2
<2.2
2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2
<2.2

<2.2

<2.2
<2.2
<2.2
<2.2


7/8/68
Total
SPC


95
90
240
250
170
130
130
75
120
130
130
600
350
600

1000

160
320
190
110


, ,I
















o


(o


.0


o


Figure 6-11
BACTERIOLOGICAL SAMPLING STATIONS


^


o,


o0


O&










Table 6-5
Nutrients Limiting Algal Growth in
.Anderson-Cue and McCloud Lakes

Anderson-Cue #77 McCloud
1/4 1/17 1/24 1/31 3/14 3/28 4/11 5/23 6/6 6/20 8/1 8/29 9/12 2/14 3/14 3/28 4/11 6/6 6/20 8/1 8/29 9/12


N

P


N, P


Fe

N, Fe

P, Fe


- + -


+ + +


+

x x +


N, P, Fe

Si x


S -


Vitamins -

Trace
metals

EDTA x x


- x x -


+ + + + + +


+ +


- X X X -







+ x


+ x

x -





x x


x

x


x


S+ + +

+ + +







+- + -


+ x


x x

x x x

x x


x -


- x -


+ x x


+-. x

- -


x -




+ -


+ + -

+ + + -


-


x
+ +' + -

- + + + x


+ = limiting
x = inhibitory
- = no change


4-
+ -

+- -



x
- x
+
- +



+
x -

x +


x +



x +

x -








Figure 6-12


I I I >1


__ .7


t

": :: :" : : : : ; : I
^I l;i I I1'


:I P : :


. .


, 1--i-O00
IAl


Note- -.Grap r4sts--pl.e--GPM vs-- time-. C'P --
w rel take as an average of the two clo est
counts for each day with a control Iflask ,ub- :
tr` ct- ed..


Time Deper dent
|PQ 0 oassity


j 1


Time hor S)









TABLE 6-6

iiumber of species and number of protozoa and microscopic algae per ml in Cue Lake on
four dates in 1965, and in McCloud Lake on one 1965 date and three 1967 dates.

Cue Lake McCloud Lake

7ZL6/ lL3/65 9/15/6 12/16 /5 8/!31t/ /6 7L9 19/l67

Coelosphaerium kuetzingium x

Gomphosphaeria lacustris x

M4erismopedia punctata 160 580 5120 192

Phormidium sp. x

Rhabdoderma lineare 8

Arthrodesmus sp. .25

Chlorella sp. 1532 1920 160 12800 640

Closteridium sp. 4

Closterium sp. 1

Cosmarium sp. 4 .25

Cylindrocystis sp. 2 .5

Dictyosphaerium 64

Elkatothrix gelatinosa 20

"uLI.i..,trum nova zealandicum 6

Euastrum sp. .25

Kirchineriella obesa 4 10








TABLE 6-6

Cue Lake McCloud Lake

7l265. 8 L31 / 5 9 5L12l365 51A5/1 /6 1/17/67 6/67 7/19/67

Mongeotia sp. 2

Oocystis 12 6 2 32 64

Ourococcus bicaudatus 320

Perioniella 4

r'd..-drigula closteroides 6

Scenedesmus 2 16 4 16 128

Sphaerocystis schroeteri 102

Staurastrum sp. 4 .25 4 .25

Westella botryoides 8 x

Xanthidium sp. 15 1.5 1 3

Pandorina morum 1.5

Euglena. gracilis x

"T lena sp. .25 5 .25

Peranema trichophorum x

Phacus suecicus 1

-cncholomonas cylindrica 1

Trachelomonas euchlora .5

Trachelomonas hispida 2 .25








TABLE 6-6

Cue Lake

7/26/65 8/3 65 915/65 1 215J65


Trachelomonas obovata

Trachelomonas rotundata

Trachelomonas volvocina

Cryptomonas erosa

-Rhodomonas lacustris

G.onyostomum semen

Merotrichia

Centritractus belonophorus

Chromulina ovalis

Chrysococeus cordiformis

Chrysococcus rufescens

Dinobryan sertularia

Mallomonas tonsurata

Mallomonas spp.

Synura uvella, colonies

Ceratium cornutum

Dinoflagellata, unidentified

Glenodinium foliaceu .


McCloud Lake

8/31/6.5. 117/67. 6/9/67 _. 7/1-9/67


6 104


48

130


128

320


.25


.5 152








TABLE 6-6
Cue Lake

726j652 31/65 J215/65 12/15/65


McCloud Lake

8j31/65 1/17/67 619/6r7 721 67i


Conyaulax apiculata

Gymnodinium fusca

Gymnodinium unispinosumn

Gymnodinium vorticella

Gymnodinium sp.

Massartia sp.

Peridiniumi cinctumr

Peridinium marchicum
0o
Peridinium umbonatum

Peridinium volzii

Peridinium willei

Peridinium wisconiense

Peridiniumi sp.

Protodinium sp,?

Asterionella formosa.

Cyclotella sp.

Navicula sp.

Rhi o solenia eriensis


304


12

176

6


2 146

56


192

4


1888





-5-


," 6-6

Cue Lake

7/276/6. 831/65 9/15/65 12/15/65


MicCloud Lake

,31/6.5 1/1 67 6/9/67 7/19J67


Heterophrys myriapoda

Leptoc., -*,,i ampullacea

Monas sp.

Monosiga ovata

2'o o f lage I la ta

Ciliata, unidentified

C- lidiumn glaucoma

SHalteria grandinella

Me sod in ium cinctum

Pleuronema chrysalis

Stentor amethystinus

Strobilidium humile

Strombidium sp.

Urotricha farcta

Vorticella sp.



Total species, 85

Total numbers


24

1690


26

2031.5


32

330


7

566.5


22

576.75


15

620


14

18496


25

4371










reported for these lakes at that time. This has proved to be the case,
and probably will continue, especially if specialists become interested
in certain groups such as diatoms and desmids where we were unable to
make species determinations for certain genera. The number of genera
and species reported in the 1967 paper was 377 for Anderson-Cue Lake
and 266 for McCloud Lake.

The list will also undergo further changes for Anderson-Cue
Lake as its nutrient budget is increased. The intentional eutrophica-
tion of this lake is expected to increase the numbers per ml of many
species, and generally when this happens the species list is reduced.
This may well happen in Anderson-Cue Lake but the species list will
nevertheless be increased because species characteristic of an enriched
water will be found. These will be species whose occurrence is now very
low. It is an easy matter to find a species when there are as many as
one per ml, but much more difficult when there is one in 10 or 100 mls.

Quantitative results have been only briefly touched upon until
now. In the beginning these lakes were characterized as oligotrophic,
and numbers per ml were expected to be low. This was based on a low con-
tent of PO4, NH3, NO3, on a pH of 5.9 to 6.4, on a no detectable COD, and
on numbers of organisms per ml. Table 6-6 lists these populations for
four dates in 1965 for Anderson-Cue Lake, and one date in 1965 and three
in 1967 for McCloud Lake. It is felt that this table indicates oligotro-
phic conditions. True, some blooms were encountered, if we accept 500 per
ml as a bloom figure. In some cases the dinoflagellates colored the
marginal water pale yellow. Nevertheless the number of plankton species
is low, and the organisms occurring in great abundance are generally small
species. There is some indication that cattle wading in the marginal
waters of McCloud Lake added enough organic substances in urine and
droppings to considerably increase the species content and numbers in the
shallow water, but aside from data on barnyard ponds as support, this is
difficult to prove. However a recent survey of the shore line of Anderson-
Cue Lake, when no cattle were present revealed a greatly reduced species
list, and low numbers per ml except for a pronounced shallow water dino-
flagellate bloom. The shoreline vegetation was also sharply reduced,
which might have been a factor. However, nutrients were certainly suf-
ficiently abundant for an occasional phytoplankton bloom.

Table 6-6 shows some biotic differences between the lakes thus
Merismopedia punctata, which has consistently occurred in McCloud (including
1968), has not appeared in Anderson-Cue. The same is true of the pelagic
ciliate Stentor amethystina. Synura uvella occurs in both lakes, and
typically is more abundant in the deeper waters; the same is true of Dino-
bryon sp. Both lakes have many species of colorless Euglenophyceae, and
both have been subject to cattle grazing in the shallow water. The dif-
ferences in species lists of the two lakes might almost disappear with pro-
longed observation, except that the nutrient level of Anderson-Cue is being
raised. Both support a varied dinoflagellate flora. Since 1965 a few
species have occurred which constitute records for Florida, as well as a
very few which are probably undescribed. Table 6-6 generally indicates a
small open water population. The small numbers of photosynthetic forms
indicates low inorganic nutrients, and the low numbers of Zooflagellata
and ciliates, the paucity of green euglenids in the open water indicates










a low organic content. Biological activity at the marginal interface is
high and a large number of species is to be expected there and in the
aufwuchs, but numbers are low except for occasional blooms.

After the enrichment of Anderson-Cue Lake began, there was no
recorded change in the microbiota until July, 1968, which might have been
attributed to increased nutrients. Rainfall was deficient in the fall
of 1967 and the spring of 1968, evaporation was high and the water level
dropped continuously. In short, there was little or no nutrient carried
in from the land. Even the shallow margin was drastically reduced. In
Anderson-Cue marginal vegetation was stranded, reducing the attached
microbiota, and at present the shoreline of the lake has a very slight
growth. Even in McCloud Lake, except at the north end the reduction is
great. This evidently reduces such recycling of nutrients to the open
water as might have occurred earlier.

Table 6-7 illustrates this very well. Four samplings in August
and October 1967 and January and February 1968 showed a sharp reduction
in the total number of species, and, except for four blooms of very small
green cells (probably mostly Chlorella or Nannochloris) and Merismopedia
punctata, total numbers per ml were low. The same species which were
present in Table 6-6 recurred except that some different ones appeared
and some old ones dropped out. The outstanding fact is that Anderson-Cue
Lake had a decline in its population; that only one single species ex-
ceeding 25 microns in an overall dimension (Gymnodinium oculatum) appeared
in appreciable numbers. Ciliates were present in only one of these four
Anderson-Cue samples, and then two ubiquitous species reached 4 per ml.
Intensive sampling might show more blooms. Thus on January 9, 1968 there
were 2592 cells of Dinobryon sertularia and 2080 cells of Synura uvella
in the water just off the bottom in Anderson-Cue Lake, but only 96 and
80 in the surface. Gymnodinium oculatum also showed a bloom of 1440 per
ml, and Peridinium umbonatum a bloom of 14400 per ml in Anderson-Cue Lake
July 1, 1968. Such blooms are transient, lasting but a few days, and
when they occur they usually are associated with reduced numbers of other
species and numbers per ml. Thus the total population per ml in Anderson-
Cue Lake surface waters on July 1, 1968 was:

Beggiatoa alba 8
Oscillatoria sp. 24
Cylindrocystis sp. 8
Xanthidium sp. 24
Small green cells 480
Mallomonas sp. 56
Navicula sp. 8
Gymnodinium oculatum 1440
Peridinium umbonatum 14400
Peridinium wolozynskya 80
Total species 10
Total organisms/ml 16530

Perhaps the reduction is inexplicable, but Lackey and Hynes (1955) found
evidence that a dinoflagellate bloom completely tied up the orthophos-
phate, thus acting as an inhibiting agent until the bloom died and re-
cycling took place.










6-7

. e-... ons -. numbers -a., ml on -.., dates in '-Loud Lake and '.-. Lake in I "' 1 ,
Ster fertilization of Cue Lake was initiated.


:. ud Lake

in 1..-


a .7-


.'" oxatiferlra

Aulasira sp.


''* .. ... 1 6 0

S -t. lauca

.. toria "'.

S. -. :ystis 1

-' ella --.

Closteriua 1

Coclastrum c. ._.

./.. tothrix -- "tinosa

.v." p ,iella colonies

Ki. :h.' .:- .ella solitaria p.n.

trium rn

... "- ... i s .. : .


1i'


124


2-


1


.'..- .*















: bicaudatus

... viridis?

-tis 1

-' ocystis planctorica

'."des' .d us --

Staurastrum sp.

- tell ,tryoides

cells, minute

:- ydomonas .

C,-. 1 o.

.tomonas erosa



7 ,. '. :lonmonas volvocina

: : '.* ovelis

Chrysococcus cow; ormis

C -.. :' ., '. r, escens



* ... colonies


"-7 6-7 (Continued)

- .. .._Lake



8
1S


-'" Lake


2.5


4

2 V )


1 '


2 1


2 2.4 7













nas -i.

S uv '. ';. -o., cells

u vella colonies



Lutherella "-

.' .' tornum semen

Merotri -



-'atium curvirostre

: *triacantha

F .

.'" oculatuta



um nasutumz

.';." ium willei

-* ." : wisconsininse

idinium f5um0bona.tmn

volzii

'" ".. ,. ., uni- ,


6-7 (Continued)



8 2


16

8





24


2

2.5


p









.. 6-7 (Continued)

.* oud -


As; t 0 "* : formosa

Asterionell. -. ? :

Bicoeca lacustris

-of' *- l ata, 1 .

,. f .: ca costata

alteria grandinella



.,"tt U :'4 ,'Y

Strombidum .


*.tal 'es,

t. tal /i.


-.. Lake


15

4411


21

4


7

1'


9










At any rate there is little evidence that there has been any
change in the microbiota of either lake beyond what might be seasonal.
Winter temperatures in 1967-68 were never very low, so it seems impro-
bable that this was a limiting factor unless these organisms are adapted
to high temperatures. In August, September and October 1967, surface
water temperatures were measured from shore outward to a distance of
27 feet. These are shown in Table 6-8. The highest was 30.80C. and the
lowest 26.1 C. A list of species in this area was compiled, and a very
large number were present, active and tolerant of these high temperatures.
Insolation hardly seems to be a factor. In fact, no discernible seasonal
changes have been noted.

Table 6-9 shows the genera and species of protozoa and micro-
scopic algae found in five samples from Anderson-Cue and McCloud Lakes
which were closely studied during the past year. The number of species
is less in each lake than was reported up to this year. Thus McCloud
yielded 266 species in 15 prior samplings (1) compared to 226 for 5
samplings in 1967-68; and Anderson-Cue yielded 315 in 25 prior samplings
compared to 218 in the five samplings in 1967-68. Evidently species
incidence is high in both lakes, regardless of the numbers per ml. If
we compare the species found in these 1967-68 samples with the prior
samplings, there are some differences. Some 65 species had not been pre-
viously recorded from these two lakes so that the number of different
species is gradually increasing as their study lengthens. There are also
25 or more which do not appear in our check list (1) for Florida; these
would increase that list to more than a thousand species.

It is not expected that the total number of species in
Anderson-Cue and McCloud Lakes will ever reach the number in the check
list. Each situation differs in some respect from others, and that dif-
ference may be precisely the combination of factors permitting a par-
ticular species to live there. By the same token we may expect the lakes
to have certain species which will rarely if ever occur elsewhere.

By controlling the nutrient level we may bring into play factors
which we can recognize. In so doing we should look for changes in the
species list, and changes in the numbers per ml of the species present.
This part of the report makes no attempt to find correlations between the
biology of the lakes and the chemistry up to this time, beyond the assump-
tion that these are oligotrophic lakes. Actually the two lakes closely
resemble each other, both in species and numbers per ml. This is shown
in Tables 6-9 and 6-10. While some differences are shown in these tables,
they are probably more seeming than real, i.e., if a larger sample had
been more intensively studied, the differences would have been lessened.

In any event we now have a qualitative and quantitative back-
ground for the microbiota of these lakes. This is not going to change
very much, year to year, unless one or both lakes change. There will be
minor changes some species will not recur in another year, some new ones
will appear. Some species will not bloom again, some others will. But if
the environment in either lake changes enough to be measured in mathematical
terms, this will be reflected in the microbiota. Thus at the end of the
1968-1969 year correlations with the chemical and physical changes should







Table 6-8

Temperature in Degrees Centigrade, Cue Lake,
on Three late summer dates
Feet m ..5/ 7 9/11 67 10/11/


.3 26.4 26.6
S3 26.4 .0
1 28.7 .1 29.1
2 .6 A .3 .2
3 .8 26.9 .6
4 1. 27.3 .3
5 .5 .4 27.8
6 .6 27.5 7.
7 ." 6 ".5 27.6
3 W 27.6 07.4
9 .7 7.7 27.3
10 .8 27.8 27.3
11^ .83 7.8 .7.2
? -'.8 27.9 27.2
j 71.8 .9 27.2
1 ,7 27.9 .2
15 .8 .0 27.2
1 ....7 .0 7.3
i7 l.7 .0 7.4
1 ".7 28.1 27.4
19 .6 ^^.I :7.3
1,1 27.2
21 .5 28.2 .2
71.5 28A1 27.2
5.15 27.1
24. 5 .15 27.3
25 1.5 .15 27.3

27 5 1 .15 27- 3










S. 6-9


t, .osoai "' o .ic e and f .. teria .. from : Loud andc
Lakes on five Recent tes

and "






*iaStoa x :



.An4c"--tis x x x

t 'a x


Aul (4 44' -.. > x x
'scus p' tonica x x x
spermumn x A
is ~'*ina x
S is ma. r, p.n.
*casa x x 2t x X x
othe e a x X. x
p x : x x x >

M r -. x x x
Berismopedia punctata x x x x x x x
Mi incerta x


Pho sp. x
Pr 'sa f -.vViatilis x

Sothrix calcicola x x
Vtoema S 4? C 3X
S" ea a aceux x X x
S2coccus ;nos x x 7 x x









' .. 6-9


J7/19L67 8Z20/LLL0/1/. J 2 '7/. 7/"/.


As.ete rococcus .. ,imn e ticus

-. ..i mt .. d

Closte. -, "cerosum
* steri1n s?.
* trrm ti
'* 'trum -*- 1 -'detjm
esTarnerium son.

lind .


mr


*" ."i5Es as:eli
' L 'l) ium m e fi che:

l' 'no


o g sp.
"- -. aucoe :
Sbes
'chner" Soli "a o ....

e' 'otI a ni.o 'ti '?': li anum
M t5 .. C ,





Pe' as trO t-tras
7- -.


,(2









6-9





Pant"os 'isa latinose x
S'leurococc us, so,

X > "0:' *' 'K y0

onxumn J x, x x x
S 1* **'. tis schroceri C
haerozomes excavate.






Tetr'C,edro:D mu.ticumn x x
1 is









. T tr edr m o ,.. '. x y.
Y100- I-




.'......' r '" .. .. CV t, '''.,
placeras vertic'"' tus 7
i 'oceras Yr 1' *
T'rioiocer..ira % So. x x ". y... x x
-ella 7 x 7
WtOiL"um A x x x x x c

gi a Ia x x













gL pum x 'Nx
Aastasi? >Fi









TA' 6-9






con'Ou LQo










ena '7.. x x
,'.*na v.rn.. ldis v x x x x :




''p '7'-l ''-< -^ B .'



7t 7 O's '7 '" ', r' '" x. .
7. S";-' trichophorum *- .. xx



Po"t; s c ar sat' n







m 'e X




hisn-
Si s 1 ''










TABLE 6-9

uCue
'r t n -- f"'*' -rt I' '/ "*"t J /1/i /2 / 1. // / 7 /J /




to.onas erosa x x x x x x

"Owthoonas trunta x x x
>d ovnos lacustris x x x x x x


t bra-unit :X
orO' limnetica x
!orodesmus hi id a x x
S... a a x..

a R7
I a Ovals 7-v.,




K e 'C.splanc tonica x x
coccus cordiformis x <
-c us esens x
.yxis b' S '
S-sost os a
", al r,< 1,,?,

in .o 1.r'tu ai a x x. "
VLa i !or Y.pu. .
,- s ell 'ens ,
'alOon ,c t .onsur.a
I Me17' 1 o
:womonas x w
Peroniella planctonica x
S d sp x x
S ve' X x x


o* y tonr lata x

,.M r r '-ic.'" i.ta.ta x x ". x x
Vacuolaria v'irescans X







(6)

6-9

Cue
S '/. 8 / 1/ / 6 .7 2/7/Z 7/1/


A.s'tG-i'inefl~la f.orfos~a x
~ i .s sp. x x
ides x x
- sira grar3nu0osa x
.cula spp. x x x x x "
'a una x
4 .'to 's "'p x


**'- *" -barnadianse x x x
Ceratium curvirostre x x 7 x x x x x x
Glen, b rm sp. x

G N* x x x x x N
a culatat'm x x
microns c x
dtniumn so. x
Remilin nasutum x x x x x x
Massrtia m.ei x x x x x
id'init'"i.i?.l ci~ntten"'! x x
"idi'nitumj "*'- tumu x. x x x: x x x x x
7' "* Iun V n ou e nsl



Per' 'ium willei, x x x

.dinium sn. x x


S-aculeata x
Ac' -'" 'ium eichor)ni x
Amoeba Q. x x x x
'Qogba ) Iis x -
villosa x x xI
Ar* r. .dentata x x x x
Arcella -' *co, :. x x x x






(7)


S. ud


.. *', (continued)

Ar-cella ,. -is
Afs: :culus radians
Aer l10storma
Chaos
.athr i .


-~~~~ *"'7 '. osa


Diff


vT !
1 '-

00 Ur-Pf
40
Peiurusa


e lata
rI


.r a is


::i3is


, ida


"is lent a
! lineare
3-
9 -S .


tris
n.. -
Bodo celery p.n.

0- s- Q "up.

'.~ II. on.m


X
x
(- *rrion ovale)


'V

""-" tans


." A I


Mas V
MaesP,







( )

6-9

Cud ue
*- 1 e ; I -, 0 / I -s r f 7 1 / _r r- .. 4 ,


(co) )

r'^' ....: t." ovata x x X :<
" comonas ocell3ata x
termo x x
' .- s i t'ut X
er, elo x

euromon's *. x x






". .- a x -plen x x
a 'o nasuta x









A 'oca olrrtvox x x
, 0 r; itacem x x x





ofx' '7 't. unidt. x x x

c .. p. .
Asp '- c trrita x x x x




.As ,. : x




*, .* -Fr :0- x S :I 1 X, ', v
Enchelydon sp. t x







Enchelydon sp. x










6-9






te8 X
.. aa x x
Frontonia actvinta xt
Frontonia x x x x
lteris l- a x x
x x x x x
o. ans x
otrichida Lu-id. x
U : or is x x
in -
..... 1T x x x x
-,. ,osus x x x
acarus x x x
S-in ta x x x x x
us es x


versatile X X X x x x


cium busaria x-'
I' fiisa x






-K
n .. x ,
',odiniu-m sp. 3;





Stenr tor x
S"" a SP i x
Str x
Stroabidium --. x < x x x
T : .'-" a sp. x x

UroLe '- '. rattulus x x x x









6-9






(con )

.tricha fara x x x x

:t ice a -. x
Ciliata '., x x. x









6-10

Croups of micro:: < t .. Cand protooa in ::tai... an-
alyses on five -.' in 1.> in : -- 0" ,
the number of occurrences.


Organism -




S: B.acteria 2 1 3 2 4

Algae 26 24 21 33
"117 101

.Ivocales 7 7 13 2 5

S-1. 39 29

Crypi- 5 5 18 5 14

Chrp- 18 24

Chloromonadida 4 2 6 4 8

. .f 1 -. lata 17 17 14 31
cillarieae ('-'toms) 7 5 8 4 6

*-da 21 24

Zoof" --lata 22 18 9 15 19

0 .ta 4


To '- "6 4" 218 410

















88










be sought. This study should be done by analysis of the microbiota
at intervals of two weeks, so that it can be determined if changes are
gradual, or if a critical point is reached beyond which changes are
abrupt.

The greatest fluctuation in species incidence will be in those
which occur in very small numbers. It is quite apparent that there is a
standing, measurable crop of Dinobryon or Synura, or Peridinium umbonatum
or Stentor amethystinum. The principal question to be answered is
whether these will increase greatly under induced eutrophication, or
whether species now encountered sparingly will increase greatly and
perhaps supplant the present common ones.











Section 7


ANALYSIS OF ENVIRONMENTAL FACTORS
AFFECTING PRIMARY PRODUCTION



A. Purpose

One of the major complicating factors in eutrophication
research is the fact that no simple relationship exists between the
process of nutrient enrichment and the trophic state of the lake.
A multitude of environmental factors as discussed in Section 2 control
the severity and degree of trophic change for any given rate of nutrient
enrichment. Similarly, limnologists have long realized that lacustrine
primary productivity is influenced by other factors besides the amounts
of available nutrients. These factors include physical parameters such
as light intensity, temperature, lake transparency and turbulence, and
chemical parameters such as micronutrient (trace metal and vitamin)
concentrations, pH ionic balance and strength, alkalinity and others.
Since primary production is a fundamentally important trophic state
indicator, an intensive investigation of its variations and controlling
factors in the experimental lake was considered essential. Accordingly
a ten day field study was conducted on Anderson-Cue Lake to determine
the short term variations in primary production and associated factors
and to delineate the factors controlling production.

B. Procedures

Seven chemical, three biological and three physical parameters
were measured three times daily from May 6, 1968, up to and including
May 16, 1968. No measurements were made on May 12.

Samples for measurement of the chemical parameters were taken
at three depths, surface, 5 ft., and 10 ft. at station seven (See Figure
4-1). The parameters measured were pH, ortho-phosphate, ammonia,
nitrate, dissolved oxygen and acidity.

The biological samples were taken from the same sampling loca-
tions as the chemical samples. Biological parameters measured were
chlorophyll a, primary production, and plankton identification and counts.
The physical parameters measured were total radiation, cloud cover, and
air and water temperature.

All of the biological and chemical parameters, except plankton
counts were measured three times each day at 10:00 AM, 12:00 AM, and
4:00 PM plus or minus one hour. Samples for plankton counts and identi-
fication were taken only once each day.

The procedures used for physical, chemical and biological
determinations were the same as those described in earlier sections of
this report.








































surface





5 ft.






10 ft.


Figure 7-1.


Days

VARIATION OF AVERAGE DAILY PRIMARY PRODUCTION OVER
THE STUDY PERIOD











Table 7-1


MEANS AND STANDARD DEVIATIONS OF PARAMETERS
MEASURED DURING TEN DAY STUDY OF
ANDERSON-CUE LAKE


Parameter Sampling Location
and Units Surface 5 Feet 10 Feet

Ortho-Phosphate .005 + .004a .002 + .002 .002 + .002
(mg P/I) .005 T .005b .001 + .001 .001 + .002
.005 + .006c .001 + .001 .001 + .001


Ammonia Nitrogen .18 + .04 .18 + .04 .22 + .08
(mg N/1) .18 + .05 .18 + .04 .22 + .06
.18 + .04 .17 + .04 .18 + .08


Nitrate Nitrogen .07 + .02 .07 + .02 .08 + .03
(mg N/1) .06 + .01 .06 + .02 .07 + .01
.06 + .01 .07 + .01 .06 + .00


Acidity 2.95 + .46 2.89 + .66 4.06 + 1.26
(mg/l as CaCO3) 2.75 + .37 2.63 + .32 3.27 + .58
2.61 + .40 2.55 + .34 3.46 + .96


pH 4.84 + .05 4.85 + .08 4.94 + .12
4.98 + .12 4.94 + .05 5.00 + .08
4.96 + .07 4.94 + .11 4.96 + .14


Water Temperature 26.2 + 1.9 25.7 + 1.4 24.8 + .4
(C) 27.2 + 2.2 25.9 + 1.4 24.9 + .5
28.2 + 2.3 26.2 + 1.2 25.1 + .5


Primary Productivity 9.86 + 3.54 4.02 + 1.50 .24 + .13
(mg C/hr-m3) 9.63 + 2.87 5.70 + 2.48 .33 + .28
12.02 + 5.01 3.82 + 1.42 1.01 + 1.38


Chlorophyll a 12.43 + 9.12 11.58 + 3.82 6.34 + 3.06
(mg/m3) 11.93 + 5.89 10.05 + 4.31 5.14 + 2.33
13.98 + 9.39 10.99 + 8.23 4.34 + 2.10

aMorning 10:00 AM
bNoon 12:00 AM
cAfternoon 4:00 PM








Table 7-1 (Continued)


Parameter Sampling Location
and Units Surface 5 Feet 10 Feet

Total Solar Radiation 542.1 + 91.2
(Langleys/Day)


Air Temperature 26.7 + 5.6
(C) 30.1 + 2.8
29.8 + 2.6


Cloud Cover 37 + 31
(%) 59 + 27
52 + 30


Plankton Counts 3527 + 1674 2675 + 1650 1237 + 759
(#/ml)






















surface
X 5 ft.
10 ft.











_______ A ----- -^ --- "


10:00 AM 12:00 AM
Time of Day


4:00 PM


Figure 7-2.


MEAN PRIMARY PRODUCTION VS TIME
OF SAMPLING


0 surface
X 5 ft.
4 10 ft.


1 2P
Plankton


3Counts
Counts


4 5
(Cells/ml x


Figure 7-3. AVERAGE DAILY PRIMARY PRODUCTION
VS PLANKTON COUNTS


r
0
4-J
U

0
Oi

^ M)
*r

P-4


r,
0

C
4-i
U /-N



04 M
-C-c



*i-1
!-

PE


6
103)










C. General Results

Detailed discussion of all the parameters and their variations
would be neither fruitful nor desirable. However, a few general comments
concerning the nature of the results are in order. Daily averages of
primary production at the three sampling depths is presented for the ten
days in Figure 7-1. The effect of depth is clearly illustrated; in all
cases surface production was the highest and 10 ft. production was by
far the lowest. Top and bottom primary production rates generally differed
by an order of magnitude or more. The peak in daily production at the
surface occurred on the sixth day and is correlated with a moderate bloom
of Synura in the water at this time. Temporal trends in the 5 ft. and
10 ft. samples are not so pronounced. Most of the chemical and physical
parameters varied within rather narrow ranges during the ten days and
displayed considerable randomness in their variations.

One of the questions this study sought to answer concerns the
degree to which a given sampling day is representative of the conditions
in the lake during the period between sampling dates. This depends on
the frequency and amplitude of the temporal variations in the parameters.
A statistical analysis was made on the variability of the data and is
partially presented in Table 7-1. The table contains a summary of the
means and standard deviations of the parameters measured over the ten day
period. Several of the chemical parameters displayed little variation
during the study period. Table 7-1 indicates that ammonia, nitrate and
pH changed over quite a narrow range. Average ortho-phosphate levels
are higher in the surface waters than at the 5 and 10 ft. levels. This
difference may be explained in part by the periodic rainfalls that occurred
during the study which deposited water high in phosphate on the lake
surface. However, nitrate and ammonia levels did not display a similar
pattern.

Table 7-1 indicates that some daily stratification occurred in
the lake; however this was slight. Mean dissolved oxygen and mean water
temperatures decreases from top to bottom were 1 mg/1 and 2.5C respectively.

Acidity values display a diurnal trend as is evident in Table 7-1.
Acidity appears to be higher in the morning and gradually drops during the
day with decreases of .5 to 1.0 mg/1 occurring. However, pH values show
very little fluctuation.

As would be expected water temperatures rose as the day progressed.
An average daily change in the order of 20C occurred at the surface with
correspondingly smaller changes occurring at the 5 and 10 ft. depths.
Air temperatures reached a maximum in the early afternoon with lowest values
occurring in the morning.

As is shown in Table 7-1, the biological parameters displayed
the greatest variation. This wide fluctuation indicates that any attempt
to interpolate the value of a biological parameter from encompassing
sample points would be quite erroneous. In Figure 7-2, 10 day mean pri-
mary production values are plotted versus time of day. Mean primary
production at the surface gradually increased from the morning until the


























o surface
x 5 ft.
A 10 ft.


4A


1 2 3 4 5
Plankton Counts (Cells/ml x


6
103)


Figure 7-4.


AVERAGE DAILY CHLOROPHYLL A VS
AVERAGE PLANKTON COUNTS


PP = 5.93 +


36 (chl. a)


0 surface


x 10 ft.


x
PP = -.48


+ .20 (chl. a)


2 4 6 8 10 12
Chlorophyll a (mg/m3)


Figure 7-6.


14 16 18


AVERAGE DAILY PRIMARY PRODUCTION VS
AVERAGE DAILY CHLOROPHYLL A


r-4
P>, --
Q. E
0 -o
s bO
0
,- o -<


0
4J)
Uc~*


0
o-

4
B


0 4
P4 J










afternoon; whereas primary production at the 5 ft. level appeared to
peak in the early afternoon. Primary production levels at 10 ft. were
very small and of little significance. Mean primary production at the
surface was higher for all sampling times than mean primary production
at 5 ft. This was quite probably due to the increased water temperature
and higher degree of solar radiation at the surface.

Figure 7-3 shows mean daily primary production at each depth
versus plankton counts at the corresponding depths. The points on the
plot are quite scattered but trends are evident. Primary production and
plankton counts were higher at the surface. The higher plankton counts
(See Table 7-1) plus the increased efficiency of the plankton at the
surface explains the higher surface primary production. Plankton counts
and primary production were correspondingly lower at the 5 ft. level and
lower still at the 10 ft. level.

In Figure 7-4 average daily chlorophyll a is plotted versus
plankton counts. The result indicates that to an extent high chlorophyll
a concentrations are associated with high plankton counts. The
chlorophyll a concentrations were higher at surface and 5 ft. levels
than at the 10 ft. level. With reference to Figures 7-3 and 7-4, it
would seem that high primary production values were generally associated
with correspondingly high plankton counts and high chlorophyll a
concentrations.

D. Species Diversity as a Trophic Indicator

As mentioned previously samples were taken each day of the study
for organism identification and counts. Major species were identified and
counts made on each species. The planktonic organisms prevalent during
the study were Synura, Dinobryon, Merotrichia, CrypItmonas, Monallantus,
Chlamydomonas, Gymnodinium, and Scenedesmus. The order in which the
organisms are listed more or less represents their abundance in descending
order.

Patten (1966) has used species diversity concepts for describing
planktonic communities. The number of species, m, and the concentration
of total individuals N (per ml) are used to determine a range of diversity
available in the plankton sample. The minimum diversity, Dmin, when
m > 1 corresponds to a situation where all individuals except (m-1) belong
to a single species, and the remainder are distributed one each to the
other species.

Dmin = n N 1 in N-(m-l) (7-1)

Any change toward equalization of the numbers in each species increases
the diversity eventually resulting in maximum diversity, Dmax, when the in-
dividuals are equally apportioned among the species.

Dmax = In N m ln (N/m) (7-2)

The community diversity, D, is determined from the distribution of indi-
viduals amongst the available species. Ni equals number in ith special.




Full Text

PAGE 1

Research Project Technical Completion Report "FACTORS AFFECTING ACCELERATED EUTROPHICATION OF FLORIDA LAKES" OWRR Project No. A-002-FLA TO: U. S. Department of the Interior Office of Water Resources Research Washington, D.C. 20240 Hugh D. Putnam, Principal Investigator Environmental Engineering Department University of Florida Gainesville August 29, 1968 NOTE: This report, after final correction and editing, will be published by the Florida Engineering and Industrial Experiment Station, College of Engineering, University of Florida, as Technical Progress Report Number 16 and Florida Water Resources Research Center Publication Number 5.

PAGE 2

TABLE OF CONTENTS Page Research Staff ...................................... II Introduction ........................................ 1 The Process of Eutrophication ......... ..... .... ..... 4 Rate of Nutrient Addition to Anderson-Cue Lake 12 Physical Characteristics of the Research Lakes and Drainage Basins ............................ 18 Routine Chemical Studies 27 Biology 43 Analysis of Environmental Factors Affecting Primary Production ............................. 90 Trophic State of Lakes in North Central Florida ..... 106 Models of the Eutrophication Process ................ 118 List of References .... . . . . . . .. 121 I

PAGE 3

Members of Research Team and Assistants Dr. Hugh D. Putnam Dr. Patrick L. Brezonik Dr. William H. Morgan Dr. James B. Lackey Professor A. L. Danis Mrs. Zena Hodor Mr. Roger Yorton Mr. Thomas Salmon Mr. H. A. Blalock Mr. Earl Shannon Mr. Michael Long Mr. Gary Ashley Mr. Larry Seymour Mr. Howard Crown Mr. Samuel Richardson Mr. Glen Brasington Mrs. Jeanne Dorsey Mr. T. L. Tang Mrs. Carol Harper II

PAGE 4

Section 1 Introduction Florida has a vast and valuable resource of fresh water considering the springs and nearly 30,000 lakes found within the state. Prac tically all of these surface waters are useful in a recreational sense and for this reason Florida appeals greatly to tourists everywhere within this country and Canada. Fishing, beating, and various contact water sports are enjoyed by both residents and out of state visitors throughout the year. Therefore, the conservation of this fresh water resource is most important to the state's economy. However, since water is so intimately involved in the total well being of the environment, impairment of aquatic systems in varying degrees will affect all the biota including man within a particular ecosystem. Essentially, the water quality of lakes and other fresh water resources mirrors the status of the total environment. Over the years, Florida lakes have been enriched gradually with nutrient salts from the land. Encroaching urbanization and intensive agricultural practices have, however, increased nutrient additions to lakes on an unprecedented scale in recent years. This enrichment has accelerated the eutrophication of surface water thereby shortening the lives of lakes and generally impairing the quality of the water. This problem, which can be reflected nationally, is acute in Florida. The shallow lake basins, long hours of sunlight and mild winter temperatures are some of the factors which make surface water particularly susceptible to the effects of enrichment and lead to sustained algal blooms throughout the year. The most classic example in Florida is Lake Apopka near Orlando. This is a 30,000 acre lake which has been extensively enriched by fertilizers from bordering citrus and winter vegetable farms, municipalities, and citrus processing plants. A hyacinth erradication program by chemical sprays over the last 20 years has left a flocculant bottom layer of undecomposed plant residues. The lake bottom is anaerobic. At all times during the year soupy algal growths are found in the surface water over the entire lake. A similar process is occurring in many other lakes within the state. Although the visible effects of eutrophication are well documented very little real knowledge exists regarding the interplay of environmental parameters during lake enrichment. Ultimately management systems must be devised to include whole drainage basins if the eutrophication problem is to be dealt with effectively. First, however, it is necessary to understand in quantitative terms what eutrophication is; what are the most effective combinations of enriching substances and how these relate, for 1

PAGE 5

example, to the physical environment of lake morphology, climate and various edaphic factors. To accomplish these objectives and ultimately offer the maximum use of a lake to those living within the basin we must know what enrichment stress can be placed on surface water without measurably impairing its quality. This can be brought about only by long term research. Projects such as that described in this report, using whole lakes as experimental units, are few in this country. More are needed especially in varying geographic locations if we are to understand completely the eutrophication process. The site for this study was selected in the sandy, scrub-oak terrain near Melrose, Florida, about 30 miles east of Gainesville. Nu merous lakes are located in this area, and two lakes located on private property were selected through the cooperation of the owners. The isolated location of these lakes assures freedom from outside interferences and urban or agricultural influences. Considerable effort was exerted in 1966 to establish a field station at the lake site and to install appropriate instrumentation. Background data on the chemistry and biology of the lakes was obtained in order to be certain of their similarity and original trophic status. It became apparent, however, that the lake originally selected for nutrient enrichment, Berry Pond (see Figure 1-1), was not similar in biological and chemical characteristics to the lake selected as the control, Anderson-Cue Lake (see Figures 1-1 and 4-1) It was then decided to use Anderson-Cue Lake as the experimental unit and to attempt its controlled eutrophication. A nearby lake, McCloud, similar to Anderson-Cue Lake in size and physical characteristics, was selected finally as the control in late 1966. McCloud Lake is located approximately one-half mile north east of Anderson-Cue Lake. 2

PAGE 6

3

PAGE 7

Section 2 The Process of Eutrophication It is axiomatic that a problem must be clearly defined before solutions can be developed. The problem of lake eutrophication has long suffered because the process, its causes, and effects have lacked clear definition. While the phenomenon of eutrophication has many ramifications the problem itself is basically two-fold. Eutrophication itself is simply the process of nutrient enrichment of natural waters. Previous workers have defined the process only qualitatively and quantitative loading rates do not necessarily specify a particular rate of eutrophication. The second aspect of the eutrophication problem is definition of its effects on the trophic state of a lake. Eutrophy or the eutrophic condition is a state of a lake defined by a variety of biological and chemical conditions. Eutrophy is of course a result of eutrophication but unfortunately there are no well defined units or quantitative measures of a trophic state. Thus it has been heretofore impossible to quantitatively relate the process of nutrient enrichment (that is eutrophication) to the effects on trophic state (that is the degree of eutrophy). In many cases it is actually the rate of eutrophication which is of primary interest. Aquatic scientists are primarily concerned with the manifestations of eutrophication on the trophic state of a lake. This implies that they are actually concerned with the rate of change in trophic state or eutrophy or the rate of change in the effects of nutrient enrichment. Stewart and Rohlich (1967) recently published a comprehensive review of the eutrophication problem. According to their review the term eutrophication has been used and defined rather loosely by different workers. However, Naumann (1931) originally defined eutrophication as "an increase of the nutritional standard (of a lake) especially with respect to nitrogen and phosphorus." There is general agreement among present workers that eutrophication is the process of nutrient enrichment. Most previous workers have cited nitrogen and phosphorus as the main eutrophying elements. There is no general agreement among authorities concerning the relative importance of nitrogen and phosphorus as limiting elements. Cases can be made for both elements, and bioassay methods have found both limiting primary production in different lakes. Many other elements and compounds (e.g., trace metals and vitamins) are essential for algal growth. However, little is known about their role in the eutrophication process. There are reasons --based on geochemical and biological considerations --to believe that lakes generally are limited by their nitrogen and phosphorus inputs, but unambiguous proof would be nearly impossible. It is also likely that input of minor essential nutrients is highly correlated with one or both of the major limiting elements. 4

PAGE 8

One of the objects of the present research project is to clarify the factors involved in eutrophication and trophic state and to relate them quantitatively to each other. The factors affecting nutrient enrichment of lakes are largely geological and cultural, as indicated in Table 2-1. The nutrient load imposed on a lake is a function of the geochemistry of its drainage basin, the hydrology of the region, climate and other natural factors. Superimposed on these natural factors are a variety of human factors, e.g., urban and agricultural runoff and the amount of domestic sewage disposed into the lake. It should also be noted that human factors can affect some of the natural forces. For example, mining operations may change the geochemistry and hydrology of the basin, and air pollution may increase the nutrient content of rainfall. For a given total nutrient influx, net enrichment may vary depending on the temporal variations in the input (whether it is a periodic slug or steady addition) (Brezonik, 1965). The effects of nutrient enrichment on the trophic state of a lake are controlled by numerous physical and chemical factors; these are summarized in Table 2-2. Limno1ogists have long realized that lake productivity is influenced by factors besides the concentrations of nutrients. This is apparent when it is realized that lakes of similar chemical composition may vary significantly in productivity. The other factors influence lake productivity primarily by affecting the distribution, availability and utilization of nutrients. Thus they influence productivity only indirectly, and because of this it is much more difficult to assess their individual importance. Similar statements can be made with regard to the factors affecting trophic state in general. Brezonik (1965) reviewed the effects of physical factors such as morphology and climate on lake productivity. Morphology has a dominant influence on the availability and distribution of nutrients in a lake and thus profoundly affects productivity and trophic status. A number of morphological parameters are important in this regard, including mean depth, steepness of bottom contour, percent littoral area, shore line irregularity and mean depth/surface area ratio. Rawson (1955 and earlier papers) considered mean depth of fundamental importance with regard to lake productivity. He found a hyperbolic relation between mean depth and long-term fish production in the five great Lakes and seven large western Canadian lakes, indicating a rapid increase in fish production as mean depth decreased below 25 meters and a slow decrease in production as mean depth increased beyond 25 meters. Similar results were obtained by relating phytoplankton and bottom fauna standing crop to mean depth of lakes, and Rawson concluded that a mean depth of 20-25 meters is the dividing point between oligotrophic and eutrophic lakes. Reasons for the dominant effect of mean depth on lake productivity are several but mostly relate to the possibility of nutrient replenishment from the underlying sediments in shallow unstratified lakes. This factor has special significance for eutrophication in Florida since most of its lakes are shallow and not stratified. Climatic factors include temperature, insolation, and wind, as it affects circulation patterns in the lake. Effects of chemical composition of the water on the availability of nutrients are also noted 5

PAGE 9

Table 2-1 Factors Affecting Nutrient Enrichment Rates (Eutrophication) of Lakes Natural Factors Geochemistry of the basin (Composition of underlying rock structures) Soil types Hydrology Size of drainage basin Short-circuiting Detention time in lake Groundwater composition Climate Precipitation Thermal structure 6 Human Factors Domestic sewage Agricultural runoff Type of farming Fertilization practices and extent Soil retentive capacity Mining operations Industrial wastes Urban runoff (Auto exhaust, lawn and garden fertilizing leaves, etc.) Nutrient leaching from drained marshes and from garbage dumps

PAGE 10

Table 2-2 Physical and Chemical Factors Controlling the Effects of Nutrient Enrichment on Trophic Status Physical Mean depth Steepness of bottom contour Shoreline irregularity Percent littoral area Mean depth/surface area ratio Wind protection by surrounding terrain Temperature Insolation Circulation which affects sedimentation rates 7 Chemical pH Balance of all nutrients needed for production Suspended solids (as affecting transparency) Nutrient concentrations Dissolved oxygen

PAGE 11

in Table 2-2. The temporal distribution of the nutrient input to a lake (whether continuous or highly seasonal) may also control the effects of nutrient enrichment on trophic state. The trophic state or degree of eutrophy of a lake may be considered to be a function of the amount of eutrophication or nutrient enrichment as modified by the edaphic factors given in Table 2-2. Trophic state is defined by many factors and cannot be adequately measured by any single parameter. The physical, chemical and biological criteria commonly used to indicate trophic state are shown in Table 2-3. Many of the parameters are only qualitative indicators. While some of the parameters are highly correlated and dependent on each other, others are at least quasiindependent. The problem of defining trophic state is a serious one for. if progress is to be made in relating the process of eutrophication to its effects criteria for trophic state will have to be well defined and quantified. Fruh et al. (1966) and Stewart and Rohlich (1967) have reviewed the parameters used to measure trophic state in detail and have discussed their assets and limitations. On a qualitative level the criteria appear to present no problems. Oligotrophic lakes are low in nutrients, have low chlorophyll and primary production levels, high transparency, are generally deep, and have few numbers of organisms but large numbers of species. Eutrophic lakes are generally the antithesis. They have high nutrient and chlorophyll levels, high primary production, low transparencies, are usually shallow, and have high algal populations distributed among few species. However, the criteria do not generally lend themselves to quantitative measures of eutrophy; i.e., using these criteria it is impossible to state how much more eutrophic one lake is compared to another. The various indicators sometimes present conflicting values for the trophic state of a given lake. Beeton (1965) reported such anomalies for some of the Great Lakes. While all criteria indicate Lake Erie to be a eutrophic lake, some biological and chemical criteria indicate that Lake Ontario is eutrophic and other chemical and physical criteria indicate the lake is oligotrophic. Most previous studies on trophic state indicators have been concerned with temperate lakes. Subtropical lakes, such as those in Florida, have considerably different characteristics, however, and the indicators of trophic state in northern lakes may not be altogether applicable in these situations. Some differences between temperate and subtropical lakes are summarized in Table 2-4. In their natural states, some Florida lakes simultaneously have characteristics of oligotrophic, eutrophic, and dystrophic temperate lakes, which implies that parameters used to define these northern lake types are not always useable in subtropical situations. Nearly all Florida lakes are shallow; and considerable water fluctuations occur between dry and rainy periods. Water level fluctuations of plus or minus five feet in lakes with normal maximum depths of only 20 feet are not infrequent, and many lakes dry up completely (or nearly so) in periods of prolonged drought. Change in water level implies a moving shore line. In Florida lakes there is often no distinctive land-lake interface, and the shore areas of lakes are often submerged land. The littoral vegetation in Florida lakes is composed of emergent and submergent aquatic species as in northern lakes, but because of the changing shore, terrestrial species are also found in the littoral area. Extended growth periods 8

PAGE 12

Physical Transparency (Secchi disc reading) Morphology (mean depth, etc.) Table 2-3 Indicators of Trophic Status Chemical Sediment type Oxygen supersaturation in epilimnion Hypolimnetic Oxygen deficit Conductivity Dissolved solids Nutrient concentrations (at spring maximum) Chlorophyll level 9 Biological Algal bloom frequency Algal species variety Characteristic algal group Littoral vegetation Fish species and biomass Characteristic zoo-plankton Bottom fauna Primary production

PAGE 13

Table 2-4 Differences in North Temperate and Semitropical Lakes Which May Bear on Eutrophication Process Northern Lakes 1. Defined shore line usually with beach 2. Thermally stratified, usually dimictic 3. Usually calcareous 4. Ice covered 5. Runoff from meltwater 6. Winter solar radiation and temperature limit primary production 10 Semitropical Florida Lakes 1. Shore-water interface i 11-defined 2. Little or no thermal stratification 3. Soft, acid water 4. Always ice free 5. No spring runoff 6. Low temperature and solar energy not evident; longer periods for optimum plant growth. Sustained yields of standing crop throughout year.

PAGE 14

lead to large standing crops throughout the year under subtropical conditions compared to highly seasonal crops in north temperate lakes. In general, seasonal changes in subtropical lakes are less evident than in northern lakes. Temperature structuring is less pronounced, and because of their shallowness few Florida lakes exhibit stable thermal stratification. The general chemical compositions of temperate and subtropical lakes differ considerably. Typical temperate lakes are calcareous, have pH values above 7, and moderate to high alkalinities. Florida lakes typically have soft acid waters and very low alkalinities. Organic color is a more common constituent in Florida lakes than in temperate lakes. Because of the difference in chemical composition, species of plankton in Florida lakes tend to differ from those in temperate lakes. Desmids are common in soft, acid waters of Florida, and diatoms are often sparse. However, blooms of blue-green algae, such as Microcystis, Anabaena, and Aphanizomenon occur in fertilized Florida lakes as in their northern counterparts. The problem of adequate criteria for trophic state will be further discussed in a later section on models of eutrophication. 11

PAGE 15

Section 3 Rate of Nutrient Addition to Anderson-Cue Lake One approach to studying eutrophication is to artificially enrich (eutrophy) a lake at a controlled rate and measure all the parameters which define trophic state. The problem then becomes a matter of relating the response of a lake (in terms of trophic structure) to the degree and rate of nutrient enrichment. The lake thus serves as a model for the process in general; this approach has been used in the present study. Intentional fertilization of lakes for scientific purposes is not a new concept. Stewart and Rohlich (1967) recently reviewed previous experiments on lake fertilization. Einsele (1941) reported one of the first experiments on lake fertilization. He applied slug doses of super phosphate to a small German lake in 1937 and 1938. Temporary increases in the phytoplankton of the lake were found but the lake soon returned to normal. A number of investigators (e.g. Ball, 1948a, b; Langford, 1948; Hooper and Ball, 1964) have attempted to increase the productivity of fish ponds by adding fertilizer. These attempts have had only moderate success. In most fertilization experiments nutrients have been added as slug applications rather than continuously. While temporary effects have been noted the ponds or lakes returned to their original condition in short periods of time. Because of the nature and purpose of previous fertilization efforts, the results from these studies are not directly applicable to the problem of cultural eutrophication. Man induced eutrophication is characterized by a more or less continuous addition of nutrients to a lake from such sources as sewage, effluent and urban and agricultural runoff, while most previous fertilization attempts have used sporadic or one time applications of fertilizer. Generally sufficient background data was not obtained to describe the trophic state of a lake in its natural temporal variations. The study reported here is viewed as a long term effort to follow the effects of a controlled nutrient input on a lake's trophic state. Two small lakes are involved; one lake is serving as a control and the other lake is being artificially eutrophied by continuous and controlled addition of nutrients. A variety of routine chemical and biological data is being collected on these lakes along with routine physical and climatic data in order to delineate the factors affecting the rate and severity6f eutrophication. Chemical and biological measurements during 1966 and early 1967 established the oligotrophic nature of Anderson-Cue Lake. In March, 1967, nutrient additions were started into the lake. It was decided to add sufficient nitrogen to raise the total N content of the water 0.50 mg N/l over a period of a year (assuming all nitrogen would stay in solutiDn). This is equivalent to 500 mg/m 3-yr. or about 10 mj/m 3-week. The volume of Anderson-Cue Lake was estimated to be 248,00Om. Thus a weekly loading of 2.48 kg N was desired. This was achieved by adding 21.2 pounds of ammonium chloride to 300 gallons of sewage effluent, which was trucked out 12

PAGE 16

to the lake site and fed into the lake with a chemical feed pump at a rate of 1.8 gallons per hour. The nutrient outfall is located 2 feet below the surface and 200 feet off the south shore of the lake in about 10 feet of water. It was decided to increase the total phosphorus content of the lake by 0.0427 mg P/l in one year. This is equivalent to 42.7 mg/m 3-yr. or 0.854 mg/m 3-week. For the whole lake a loading rate of 0.212 kg P/week is indicated. This was achieved by adding 2.47 lb. of Na3 P0 4 to the sewage effluent each week. Originally it was planned to add only sewage effluent to the experimental lake. This would have been feasible if Berry Pond (1 acre surface, maximum depth, 13 feet) had been used as originally planned, but the trophic characteristics of this lake rendered that impossible. With the larger Anderson-Cue Lake as the experimental lake, nearly a million gallons of sewage effluent would have to be transported to the lake site annually for the desired nutrient loading rate. Logistics thus precluded the use of sewage effluent alone, and it became necessary to enrich effluent with nitrogen and phosphorus compounds. The above nutrient addition rates compare closely with those estimated for the nutrient budget of Lake Mendota, Wisconsin, by Lee et al., (1966). This eutrophic lake receives a heavy influx of nutrients from agricultural drainage, but ground water and atmospheric precipitation also make important contributions. The nitrogen loading of Lake Mendota was estimated to be 556,000 lb. per year, or 534 mg/m 3-yr. Of this quantity, Brezonik and Lee (1968) have estimated that two-thirds or 360,000 pounds remains in the lake and is deposited in the sediments, while the remainder is lost through the outlet and by denitrification. The phosphorus budget for Lake Mendota was estimated to be 44,900 lb. per year or 42.7 mg P/m3-year. Relatively few other lake nutrient budgets have been established. Mortimer (1939) constructed a nitrogen balance for Lake Windermere (England). He found a close balance between input and output --326 and 318 metric tons, respectively. Hutchinson (1957) felt that nutrient inflow and outflow normally would balance closely in oligotrophic lakes, but not in eutrophic lakes. Rohlich and Lea (1949) reported an extensive nutrient balance on Lake Mendota, Wisconsin. Of the estimated 156 metric tons of nitrogen entering the lake annually, only 41 tons left through the surface outlet. Corresponding values for phosphate were 16.4 and 11.6 metric tons. Partial nutrient budgets were determined for the lower Madison lakes by Sawyer et al. (1945). However, only soluble phosphorus and inorganic nitrogen inputs were measured rather than total values, and the usefulness of the results are thus lessened. Aside from the nutrient balances on Lake Tahoe (McGauhey et al., 1963) and Lake Washington (Edmondson, 1966) no other definitive nutrient budgets are known. Cer tain aspects of nitrogen and phosphorus budgets and sources have been treated by various workers. Brezonik (1968), Feth (1966), and Fruh (1967) have reviewed these studies in considerable detail. 13

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Table 3-1 lists the most common nutrient sources and sinks for lakes. Only some of these are applicable to the study lakes. Artificial enrichment represents the most significant nutrient source for AndersonCue Lake. The possible natural sources of nitrogen are biological fixation, atmospheric precipitation, airborne particulates and surface and subsurface runoff. Preliminary results indicate the rainfall directly on the lake surface is the most important natural source. Nitrogen fixation has not yet been measured in the lake, but the near absence of bluegreen algae in the biota of the lake implies that it does not occur. While bacterial fixation is possible, available carbon substrates are low and indicate the source is probably negligible. Contributions from runoff also appear to be small. The amount of runoff draining into the lake is apparently low, and the soil is so nutrient depleted that rainfall runoff would pick up little or no additional nutrients in passing through and over the soil. Measurements 'of the nutrient content of the rainfall were made periodically in 1967 and 1968. A summary of the results are shown in Table 3-2. The nitrogen content of rainfall appears to be quite variable. However, these results can be combined with the rainfall amounts (see Section 4, Table 4-1) to yield an estimate of the total nitrogen contribution of rainfall to Anderson-Cue Lake. For 1967, 49.4 kg nitrogen was added to the lake by rainfall directly on the lake surface. This compares to about 124 kg N added in the nutrient mixture. Actually a greater disparity between these two sources exists than is indicated by the magnitude of the two numbers. The rainfall contribution is diluted in a large volume of water, whereas the nutrient mixture is highly concentrated and contributes an insignificant amount of water to the lake. No phosphate analyses are available for 1967; results from 1968 indicate a wide range of phosphatE-'in rain water --from about 1 to 25pg P/l with a mean content of 10 pg/l. Assuming this mean represents the average phosphorus content of rainfall in 1967, 1.05 kg P was contributed by rainfall in 1967. This compares with 10.6 kg added to the lake in the nutrient mixture. These results are summarized as a nutrient budget for Anderson-Cue Lake in Table 3-3. 14

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Table 3-1 Sources and Sinks for the Nutrient Budget of a Lake Sources 1. Airborne Rainwater Aerosols and dust Leaves and miscellaneous debris 2. Surface Agricultural runoff and drainage Urban storm water runoff Marsh drainage Runoff and drainage from uncultivated land Domestic waste effluents Industrial waste effluents Wastes from boating activities 3. Underground Natural groundwater Subsurface agricultural and urban drainage Subsurface drainage from septic tanks near lake shore 4. In situ ---Nitrogen fixation Sediment leaching 15 Sinks Effluent loss Groundwater recharge Fish caught or removed Weed harvesting Insect emergence Evaporation (aerosol form-ation from surface foam) Denitrification Sediment deposition of detrital particles Inorganic precipitation (for calcium phosphate, and some trace metals) and deposition into sediments.

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Nutrient Content Date NH (1) 3 1967: 1/31 -2/7 0.10 2/7 -2/14 0.04 5/2 -5/9 0.54 5/30 -6/6 6/6 -6/l3 0.11 6/l3 -6/27 0.74 6/27 -7/11 0.08 8/15 -8/22 0.15 8/31 -9/6 0.25 10/3 10/10 0.40 10/26 -11/2 0.51 11/9 -11/16 0.61 12/12 -12/19 0.06 1968: 1/1 -1/8 0.65 1/29 -2/5 0.71 2/26 -3/4 0.80 5/20 -5/27 0.02 6/17 -6/24 0.02 7/15 -7/22 0.01 (1) Values in mg N/1 (2) Values in mg P/1 Table 3-2 of Rain at Anderson-Cue Lake N02 (1) N03 (1) P0 4 -3 (2) TR 0.07 0.04 0.005 0.04 0.002 0.03 0.002 0.05 0.12 0.06 0.21 0.004 0.67 0.003 0.05 0.006 0.17 <0.001 0.016 0.81 0.007 0.27 0.025 0.002 0.05 0.009 0.003 0.14 0.009 0.003 0.08 0.008 16

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Table 3-3 Annual Nutrient Budget for Anderson-Cue Lake(l) Nitrogen kg mg/1 of lake water Sewage and nutrient mixture Rainfall on lake surface 124 49 0.50 0.20 Total 173 0.70 Other sources not yet completely evaluated are nitrogen fixation, ground water seepage, subsurface runoff, and airborne particulates, including leaves and miscellaneous debris. Contributions from these sources are thought to be relatively small. Phosphorus kg mg/1 of lake water Sewage and nutrient mixture Rainfall on lake surface 10.60 1.05 0.043 0.004 Total 11.65 0.047 Other phosphorus sources are groundwater, subsurface runoff and airborne particulates. Contributions from these sources are thought to be small. (1) (2) Rainfall based on 1967 calendar year; nutrient mixture contribution based on year from April 1, 1967 to March 31, 1968; nutrient addition was started in March, 1967. This is the concentration which would result if the amount of the nutrient shown in column 1 were diluted to the volume of the lake (approximately 248,000 m 3 during 1967). 17

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General Section 4 Physical Characteristics of the Research Lakes and Drainage Basins Anderson-Cue and McCloud Lakes are located in a region of high sand hills with many circular to elliptical basins which have resulted from solution of the underlying limestone. Both lakes have small drainage basins with no influent or effluent streams. The tops of many of the surrounding hills reach elevations of 190 to 220 feet, MSL. Westward at Melrose the terrain changes from sand hills to the Okefeenokee Terrace, a poorly drained terrace 140 to 160 feet, MSL. Eastward, beyond Baywood, the sand hills are bound by lower marine terraces. The immediate area of the research lakes is the Trail Ridge portion of the Central Highlands. Three hydrographic surveys of Anderson-Cue Lake have been made since the fall of 1965. Echo soundings were made in November 1965; a stadia survey was made in July-August 1967; and echo soundings were again made in March 1968. A hydrographic map of the lake was prepared using these data and is shown in Figure 4-1. The highest level shown on the map was the shoreline which stood at 125.78 feet, MSL, in March 1966 at which time the lake had a surface area of 19.3 acres and a volume of approximately 201 acre feet. When it was decided to use McCloud Lake instead of Berry Pond as the control body of water in late 1966 the volume of water in McCloud Lake exceeded that in Anderson-Cue Lake by approximately 15 per cent. This information was obtained by stadia survey. Yearly excess precipitation over evaporation (30 year record) is 12 to 18 inches in the xeric hills surrounding Anderson-Cue Lakel The excess precipitation and runoff percolate downward through breaks in the sands and clays of an aquifuge that overlies the Floridan aquifer. The influent drainage has resulted in a subsidence karst landscape which forms a principal recharge area in North Florida for the Floridan artesian system. Analysis of the water level data for Anderson-Cue Lake, the surrounding water table data, and the rainfall and evaporation records indicates that there is very little contribution from surface and subsurface runoff to the lake. Sands covering the basin are porous. Downward seepage rates are high and surface runoff is exceedingly low. The relatively small water level fluctuation (except during periods of drought) 1 These data are not applicable to the research lake itself. 18

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Figure 4-1 HYDROGRAPHY ANDE RSON-(UE LAKE o 100 I 290 FEET 300 I 49 0 C on tours Referenced To MSL 7/31/68 19 o INELLNO.4 N

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further indicates that the lake bottom, although originally hydrologically connected with the Floridan aquifer, is effectively sealed by organic deposits. Geology Materials exposed in the sand hills are largely of two types: very fine surface sands and the underlying kaolinitic gravels, sands and sandy clays. These sediments are known as the Citronelle Formation. Well borings show an aquifuge of from 80 to 100 feet of phosphatic sands, sandy clays and clays lies below the surface. These materials are known as the Hawthorne Formation of Lower and Middle Miocene Age. Underlying the Hawthorne Formation is the Floridan aquifer, the upper portion of which is the Ocala Limestone of Eocene Age. The piezometric surface of the water in the Floridan aquifer is approximately 90 feet above MSL in the vicinity of Anderson-Cue Lake. The porous sand and gravel of the Citronelle Formation contains a perched water table above the aquifuge --the Hawthorne Formation. Anderson-Cue Lake is itself a perched lake. The lake level is the result of a balance between percipitation, evaporation and outflow into the water table aquifer and Floridan aquifer. The vegetation in both lake basins is sparse and primarily scrub oak, indicative of poor nutrient conditions. There is no human habitation in either basin. The major source of nutrients for the lakes in their natural states appearsto be from the atmosphere via precipitation and airborne particulates. Instrumentation A Gurley water level recorder with staff gage and a recording rain gage were installed at Anderson-Cue Lake in February 1966. In September 1967 an Aerovane wind recorder and Foxboro hygrothermograph were installed. The transmitter for the wind recorder was mounted on a pole approximately 150 feet from the south shore of the lake and three feet above the water surface. Examples of some of the instrumentation are shown in Figure 4-2. Meteorological and Hydrological Phenomena Anderson-Cue Lake lies in a shallow valley oriented in a NNE SSW direction and is surrounded by scrub oak and pine trees. These characteristics have a marked effect on the air-flow over the water surface. The air speed in general is calm to light (0-7 mph). The prevailing winds are from 30 to 60 degrees (NNE to NE) and from 210 to 240 degrees (SSW to SW). When a tropical storm or frontal system passes 20

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View of Anderson-Cue lake looking Northwest Unloading Sewage Effluent into Storage Tank Figure 4-2 21 Checking Rain Gage at lake Site Checking Hygrothermograph at lake Site

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over or close to NE Florida the wind direction is influenced by such phenomena and higher wind speeds are recorded. A wind rose for the period October 1967 --June 1968 is shown in Figure 4-3. The only significant currents in shallow Anderson-Cue Lake are wind currents. A NE wind causes the surface water to flow toward the SW and a SW wind causes the surface water to flow toward the NE. In bodies of water larger than Anderson-Cue Lake such surface water currents flow to the right of the wind and set up a clockwise circulation. In Anderson-Cue Lake, however, these currents cause a pile-up of water on the leeward shore which is returned by fan-outs in both clockwise and counter-clockwise directions. Due to long periods of calm and very light and variable winds the lake is considered to be in an equilibrium state throughout its mass. Many factors must be considered in attempting to explain the fluctuations of the lake level and the water table in the research area. These include evaporation, precipitation, and flow to the water table aquifer and Floridan aquifer. The most complex of these factors is evaporation. The question arises as to what per cent of time in a certain period was the variation of temperature with height such as to lead to condensation on or evaporation from the lake surface. An inversion of the dewpoint will develop if the surface acts as a heat sink to remove water vapor. This condition can be expected during clear nights when there is strong radiation from the ground; during times of high relative humidity; and during times of the build-up of surface inversions which occur frequently in the Anderson-Cue Lake area. In fact, about 50 per cent of the time the water vapor flux is directed downward. This reversal of evaporation is evident during non-daylight hours when winds are persistently less than 7 mph and relative humidity greater than 90 per cent. It is interesting to note from the rain gage records of the past year that during the periods when the vapor flux is directed upward (generally from 0800 hours to 1800 hours) approximately 0.12 to 0.15 of an inch of water is evaporated daily. This indicates the large amount of evaporation from the lake surface that can be expected unless the amount of precipitation plus condensation received when the lake acts as a heat sink can overcome the evaporation losses and losses to the water table aquifer and Floridan aquifer. Water in the water-table aquifer is unconfined so that its surface is free to rise and fall with the variance in rainfal12 As may be deduced from Figure 4-4 (refer to Figure 4-1 for location of test wells) the water table slopes toward the lake on the western side and 2 Rainfall on the Anderson-Cue Lake basin for the period March 28, 1966 through June 30, 1968 was deficient by 13.85 inches (the closest "departure from normal" data are accumulated at Gainesville, approximately 20 miles to the west). For the period November 2, 1967 through June 30, 1968 the deficiency was 8.56 inches. 22

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Figure 4-3 ANDERSON CUE LAKE WIND ROSE October 1, 1967 -June 30, 1968 Calm-lll 1-3 MPH-III SCALE: 1 mm = 3 HOURS 23 4 -7 MPH C}->7 MPH

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.... II) :IE I Jillllllllllllllllllllllllllllllllllllllllllllllllllill11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 : NOTE: The initial plotting point for Well No. 2 should have been 123.27 feet, MSL.

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away from the lake on the eastern side. Because the piezometric surface of the Floridan aquifer is below the level of the lake, water cannot move from the Floridan aquifer to the lake. The net ground water flow during the period of study has been composed only of out-flow to the water-table aquifer and out-flow to the Floridan aquifer. During the period of drought experienced since March 1966, it may be assumed that the greatest ground water loss from the lake has moved eastward into the water-table aquifer. As shown in Table 4-1, for the period March 28, 1966 through June 30, 1968, evaporation losses exceeded rainfall by 24.09 inches and approximately 64 acre feet of lake water was lost to the aquifers. 25

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From To Table 4-1 ANDERSON-CUE LAKE Hydrological Data (1) (2) (3) Dates Lake EvaEoration Rainfall Lake Level (in. ) (in. ) (ft.--MSL) 3/28/66 125.78 4/26/66 4.73 1.42 125.33 5/25/66 4.89 3.99 125.04 6/22/66 6.04 5.96 124.69 7/21/66 6.48 2.45 124.25 8/18/66 6.25 8.70 124.43 9/13/66 4.84 5.00 124.41 10/11/66 3.87 5.45 124.51 11/08/66 3.17 1.56 124.21 12/06/66 2.53 0.05 123.75 1/03/67 2.12 2.67 123.61 3/28/67 9.53 9.15 123.61 5/02/67 7.18 1. 65 122.99 5/31/67 7.58 7.92 122.83 6/27/67 5.35 7.66 123.07 8/01/67 6.24 8.12 123.33 9/06/67 5.77 10.91 123.81 10/03/67 5.24 1.38 123.66 11/02/67 4.19 1.32 123.46 12/03/67 3.11 0.00 122.99 1/04/68 2.37 5.60 123.07 1/31/68 2.10 0.24 122.63 2/29/68 2.59 1.35 122.17 3/31/68 4.14 1.42 121.59 4/30/68 6.63 0.45 120.83 5/31/68 6.95 6.09 120.49 6/30/68 6.09 5.38 120.02 129.98 105.89 -(69.12 in. ) Summary: 129.98 (1) 69.12 (3) -105.89 (2) -24.09 24.09 in. 45.03 in. or approximately 64 acre feet lost to aquifers Note: Lake evaporation is computed from data collected at the U. S. Weather Bureau evaporation station at Gainesville, Florida. Pan coefficients are those used for Lake Okeechobee, Florida: Kohler, M.A., 1954, Lake and Pan Evaporation in Water Loss Investigations --Lake Hefner Studies, Technical Report: U.S. Geological Survey Prof. Paper 269, p. 128. 26

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Section 5 Routine Chemical Studies The trophic state of the lake is manifested in a variety of chemical and biological parameters. This section will summarize the routine chemical data obtained; biological results will be presented in the following section. Results for Anderson Cue Lake, the experimental lake, extend for a period of nearly three years-from 1966 to the present. McCloud Lake, the control, has been sampled routinely since the beginning of 1967. During 1966 and 1967 sampling was approximately biweekly, especially for the important nutrient parameters. Since January 1, 1968, sampling has been on a monthly basis because rather minor variations were noted in more frequent sampling. This sampling schedule has allowed more time for a variety of other special studies to be conducted. Parameters measured routinely (biweekly or monthly) include dissolved oxygen, pH, conductivity, acidity, dissolved and suspended solids, ortho and total phosphate, total and particulate organic nitrogen, ammonia, nitrite, and nitrate. In addition, data has been routinely collected on physical conditions such as water temperature and Secchi disc transparency. Other major and minor chemical constituents have been determined less frequently. These include chloride, sulfate, calcium, magnesium, sodium, potassium, silica, iron, manganese, chemical oxygen demand and biochemical oxygen demand. Chemical characterization of lake sediments has included determination of percent volatile solids, total organic nitrogen, ammonia, total phosphate, iron, and manganese. Three permanent sampling stations were located in Anderson Cue Lake. Stations 4 and 7 are in the centers of the lake's two basins, and Station 8 is on the south shore in about 3 feet of water. The location of these stations is shown in Figure4-1. Two permanent stations are located in McCloud Lake, Station 11 in about 21 feet of water near the center of the lake and Station 12 near the north shore in 3 feet of water. The two lakes are typical of the small lakes in the Trail Ridge portion of the Central Highlands. Table 5-1 summarizes the chemical characteristics of the lakes. Few significant changes in gross chemical composition have been noted during the period of record. Both lakes are colorless, low in dissolved solids and extremely soft. The waters are acidic, with typical pH values ranging between 4.6 and 5.5. The waters have little buffer capacity and essentially no alkalinity. Consequently, acidity titrations have been used to estimate total CO2 Specific conductance has increased in Anderson Cue Lake from about 25 mho cml to about 38 tLmho cm1 over the last 18 months. Corresponding increases in MCCloud Lake have been less -from 30 to 35 kLmho cml Some of the increase would seem to be the result of excess evaporation over precipitation during the period; nutrient additions were probably responsible in part for the increase in the experimental lake. 27

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Table 5-1 Chemical Composition of Anderson-Cue amd McCloud Lakes and Const ituent Anderson-Cue Lake McCloud Lake Spec. Conductance 25-38 28-35 pH 4.5-5.2 4.5-5.5 Acidity as CaC03 1. 0-4. 0 1. 0-4. 0 Cl-5.1-7.5 5.0-7.0 SO = 4 4.0-6.0 3.5-7.0 Na+ 2.3-2.9 2.5-3.2 K+ 0.4-0.5 0.1-0.3 Ca+ 2 0.5-0.8 0.3-0.7 0.5-0.6 0.5-0.6 Total Org. N 0.3-0.4 0.3-0.4 Particulate Org. N 0.1-0.4 0.1-0.3 NHrN 0.03-0.4 0.02-0.2 N02-N 0.001-0.002 0.001-0.002 NOj-N 0.04-0.2 0.01-0.2 Total Phosphate 0.00-0.04 0.00-0.03 Ortho Phosphate 0.00-0.02 0.00-0.01 Silica 0.1-0.2 0.1-0.2 Rainwater 10-15 5.3-6.8 1.2-3.0 2.2-2.5 0.1-0.4 1.4-3.1 0.3-0.4 0.1-0.5 0.001-0.002 0.05-0.5 0.01-0.03 1 Values represent normal range but do not include some extremes. All concentrations in mg/1; specific conductance as mho-cm1 ; 28

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tv \0 cU c.: w l30 t '. 2.6 22-18 10 12 -.i ""(.,t) 10';?:: .. z w 6 x o o w :J Vi Q 2. 61 '0 JAN. FEB. MAR. MAY 0VNE JULY A Uq. OCT. NOv. DEC. I N CJ,lF 1967 ..

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The low dissolved solids and ionic content of the lakes are indicative of the waters' origin, i.e. atmospheric precipitation. Table 5-1 lists some comparative values for the chemical composition of rain water at the lake site. Concentration of major ions compare rather closely for the lakes and rain water. While concentrations of major ions are not likely to limit primary production in either lake, the paucity of several is likely to select against certain types of organisms. Low silica probably is a contributor to the small diatom populations; low calcium and magnesium indicate the waters are unsuitable for macrophytes like Chara and some algae which prefer hard water. Neither lake shows much evidence of stable thermal stratification at any time of year. Temperature profiles are usually within one degree Celsius from top to bottom. Somewhat larger differentials (30C) were some times found in MCCloud Lake during periods of high water, but the thermocline occurred in the bottom few feet in these cases, and most of the lake was freely circulating. During periods of intense warming and calm weather, temporary stratification may occur in either lake, but this has no significance with regard to the present study. Water temperatures range from about l20C in winter to about 320C in mid summer. Dissolved oxygen profiles also show little change with depth; top and bottom values are usually within one mg/l. There is no evidence for oxygen depletion in the bottom water of either lake, but considering the lack of thermal stratification and the oligotrophic conditions, this is not surprising. Seasonal variations in dissolved oxygen largely reflect changes in solubility with temperature. Figure 5-1 shows the surface temper ature and dissolved oxygen values for 1967 in Anderson-Cue Lake; the results for MCCloud Lake and for other years are similar. Values are generally near saturation, but a slight tendency toward undersaturation has been noted. The rates of photosynthesis in the lakes are too low to markedly influence dissolved oxygen, but slight diurnal variations in dissolved oxygen have been noted. Greatest attention in tlie chemical analyses has been focused on nitrogen and phosphorus compounds, which presumably are most critical in eutrophication. Both lakes were extremely depleted in nitrogen and phosphorus before enrichment began. Ammonia ranged between 0.02 and 0.06 mg Nil; nitrate was less than 0.04 mg and total organic nitrogen averaged about 0.3 mg Nil. Ortho phosphate was often undetectable and averaged less than 5 )J..,P/l. Total phosphate showed similarly low concentrations. Nutrient addition to Anderson Cue Lake began in March of 1967. Figures 5-2 to 5-6 show the temporal variations in total organic nitrogen, ammonia, nitrate, total phosphate and orthophosphate, respectively, in the 18 months from January, 1967, to June, 1968. The points on each plot represent mean values for all sampling stations in each lake. The effects of nutrient enrichment are most clearly shown in the ammonia, nitrate and total phosphate graphs. Increases have been noted in both lakes during this period, but average values are consistently higher in Anderson-Cue Lake. There are several possible explanations for the increases in MCCloud Lake. Water levels have fallen considerably in the lakes, especially since fall of 1967, because 30

PAGE 39

of a deficiency in rainfall over evaporation and ground water seepage. Concentration resulting from evaporation may have had some effect, but other changes resulting from the lower lake levels may be more important. One possibility is increased sediment-water exchange of nutrients in the now shallower lakes. The nutrient rich sediments from the lake centers are now closer to the shallower shore areas. Another possibility is-that the newly exposed land (previously submerged littoral zone) may have contributed nutrients to the lake from dying aquatic macrophytes. Other possible explanations for the increases are changes in analytical procedures during this study and the natural variability of nutrient concentrations in lakes of this type. It will be interesting to follow the nutrient levels in McCloud Lake as the water levels return to normal. The appearance of seasonal trends are less obvious in the nutrient results than is typical for temperate lakes, but most changes can be explained by seasonal and biological factors. During the first year of nutrient enrichment (March, 1967 to March, 1968) approximately 124 kg nitrogen and 10.6 kg phosphorus, mostly as ammonia and ortho-phosphate, were added to the experimental lake through the nutrient outfall. This was sufficient to increase the Nand P levels in the lake by 0.5 and 0.047 mg/l, respectively, at the lake's volume in 1967, if all the nutrient material remained in the lake. Inspection of Figures 5-2 to 5-6 shows this clearly was not the case. Increases in total Nand P concentrations do not approach these levels and much of the added nutrient evidently was deposited in the sediments or was lost through ground water seepage. This has been found to be the case in other lakes where nutrient budgets have been constructed (see Section 3). This would seem to imply an important role for sediment regeneration of nutrients in the eutrophication process. Possibly the onset of deleterious conditions in the eutrophication process is contingent upon exhaustion of the sediment's capacity to retain nutrients. Several studies have shown that the lakes are well-mixed and nearly homogeneous chemica1l. Table 5-2 shows mean values for pH, acidity and dissolved oxygen in the surface water of the different stations. The results also show the chemical similarity of the two lakes. A detailed Station 4 7 8 11 12 Table 5-2 Mean Values for Some Chemical Parameters at the Permanent Sampling Stations Acidity .E.!! Dissolved Oxygen 3.1 4.61 7.8 2.8 4.65 8.0 3.0 4.62 8.0 3.4 4.88 8.2 3.0 4.75 8.2 36

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study of the lateral variations in ammonia, and othophosphate gave further evidence of the experimental lake's comparative homogeneity. This is not to say that there are no differences at all. Figure 5-7 shows a slight trend for higher ammonia near the southern shore. In general ortho phosphate was higher in shore areas than in the lake center (Figure 5-8), but values for the southern shore were the lowest in the lake. The high ortho phosphate values in the northwest portion of the lake probably represent a minor source of pollution from cattle grazing in this area during this period. The results indicate that the routine stations are representative of the conditions throughout the lakes within the limits of accuracy desired for this project. The studieS' also imply rapid mixing in Anderson-Cue Lake since Il,O concentration gradients resulting from the nutrient outfall were detected. Because of the probable importance of sediments in eutrophication, considerable effort has been directed toward delineation of their role as a nutrient source and sink. As a first step the chemical characteristics and variations in sediment types have been determined for both lakes. Representative results for Anderson-Cue Lake are shwwn in Figure 5-9 to 5-11. Several sediment types are evident in Anderson-Cue Lake: near shore the bottom is sand covered detritus and viable organisms. In parts of the deep regions brown peat-like sediments are evident with much fibrous and undecomposed plant material. In other areas the sediments are darker and finer grained, more like the ooze or Schlamm of alkaline lakes. The sediments of McCloud Lake have not been as well characterized, but peat-like sediments are less in evidence there. The results indicate that the lake's sediments are actually higher in nitrogen and phosphorus than sediments from some eutrophic lakes. For example, sediments from Lake Mendota, Wisconsin, have from 200 to 1200 ppm phosphorus and 2000 to 14,000 ppm total organic nitrogen (Hasler, 1963). The sediments in this alkaline lake are over 30 percent precipitated calcium carbonate, whereas those in the lakes of this study are composed largely of organic matter. The sediments in Anderson-Cue Lake are enriched in nitrogen and1phosphorus compared to the overlying water and represent a potential nutrient source. Leaching and incubation studies with the sediments are underway, the results of which should indicate the role of the sediments in nutrient storage and release in lakes. 37

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.18 18 17 .17 .24 .19 .16 .20 .21 .21 .20 .21 .21 .21 .20 .19 Sewage e Outfall .27 .19 .20 .21 .25 Figure 5-7 Lateral Variations of Ammonia in Ande.rson-Cue Lake, January, 196B. Concentrations in mg Nil. 38

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5 5 7 4 344 3 4 2 6 6 5 2 3 6 4 3 2 4 3 4 Sewage Outfall 3 2 3 2 2 2 2 1 1 200 Figure 5-8 Lateral Variations of Ortho-Phosphate in Anderson-Cue Lake, January, 1968. COncentrations in}t;g P/l. 39

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.49. 92 .10 17 .13 8 .33 .18 09 25 18 .32 29 @ .23 32 .80 19 .56 30 .17 18 [7J .09 19 0, .18 .08 44 34 .34 16 .08 16 .38 11 .13 20 .36 19 .18 19 Figure 5-9 Nitrogen in Anderson-Cue Sediments. Top number is ammonia; bottom number is total organic Values in mg -N/g drywt. of sediment. 40

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3.9 1270 7.7 290 7.4 3070 e 6.7 550 9.6 1080 141 5.6 890 8.0 800 9.5 3.3 1.6 530 730 470 17.0 80 1.3 330 5.1 170 4.6 m 4.6 100 7.2 1080 2.2 870 Figure 5-10 Ph.osphate in Anderson-Cue Sediments. Top number is ortho phosphate, bottom number is total phosphate values in Pig dry wt. of sediments. 41

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56 1.58 .69 .58 52 2.94 68 .49 67 .60 64 .30 30 1.24 68 1.49 .27 81 .11 39 3.16 15 .40 53 .82 49 .18 49 1.30 Figure 5-11 Percent Volatile Solids (Top Number) and Total Iron (Bottom Number) in Anderson-Cue Sediments. Iron values in mg Fe/ g dry wt. of sediment. 42

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Section 6 BIOLOGY Introduction The biological effects of lake enrichment have been followed in Anderson-Cue Lake during the period of this project in order to gain a better understanding of the eutrophication process. Both routine and specially designed experimental procedures have been employed for this purpose. These have included the assessment of phytoplankton systematics, accession of species, and primary productivity. Standing crop measurements have been made by chlorophyll determinations. Littoral plant growth has been estimated by periodic cropping of square-meter plots. Horizontal distribution of bacterial species have been made quarterly. Nutrients limiting algal growth have been determined by bioassay techniques. The last part of this section is devoted to the microbiotic ecology of Anderson-Cue Lake (experimental) and McCloud Lake (control). Primary Productivity Figure 6-1 shows that primary productivity in Anderson-Cue Lake in 1968 has been from two to twelve times that in McCloud Lake. No attempt has been made to quantitate the relationship between nutrient addition and enhancement of primary productivity, but use of a pure-culture indicator strain in the C-14 uptake technique may soon make this possible. Peaks in diurnal variations in photosynthesis occur at mid-morning and midafternoon during August suggesting an inhibitory effect of intense sunlight on the upper layer of water. (Note that times on the graph are Eastern Daylight-saving Time which runs approximately one hour ahead of sun time.) Tables 6-1 and 6-2 show that at the ten-foot level there has been a sharp decrease in fixation rate in Anderson-Cue Lake while no such change has been observed at the same level in the rate of fixation in McCloud Lake. This suggests increased turbidity in the water of Anderson-Cue Lake. In fact, water samples taken at or near the surface are visibly more turbid than corresponding samples from McCloud Lake. Findenegg (1964) has used productivity profiles to characterize the degree of eutrophication in lakes. He raises the point that there is a limit in the degree to which eutrophication raises production due to the decrease in light transmission concomitant with increase in phytoplankton per unit volume. Chlorophyll Figures 6-2, 6-3 and 6-4 show that the chlorophyll content of Anderson-Cue Lake water in 1968 increased two to three times over that of the past year. Predictably, values rise as hours of sunlight per day 43

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'. >10 Mg/M 3 D 5 10 Mg/M3 o -5 Mg/M Figure 6-8 Horizontal Distribution of Chlorophyll a Anderson Cue Lake, 2./15/68 -54 3

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Figure 6-9 D 3 >10.6 Mg/M 3 9.5-10.5Mg/M 3 8.1 9.4Mg/M 7. 0 8. 0 Mg 1 M 3 Horizontal Distribution of Chlorophyll a Anderson -Cue Lake, 3/12/68 -55

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Figure 6-10 Horizontal Distribution of Chlorophyll a Anderson-Cue Lake, 4/9/68 -56 D > 15 Mg/M3 10.1 -15 Mg/M3 3 4.1 10 Mg/M 3 o -4 Mg/M

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Table 6-3 Standing Crop Estimates of Cue and McCloud Lakes March -May, 1967 Plant Plant % Station Dry Wt. /g Ash Wt. /g Organic Matter Organic Matter Cue 1 17.5749 4.1382 13 .4367 76.4 3 12.2894 0.8118 11.4776 93.4 5 18.9235 4.4170 14.5065 76.7 6 44.3655 5.2483 39.1172 88.2 7 5.2773 1. 3142 3.9631 75.1 McCloud 1 11.9673 0.7494 11.2179 93.7 2 55.4363 7.7995 47.6368 85.9 3 31.0443 1.6050 29.4393 94.8 June -August, 1967 Cue 1 36.6874 3.9242 32.7632 89.3 2 22.0299 2.0512 19.9787 90.7 3 19.3535 2.5064 16.8471 87.0 5 105.7579 6.6955 99.0624 93.7 7 39.8170 2.3864 37.4306 94.0 McCloud 1 21. 3215 2.8341 18.4874 86.7 2 27.0365 1.2425 25.7940 95.4 3 50.8171 3.9842 46.8329 92.0 October December, 1967 Cue 1 0.6651 0.0773 0.5878 88.4 2 5.0363 0.7867 4.2496 84.4 3 7.7053 2.0148 5.6905 73.8 6 10.1398 2.0935 8.0463 79.4 McCloud 1 3.6714 0.6179 3.0535 83.2 January March, 1968 Cue 1 1. 3599 0.2388 1.1211 82.4 2 2.8250 0.6043 2.2207 78.6 3 2.0906 0.2597 1. 8309 87.6 5 5.9957 1.0297 4.9662 82.8 6 0.7454 0.1124 0.6330 84.9 7 2.2399 0.2808 1. 9591 87.5 57

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Table 6-3 (Continued) Plant Plant % Station Dry Wt. /g Ash Wt. /g Organic Matter Organic Matter January March, 1968 McCloud 1 1. 7174 0.3277 1.3897 80.9 2 1.9834 0.1669 1.8165 91.6 3 1.2515 0.1402 1.1113 88.8 April -June, 1968 Cue 1 44.5779 9.0419 35.5360 79.7 2 24.8772 6.4809 18.3963 74.0 3 21.4956 4.8200 16.6756 77 .6 5 83.6573 9.7295 73.9278 88.4 6 36.9836 12.0098 24.9738 67.5 7 38.1837 13.8765 24.3072 63.7 McCloud 1 43.7322 5.9879 37.7443 86.3 2 23.5226 3.7630 19.7596 84.0 3 41.6614 8.6337 33.0277 79.3 Summary March 1967 March 1968 Cue 1 56.2873 8.3785 47.9088 85.1 2 29.8912 3.4422 26.4490 88.5 3 41.4388 5.5927 35.8461 86.5 5 130.6771 12.1422 118.5351 90.7 6 55.2507 7.4542 47.7965 86.5 7 47.3342 3.9814 43.3528 91.6 McCloud 1 38.6776 4.5291 34.1485 88.3 2 84.4562 9.2089 75.2473 89.1 3 83.1129 5.7294 77.3835 93.1 58

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widely fluctuating levels of coliforms, probably as a result of local fauna. There seems no generalized pattern of bacterial growth which would result from physical factors. A comparison of values for January and July does not show significant seasonal variation., (See Table 6-4 and Figure 6-11). Bioassay The bioassay for limiting growth substances has been carried out by the isotopic carbon method first reported by Goldman. The results as shown in Table 6-5, although qualitative, show clearly that phosphorus was the only consistently limiting factor of algal growth in Anderson-Cue Lake. The seasonal pattern is the same through the year regarding the demand of phosphorus by the At no time was phosphorus at v a level to satisfy the growth requirements of the lake Sulfur was limiting during the early spring of 1967 in the experimental lake and in the late summer in the control lake. Since a sulfur deficiency has not been noted since that time, no special significance is given these results. A special study to relate the uptake of phosphorus (as indicated by C-14 fixation) with time showed a near linear response up to 72 hours following phosphorus addition. The results show that algal growth as a response to phosphorus can be estimated at between 24 and 72 hours. The lag in growth as measured by C-14 uptake before 24 hours of incubation may reflect the lag in phosphorus transfer from the medium into the cell (See Figure 6-12). Microbiotic Ecology of Anderson-Cue and McCloud Lakes The original microbiotic work on Anderson-Cue and McCloud Lakes concentrated on learning what organisms were found in the lakes; which ones were found on the marginal shallow bottom and among the vegetation in this area, to a depth of two feet, as compared with the kinds and numbers in the open surface waters, and with those in the waters near the sediment water interface where the lakes attained their greatest depths. This original work was finished, insofar as general information is concerned, in 1965, 1966 and early 1967. A portion -enough to give the general picture -is presented in Table data is too voluminous for all of it to be presented, but it is expected that at the conclusion of the project a complete list of species found in each lake, together with such changes in biotic composition as may have occurred, will be given. The second phase of the work is concerned with such changes, especially those due to the addition of nutrients to Anderson-Cue Lake, and a comparison of the two lakes. This work is underway. The qualitative aspects of this work were largely attained and reported by Lackey and Lackey (1967), but the statement was made that continued examination would probably greatly increase the numbers of species 59

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0o No./Station 1/A7 2/A2 3/A3 4/B1 5/B2 6/B3 7/C1 8/C2 9/C3 1O/C4 H/c5 12/C6 13/C7 14/D1 15/D2 16/D3 17/D4 18/D5 19/D6 20/D7 21/D8 22/D9 23/E1 24/E2 25/E3 26/E4 27/E5 28/F1 29/F2 1/23/68 MPN Coliforms 8.0 23.0 2.0 5.0 5.0 49.0 5.0 5.0 5.0 2.0 <2.0 2.0 <2.0 5.0 <2.0 2.0 <2.0 8.0 <2.0 2.0 2.0 <2.0 49 2.0 2.0 2.0 <2.0 >16D9 8.0 1/23/68 MPN Fecal Coliforms <2.0 <2.0 2.0 2.0 <2.0 4.0 <2.0 5.0 5.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 2.0 <2.0 ;5.0 <2.0 <2.0 2.0 <2.0 14 2.0 <2.0 <2.0 <2.0 >1609 <2.0 Table 6-4 Bacteriological Data 1/23/68 1/23/68 7/8/68 MPN Total MPN Enterococci SPC Coli forms 2.2 1500 <2.2 130 <2.2 230 <2.2 180 <2.2 150 <2.2 140 <2.2 600 7.0 <2.2 140 <2.0 <2.2 100 9.2 <2.2 180 5.1 <2.2 120 <2.2 <2.2 360 13.0 <2.2 100 <2.2 <2.2 790 9.2 <2.2 83 5.1 <2.2 140 5.1 <2.2 130 5.1 <2.2 150 2.0 <2.2 120 9.2 <2.2 76 9.2 <2.2 87 2.2 <2.2 SO 17 2.2 870 2.2 <2.2 610 2.2 <2.2 338 <2.2 <2.2 83 9.2 <2.2 168 2.2 <2.2 340 2.2 <2.2 360 5.0 7/8/68 MPN 7/8/68 7/8/68 Fecal MPN Total Co1iforms Enterococci SPC 7.0 <2.2 340 <2.0 <2.2 130 9.2 <2.2 110 2.2 <2.2 170 <2.2 <2.2 130 13.0 <2.2 130 2.2 <2.2 440 9.2 <2.2 610 2.2 <2.2 150 2.2 <2.2 180 5.1 <2.2 330 2.0 <2.2 490 2.2 <2.2 350 9.2 <2.2 100 2.2 <2.2 97 7.0 <2.2 120 <2.2 <2.2 470 <2.2 <2.2 230 <2.2 <2.2 260 5.1 <2.2 150 2.2 <2.2 78 2.2 <2.2 620 5.0 <2.2 130

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0\ t-' Table 6-4 (Continued) 1/23/68 MPN No. /Station Co1iforms 30)/F3 2.0 31/F4 2.0 32/F5 918 33/G1 33.0 34/G2 79.0 35/H1 4.0 36/H2 7.0 37/H3 <2.0 38/H4 2.0 39/H5 2.0 40/11 2.0 41/12 2.0 42/13 17.0 43/14 70.0 44/J1 13.0 45/J2 8.0 46/J3 8.0 47/K1 <2.0 48/K2 <2.0 49 <2.0 50 2.0 1/23/68 MPN 1/23/68 Fecal MPN Coli forms Enterococci 2.0 5.0 <2.0 <2.2 918 23.0 5.0 2.2 33.0 <2.2 <2.0 <2.2 2.0 <2.2 <2.0 <2.2 2.0 <2.2 <2.0 <2.2 <2.0 <2.2 <2.0 <2.2 11.0 <2.2 23.0 13.0 <2.0 <2.2 5.0 13.0 2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.2 <2.0 <2.2 ---7/8/68 1/23/68 7/8/68 MPN 7/8/68 7/8/68 Total MPN Fecal MPN Total SPC Coliforms Co1iforms Enterococci SPC 1500 16.0 2.2 <2.2 95 24 5.0 <2.0 <2.2 90 170 2.0 <2.0 <2.2 240 170 9.0 9.0 <2.2 250 68 7.0 7.0 2.2 170 65 17 .0 13.0 <2.2 130 69 5.0 5.0 <2.2 130 52 5.0 5.0 <2.2 75 63 2.0 2.0 <2.2 120 110 5.0 2.0 <2.2 130 84 11.0 11.0 <2.2 130 27 8.0 5.0 <2.2 600 65 2.0 <2.0 <2.2 350 300 5.0 2.0 <2.2 600 600 610 14.0 8.0 <2.2 1000 830 21 4.0 <2.0 <2.2 160 140 8.0 2.0 <2.2 320 17 2.0 <2.0 <2.2 190 110 7.0 <2.0 <2.2 110

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Figure 6-11 BACTERIOLOGICAL SAMPLING STA TIONS 62

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Table 6-5 Nutrients Limiting Algal. Gro'iith in A...'l.derson-Cue and McCloud Lakes Anderson-Cue 1/:7 McCloud 1/4 1/17 1/24 1/31 3/14 3/28 4/11 5/23 6/6 6/20 8/1 8/29 9/12 2/14 3/14 3/28 4/11 6/6 6/20 8/1 8/29 9/12 + x x x x p + + + + + + + + + _J.. + + + x x x + + I N, P + + + + + + + x + Fe + + + + x x x x x -x x N, Fe + -x + + P, Fe + -l+ + I 0\ W N, P, Fe + + x + x + 5i x x + x x x + + I T .. X + S -+ x x x x + + + x + + Vitamins + x x x + + Trace x metals + x x x x I T +. + x + + EDTA x x x x + + + x x + + limiting x = inhibitory = no change

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TABLE 6-6 Number of species and'number of protozoa and microscopic algae per ml in Cue Lake on four dates in 1965, and in HcCloud Lake on one 1965 date and three 1967 dates. Cue Lake McCloud Lake 71221.65 81.31/65 9/15/65 12/15/65 8/31/65 11.171.67 6/9/67 7L19/67 Coelosphaerium kuetzingium Gomphosphaeria lacustris t1erismopedia puncta ta Phormidium sp. Rhabdoderma lineare Arthrodesmus sp. Chlorella sp. Closteridium sp. Closterium sp. Cosmarium sp. Cylindrocystis sp. Dictyosphaerium Elkatothrix gelatinosa Euastrum nova Euastrum S1;>. Kirchineriella cbesa 1532 4 2 6 x x x .25 1920 4 .25 1 160 160 .5 20 .25 4 580 5120 192 8 12800 640 64 10

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TABLE 6-6 Cue Lake 7/26/65 8/31/65 9/15/65 12/15/65 Mongeotia sp. 2 Oocystis 12 Ourococcus bicaudatus Perioniella 4 quB.drigula closteroides 6 Scenedesmus 2 16 Sphaerocystis schroeteri Staurastrum sp. 4 .25 4 Westella botryoides 8 x Xal1thidium sp. 15 1.5 Pandorina morum 1.5 Euglena gracilis x Euglena sp. .25 5 Peranema trichophorum x Phacus suecicus 1 Trachelomonas cylindrica 1. Trachelomonas euchlora .5 Trachelomonas hispida 2 6 4 102 1 .25 .2.5 -2-McCloud Lake 2 32 64 320 16 128 .25 1 3

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Trachelomonas obovata Trachelomonas rotundata Trachelomonas volvocina Cryptomonas erosa Rhodomonas lacustris Gonyostomum semen Merotrichia Centritractus belonophorus Chromulina ovalis Chrysococeus cordiformis Chrysococcus rufescens Dinobryan sertularia l'1allomonas tonsurata Mallomonas spp. Synura uvella, colonies CeratiQm cornutum Dinoflagellata, unidentified Glenodinium foliaceuill TABLE 6-6 Cue Lake 7/26/65 8L31/.65 1 18 4 12 28 4 1 32 4 x 8 5 12 4 1 12 4 7 x 15 x 48 130 1 -3-McCloud Lake 8 L 31/65 _llJli2-.L_!!l2if?2_-11J2L 67 6 6 2 1 2 .25 10 .5 104 16 152 128 320 4 64 64 8 8

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Q'\ 00 Gonyaulax apicula taL G}T1.m:1odinium fusea Gymnodinium unispinos\JJTI GyrrLnodinium vorticella Gymnodinium sp. jVlassartia sp. Peridinil.lm cinctum Peridinium marchicum Peridiniu1l1 umbona.tum Peridinium "\rolzii Peridinium w:Ll1ei Pe:cidinium vlisconiense Peridinium sp. Protodinium sp. '( Asterionella formosa. Cyclotella sp. NavicuLst. sp. J{hizosolenia eriensis TABLE 6;...6 Cue La}::e Zl1...L.5 4 304 29 4 4 6 2 .5 20 1 .5 rl ..:) 8 12 176 64 6 x .5 1 L{.-HcClouc1 Lake 8 lL.i. __ 1. Ll? 16 6 L7 /67 21l2i!: 7 32 4 192. 10 {l 24 2 146 1888 56 40 1 e 5 80 65 t: .j 2

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Heterophrys myri.'lpoda Leptochlamys ampulla,eea l"'[onas SD L [i[onosiga ovata ;';1,00 f lage 110. ta Ciliata, unidentified Cyclidium glaucoma 0'1 Halteria grandinella Hesodin,iulTI cinctum Pleuronema chrysalis Stentor amethystinus Strobili.dit.un humile Strombidium sp. Urotricha farcta Vorticella ep. Total species, 85 Tota.1 nurnbers TABLE 6-6 Cu.e Lake li.2 6 L 6,5 ._ 3J., 31,,[,62... .. .2L1.':2L 6 :Lq,"J2J l:}L 2 8 6 x :2 iC 26 1690 2031.5 1 ,t J.2 1 32 330 3 7 566.5 -5fv!.cCloud Lake ,8 LTU 65.-U1ZlJS 7 _,6 6 7 6(1 10 t:' .J 1 1 1 v' .-! .... e .5 4,6 22 15 1 (I_ 25 576.75 620 1814 t}371

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reported for these lakes at that time. This has proved to be the case, and probably will continue, especially if specialists become interested in certain groups such as diatoms and desmids where we were unable to make species determinations for certain genera. The number of genera and species reported in the 1967 paper was 377 for Anderson-Cue Lake and 266 for McCloud Lake. The list will also undergo further changes for Anderson-Cue Lake as its nutrient budget is increased. The intentional eutrophication of this lake is expected to increase the numbers per ml of many species, and generally when this happens the species list is reduced. This may well happen in Anderson-Cue Lake but the species list will nevertheless be increased because species characteristic of an enriched water will be found. These will be species whose occurrence is now very low. It is an easy matter to find a species when there are as many as one per ml, but much more difficult when there is one in 10 or 100 mls. Quantitative results have been only briefly touched upon until now. In the beginning these lakes were characterized as oligotrophic, and numbers per ml were expected to be low. This was based on a low content of P0 4 NH3 N03' on a pH of 5.9 to 6.4, on a no detectable COD, and on numbers of organisms per ml. Table 6-6 lists these populations for four dates in 1965 for Anderson-Cue Lake, and one date in 1965 and three in 1967 for McCloud Lake. It is felt that this table indicates oligotrophic conditions. True, some blooms were encountered, if we accept 500 per ml as a bloom figure. In some cases the dinoflagellates colored the marginal water pale yellow. Nevertheless the number of plankton species is low, and the organisms occurring in great abundance are generally small species. There is some indication that cattle wading in the marginal waters of McCloud Lake added enough organic substances in urine and droppings to considerably increase the species content and numbers in the shallow water, but aside from data on barnyard ponds as support, this is difficult to prove. However a recent survey of the shore line of AndersonCue Lake, when no cattle were present revealed a greatly reduced species list, and low numbers per ml except for a pronounced shallow water dinoflagellate bloom. The shoreline vegetation was also sharply reduced, which might have been a factor. However, nutrients were certainly sufficiently abundant for an occasional phytoplankton bloom. Table 6-6 shows some biotic differences between the lakes -thus Merismopedia punctata, which has consistently occurred in McCloud (including 1968), has not appeared in Anderson-Cue. The same is true of the pelagic ciliate Stentor amethystina. Synura uvella occurs in both lakes, and typically is more abundant in the deeper waters; the same is true of Dino Both lakes have many species of colorless Euglenophyceae, and both have been subject to cattle grazing in the shallow water. The differences in species lists of the two lakes might almost disappear with prolonged observation, except that the nutrient level of Anderson-Cue is being raised. Both support a varied dinoflagellate flora. Since 1965 a few species have occurred which constitute records for Florida, as well as a very few which are probably undescribed. Table 6-6 generally indicates a small open water population. The small numbers of photosynthetic forms indicates low inorganic nutrients, and the low numbers of Zooflagellata and ciliates, the paucity of green euglenids in the open water indicates 70

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a low organic content. Biological activity at the marginal interface is high and a large number of species is to be expected there and in the aufwuchs, but numbers are low except for occasional blooms. After the enrichment of Anderson-Cue Lake began, there was no recorded change in the microbiota until July, 1968, which might have been attributed to increased nutrients. Rainfall was deficient in the fall of 1967 and the spring of 1968, evaporation was high and the water level dropped continuously. In short, there was little or no nutrient carried in from the land. Even the shallow margin was drastically reduced. In Anderson-Cue marginal vegetation was stranded, reducing the attached microbiota, and at present the shoreline of the lake has a very slight growth. Even in McCloud Lake, except at the north end the reduction is great. This evidently reduces such recycling of nutrients to the open water as might have occurred earlier. Table 6-7 illustrates this very well. Four samplings in August and October 1967 and January and February 1968 showed a sharp reduction in the total number of species, and, except for four blooms of very small green cells (probably mostly Chlorella or Nannochloris) and Merismopedia punctata, total numbers per ml were low. The same species which were present in Table 6-6 recurred except that some different ones appeared and some old ones dropped out. The outstanding fact is that Anderson-Cue Lake had a decline in its population; that only one single species exceeding 25 microns in an overall dimension (Gymnodinium oculatum) appeared in appreciable numbers. Ciliates were present in only one of these four Anderson-Cue samples, and then two ubiquitous species reached 4 per ml. Intensive sampling might show more blooms. Thus on January 9, 1968 there were 2592 cells of Dinobryon sertularia and 2080 cells of Synura uvella in the water just off the bottom in Anderson-Cue Lake, but only 96 and 80 in the surface. Gymnodinium oculatum also showed a bloom of 1440 per ml, and Peridinium umbonatum a bloom of 14400 per ml in Anderson-Cue Lake July 1, 1968. Such blooms are transient, lasting but a few days, and when they occur they usually are associated with reduced numbers of other species and numbers per ml. Thus the total population per ml in AndersonCue Lake surface waters on July 1, 1968 was: Beggiatoa alba Oscillatoria sp. Cylindrocystis sp. Xanthidium sp. Small green cells Mallomonas sp. Navicula sp. Gymnodinium oculatum Peridinium umbonatum Peridinium wolozynskya Total species Total organisms/ml 8 24 8 24 480 56 8 1440 14400 80 10 16530 Perhaps the reduction is inexplicable, but Lackey and Hynes (1955) found evidence that a dinoflagellate bloom completely tied up the orthophosphate, thus acting as an inhibiting agent until the bloom died and recycling took place. 71

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-....J N TABLE 6-7 Species and numbers per ml on four dates in McCloud Lake and Cue Lake in 1967-68, after fertilization of Cue Lake was initiated. McCloud Lake Cue Lake 8/20/67 10/3/67 1/9/68 2/7/68 2 8/20/67 10/3/67 1/9/68 2/7/68 Achromatiumoxaliferum Aulasira sp. Lyngbya sp. Merismopedia punctata Merismopedia glauca Oscillatoria sp. Synechocystis sp. Chlorella spp. 160 1 Closterium 1 160 24 9840 1 4 4 640 8 124 Coclastrum cambricum 1 Elkatothrix gelatinosa 4 Kirchneriella colonies 1 Kirchneriella solitaria p.n. 8 Netrium sp. 1 Oocystis spp. 8 48 304 240 32

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-...J W Ourococcus bicaudatus Protococcus viridis? Sphaerocystis gigas TABLE 6-7 '(Continued) McCloud Lake .. 8/20/67 10/3/67 1/9/68 .. :.17/68 8 100 Sphaerocystis planctorica Scenedesmus spp. 2 4 Staurastrum sp. Westella botryoides 4 Green cells, minute 320 2420 Chlamydomonasspp. 8 Chroomonas sp. 8 Cryptomonas erosa 20 20 8 Rhodomonas 20 4 8 Trachelomonas volvocina Chromulina ovalis 8 Chrysococcus coidoformis Chrysococcus Dinobryon spp. cells 40 Dinobryon spp. colonies 2 1 Cue Lake 8/20/67 10/3/67 1/9/68 2/7/68 8 148 20 1 2.5 1 16 1480 8 32 24 8 44 36 8 40 1 6 8 4 96 2 24 7

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6-7 (Continued)

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TABLE 6-7 (Continued) McCloud Lake Cue Lake 8/20/67 10/3/67 1/68 2/7/68 8/20/67 10/3/67 1/9/68 2/7/68 formosa Asterionella gracillma Bicoeca lacustris Zooflagellata, unid. 12 Aspidisca costata Ha,l teria grandinella Stentor amethystina Strobilidium humile Strombidum sp. 2 Total No. species, 40 14 Total No./ml. 634 2 .5 20 423 26 40 11 12433 32 8 4 4 15 4411 2 2 21 432 20 583 7 1825 24 9 409

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At any rate there is little evidence that there has been any change in the microbiota of either lake beyond what might be seasonal. Winter temperatures in 1967-68 were never very low, so it seems improbable that this was a limiting factor unless these organisms are adapted to high temperatures. In August, September and October 1967, surface water temperatures were measured from shore outward to a distance of 27 feet. These are shown in Table 6-8. The highest was 30.8C. and the lowest 26.10C. A list of species in this area was compiled, and a very large number were present, active and tolerant of these high temperatures. Insolation hardly seems to be a factor. In fact, no discernible seasonal changes have been noted. Table 6-9 shows the genera and species of protozoa and microscopic algae found in five samples from Anderson-Cue and McCloud Lakes which were closely studied during the past year. The number of species is less in each lake than was reported up to this year. Thus McCloud yielded 266 species in 15 prior samplings (1) compared to 226 for 5 samplings in 1967-68; and Anderson-Cue yielded 315 in 25 prior samplings compared to 218 in the five samplings in 1967-68. Evidently species incidence is high in both lakes, regardless of the numbers per mI. If we compare the species found in these 1967-68 samples with the prior samplings, there are some differences. Some 65 species had not been previously recorded from these two lakes so that the number of different species is gradually increasing as their study lengthens. There are also 25 or more which do not appear in our check list (1) for Florida; these would increase that list to more than a thousand species. It is not expected that the total number of species in Anderson-Cue and McCloud Lakes will ever reach the number in the check list. Each situation differs in some respect from others, and that difference may be precisely the combination of factors permitting a particular species to live there. By the same token we may expect the lakes to have certain species which will rarely if ever occur elsewhere. By controlling the nutrient level we may bring into play factors which we can recognize. In so doing we should look for changes in the species list, and changes in the numbers per ml of the species present. This part of the report makes no attempt to find correlations between the biology of the lakes and the chemistry up to this time, beyond the assumption that these are oligotrophic lakes. Actually the two lakes closely resemble each other, both in species and numbers per mI. This is shown in Tables 6-9 and 6-10. While some differences are shown in these tables, they are probably more seeming than real, i.e., if a larger sample had been intensively studied, the differences would have been lessened. In any event we now have a qualitative and quantitative background for the microbiota of these lakes. This is not going to change very much, year to year, unless one or both lakes change. There will be minor changes some species will not recur in another year, some new ones will appear. Some species will not bloom again, some others will. But if the environment in either lake changes enough to be measured in mathematical terms, this will be reflected in the microbiota. Thus at the end of the 1968-1969 year correlations with the chemical and physical changes should 76

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]2 1 2 ""';,"' d ,," n 7 ';} 10 1 l 1 f""'!l 1 l:t. 1 .if' 1 6 1 7 1 8 1. 9 <"Ii l.t ',1:.: ,-... 1Ji Temperature in Degrees Centigrade, CUe Lake, on Three late summer dates 15/ 12/ 1 11/ 26it @ A.r 4 t:! I'. 29 .. 1 ?) c. 3 [,>") e 26. C4 ')0 '" "" .' 27 '< "'-.-.Y .. 27 4 ,-I r::. ..,,1 5 27 6 "7 t:-b' 0 f"\ ..., 7 ""'l I Ll ')"'1 Q ?I >., I k". Q ...,. .l 27 9 27 27 27 9 'II ""'g 28 () 0 .,,., ,k, ; e 0 1 ... 28 1 27 1 21 28 .... 27 .:., I "I 5 'i'''''' .l. .t. I .. 28. 1 5 ""'l' if:'} .. 28 1 5 i ,-27 ,,) 28 1 ,5 ')''f J 77 '" 0 0 i 2 6 8 6 4 '" 3 r; ,t, '1 ;1..., ') L., 2 ? 3 b v 4 3 2 I-') 1 3 3 .) r,

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--.J 00 TABLE 6-9 Protozoa, Microscopic Algae and Bacteria Recorded from McCloud and Cue Lakes on five Recent Dates McCloud Cue Organism Group and Species 7L14167 8120167 10/11 6 7 2/7/68 711L68 7L19L67 8/20L67 1011/67 2L7L68 SulfUr Bacteria Achromatium oxaliferum x x x x x Beggiatoa alba x x Blue green Al8jae Anacystis sp. x x x Anabaena spp. x x x x x x x Aphanocapsa pulehra x x Aphanothece sp-. x x Aulasira implexa x x Calothrix sp. x x Chroococcus planctonica x x x Cylindrospermum sp. x x Eucapsis alpina x Eucapsis major, p.n. x Gleocapsa magma x x x x x x Gleothece sp. x x x Hapalosiphon pumillus x x x x x x Lyngbya spp. x x x x x x Merismopedia glauca x x x x x xx x x x Merismopedia punctata x x x x x x x IvIicrocystis incerta x Nodularia spumigena x x Oscillatoria spp. x x x x x Phormidium sp. x x Pleurocapsa fluviatilis x Rhabdoderma lineare x x Schizothrix calcicola x x Scytonema sp. x Stigonema turfaceum x x x Spnechococcus aeruginosa x x x x x

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(2) TABLE 6-9 McCloud Cue 7[14[67 8[20[67 10[1[67 2[7[68 7[1[68 7[19[67 8[20[67 10[1[67 2L7[68 7LIL6.8.. Chloro2hlceael Green Algae Ankistrodesmus falcatus x x Arthrodesmussp. x x x x Asterococcus limneticus x x x Chaetonema irregulare x Characium sp. x. Chlorella spp. x Closterium acerosum x x Closterium sp. x x x x x x x x x Coelastrum ch8dati x Coelastrum prsboscideum x x x Cosmarium spp. x x x x x x x x x Crucigenia ap'iculata x Cylindrocystis sp. x x x x x X ""-l Desmidium Bailey! x x x x x X \0 Dictyosphaerium Nagelianum x Dictyosphaerium pulchellum x x x x Doeidium sp. x x x Elkatothrix gelatinosa x x Eremosphaera viridis x x Euastrum spp. x x x x x x x x x Gymnozyga Moniliformis x x x x Hormidium sp. x Hyalotheca mucosa x Kirchneriella abesa x Kirchneriella solitaria pn x x Micractinium pusillum x x x x x x x Microthamnion Kuetzingianum x Mougeotia spp. x x x x x x x x is calospora x Netrium sp. x x x x x x x Oedogonium sp. x x x x x x Oocystis spp. x x x x x Ourococcus bicaudatus x x Pediastrum tetras x Penium sp. x

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00 0 TABLE 6-9 McCloud 7/14/67 8/20/67 10/1/67 2/7/68 7/1L68 Planktosphaeria gelatinosa x Pleurococcus spo Pleurotaenium sp. x x Quadrigula closteroides x x Scenedesmus spp_ x x x x Sirogonium spo x x Sphaerocystisschroeteri x Sphaerozoma excavata x Spirogyra spo x x x Spirotaenia condensata x Spondylosium, planun Staurastrum spp. x x x Tetraedron constrictum Tetraedron muticum x Tetraedron x x Tetmemorus granulatus Triploceras verticil latus Triploceras gracile Triploceras sp. x x x x Westella botryoides x Xanthidium spp. x x x x Zyg-,nema spo x x x Green cells v x Volvocales Cartert"a spo x Chlamyodomonas x x x x Chlorogonium sp. x Endorina elegans x x Gonium pectorale x x x Gonium sociale x Green flagellates x E:yglenophyceae Anisonema emarsrtna tum x x Astasia Klebsii (3) Cue 7/19/67 8/20/67 10/1L67 217/68 7/1/68 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

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00 t-' 6-9 McCloud 7/14/67 8/20L67 lOLIL67 2L7L68 7LIL68 Astasia longa x Copromnas subtilis x Cyclidiopsis pseudomermis x Dinema grisoleum Dis t igma prOit:eus x Entosiphon sulcatUm x x x x Euglena deses Euglena minima Euglena mutabilis x x x x Euglena pisciformis Euglena polymorpha Euglena spirogyra x x Euglena viridis x x x x Euglena sp. x x Gyropaigne kosmos x Heteronema acus x Heteronema ttrispira x Menoidium sp. x Notosolenus apocamptus x Notosolenus trichophorum x x x x Peranema trichophorum x x x x Petalomonas carinata Petalomonas praegnans Petalomonas pusillus x Petalomonas quadrilineata Petalomonas sp. x Phacus caudatus x Phacus longicauda Phacus pleuronectes Phacus triqueter Rhabdomonas incurvuum Sphenomonas quadangularis Sphenomonas teres x x Trach cylindrica Trach euchlora x Trach hispida x x Trach volvocina x Tropidoscyphus octacostatus (4) Cue 7L19L67 8/20L67 1 00)67 2L7L6 70)68 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

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(5) TABLE 6-9 McCloud Cue 7L14L67 8L20L67 lOllL67 2L7L68 7LIL6 7 L19L67 8L20LLOjJl 2/7j68 7/1/68 Chroomonas gp. x x Cryptomonas erosa x x x x x x x x x x Cryptomonas ovata x x x x x x x x x x Cyathomonastruncata x x x x Rhodomonas lacustris x x x x x x Chrysophvcea-e Botryococcus braunii x Chlorobotrys limnetica x x Chlorodesmus hispida x x x Chromulina globosa x Chromulina ovalis x Chromulina sp. x x x Chrysidiastrum ocellatum x 00 Chrysochromulina parva x N Chrysocapsa planctonica x x Chrysococcus cordiformis x x x Chrysococcus rufesens x x Chrysophyxisbipes x x x Chrysostephanosphaera globulifera x x Conra.docystis dinobryonis x Dinobryon divergens x x Dinobryon sertularia x x x x x Lagynion ampulla x Lutherella adhaerens x Hallomonas tonsurata x x sp. x x x x x x x x x Ochromonas sp. x x Peroniella plane tonica x Rhipidodendron splendidum x x Synura uvella x x x x x x Chloromonadida Gonyostomum lata x Gonyostomum semen x x x x x x x Merotrieha eapitata x x x x x Vacuolaria virescans x

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(6) TABLE 6-9 McCloud Cue 7/14/67 8/20/67 10/1/67 2/7/68 7/1/68 7/19/67 8/20/67 10/1/67 .. 2/7/68 7/1/68 Diatoms Asterionella formosa x Cocconeis sp. x x Frustulia rhomboides x x Melosira granulosa x Navicula spp. x x x x x x Synedra ulna x Diatoms, untd ,x Dinoflagellate. Bernadiellaternadiense x x x Ceratium curvirestre x x x x x x x x x Glenodiniunt sp. x Gonyaulax triacantha x x x x x x 00 Gymnodinium.fusca x x x x x x w Gymnodiniumoculatatum x x x Gymnodinium microns x x x Gymnodinium sp. x x Hemidin nasUtum x x x x x x Massartia musei x x x x x x x Peridinium cintum x x Peridiniumumbonatum x x x x x x x x x Peridinium vancouverensis x Peridinium volzii x x x x Peridinium willei x x x Peridinium wisconsinensis x x x Peridinium sp. x x Rhizo12oda Acanthocystis aculeata x Actinosphaerium eichorni x Amoeba radiosa x x x x Amoeba vespertilis x x x Amoeba villosa x x x Arcella dentata x x x x Arcella disco ides x x x x

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(7) TABLE 6-9 McCloud Cue 7/14/67 8/20/67 10/1/67 2/7/68 7/1/68 7/19/67 8/20/6i 10/1/67 2/7/68 7/1/68 Rbizopoda (continued) Arcella mitrata x x x Arcella vulgaris x x x x x Astrodisculus radians x Awerintzia cyclostoma Chaa s c cl:laes Clathrulinaelegans x x Cochlopodium bilimbosum x Difflugia aeuminata x Difflugia globosa x Difflugia lebes x x x x Difflugia x x x Euglypha alveolata x x Heterophrys myriapoda x x 00 Lesquereusia spiralis x x Nuc learia scimplex x x x x x x x Pelomyxa sp. x x x Phryganella sp. x Pseudodifflugia gracilis x Raphidiophrys elegans x x Raphidiophrys pallida x x Sphenoderia lenta x Trinema lineare x Vtlhlkampfia limax x Vampyrellailateritia x x Zonomyxa violacea x x Zooflagellata Bicoeca lacustris x x x x x Bodo agilis p.n. x Bodo celer p.n. x x Bodo elongata. x Bodo sp. x x Calycomonas ovale (=Kephyrion ovale) x x Kephyrion ovum x Mastigamoeba rep tans x Mastigamoeba sp. x

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(8) TABLE 6-9 McCLoud Cue 7/14/67 8/20/67 10/1/67 2/7/68 711L68 7/19L67 8/20/67 10/1/67 2/7[68 7L1L68 Zooflaaellata (continued) Monas spp. x Monosiga ovata x x x x Oicomonas ocellata x Oicomonas termo. x x x Phalansterum digitatum x Phanerobia pelophila x Pleuromonas jaculans x x x Rhipidodendron splendidum x x Rynchobodo .. nasu ta x Spharoeca volvox x Spiromonas angusta x x Spongomonas uvella x x x Zooflagellata unid. x x x x 00 VI Ciliata Acin.eta sp. x Aspisdisca costata x x Aspisdisca linneaus x Aspisdisca turrita x x x x x Aspisdisca sp. x Bursaridium diffcile x x x x Chaenea elongata x Chilodonella cucullus x x x x x Cinetochillum margari taceum x x x x Cinetachelum marina x x x x Coleps hirtus x x x x Cothurnia butachlii x Crestigera phenix x x x Cyclidium glaucoma x x x x x x x Cyctolophocs'ia mucicola x x x Dicleptus anser x Dicleptus gigas x Drepanomus dentata x x Drepanomus sp. x x x x x Enchelydon sp. x

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(9) TABLE 6-9 McCloud Cue 7/1A/67 8j20J67 10/lj67 217/68 7/1/68 ... _--"'-_ ... -. -,--_. ... ..... _-----_._ .... _--_ .. _-----_ .. __ .. ....... -l119LQ7 'fJ/20/ 10/1/67 2/7/66 711168 Ciliata (continued) Epiclintes ambiguus x Espejoia &p. x x Frontonia acuminata x Frontonia leucas x x x x Halteria grandinella x x. Hemiophys sp. x x. x. x x Holophrys nigricans x Hyp otricmdaunli6t: x Lembus fusiformis x. x Lembus infusionema x Lembus pusillus x x x x Lexocyshalus granulosus x x x 00 Mesodiniumacarus x x x 0Mesodinium cinctum x. x x x x. Metopus es x Nassula sp. Ophrydium versatile x. x x x x x Oxytricha di.scoeephalus x Oxytricha pelionella x x x x x Paramecium busaria x x Podophryafixa x Prorodon sp. x x x Sacculus sp. n.g. x Saprodinium sp. x x irostomum teres x x x x Stentor x x x x x Stentor coereulus x Stentor sp. x Stichotricha segunda x x Strobilidium humile x Strombidium sp. x x x x x Tetrahymena x x Urocentrum turbo x Uroleptus rattlllus x x x x

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)10) TABLE 6-9 McCloud Cue 7/14/67 8/20/67 10/1/67 2/7/68 7/1/68 7/19/67 8/20/67 10/1/67 2/7/68 7/1/68 Ciliata (continued) Urotricha farcta x x x x x Vas 1a parvula x x Vorticella sp. x x x Ciliata unid. x x x

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TABLE 6 ... 10 Groups of microscopic algae and protozoa in detailed an-alyses on five dates in 1967-68 in McCloud and Cue lakes, and the number of occurrences. Organism Group Total McCloud Cue Species No. No No. -No. species occur. species occur. Sulfur Bacteria 2 1 3 2 4 Blue Green Algae 26 24 53 21 33 Green Algae 58 48 117 39 101 Volvocales 7 7 13 2 5 Euglenophyceae 39 23 40 29 50 Cryptophyceae 5 5 18 5 14 Chrysophyceae 23 23 33 18 24 Chloromonadida 4 2 6 4 8 Dinoflagellata 17 17 36 14 31 Bacillarieae (Diatoms) 7 5 8 4 6 Rhizopoda 31 21 40 24 33 Zooflagellata 22 18 23 15 19 Ciliata 59 42 82 41 82 Totals 290 226 472 218 410 88

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be sought. This study should be done by analysis of the microbiota at intervals of two weeks, so that it can be determined if changes are gradual, or if a critical point is reached beyond which changes are abrupt. The greatest fluctuation in species incidence will be in those which occur in very small numbers. It is quite apparent that there is a standing, measurable crop of Dinobryon or Synura, or Peridinium umbonatum or Stentor amethystinum. The principal question to be answered is whether these will increase greatly under induced eutrophication, or whether species now encountered sparingly will increase greatly and perhaps supplant the present common ones. 89

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A. Purpose Section 7 ANALYSIS OF ENVIRONMENTAL FACTORS AFFECTING PRIMARY PRODUCTION One of the major complicating factors in eutrophication research is the fact that no simple relationship exists between the process of nutrient enrichment and the trophic state of the lake. A multitude of environmental factors as discussed in Section 2 control the severity and degree of trophic change for any given rate of nutrient enrichment. Similarly, 1imno1ogists have long realized that lacustrine primary productivity is influenced by other factors besides the amounts of available nutrients. These factors include physical parameters such as light intensity, temperature, lake transparency and turbulence, and chemical parameters such as micronutrient (trace metal and vitamin) concentrations, pH ionic balance and strength, alkalinity and others. Since primary production is a fundamentally important trophic state indicator, an intensive investigation of its variations and controlling factors in the experimental lake was considered essential. Accordingly a ten day field study was conducted on Anderson-Cue Lake to determine the short term variations in primary production and associated factors and to delineate the. factors controlling production. B. Procedures Seven chemical, three biological and three physical parameters were measured three times daily from May 6, 1968, up to and including May 16, 1968. No measurements were made on May 12. Samples for measurement of the chemical parameters were taken at three depths, surface,S ft., and 10 ft. at station seven (See Figure 4-1). The parameters measured were pH, ortho-phosphate, ammonia, nitrate, dissolved oxygen and acidity. The biological samples were taken from the same sampling locations as the chemical samples. Biological parameters measured were chlorophyll primary production, and plankton identification and counts. The physical parameters measured were total radiation, cloud cover, and air and water temperature. All of the biological and chemical parameters, except plankton counts were measured three times each day at 10:00 AM, 12:00 AM, and 4:00 PM plus or minus one hour. Samples for plankton counts and identification were taken only once each day. The procedures used for physical, chemical and biological determinations were the same as those described in earlier sections of this report. 90

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1 1 1 1 p 0 'r-! .IJ ........ 1 cJ 1-1 ::I...c: 'lj I 0("") 1-1 8 P-I8 u :>'00 1-1 8 CIl'-" 8 'r-! 6 1-1 P-I 4 2 0 -e surface ."---111_---" 5 ft. 10 ft. 1 3 5 7 9 11 Days Figure 7-1. VARIATION OF AVERAGE DAILY PRIMARY PRODUCTION OVER THE STUDY PERIOD 91

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Table 7-1 MEANS AND STANDARD DEVIATIONS OF PARAMETERS MEASURED DURING TEN DAY STUDY OF ANDERSON-CUE LAKE Parameter and Units Ortho-Phosphate (mg P/1) Ammonia Nitrogen (mg N/1) Nitrate Nitrogen (mg N/1) Acidity (mg/1 as CaC03 ) pH Water Temperature (OC) Primary Productivity (mg C/hr-m3 ) Chlorophyll a (mg/m3 ) aMorning 10:00 AM bNoon 12:00 AM CAfternoon 4:00 PM Sampling Location Surface 5 Feet .005 + .004 a .002 + .002 .005 + .005 b .001 + .001 .005 + .006 c .001 + .001 --.18 + .04 .18 + .04 .18 "+ .05 .18 + .04 .18 + .04 .17 + .04 .07 + .02 .07 + .02 .06 + .01 .06 + .02 .06 + .01 .07 + .01 --2.95 + .46 2.89 .66 2.75 + .37 2.63 + .32 2.61 + .40 2.55 + .34 -4.84 + .05 4.85 + .08 4.98 + .12 4.94 + .05 4.96 + .07 4.94 + .11 -26.2 + 1. 9 25.7 + 1.4 27.2 + 2.2 25.9 + 1.4 28.2 + 2.3 26.2 + 1.2 --9.86 + 3.54 4.02 + 1.50 9.63 "+ 2.87 5.70"+ 2.48 12.02 + 5.01 3.82 + 1.42 -12.43 + 9.12 11.58 + 3.82 11.93 + 5.89 10.05 + 4.31 13.98 + 9.39 10.99 + 8.23 --92 10 Feet .002 + .002 .001 + .002 .001 + .001 -.22 + .08 .22 + .06 .18 + .08 .08 + .03 .07 + .01 .06 + .00 4.06 + 1.26 3.27 + .58 3.46 + .96 -4.94 + .12 5.00 + .08 4.96 + .14 -24.8 + .4 24.9 "+ .5 25.1 + .5 -.24 + .13 .33"+ .28 1.01 "+ 1.38 -6.34 + 3.06 5.14 + 2.33 4.34 + 2.10

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Table 7-1 (Continued) Parameter Sampling Location and Units Surface 5 Feet 10 Feet Total Solar Radiation 542.1+91.2 -(Lang1eys/Day) Air Temperature 26.7 + 5.6 (OC) 30.1 + 2.8 29.8 + 2.6 -Cloud Cover 37 + 31 (%) 59 + 27 52 + 30 -Plankton Counts 3527 + 1674 2675 + 1650 1237 + 759 UF/m1) 93

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12 10 8 6 2 o 14 12 I::l 10 0 .u u,......, ;:l H 8 '"O..c: 0 I Ht'") p... S ........ :>-.u 6 -H 00 cO s S'-" H p... 4 2 0/ / <:) surface X 5 ft. \. 10 ft. 4 10:00 AM 12:00 AM Time of Day 4:00 PM Figure 7-2. MEAN PRIMARY PRODUCTION VS TIME OF SAMPLING (!> CD <:> 0 C!l0 )( X >< )( X A 41 2 3 4 5 6 7 Plankton Counts (Cells/m1 x 10 3 ) Figure 7-3. AVERAGE DAILY PRIMARY PRODUCTION VS PLANKTON COUNTS 94 <:) surface X 5 ft. .c. 10 ft. / /

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c. General Results Detailed discussion of all the parameters and their variations would be neither fruitful nor desirable. However, a few general comments concerning the nature of the results are in order. Daily averages of primary production at the three sampling depths is presented for the ten days in Figure 7-1. The effect of depth is clearly illustrated; in all cases surface production was the highest and 10 ft. production was by far the lowest. Top and bottom primary production rates generally differed by an order of magnitude or more. The peak in daily production at the surface occurred on the sixth day and is correlated with a moderate bloom of Synura in the water at this time. Temporal trends in the 5 ft. and 10 ft. samples are not so pronounced. Most of the chemical and physical parameters varied within rather narrow ranges during the ten days and displayed considerable randomness in their variations. One of the questions this study sought to answer concerns the degree to which a given sampling day is representative of the conditions in the lake during the period between sampling dates. This depends on the frequency and amplitude of the temporal variations in the parameters. A statistical analysis was made on the variability of the data and is partially presented in Table 7-1. The table contains a summary of the means and standard deviations of the parameters measured over the ten day period. Several of the chemical parameters displayed little variation during the study period. Table 7-1 indicates that ammonia, nitrate and pH changed over quite a narrow range. Average ortho-phosphate levels are higher in the surface waters than at the 5 and 10 ft. levels. This difference may be explained in part by the periodic rainfalls that occurred during the study which deposited water high in phosphate on the lake surface. However, nitrate and ammonia levels did not display a similar pattern. Table 7-1 indicates that some daily stratification occurred in the lake; however this was slight. Mean dissolved oxygen and mean water temperatures decreases from top to bottom were 1 mg/1 and 2.50C respectively. Acidity values display a diurnal trend as is evident in Table 7-1. Acidity appears to be higher in the morning and gradually drops during the day with decreases of .5 to 1.0 mg/1 occurring. However, pH values show very little fluctuation. As would be expected water temperatures rose as the day progressed. An average daily change in the order of 20C occurred at the surface with correspondingly smaller changes occurring at the 5 and 10 ft. depths. Air temperatures reached a maximum in the early afternoon with lowest values occurring in the morning. As is shown in Table 7-1, the biological parameters displayed the greatest variation. This wide fluctuation indicates that any attempt to interpolate the value of a biological parameter from encompassing sample points would be quite erroneous. In Figure 7-2, 10 day mean primary production values are plotted versus time of day. Mean primary production at the surface gradually increased from the morning until the 95

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cdl ,-l ,-l :>..,..... .e:C""l o..S 0-1-1 00 o S ,-l "-" .e: u 0 .,-1 +.I ,..... UC""l ::l S "d o 1-1 I-I.e: P-I -u :>"00 1-1 S cd"-" S ,-1 1-1 P-I 24 x 20 .. (!) 16 C> 12 -8 4 0 14 12 10 8 6 4 2 0 0 )C " surface x 5 ft. A 10 ft. o o surface x 10 ft PP -.48 + .20 (chl. a) 0 2 4 6 8 10 12 Chlorophyll (mg/m3 ) 14 Figure 7-6. AVERAGE DAILY PRIMARY PRODUCTION VS AVERAGE DAILY CHLOROPHYLL A 96 16 18

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afternoon; whereas primary production at the 5 ft. level appeared to peak in the early afternoon. Primary production levels at 10 ft. were very small and of little significance. Mean primary production at the surface was higher for all sampling times than mean primary production at 5 ft. This was quite probably due to the increased water temperature and higher degree of solar radiation at the surface. Figure 7-3 shows mean daily primary production at each depth versus plankton counts at the corresponding depths. The points on the plot are quite scattered but trends are evident. Primary production and plankton counts were higher at the surface. The higher plankton counts (See Table 7-1) plus the increased efficiency of the plankton at the surface explains the higher surface primary production. Plankton counts and primary production were correspondingly lower at the 5 ft. level and lower still at the 10 ft. level. In Figure 7-4 average daily chlorophyll is plotted versus plankton counts. The result indicates that to an extent high chlorophyll concentrations are associated with high plankton counts. The chlorophyll concentrations were higher at surface and 5 ft. levels than at the 10 ft. level. With reference to Figures 7-3 and 7-4, it would seem that high primary production values were generally associated with correspondingly high plankton counts and high chlorophyll concentrations. D. Species Diversity as a Trophic Indicator As mentioned previously samples were taken each day of the study for organism identification and counts. Major species were identified and counts made on each species. The planktonic organisms prevalent during the study were Synura, Dinobryon, Merotrichia, Cryptomonas, Monallantus, Chlamydomonas, Gymnodinium, and Scenedesmus. The order in which the organisms are listed more or less represents their abundance in descending order. Patten (1966) has used species diversity concepts for describing planktonic communities. The number of species, m, and the concentration of total individuals N (per ml) are used to determine a range of diversity available in the plankton sample. The minimum diversity, Dmin' when m > 1 corresponds to a situation where all individuals except (m-l) belong to a single species, and the remainder are distributed one each to the other species. D. =1nN! ml.n Ln N-(m-l) (7-1) Any change toward equalization of the numbers in each species increases the diversity eventually resulting in maximum diversity, D max when the individuals are equally apportioned among the species. D -ln N '. -m ln (N/m) max (7-2) The community diversity, D, is determined from the distribution of individuals amongst the available species. Ni equals number in ith special. 97

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Table 7-2 SPECIES DIVERSITIES FOR TEN DAY STUDY Date Surface May 6, 1968 32 a* 5316 b* 2669 c* .50d* May 7, 1968 33 6076 3373 .45 May 9, 1968 35 10680 3630 .66 May 13, 1968 52 3555 1095 .71 May 16, 1968 72 6521 3701 .44 a denotes minimum diversity b denotes maximum diversity c denotes actual diversity d redundancy Location 5 Feet 25 6633 4223 30 3264 2229 42 8546 3733 44 2992 1512 36 2625 1683 -units are Special Diversity Units (SDU) 98 .36 .32 .57 .50 .36 10 Feet 46 4845 1962 .60 37 2684 1190 .56 35 1877 527 .73 21 2924 238 .20 48 2032 1036 .50

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D = ln N m i = 1 (7-3) The position of D in the interval between D. and D can be expressed ma to produce a measure of dominance. ThLs varLable LS named the redundancy, R, and is defined as R = Dmax -D Dmax -Dmin (7-4) High redundancies (0 R 1) indicate that the sample is dominated by large numbers of one or more species. If there is entirely no dominance (D = D ) then the redundancy is zero. The redundancy increases to the extent of departure from a uniform distribution of species. Species diversities were calculated from the 10 day plankton counts by programming equations (1) to (4) on an IBM 360 computer. These results are presented in Table 7-2. The first and second figures in each block are minimum and maximum diversities respectively. The third figure is the species diversity for the sample taken at the indicated location and day. In this study the diversities were generally about half way between minimum and maximum diversity values. The fourth figure is the redundancy. Redundancies ranged from .20 to .73. Samples with high redundancies tended to be heavily populated with Synura cells. In general surface samples displayed higher diversities than 5 and 10 ft. samples. This suggests that species diversity is positively correlated with total plankton counts, since total counts were higher at the surface (See Table 7-1). The intermediate diversity levels suggest that Anderson-Cue Lake is in an oligotrophic to mesotrophic state since high diversities and relatively low counts are generally associated with such situations. As eutrophication progresses, decreases in diversities would be expected, as a few organisms become dominant. Patten (1966) has shown that species diversities and redundances show definite seasonal fluctuations. In order to utilize the results of this study to the most benefit, it would be necessary to determine species diversity throughout the year in order to obtain an estimate of their annual variability. Nevertheless, species diversity concepts are valuable measures of trophic state in a lacustrine system. E. Multiple Regression Analysis The results summarized above indicate that primary production is affected by a multiplicity of factors. None of the measured parameters show significant correlation with primary production when the latter are plotted as a function of the former using all the sampling points from the 10 day study. Apparently different factors limit production at different times, and the factors affecting production at one depth may not always be those limiting production at another. This fact is made apparent in Figure 7-5, a plot of primary production versus chlorophyll for all values obtained in the study. Essentially no correlation exists when all values are considered. However, certain trends become apparent when the data are grouped according to depth. While a large amount of scatter remains, there is a definite trend toward lower production per unit 99

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20 18 16 r-. 14 !-l ..c:: I (Y) -.e 12 C) t-' 00 0 0 S '-" Q 10 0 'r-! +J () ::l '1j 8 0 !-l P-! :>-. !-l 6 td S 'r-! !-l P-! 4 2 0 0 <:) I C!> 0 CZI 0 0 <:) 0 X (1) (l) 0 S <:) (1( X Ci) (1) e CD x g >( )C (l) G )( )( X )<. x,c C!1 ')( )< )( )( >< )c X x >< )( X ')( X )( X 4 ')( ..0 .0.0. 04 4 8 12 16 20 24 28 32 Chlorophyll (mg/m3 ) Figure 7-5. PRIMARY PRODUCTION VS CHLOROPHYLL A I 36 40 c;P o surface x 5 ft. .0. 10 ft. 44 48 52

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chlorophyll concentration with increasing depth. In order to further delineate the factors controlling production, the data have been subjected to multiple regression analysis. The method of simple linear regression as described by Ostle (1963) was utilized. The model (Eq. 7-5) assumes the dependent variable (Y) is distributed normally with mean and variance cr2 : (7-5) where A = intercept value; B l B2' ... Bp = the regression coefficients; Xl' ... xp = the independent variables. A multiple regression and 'correlation program was used with the IBM 360 computer to analyze the data. In most of the regression analyses primary production was selected as the dependent variable and was regressed against combinations of the physical, chemical and biological parameters to determine the possible relationships among the variables. A variety of combinations of the data were analyzed. In some runs all the sampling points were considered as one set of about 90 results (3 depths x 3 times daily x 10 days); in other runs the results were daily means at each sampling depth or were integrated or mean values with respect to depth at each sampling time. Averaging tended to lessen the random component due to analytical errors and unknown (and unmeasured) variables affecting production. Some of the more interesting results are presented below. A simple regression of average daily primary production versus average daily chlorophyll was made. The plot is shown in Figure 7-6 with the regression line drawn through the points and the regression equation given. There is a definite positive correlation between primary production and chlorophyll concentrations at the surface and 10 ft. depth. The analysis of variance is presented in Table 7-3 for average daily primary production at the surface versus average daily chlorophyll a. Note the relatively high correlation coefficient. Average daily primary production at the surface was regressed against average daily levels of dissolved oxygen, ortho-phosphate, nitrate, and ammonia at the surface. The analysis of variance, multiple correlation coefficient and resulting regression equation are given in Table 7-4. The multiple regression coefficient is high and the analysis of variance indicates significant regression. It might be concluded that a definite linear relationship exists between primary production, dissolved oxygen, nitrate and ammonia. However, it should be noted that the range of values for the independent variables is very narrow (Table This restricts the confidence interval of the regression equation, and attempts to use the equation for prediction outside this narrow range may not be justified. Primary production was also regressed against acidity and pH 101

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Source of Variation Regression Deviation From Regression Total Table 7-3 ANALYSIS OF VARIANCE FOR PRIMARY PRODUCTION VERSUS CHLOROPHYLL A Degrees of Sum of Mean Freedom Squares Squares 1 22.11023 22.11023 8 18.34338 2.29292 9 40.45361 *** -denotes significance at 99% confidence level Correlation Coefficient = .74 102 F Value 9.64281 ***

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Source of Variation Due to Regression Table 7-4 ANALYSIS OF VARIANCE FOR PRIMARY PRODUCTION VERSUS DISSOLVED OXYGEN, ORTHO-PHOSPHATE, NITRATE AND AMMONIA Degrees of Sum of Mean Freedom Squares Squares 4 31. 33093 7.83273 Deviation About Regression 5 9,12268 1.82454 Total 9 40.45361 -denotes significance at 90% confidence level Cumulative Multiple Regression Coefficient = .88 Regression Equation: F Value 4. PP -79.2 + 10.9(DO) 269.3(OP) + 86, 1 (N03 ) + 10,8 (NH3 ) PP primary production (mgC/hr-m 3 ) DO dissolved oxygen (mg/1) OP ortho-phosphate (mg/1) N03 nitrate-nitrogen (mg/l) NH3 ammonia-nitrogen (mg/1) 103

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levels at the surface with the resulting regression equation: PP -32.4 + 3.3 (AC) + 6.8 (pH) AC = acidity (mg/l as CaC0 3 ) pH = negative cogarithm of hydrogen ion concentration Again, the range of acidity and pH values was quite narrow and prediction outside this range would be done with very little confidence. Depth profiles of photometer readings were also taken during the ten day study. The relationship between average daily surface photometer readings and average daily surface primary production is interesting. The regression equation and correlation coefficient are presented below. PP = 16.8 .94(PHO) correlation coefficient = -.60 PP = primary production (mgC/hr-m 3 ) PHO photometer reading (light units) The results indicate a negative correlation between surface production and surface light intensity. This suggests that increased light (above a certain level) had an inhibitory effect on the carbon fixing organisms present in the lake during this study. Primary production values at each sampling time were with respect to depth giving one primary production value (mgC/hr-m ) for each time. The resulting values for mid-day sampling period were regressed against average chlorophyll concentrations over depth for the same sample period giving the following regression equation: PP12 = 6.1 + 1.2(CH12). correlation coefficient = .62 PP12 CH12 = primary production at 12:00 noon (mgC/hr-m 3 ) = average chlorophyll concentration over depth at 12:00 noon (mg/m 3 ) As shown previously a positive relationship exists between primary production and chlorophyll concentrations. In one instance average chlorophyll concentrations at the 5 ft. depth were regressed against plankton counts as the independent variable. The resulting regression equation is shown below. There is a positive relationship between chlorophyll a concentrations and plankton counts. This might be expected since the organisms identified were phytoplankton but the scatter indicates the chlorophyll content of individual cells varies rather considerably as other workers have found. CH = 2.45 + .002(OC) 104

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correlation coefficient = .75 CH = chlorophyll a concentration (mg/m3) OC = plankton cou;ts at 5 ft. (#/ml) It should be noted that no definite correlations were found between chlorophyll and plankton counts at the surface and 10 ft. depths. Many other regressionscombinations were tried and most appeared insignificant. This implies that there is much to be learned about the complexity of variables influencing primary production. Although some of the regressions were significant it is not yet possible to estimate primary production by measuring a few of the parameters from the multi-parameter environment; therefore the method of multi regression analyses is limited as a predictive tool. However, the general approach shows promise. It is proposed to use more sophisticated procedures on future studies. For example, the procedures of multivariate analysis especially lend themselves to studies such as this, where the interaction of a large number of variables is considered. Some of the specific procedures proposed for use are the techniques of canonical correlation and factor analysis. F. Conclusions Several general conclusions may be drawn from this study. First, it is obvious from the study that chemical parameters changed very little over a ten day period, but biological parameters showed relatively large changes. The fact that biological parameters changed so much from day to day makes interpolation between successive samples a risky venture. For example, two primary production measurements taken two weeks apart give the experimenter very little indication what values of primary production might have occurred in the lake between these two samples. The principles of multiple regression demonstrated numerous significant relationships between parameters measured during the study. It should be emphasized that the regression equations obtained for prediction should be used only within the relatively narrow range of parameter values observed. 105

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Section 8 Trophic State of Lakes in North Central Florida Limnological studies have been sparse in Florida, and consequently little background information is available concerning the quality and nature of most lakes in the state. This is unfortunate in that the state has such a large number of lakes which figure heavily in its recreational (hence economic) assets. It is hardly the function of an academic research project to act in a mere data gathering or surveillance capacity. This is the responsibility of governmental survey and enforcement agencies. On the other hand, it is obvious that some data collection is necessary in a project like the present one. The paucity of requisite background data has necessitated a greater effort in this direction than would have otherwise been appropriate. A survey of the physical, chemical and biological features of lakes in north central Florida was begun in 1968. This was undertaken for several specific objectives: 1) to assess the present trophic quality of lakes in this region; 2) to provide baseline data for future studies on the rates of changes in the quality of these lakes; 3) to gather sufficient information to evaluate the appropriateness of present trophic state criteria in sub-tropical lakes; and 4) to provide necessary data to construct an equation or index (or indices) for trophic state in subtropical lakes. An extensive sampling program on lakes in Alachua County (the location of Gainesville) was initiated during May and June of 1968. All significant lakes in the county were sampled; criteria for significance were size (all lakes larger than about three acres were sampled) and economic or recreational value (any lake with either a public or private access road was considered significant in this regard). Thirtyseven lakes located entirely or partially within Alachua County were found on U.S.G.S. topographic maps. These lakes and their locations are listed in Table 8-1 and shown in Figure 8-1. Only 25 of the lakes have names some of these appear on the topographic maps; others are known only to local residents. Six of the lakes shown on the topographic maps dried up completely prior to sampling in early June; many of the other lakes were at a considerably lower than normal stage, and hence they were smaller than indicated on maps. These facts result from the general drought conditions in the area during the first part of 1968 and the several year trend in deficient rainfall throughout north central Florida. It is obvious from Figure 8-1 that the lakes are not uniformly distributed throughout the county. Most of the lakes are situated in the eastern half of the county, and the four major lakes are in the eastern one-third. The terrain surrounding the lakes is remarkably varried, considering the small geographical area. Most of the lakes in the eastern part of the county have heavily forested shorelines, but the type of forest varies for different lakes. The large lakes have an outlet and one or more inlet streams, but many of the small lakes have neither. Further details about the drainage basins and general land-forms in the county can be found in Clark et al. (1962). 106

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Table 8-1 Lakes Sampled in Alachua County Number Name Location Type 1 Depth 2 Area 3 1 Santa Fe Lake North of Melrose OC 8 1835 2 Little Sante Fe Lake North of Lake (1) OC 469 3 Hickory Pond West of Lake (2) OC 4 32.5 4 Lake Altho East of Waldo OC 6.5 228 t-' 0 5 Lake Boullar Southwest of Melrose MC 2.5 56.8 ...... 6 Clearwater Lake Southeast of Melrose 0 3.5 7 Lake Hawthorne Hawthorne E 3.5 35.5 8 Little Orange Lake Southeast of Hawthorne M 3 241 9 Moss Lee Lake South of Lake (8) D 3.5 56.8 10 Unnamed Northwest of Lake (9) Dry 49.7 11 Lake Jefford Northeast of Lake (13) E 4 85.2 12 Still Pond East of Lochloosa M 1.5 13 Lake Lochloosa Southeast part of county E 3 2484 14 Orange Lake Southeast part of county E 4 3105

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.. Table 8-1 Continued Number Name Location Type 1 Depth 2 Area 3 15 Lake Palatka South of Lake (16) D 1.5 24.8 16 Newnan's Lake East of Gainesville HE 2 2562 17 Lake Mize Northeast of Gainesville D 25 0.9 18 Bivan's Arm South of Gainesville HE 3 61.7 19 Lake Alice U. of F. campus S 1.5 31.6 20 Unnamed South of Gainesville E 3 4.4 ...... 0 21 Unnamed East of Gainesville E 1.5 3.0 00 22 Calf Pond Southeast of Gainesville E 1 5.8 23 Perch Lake South of Lake (22) Dry 1.9 24 Unnamed Southwest of Lake (16) Dry 7.8 25 Lake Wauburg Northwest of Micanopy E 3 103 26 George's Pond West of Lake (25) E 1.5 22.9 27 Tuscawilla Lake South of Micanopy 0 2.5 63.9 28 Unnamed West of Levy Lake Dry 4.3 29 Unnamed North of Lake (28) Dry 5.2 30 Lake Kanapaha Southwest of Gainesville E 1 84.3 31 Unnamed West of Gainesville M 1 7.4

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I-' o \.0 Table 8-1 Continued Number Name Location 1 2 Type Depth 3 Area 1 2 3 4 32 33 34 35 36 37 Clear Lake Unnamed Unnamed Unnamed Unnamed Watermelon Pond Symbols are as follows: o oligotrophic M meso trophic E eutrophic HE hypereutrophic D Dystrophic S senescent Southwest of Gainesville Northwest of Gainesville North of .Lake (33) West Gainesville North part of county Southwest part of county C high organic color in lakes EC M 0(4) Dry M o 1 3 2.5 4.3 2.2 5.4 2.8 124 632 Dystrophic lakes have high color, low pH, and generally few organisms. Lakes typed as C have high color but have other characteristics of eutrophy or oligotrophy. Depth in meters Area in hectares This lake was completely covered with a dense growth of duckweed (Lemna) but other characteristics generally indicated oligotrophy.

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L-----.---------1 () 2.7 --1------------I I Figure 8-1 Location of Lakes in County, Florida llO N. t 0 2 .,. MILES

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The physical, chemical and biological parameters measured on the lakes are enumerated in Table 8-2. Collection of these data has been completed for the lakes in Alachua County. However, processing and analysis of the data for the third and fourth. objectives listed above are as yet incomplete. A special report covering all aspects of this work is in preparation and will be published as a bulletin of the University of Florida Engineering and Industrial Experiment Station. Even cursory inspection of the results discloses the graphic disparities in trophic conditions among the lakes. In fact, inspection of the lakes themselves illustrates this in a gross way. Table 8-1 includes an initial attempt to classify the lakes according to the usual trophic types. Geographical patterns in trophic type are not striking, but the lakes in the Santa Fe River basin are all oligotrophic (and also somewhat colored), while lakes in the Orange Creek basin are generally enriched. Some of the smaller lakes in the upper portions of the latter basin are also oligotrophic. Lakes located in urban and suburban Gainesville are mostly eutrophic, and cultural influences may have exerted some stress on these lakes. The trophic indicators do not give clear indications of trophic state for all the lakes. In some cases different parameters give conflicting results. To quantify the trophic states of these lakes in any meaningful form will require synthesis of the data into more digestible form by appropriate mathematical and statistical analyses. Conditions in most of the large lakes in Alachua County leave much to be desired. The most relevant data concerning trophic state in these lakes are summarized in Table 8-3. Whether the conditions result from natural or cultural causes cannot be stated with certainty in each case. Lake Santa Fe is the largest oligotrophic lake in the county. Its maximum depth (about 8 meters) is hardly impressive, but the lake shows some thermal stratification and is by far the deepest of the four largest lakes in the county. Lake Santa Fe has a very small drainage basin, the majority of which is forest. A number of cottages and homes dot the shoreline, but no other urban or agricultural eutrophying influences are apparent. Edaphic circumstances seem to be responsible for the comparative oligotrophy of this lake. NeWnan's Lake, Orange Lake, and Lake Lochloosa are the largest lakes in the county and lie in the Orange Creek drainage basin. All show considerable evidence of eutrophy. Newnan's Lake is especially peccant; its extreme shallowness is no doubt a contributing factor. The high trophic states of the Orange Creek basin lakes are at least partially the result of edaphic (especially geological) considerations. The Hawthorn formation, a phosphatic clay and sandy clay deposit, is:exposed in most of the northeastern half of Alachua County (Odum, 1953; Clark et al.,1962). Newnan's Lake lies within this formation, and Hatchet Creek, its major influent stream, drains a considerable area in this formation (Figure 8-2). Orange Lake and the southern half of Lake Lochloosa lie in the Ocala limestone formation, but both lakes receive much of their water from the Hawthorn 111

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formation (Figure 8-2). Lake Santa Fe lies wholly within the Hawthorn formation outcropping, but this circumstance is ameliorated by the lake's small drainage basin. Orange and Lochloosa Lakes are shallow, and the above geologic and hydrologic features imply they are probably trailing shortly behind Newnan's Lake on the same avenue of degradation and extinction. The large lakes in the Orange Creek basin produce an abundance of fish and are popular with sport fishermen. The advanced eutrophy of these lakes indicates game fishing may be in somewhat precarious positions, and complete take-over by rough and trash fish could conceivably be imminent, particularly in Newnan's Lake. Trophic characteristics of the smaller lakes in Alachua County show wide variations. Results from some of the more important and interesting small lakes are shown in Table 8-4. All four of the major trophic types can be found, and some of the lakes defy simple classification. Nearly all the lakes are shallow (less than 5 meters) and show little evidence of stable stratification. Lake Mize (maximum depth about 24 meters) is a notable exception. This lake is monomictic and remains stratified from early spring to late fall. Lake Mize exhibits all the characteristics of dystrophy --high color and acidity, low pH, few organisms, etc. (Nordlie, 1967). Clearwater Lake, Moss Lee Lake, and Watermelon Pond are probably the most oligotrophic of the small lakes. Hickory Pond is also oligotrophic, but color gives it some characteristics of dystrophy. A number of the small lakes have some oligotrophic and some eutrophic characteristics at the same time. These lakes are classified as mesotrophic; Little Orange Lake, Lake Boullar and Lake # 36 are examples. These lakes may be undergoing transition from oligotrophy to eutrophy. Alternatively, these may be examples of the inadequacy of trophic criteria developed for temperate lakes when applied to subtropical lakes. Bivans Arm, Clear Lake,.and George's Pond are examples of highly eutrophic lakes in the county. The former two may be thus because of cultural influences. Bivans Arm receives urban runoff from south Gainesville, some septic tank and domestic sewage drainage, and runoff from University of Florida Experimental cattle farms. Clear Lake is surrounded by homes with septic tanks. Lake Alice has been classified senescent. This lake was once eutrophic, but in recent years water hyacinths have taken over nearly all of the lake's surface. The lake is very shallow, and decaying vegetation and sediments produce obnoxious odors. Lake Alice receives treated sewage effluent from the University of Florida waste treatment plant. Nutrient concentrations in the lake do not reflect this enrichment source; evidently the extensive hyacinth growths assimilate the nutrients rapidly. Because of the light cover produced by the hyacinths, the lake is almost devoid of phytoplankton. It should be pointed out that the classifications shown in Table 8-1 are general and tentative. An oligotrophic classification does not imply that a lake never has a high standing crop of phytoplankton or that none of the trophic criteria indicate eutrophy. The converse applies to lakes with eutrophic classifications. These lakes may have some oligotrophic 112

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characteristics and do not always have noxious blooms of algae. Analysis of the data is continuing in order to derive more useful and precise indicators of trophic state. In addition the sampling program is being expanded to determine the trophic states of the major lakes in adjoining counties. 113

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I-' I-' .j> Figure 8-2 Geologic Map of Alachua County (After Clark et al., 1962). D Alachua Formation !TIT, LlJJ Ocala Group n,\',\\ W Hawthorn Formation 1/,'/,1 // Higher terrace deposits D Citronelle Formation

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Table 8-2 Parameters Measured in Lake Survey Lake depth Lake area Temperature profile A. Water Acidity Alkalinity Calcium C.O.D. Chloride Color Conductance Fluoride Iron B. Sediments Ammonia Organic nitrogen Total phosphate Physical Chemical Magnesium Manganese Organic nitrogen Ammonia riitrogen Nitrate nitrogen Oxygen, dissolved pH Orthophosphate Biological Algal identification and counts Chlorophylls a, b, and c Total carotenoids 1lS Secchi disc transparency Land use in lake basin Shoreline development Total phosphate Potassium Silica Sodium Suspended solids Total solids Sulfate Turbidity Percent volatile solids Iron Manganese Species diversities indices of algae Visual classification of vegetation surrounding lake

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Table 8-3 Characteristics of Large Lakes in Alachua County, Floridal Lake S.D. Condo pH o-P04 T-P0 4 TON NH3 NO-3 T.S. Organisms Chlor Altho 4 57 6.7 0.019 0.05 0.92 0.30 0.10 165 633 36.2 Lochloosa 2.5 108 8.0 0.038 0.08 1.40 0.18 0.10 192 5672 50.3 Newnan's 1.3 73 9.5 0.020 0.27 3.14 0.28 0.25 263 2525 65.6 Orange 2.5 65 8.6 0.034 0.08 1. 65 0.11 0.11 192 2234 74.2 Santa Fe 6 52 7.6 0.030 0.04 0.80 0.23 0.10 85 28 13.7 t-' t-' 0\ Tuscawilla 3 56 7.5 0.15 0.25 1.47 0.13 0.24 184 341 58.3 Wauburg 1.5 82 7.4 0.14 0.28 2.26 0.10 0.09 243 9288 32.3 1 Parameters and their units are as follows: S.D. = Secchi Disc transparency, feet; Condo = specific conductance at 25 C, p mho cml ; o-P04 ortho phosphate, mg P/l; T-P04 = total phosphate, mg P/l; TON = total organic nitrogen, mg N/l; NH3 and NO= ammonia and nitrate, resp., mg N/l; T.S. = total solids, mg/l; organisms total phytoplankton coclnt, numbers/ml; chlor = chlorophyll a, b, and c, mg/m3 Most values represent averages of top and bottom samples.

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Table 8-4 Characteristics of Selected Small Lakes in Alachua County, Floridal Lake S.D. Condo pH o-P04 T""PO 4 TON NH3 NO3 T.S. Organisms Chlor Alice 4 499 7.1 0.085 1.06 0.75 0.09 0.05 650 16 37.8 Bivans Arm 1 348 8.7 0.052 1.30 4.40 0.14 0.14 750 2600 23.2 Clear 1 146 9.4 0.030 0.48 1.01 0.09 0.09 142 5896 Clearwater 9 37 5.6 0.008 0.02 0.56 0.15 0.05 9 5.6 I-' I-' ...... Hawthorne 3 174 8.7 0.018 0.05 1.46 0.12 0.08 310 26,209 33.3 Hickory Pond 47 7.0 0.029 0.08 0.72 0.12 0.07 213 119 36.2 Jefford 2 64 7.2 0.076 0.08 0.71 0.20 0.17 167 3824 28.3 Kanapha 1 141 9.2 0.028 0.39 4.11 0.41 0.20 347 11,736 204.4 Little Orange 2 52 7.3 0.042 0.07 2.10 0.10 0.27 275 2352 28.0 Mize 7 55 6.1 0.240 0.68 0.20 0.13 242 88 25.8 Watermelon 23 6.9 0.040 0.05 0.90 0.03 0.10 104 125 1134 0 2 48 5.5 0.300 0.32 0.86 0.10 0.10 161 18 16.3 1 Parameters and units same as in Table 8-3. Values for most lakes are averages of top and bottom samples. 2 The surface of this lake was covered with a dense layer of duckweed (Lemna).

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Section 9 Models of the Eutrophication Process It should be apparent from previous sections that the problem of eutrophication is vastly complicated. The natural and human factors in lacustrine nutrient enrichment are multitudinous; the environmental parameters affecting trophic state are beyond simple description. In addition, the eutrophication problem has ramifications beyond the purely technical. In lake management and eutrophication control and alleviation, socio-economic considerations become involved. In effect, the eutrophication problem is not one but many, and in order to solve it the efforts of many disciplines must be utilized. It is difficult to imagine solution of the problem and its attendant complexities and ramifications without the use of some unifying and simplifying methodologies. A group of such tools --in fact an entire concept of solving complex problems --has been developed in recent years and is commonly referred to as systems analysis or operations research. This method relies heavily upon advanced mathematical concepts and especially on computer assisted solutions. One of the fundamental principles of systems analysis is that complex problems or systems consisting of many variables can be divided into a number of simpler components each containing relatively few variables. The small components are more amenable to detailed analysis and solutions to the overall problem can be attained in essence by integrating the partial solutions. A second principle of systems analysis is the concept of the model. A model is simply an approximation of the real system. It consists of the essential system elements and the variables which affect their interactions. Quantitative system models are constructed from various types of determinate and stochastic mathematical expressions. With the advent of high speed computer techniques, systems analysts have been able to construct sophisticated models with the many components and variables needed to describe involute real systems. Systems analysis techniques have been widely applied to complicated industrial and governmental management problems. The great expansion in the area of water resources management in recent years has been closely associated with theories of systems analysis techniques (Hufschmidt et al. 1962). Applications of these methods to water quality management is somewhat less advanced and largely concerned with effects of pollution on the dissolved oxygen regime of rivers and streams (e.g., Thoman, 1966; O'Conner, 1966). Ecosystems being characterized by their labyrinthine natures, ecologistshave increasingly relied on the systems analysis approach in their studies (Watt, 1968). Eutrophication is one of the most involved and critical problems facing aquatic scientists and water quality control agencies today. The tools of systems analysis should be invaluable to investigators of the problem. Heretofore there has been no direct application of these methods to the problem although there have been related applications in aquatic ecosystem studies. The remainder of this section will briefly summarize the intended application of systems analysis and mathematical modeling in the present study on eutrophication. 118

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The experimental portions of this study are still under way, and much work remains. Since the primary function of systems analysis techniques is in data analysis and in synthesis of predictive models and equations, the greatest application of the methods to this project lies in the future. Five aspects of eutrophication can be mentioned as especially appropriate for systems analysis and modeling, and work is proceeding in these areas. 1. Derivation of a eutrophication rate function. Eutrophication is the process of lake nutrient enrichment and, as such, can be defined in terms of the net nutrient flux to a lake. In order to quantify the process, an equation or function should be derived such that a given flux of the essential (limiting) nutrients defines a unique rate of eutrophication. As an approximation, eutrophication might be represented by some function of nitrogen and phosphorus input, assuming trace elements do not limit lake productivity over long periods of time. Some possible functions have been briefly discussed elsewhere (Brezonik, 1968), but further developmental work is needed. Such functions would necessarily be somewhat arbitrary, but that should not limit their usefulness. As the contributions of nutrients from various sources become better known and understood, it should further become possible to model the eutrophication rate function in terms of certain measured environmental parameters (amount of rainfall, area and population of the drainage basin, land usage patterns, etc.). 2. Dynamic models of aquatic ecosystems. The effects of nutrient enrichment on the aquatic ecosystem depend on a variety of edaphic factors. Ecosystems can be described as multi-compartment models (each compartment representing a trophic level of nutrient or energy reservoir), and the interactions among the compartments can be defined by series of differential equations. Environmental control of exchanges between ecosystem compartments can be indicated in such models by appropriate forcing functions or by transfer coefficients which could be functions of certain environmental conditions. The effects of nutrient enrichments on the dynamics and equilibrium of aquatic ecosystems could be studied by appropriate in situ experimentation, data collection, and analysis of such data with suitable dynamic ecosystem models. Much theoretical work could also be done with such models using artificial or computer generated data. The works of Patten (1966) and Odum (1960, 1967) are noted as pertinent to this approach. Some applications of this method to the problem of eutrophication were also discussed by Brezonik (1968). 3. A trophic state equation. As previously noted, trophic state of a lake is loosely defined and only a qualitative term. No single parameter defines trophic state; rather it is a summation of many chemical and biological conditions. Little progress can be made until eutrophication and trophic state are more precisely defined --even if the de:initions are arbitrary. One possible avenue would be to develop a trophic state parameter as some simple function of the indicators shown in Table 2-3. The nature of the trophic state function is still speculative; however, such an expression may involve the following variables 119

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(among others): Trophic State = F (Annual primary production, algal biomass, Secchi disc transparency, maximum spring nutrient concentrations) (9-1) The relative importance of the different variables would necessarily be arbitrary. Simple regression analysis would not be useful to develop this equation since only independent variables are known while the dependent variable (trophic state) is what we are seeking to define. A possible approach would be to arbitrarily define several trophic state equations and determine which gives the highest correlation with the nutrient input or eutrophication function. Canonical correlation analysis may be useful in this regard. The work reported in Section 8 was instigated in order to obtain the necessary data on Florida lakes for this analysis and for development of a trophic state equation. 4. Factors affecting primary production. The importance of primary production in any study of eutrophication or measure of trophic state can hardly be over-emphasized. Thus, studies which further our knowledge of the environmental factors controlling primary production may have important implications regarding the present problem. Stochastic techniques such as multiple regression and correlation analyses and multivariate procedures like canonical correlation and factor analysis are especially suitable analytical devices for field investigations of primary production. Not only the controlling factors but also the amplitude and frequency of the variations in primary production should receive further attention in eutrophication studies. The study reported in Section 7 of this report represents our initial efforts to study this problem. 5. Economic analysis of the eutrophication problem. There are many degrees of eutrophication and its manifestations, many alternatives for their control and prevention, and only finite resources available to do the job. Thus, it becomes a highly involved problem to determine how much eutrophication to allow and how much money and other resources to spend for its prevention, control, or alleviation. This is an optimization problem in which we desire to maximize the benefits at a given cost or minimize the cost at a given level of benefits. Optimization is a familiar problem in systems analysis. Involved are cost-benefit analyses, i.e., for a given amount of resources spent to remedy the problem, what and how many benefits accrue. One of the major stumbling blocks is quantification of some of the aesthetic and recreational benefits associated with oligotrophy and mesotrophy. However, further work on this aspect will have to await clearer definitions of the eutrophication process and its effects and answers to some of the more basic questions discussed above. 120

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