Ecological Research Series
BROWNS FERRY
BIOTHERMAL RESEARCH SERIES
I. Colonization by Periphyton,
Zooplankton, and Macroinvertebrates
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for t,hejr long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-78-020
February 1978
BROWNS FERRY BIOTHERMAL RESEARCH SERIES
I. COLONIZATION BY PERIPHYTON,
ZOOPLANKTON, AND MACROINVERTEBRATES
by
Brian J. Armitage, Thomas D. Forsythe,
Elizabeth B. Rodgers, and William B. Wrenn
Biothermal Research Section
Division of Forestry, Fisheries, and
Wildlife Development
Tennessee Valley Authority
Decatur, Alabama 35602
TV-35013A
Project Officers
Thomas H. Ripley Kenneth E. Biesinger
Division of Forestry, Environmental Research Laboratory
Fisheries, and Wildlife Development 6201 Congdon Boulevard
Forestry Building Duluth, Minnesota 55804
Norris, Tennessee 37828
This study was conducted
in cooperation with
Tennessee Valley Authority
Norris, Tennessee 37828
ENVIRONMENTAL RESEARCH LABORATORY - DULUTH
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
DULUTH, MINNESOTA 55804
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DISCLAIMER
This report has been reviewed by the Environmental Research Laboratory-
Duluth, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, nor does mention
of trade names or commercial products constitute endorsement or recommen-
dation for use.
ii
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FOREWORD
The aquatic environment must be protected from the adverse effects of
thermal dishcarges. Large volume thermal discharges, if not properly managed,
can have deleterious effects on fish populations and their food chain organisms
and thus ultimately diminish the quality of man's environment; conversely,
excessive control measures can result in economic penalties to the public. A
balance must therefore be attained between the industrial utilization of water
and the maintenance of a high-quality environment. The Browns Ferry Biothermal
Research Station contributes to the search for this acceptable balance through
investigations on
—the effects of increased temperature on growth, survival,
reproduction of sport and commercially important fish species
and their food organisms, and
—the effects of increased temperature on the ecological
relationships between fish and their food organisms.
This report focuses on the ecology of organisms in the experimental
system which will constitute the food chain for the fish species to be
investigated. Specifically, this report addresses the colonization of the
experimental system, under natural thermal conditions, by the food chain
organisms and thus serves as the baseline for future studies that will be
conducted under conditions of elevated temperatures.
Clyde W. Voigtlander
Senior Aquatic Ecologist
Division of Forestry, Fisheries,
and Wildlife Development
Tennessee Valley Authority
Norris, Tennessee 37828
iii
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ABSTRACT
Colonization studies on a series of 12 outdoor experimental channels
supplied with water from Wheeler Reservoir (Tennessee River) were completed
at the Browns Ferry Biothermal Research Station in Alabama. Species
composition, dominance, seasonal patterns, colonization rates, and biomass
estimates were determined over a 24-month period for periphyton, zooplankton,
and macroinvertebrates. The periphyton assemblages were highly productive
and diverse. Colonization of bare surfaces was extremely rapid during summer
months. Zooplankton was abundant and was composed primarily of shallow-water
forms. Macroinvertebrates quickly colonized the biothermal channels by way
of inflowing reservoir water and by air. Macroinvertebrate diversity was as
great as or greater than that in Wheeler Reservoir and represented taxa found
in both littoral and open-water areas. In general, the species composition
and the relative densities of algal and invertebrate organisms that colonized
the channels indicated that the channels successfully simulate reservoir
ecosystems for those trophic levels.
The work upon which this publication is based was performed pursuant to
an Interagency Agreement between the Tennessee Valley Authority and the
Environmental Protection Agency. This report was submitted in partial
fulfillment of Contract No. TV-35013A by the Tennessee Valley Authority under
partial sponsorship of the U.S. Environmental Protection Agency. This report
covers field work from March 1974 to February 1976, and analyses completed as
of March 1977.
iv
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CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vii
1. Introduction 1
2. Research Facility 2
3. Conclusions 5
4. Periphyton 7
Scope 7
Materials and Methods 7
Results and Discussion 8
5. Zooplankton 19
Scope 19
Materials and Methods 19
Results 21
Discussion 22
6. Macroinvertebrates 30
Scope 30
Materials and Methods 30
Results 31
Discussion 32
References 45
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FIGURES
Number Page
1. Planview of experimental channels and auxiliary facilities 3
2. Profile of Browns Ferry biothermal experimental channel 4
3. Number of periplvyton species identified from the biothermal
channels (plotted by quarterly accumulations) 16
4. Mean values for active chlorophyll &_ during the colonization
period (15 cm depth) 17
5. Vertical profiles of active chlorophyll a. after 1 and 3 weeks
colonization 18
6. Diel^, periodicity of Simooephalus vetulus (large cladoceran)
in a channel during the winter * . 24
7. Total microcrustacean plankton density (numbers/m3) and dry weight
biomass (mg/m3) in a channel for the 1974 and 1975 sampling
periods 26
8. Water temperature and density of the seven dominant taxa in
one channel for the 1974 and 1975 sampling periods 27
9. Species composition in terms of percent numbers and percent
biomass for 1974 and 1975 sampling periods 28
vi
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TABLES
Number Page
1. Algal taxa found in the biothermal channels 10
2. Increases in the number of algal species colonized after 3, 7,
and 10 days ^ 15
3. Number of algal species colonizing bare substrates at 15, 46,
and 76 cm depth 15
4. Microcrustacean plankton found in channels as of 1975 25
5. Average percent relative abundance in terms of numbers and
biomass in one channel and in terms of numbers in Wheeler
Reservoir 29
6. Macroinvertebrate taxa identified in biothermal channels during
colonization period 34
7. Macroinvertebrate taxa observed in three sample areas on
succeeding dates 39
8. Population trends of taxa sampled in channels between summer,
1974 and spring, 1976 42
9. Numbers and dry weights of organisms per m2 on wall areas on
successive sampling dates in 1976 44
vii
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SECTION 1
INTRODUCTION
As early as 1968, the Tennessee Valley Authority (TVA), in collaboration
with the Federal Water Pollution Control Administration, now the Environmental
Protection Agency (EPA), recognized the need to acquire scientific information
that could be used for reliable prediction of the effects of increased
temperature on aquatic organisms. A plan was initiated to build a research
facility in which aquatic organisms could be held under essentially natural
conditions but maintained under the closer controls that approached laboratory
conditions. Construction of this facility, which began in 1972, is essentially
complete.
The primary feature of the facility is a series of 12 temperature-
controlled outdoor channels. The project objectives are to: (1) Determine
the effect of increased annual temperature on the growth, survival, and
reproduction of warm-water fishes with emphasis on sport and commercially-
valuable reservoir species; (2) determine the effect of increased annual
temperature on the species composition and production of algae, macroinverte-
brates, and zooplankton; and (3) determine the effect of increased annual
temperature on ecological relations between fish and their food organisms.
Attainment of the above objectives will provide data for establishing or
adjusting temperature criteria for warm-water streams and reservoirs, and for
establishing thermal regimes for optimal production of specified groups of
aquatic organisms.
Prior to the initiation of the heated water experiments, the channels were
colonized by Tennessee River organisms over a three-year period (1974-1976)
under ambient temperature conditions. This report documents the establishment
of the primary and intermediate trophic levels in the channels during the first
24 months.
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SECTION 2
RESEARCH FACILITY
The research station is located adjacent to TVA's Browns Ferry Nuclear
Plant on the north bank of the Tennessee River (Wheeler Reservoir),
approximately 10 miles (16 km) southwest of Athens, Alabama. Water
temperature and flow are controlled in 12 concrete channels (114 m long,
4.3 m wide, and 2 m deep) (Figure 1). The substrates (natural reservoir
sediments and limestone rock) are arranged to provide six alternating
pools and six rock areas in each channel (Figure 2). Other major components
include: six tubular heat exchangers located near the inlets of the channels;
high-temperature and low-temperature pumping stations; five secondary fish-
holding ponds; a laboratory-office building; and a water-quality monitoring
system that includes a minicomputer (32-K memory).
For this 24-month colonization study, water was pumped to the channels
from Wheeler Reservoir at the same rate as that at which it will be pumped
for the heated water experiments. Water discharge is about 0.66 m3/min
(180 gal/min) with a channel retention time of approximately 14 hours.
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CO
L_
SECURITY FENCH
ACCESS ROAD
FISH
• • imn
CHANNELS |
c
HOLDING
PONDS
g
^ VALVE
BOX
/
(
D c=
1=
C
D c
D
XJTLET \ INLET
BARRIER
SCREENS
REMOVEABLE
« * llfXMIIIKXXHIUj!,! 1 — ~
t—
STRAINERS
HIGH TEMPERATURE I
PUMPING STATION I
NEAR CONDENSER O
DISCHARGE OUTLET O
,J
LOW TEMPERATURE
PUMPING STATION
ON WHEELER RESERVIOR
Figure 1. Planview of experimental channels and auxiliary facilities.
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BARRIER SCREEN
(Zrnrn ICSH)
WATER LEVEL
h*~1
' ' 'yy S / ' S / S / S • ' r s f / s s / S *',,./ X x * *
/ ' ' / / // / // ' / / / / ////// / / / / ' / ' UUD-SILT / ' / / '
/'////////,/////////// / / / / / / / "U,U xSIJfT / / / / /
/ / / S / / S S / / / / J / / / / / / / S / S S / /^//S /_ s s / / / / / '
OUTLET
Figure 2. Profile of Browns Ferry biothermal channel.
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SECTION 3
CONCLUSIONS
On the basis of 24 months of colonization studies and observations, we
have derived the following conclusions concerning the non-chordate biota of
the biothennal channels:
1. Initial filling of the channels was accompanied by high algal
productivity and biomass.
2. Chlorophyll ji concentrations of periphyton on wall and rock areas
were highest during the late summer and early fall.
3. The biomass (as chlorophyll a) and species richness of the
periphyton were within ranges reported in the literature.
4. Colonization rates were greater during the summer in terms of both
species numbers and biomass.
5. Zooplankton community composition became more complex as
colonization proceeded; seven groups (S-imocephalus, daphnids, Bosmina3
Ceriodaphniaj cyclopids, Chydovus, and ostracods) were dominant.
6. The channels are selective for shallow-water zooplankton species.
No established populations of open-water forms were found.
7. The channel design allows convenient sampling of zooplankton,
although the diel periodicity patterns of most species necessitate night
sampling.
8. The biothermal channels provide excellent habitat for colonization
or macroinvertebrate species native to the Tennessee River.
9. Pool areas in the channels are suitable for invasion by Hexagenia
bilineataj bivalve molluscs including Corbioula manilens{.s3 Anodonta imbeciles,
and Etipt-Lo srassidens; relatively large operculate gastropods such as Pleuroaera
oanal-iculatwn-, the leech, Erpobdella punctata; and certain midges of the
subfamily Chironominae. All of these organisms are found also in open-water
benthic areas of Wheeler Reservoir.
10. Rock and wall areas offer suitable habitat for the amphipods Hyalella
azteoa and Crangonyx sp., relatively small pulmonate and operculate Gastropoda,
heptageniid and baetid Ephemeroptera, psychomyiid and hydroptilid Trichoptera.
and a wide variety of Odonata and Chironomidae.
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11. Organisms dominant in terms of numbers were the Oligochaeta,
Pelecypoda, Amphipoda, Gastropoda, and Chironomidae.
12. Channels drawn down for two months in late fall successfully
recolonized. Gastropoda, Amphipoda, and Chironomidae showed definite
increased densities after drawdown.
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SECTION 4
PERIPHYTON
SCOPE
The biothermal channels are similar to the littoral areas of many
reservoirs, because of water depth and substrate types. The absence in the
channels of aquatic vascular plants and of extreme wave activity are the
apparent principal differences. In water bodies with well-developed littoral
zones, the attached algae usually contribute a major share of the annual
productivity of the system (Hutchinson, 1975; Wetzel, 1975). Species diversity
is also usually high, with species lists commonly showing 100-300 species
present in the littoral zones (Hutchinson, 1975). Beginning in June, 1974,
an evaluation was undertaken of the periphyton naturally colonizing the bio-
thernal channels. The purposes of the initial colonization studies were:
(1) to determine species composition and dominance patterns; (2) to identify
seasonal shifts and cycling in the periphyton community; (3) to estimate species
invasion rates and ascertain the sequence in which species became established;
and (4) to estimate the biomass of periphyton produced with time.
MATERIALS AND METHODS
Samples for species identification were taken from scrapings of walls
and rock areas, from floating mats, from cores of pool sediments, and from
artificial substrates (cellulose acetate strips, plexiglas plates, glass
slides, styrofoam sheets). Identifications were made to the species level
whenever possible.
Colonization of artificial substrates was compared with that of natural
substrates in the channels. Although periphyton assemblages on all
artificial substrates tested approximated those on natural substrates,
cellulose acetate was slightly superior. This material had the additional
advantage of being easy to cut in various dimensions. Therefore, the major
portion of the results was obtained employing this material. Strips (5 cm x
50 cm) were suspended horizontally at a depth of 15 cm and allowed to be
colonized for two, three, and four weeks. Smaller strips (2.5 x 5 cm) were
implanted in rubber stoppers and suspended at depths of 15, 46, and 76 cm.
Long strips (2.5 x 105 cm) were also hung vertically in the water column for
pigment-depth profiles.
Species invasion sequences were interpreted on a presence/absence basis.
Three-dimensional colonies, branched filaments, mucilaginous colonies, tapering
filaments, and dividing mother cells complicated attempts at quantification
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either by cell counts or cell volumes. Recent experiments using tetrazolium
violet have indicated that a significant number of algae colonizing artificial
substrates (which would normally be counted using conventional microscopic
techniques) were not metabolically active. Tetrazolium violet is a tetrazolium
salt which forms a violet precipitate in actively metabolizing cells via the
electron transport system (Dozier, OREL, unpublished). The 2.5 x 5.0 cm strips
for species invasion sequences were normally collected after 3, 7, and 10 days.
Species invasion sequences and colonization rates were examined periodically.
Chlorophyll was analyzed following methods of EPA (1973) and Vollenweider
(1974). Correction was applied for phaeophytin. Active chlorophyll a_ is
reported as yg chl a*/cm2.
RESULTS AND DISCUSSION
During 1974-75, 124 taxa of algae were identified (Table 1). Of these,
100 taxa were identified to the species level (greens [36], charophytes [1],
euglenoids [2], diatoms [55], blue-greens [6]). Most of these taxa were
epilithic or epiphytic; the epipelic taxa received only a cursory examination.
Although the absence of aquatic vascular plants in the channels has possibly
eliminated an important habitat normally present in the littoral zones of
lakes and reservoirs, the diversity of algae colonizing the biothermal channels
is comparable with that of many reservoirs.
During spring 1974, following the initial filling of the channels with
water pumped from Wheeler Reservoir, massive blooms of Hydrodictyon reticulation
developed in the channels. Floating mats of this species eventually
concentrated at the lower ends of the channels. Following this bloom, smaller
random blooms of Spirogyra grati-ana^ Sp. nitida^ and Cladophora glomerata
occurred along the walls or on the rock areas. Very few diatom species were
in evidence. The periphyton community during winter 1974-75, was dominated by
Oedogonium kurzii,, StigeoolonLum sp., and a few epilithic and epiphytic diatoms
(Melosira varians, Coocone-is disoulus, Synedra aous) were subdominants. These
eventually gave way to other filamentous and coccoid green algae of insignificant
biomass during early spring. A brief bloom of Hydrodietyon retiaulatwn occurred
in several channels during May 1975; however, its intensity and duration were
well diminished, compared with the 1974 bloom. Concurrent with the restricted
bloom of Hydrodictyon, Spirogyra gratiana and Sp. nit-ida began to form mats
attached to the walls and rock areas. These species attained their greatest
biomass in late August and September 1975. Because of silt accumulation on
the Spirogyra filaments (probably attracted to an extracellular poly-
saccharide excreted by these species), the mats became denser and more closely
appressed to the substrates. Subsequently, diatoms colonized the silt surface,
followed by blue-greens. Occasionally during the summer, random patches of
Cladophora 'glomerata appeared, and Chaetophora elegans was codominant with
Spirogyra on substrates exposed during September. The demise of Spirogyra
paralleled dropping temperatures during October and November. Scrapings from
artificial and natural substrates during October-December 1975 were dominated
by Melosira varians and Oedogon-ium kwczi-i.
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From March 1974 to December 1975, the number of species identified
•increased in a predictable fashion (Figure 3). The number of diatom species
was not appreciable, however, until winter 1975. Desmids also were quite
scarce until late summer 1975. Constant introduction of species from the
reservoir should add to the channels' flora in forthcoming seasons. The
absence of vascular aquatic plants and the annual drawdown of the channels
prior to a new experiment, however, could limit the expected increase of
species numbers.
The sequence of colonization in summer and winter 1975 varied not only
in the species present but also in the number of species and in the rates of
colonization (Table 2). During the summer an artificial substrate was coated
first by bacteria. This was followed by colonization by a few species of
diatoms (Aohnanthes linearis, Gomphonema parvulwn, Nitzschia palea)_ and
coccoid greens. Prostrate colonies of Protoderma viride and Stigeoclonium sp.
then covered large areas, concomitant with the appearance of filaments of
Spipogyra spp. Chaetophora elegans often served as the codominant with
Spirogyra spp. during the late summer. The winter colonization was also
initiated by bacteria but was followed by 15-20 different species of diatoms,
particularly Cyrribella tumida, Cym. tw?gida3 Gomphonema angustatum, Melosira
varians, Nitzsohia acieulariSj and Synedra aous. Melosira varians clearly
dominated the periphyton assemblage after 5-7 days of exposure. After about
two weeks of exposure, Oedogoniwn kurzii began to colonize the substrates,
eventually^dominating or codominating with M. varians. Examination of natural
substrates revealed an assemblage of periphyton virtually identical with that
on artificial substrates. Oedogoniwn kurzii supported an epiphytic diatom
flora, in contrast with the summer species of Spirogyra whose mucilaginous
excretions barred such exploitations.
Chlorophyll ja, corrected for phaeophytin (chl a*}, was the major biomass
estimator during the 1974-75 colonization period. Variation among channels
was often high, possibly due to differences in flow rates for each channel.
Most chlorophyll samples were taken from artificial substrates that were
allowed to be colonized for two weeks (Figure 4). No statistically significant
variation (P > 0.05) was noted among replicates (3-9) within any one channel.
Typical vertical profiles for chl a* and species numbers for the summer months
are shown in Figure 5 and Table 3, respectively. Winter profiles were.more
uniform and fewer species were present.
In general, the productivity of new water bodies is initially high, due
to the influence of organic matter and nutrients originating from flooded
substrates (Zhadin and Gerd, 1961; Rodhe, 1964; Leentvaar, 1966; Biswar, 1969;
Funk and Gaufin, 1971). The biothermal channels were no exception to this
"hay-infusion" phenomenon, as evidenced by the extensive mats of Hydvodiotyon
vetioulatum and Spivogyra spp. Chlorophyll a_ concentrations of epilithic
periphyton attached on walls and rock areas fell within the expected range
(100-1200 mg chl a^ / m2) suggested by Hutchinson (1975). The species richness
also was normal for a littoral habitat. Although some variations existed among
channels in terms of biomass, the species and dominance patterns for the channels
were relatively consistent. This consistency should provide a good foundation
for judging the effects of various thermal regimes upon the periphyton
communities.
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TABLE 1. ALGAL TA£A FOUND IN THE EXOTHERMAL CHANNELS
Class
Order
Species
Chlorophyceae
Volvocales
Tetrasporales
Chlorococcales
Ulotrichales
Chaetophorales
Oedogoniales
*3
Chlamydomonas sp.
Pandorina movwn Bory
Gloeocystis gigas (Kuetz.) Lagerheim
Palmodiotyon vivide Kuetzing
Ankistrodesmus faloatus (Corda) Ralfs
Chayaoiwn arribiguum Herman
Chlovoooocwn hurrrieola (Nag.) Rabenh.
Chodatella quadriseta (Lemm.) G.M. Smith
Hydrodictyon reticulation (L.) Lagerheim
Pediastrum duplex
var. gYac-ilirmm West & West
Pediastrum simplex (Meyen) Lemmermann
Soenedesmus quadrioauda (Trup.) de Berb.
Microspora stagnorum (Kuetz.) Lagerheim
Stichoeoccus subtilis (Kuetz.) Klercher
Ulothrix sonata (Weber & Mohr) Kuetzing
Chaetophora elegans (Roth) C.A. Agardh
Microthaimion sp.
Protoderma viride Kuetzing
Stigeoclonium sp.
Oedogonium kurzii Zeller
3 Exact species unknown due to the absence of certain essential
diagnostic characteristics.
10
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Class
Chlorophyceae
Order
Siphonocladales
Zygnematales
Species
Charophyceae
Charales
Euglenophyceae
Euglenales
Cladophora glomerata (L.) Kuetzing
Mougeotia sp.
Spi-rogyra gratiana Transeau
Spirogyra nitida (Dillw.) Link
Spirogyra. sp.
Closterium lunula Nitzsch.
Closterium monilifenm Ehrenb.
Cosmajfiim bo try tie
var. tumidum Wolle
Cosmariim exiguum Arch.
Cosmarium margaritatwn (Lund.) Roy & Bliss
Cosmariwn oohthodes.
var. cmoebwn West & West
Staurastmm botpophilum Wolle
Statafastrum orbiculare Ralfs
Staurastvum paradoxim W. West
StaurastPim twegesoens de Not
Chora schueinitzii A. Braun
Euglena sp.
Phaous orbicularis Huebner
11
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TABLE 1 (continued)
Class
Order
Species
Bacillariophyceae
Eupodiscales
Fragilariales
Achnanthales
Cyclotella stelligera Cleve & Grun
Melosira distorts
var. humilis A. Cleve
Melosira granulata (Ehrenb.) Ralfs
Melosira granulata
var. angust-issima 0. Mull.
Melosira varians C. A. Agardh
Stephanodiscus astrea
var. minutula (Kuetz.) Grun.
Astevionella formosa Hassal
Diatoma hiemale (Roth.) Heib.
Fragilctria oonstruens (Ehrenb.) Grun.
Frag-ilaria crotonensis Kitton
Opephora martyi Herib.
Synedra aoti-nastifop'ides Lemmermann
Synedra aous Kuetzing
Synedra rumpens Kuetzing
Syndra ulna (Nitzsch.) Ehrenberg
Synedra ulna
var. longissima (W. Smith) Brun.
Tabellaria fenestrata (Lyngb.) Kuetzing
Tabellaria flocoulosa (Roth.) Kuetzing
Achnanthes exigua Grun.
Aehnanthes lonoeolata
var. dubia Grun.
Achnanthes Hnearis (W. Smith) Grun,
12
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TABLE 1 (continued)
Class
Order
Species
Bacillariophyceae
Achnanthales
Naviculales
Cocconeis disoulus (Schum.) Cl.
Cocconeis placentula Ehrenberg
Rhoicosphenia curvata (Kuetzing)
Grun. ex Rabh,
Frustulia rhomboides (Ehrenb.) Det.
Gyrosigma spencerii (Quek.) Griff.
& Henfr.
Navicula crucicula (W. Smith) Donk.
Navicula mutica Kuetzing
Navioula radiosa Kuetzing
Naviaula sp.
Pinnularia biceps Greg.
Pinnularia viridis (Nitz.) Ehrenberg
Stauroneis anoeps Ehrenberg
Gomphonema angustatwn (Kuetz.) Rabenh.
Gomphonema oli-vaoeum (Lyngb.) Kuetzing
Gomphonema parvulum Kuetzing
Gomphonema truncation Ehrenberg
Amphora sp.
Cymbella affinis Kuetzing
Cymbella minuta Hilse ex Rabenh.
Cyrnbella prostrata (Berk.) Cl.
Cymbella tunrida (Berb. ex Kuetz.) V. H.
Cyrnbella turgida Greg.
13
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TABLE 1 (continued)
Class
Order
Species
Bacillariophyceae
Nitzschiales
Surirellales
Cyanophyceae
Chroococcales
Oscillatoriales
Nostocales
Nitzschia aoicularis W. Smith
Nitzsohia dissi-pata (Kuetz.) Grun.
Nitzsohia palea (Kuetz.) W. Smith
Nitzschia sigma W. Smith
Ni-tzsehi-a ticyblionella Hantzsch.
N-itzsohia vernrieularis (Kuetz.) Grun.
Ni-tzsohia sp.
Cymatopleura solea (Berb.) W. Smith
Swrirella angustata Kuetzing
Surirella patella Ehrenberg
Surirella patella
var. neupaueri (Pant.) Cleve-Euler
Swrirella sp.
Meri-smopedia punctata Meyen
Oscillatoria geminata Menegh.
Oscillatoria lacustris (Kleb.) Geitler
Oso-Lllatoria nigra Vaucher
OsoillatoTia princeps Vaucher
Pleotonema nostocoman Bornet
14
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TABLE 2. INCREASE IN'THE NUMBER OF ALGAL SP.ECIES COLONIZED AFTER
3, 7, AND 10 DAYS
January-
July-
Days
Exposed
3
7
10
3
7
10
~~ a
Species (x)
16
29
38
45
46
52
Species (total) Range
25
47
59
49
58
62
11-19
24-33
34-46
39-47
42-48
46-57
Mean number of species found on all strips examined (January- 6
channels; July- 4 channels).
Total number of species found on all strips.
TABLE 3. NUMBER OF ALGAL SPECIES COLONIZING BARE SUBSTRATES
AT 15, 46, AND 76 CM DEPTH
August-
Depth
15 cm
46 cm
76 cm
Species (x)
31
33
26
Species (total)0
50
56
42
Range
27-35
28-41
25-29
Three days colonization period.
Mean number of species found on all strips examined in four
channels.
Total number of species found on all strips at each depth.
15
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u
a.
u.
o
140
120
100
80
60
40
20
A
\\ \\ |! ! I'll
A
rt i i ii i:
i i
i :
flBBiillH
QTR.» 2 3
1974
2 3
1975
Figure 3. Number of periphyton species identified from the
biothermal channels (plotted by quarterly accumulations).
-------
23
JJ ASONDJ FMAMJJASOND
Figure 4. Mean values for active chlorophyll ji during the colonization period (.15 cm depth).
-------
00
week -> 1
0.5
1.0
1.5
~ 2.0
u
a
2.5
3.0
3.5
4.0
5 10
80
Figure 5. Vertical profiles of active chlorophyll a. after 1'and 3 weeks colonization.
-------
SECTION 5
ZOOPLANKTON
SCOPE
Before the biothermal channels were colonized in 1974, the importance of
zooplankton in such experimental ecosystems was unknown, since many zooplankton
species require open water or cannot tolerate flowing waters (Hutchinson,
1967). The channels were designed to simulate reservoir flows that should
not severely limit zooplankton occurrence. Water velocity was adjusted to
about 0.14 m/min in pool sections and 0.56 m/min over shallow rock sections.
Tennessee River water is pumped continuously to the channels at a rate of 0.66
m3/min (180 gal/min) and passes through a 2-mm mesh-opening screening system,
which allows introduction of most reservoir plankton species.
Because some species of fish to be studied will reproduce in the channels,
a well-developed zooplankton community would be desirable to supply natural
forage £or larval and juvenile stages. The well-known "critical period" for
larval fish is successfully transcended only when the right quantity 'and
variety of zooplankton food is present at the initiation of feeding.
The purpose of the zooplankton study was the quantitative assessment of
colonization in a channel by analyzing changes in zooplankton abundance and
species composition from April through October for two years, 1974 and 1975.
Presented here are data for microcrustacean populations only in one channel
where there was no fish predation. Planktonic rotiferan populations, although
numerous at times, contributed only a small portion to the total zooplankton
biomass and were relatively unimportant as food for fish (except as a first
food for larvae).
MATERIALS AND METHODS
Zooplankton are known to have patchy distributions in nature, which often
makes representative sampling difficult. An additional difficulty is that
shallow-water ecosystems often contain many species adapted to benthic habitats.
Furthermore, many littoral species are benthic during the day and migrate into
the plankton of the more open water during the night (Hutchinson, 1967). To
sample a shallow-water ecosystem representatively, investigators must take
large-volume samples or many small samples (preferably at night) spaced
throughout the study area.
Many small samples provide the more accurate estimation of patchiness,
but they are often costly to obtain and analyze. In this study, assessment
19
-------
of patchiness was not an objective, so composite sampling and large-volume
sampling were effectively used to factor out patchiness.
Several types of sampling methods were considered. Plankton traps and
water bottles were judged not appropriate for this study because of the
large number of samples needed to obtain large composite volumes (>1 m3) and
high numbers of individuals. Use of a plankton pump was considered. Large
volumes could be obtained more rapidly and many locations within a channel
could be sampled, but the pump would require two operators. The method
selected was that of towing a plankton net horizontally by hand along the
length of each pool and combining all pool samples. The advantages of the
net were that: (a) it sampled volumes of up to 15 m3, approximately 3%
of the total channel volume; (b) it sampled at a constant depth when towed
horizontally; (c) it simplified collection of samples by one person; and
(d) it collected large amounts of plankton, which made subsampling more
convenient and enumeration more accurate than would be possible with small
samples.
Samples were collected with a 0.3 m diameter, No. 10 (153 y mesh) plankton
net. Copepod nauplii and small immature ostracods were the only microcrusta-
ceans shown to pass through the No. 10 net. Its efficiency was assumed to be
0.85 (after Cummins, 1969). Estimate of volume filtered, 4.1 m3, was judged
to be precise, since the distance walked in towing could be measured accurately
and replicated.
A preliminary test was conducted to assess zooplankton diel periodicity,
sampling reproducibility, and enumeration error so that an efficient sampling
routine could be determined. A nested experimental design was used over a
24-hour sampling period in December 1974. The nesting consisted of twelve
sampling times a day (every other hour), at which four samples were collected,
and of two subsample enumerations of each sample. Samples were collected at
a constant depth of 0.2 m and distance from the channel wall of 0.5 m. All
species showed overwhelming diel periodicity (shown only for the dominant
species, Simooephalus, in Figure 6). A Nested-ANOVA gave the variance
components of 84% due to sampling time, 7% due to sample replication, and 8%
due to enumeration error. Only 13% of the Simocephalus collected were taken
during daylight hours. The zooplankton concentrate near vegetation during
the daytime (i.e., attached wall algae, rock areas, and Chora in pools) and
most species migrate from these daytime habitats at night (unpublished data).
Time of day is thus critical to sampling success.
All samples for this study were collected two hours after sunset on
the nights of full and quarter moons. Hall, et al., (1970) found it necessary
also to sample at night and noted similar diel phenomena in shallow
experimental ponds. Zooplankton are more evenly distributed during dark
hours so that sampling at night is more efficient and collections are more
representative of existing populations than are daytime collections.
Zooplankton counts were converted to biomass using literature values
for individual dry weights (Hall, et al. , 1970). Although time and equipment
did not allow direct dry-weight determinations, biomass estimates were
necessary because future studies will relate zooplankton standing crop to
20
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fish feeding patterns. Dry weights for taxa not given by Hall were approxi-
mated by size comparison with taxa of known weight. Average weights of
cladoceran species were approximated by assuming a one-to-one ratio of adults
to juveniles. Adult copepod species (mostly Mesocyclops edax) were combined
intp one category and given an average dry weight of 12 yg. The counts of
species within the genera Cepi,odaphnia3 Daphnia3 and Simooephalus were
combined by genus for the biomass conversions.
Microcrustacean populations in Wheeler Reservoir were compared with
those in the channels through data obtained from the Nuclear Compliance
Monitoring Program, Water Quality and Ecology Branch, Division of Environmental
Planning, TVA. Samples taken in duplicate on three dates in the reservoir,
upstream and downstream from the channel intake water pump in 1974 and 1975,
provide the data for these comparisons.
RESULT?
Table 4 lists the species found in the channels through 1975. The dry
weights used to convert counts to biomass for dominant species are given.
Leptodora and Diaphanasoma (common in the reservoir) were also present but
are not included, as these species occurred only when the channel flows were
adjusted nearly to zero. It appears that normal channel flows are sufficient
to inhibit these two species. The species present are typical of shallow-
water or littoral zooplankton communities. A revised list for 1976 would
include several new colonizing species; most notable are Daphnia ambigua3 D.
catawbdj and D. parvula. Also, the abundance of many benthic chydorid
species increased in 1976, especially in channels with fish predation.
Figure 7 depicts seasonal changes in total microcrustacean plankton
abundance and dry weight biomass for the months sampled in 1974 and 1975.
Zooplankton densities were relatively low in 1974 and high in 1975. The
decline in zooplankton in 1974 corresponded with the colonization of
filamentous algae which reached nuisance proportions by July (see Section 4).
In 1975 the algae declined and beds of Chora became established in pool areas.
It is apparent that dense algal growths drastically prevented zooplankton
colonization, since only in the absence of such growths did it proceed. Had
growths of filamentous algae continued heavy in 1975, the cause/effect
relation between the algae and zooplankton could have been investigated. As
it was, algal densities were not high in 1975, and no definitive comment can
be made as to cause and effect. Other factors such as anoxia, increased pH,
or H2S toxicity could have been instrumental in causing the observed
zooplankton decline, either directly or indirectly, solely, or as a complement
to the algal abundance.
Figure 7 also presents abundance data for total microcrustacean plankton
collected from the reservoir in the vicinity of the intake which serves as
the water source for the channels. In 1974 the abundance was low in the
channels compared with that of the reservoir, but it was similar or higher
in 1975.
21
-------
Figure 8 shows water temperature in the channel and abundance data for
individual species. The water temperature was taken with a continuous
recorder. After May 1974 there were no microcrustacean plankton populations
established of any significant density. In 1975 zooplankters of several
species were abundant. Ostracods, absent in 1974, colonized in 1975. Daphniaa
Ceriodaphnia, and Bosmina showed the most striking increases in abundance in
1975. Copepod densities were similar in the two years. Also depicted in
Figure 8 are densities of Daphnia, Bosmina, and copepods from Wheeler
Reservoir. The channel was similar to the reservoir in terms of Bosmina and
adult copepod populations. The dominant copepod in both ecosystems was
Mesocyelops edax.
Figure 9 shows the species composition (percent occurrence) in terms of
both numbers and biomass for the dominant species given in Figure 7. Data
are given for both parameters because biomass alone may overemphasize the
importance of large individuals, and numbers alone may overemphasize the
importance of small, numerous individuals. In terms of numbers, the small
species, Bosmina, was overwhelmingly dominant in 1974, but in 1975 no single
species dominated numerically. Ostracods became established after being
absent in 1974. In terms of percentage biomass, Figure 8 shows that
Simoeephalus dominated alone in 1974. Daphnia, Simooephalus3 and ostracods
made up most of the community biomass in 1975. The community composition
became more diverse and equable in 1975 compared to 1974.
Table 5 summarizes all the data and presents an overall picture of
zooplankton colonization. Shown are yearly average microcrustacean
percentage occurrences in terms of numbers and biomass for the channel and
numbers only for the reservoir. About 77% of the reservoir microcrustaceans
were Bosmina followed by copepods at about 20% (for the dates sampled). In
the channel in 1974 Bosmina (47%) was numerically dominant followed by
Simooephalus (18%) and Chydorus (15%). In 1975 Bosmina (29%), Simooephalus
(5%), and Chydorus (10%) all decreased in dominance. Groups becoming more
extensively colonized in 1975 were ostracods (22%), Ceriodaphnia (13%),
Daphnia (10%), and copepods (10%). In 1975 five species each represented
over 10% of the total community biomass; however, there were only two such
species in 1974.
DISCUSSION
The microcrustacean plankton colonizing the channels showed establishment
of increased diversity with time. The lack of equability in 1974 is shown
in that Bosmina dominated numbers and Simooephalus dominated biomass.
Pioneer ecosystems typically undergo such succession leading to diverse
assemblages of biota (Odum, 1973). It is evident that by late 1975, almost
two years after colonization began, there was a well-structured zooplankton
community in the channel. Although the ecology of individual species has
not been discussed in detail here, it can be concluded that the zooplankton
community in the channel was represented primarily by shallow-water forms.
The success of the channels in simulating a reservoir ecosystem can be
judged in part by the diversity of biota that become colonized. For
22
-------
zooplankton investigations, the channels offer ecosystems that are relatively
easy to study but that are still as complex in species composition as most
natural ecosystems. The channels were constructed with distinct areas of
silt pools and limestone rocks to offer habitat diversity to colonizing
organisms. It has become increasingly evident that spatial heterogeneity in
ecosystems correlates directly with species diversity (e.g., MacArthur, 1972),
The channels are successful in terms of their potential usefulness for
studying zooplankton ecology under controlled seminatural conditions.
23
-------
DARKNESS 1650 TO 0630 MRS.
1150
920
690
cr
UJ
m
460
230
COUNTS11 SO
50
tfi
UJ
40
CD
30
2O
tt
UJ
m
10
1400 1800 2200 0200 0600
HOUR OFDAY(DEC. 1974)
1000
1400
Figure 6. Diel periodicity of Simocephalus vetulus (large cladoceran)
in a channel during the winter. Diel temperature ranges on the
sampling date (December 1974) were 7-15 C air and 5.5-7.5 C water.
Four samples were collected every other hour for a 24-hour period by
towing a 0.3 m diameter plankton net horizontally the entire length
of the channel (112 m) at a constant depth of 0.1 m and a constant
distance from the channel wall of 0.5 m.
24
-------
TABLE 4. MICROCRUSTACEAN- PLANKTON FOUND IN CHANNELS AS OF 1975. INDIVIDUAL
DRY WEIGHTS IN MICROGRAMS FOR CONVERTING COUNTS TO BIOMASS ARE GIVEN FOR
DOMINANT SPECIES
Group
Species
Dry Weight (yg)
Daphnidae
Sididae
Bosminidae
tfecrothricidae
Chydoridae
Cyclopoida
Calanoida
Ostracoda
Simooephalus vetulus
S. serrulatus
Daplmia laevis
D. pulex
CeriodapTrnia retieu.la.ta
C. quadrangula
Moina affinis
Seapholeberis kingi
Sida crystallina
Latona setifera
Bosmina longirostris
Maorothrix rosea
Ilyooryptus spinifer
Chydorus sphaericus
C. globosus
Disparalona rostrata (Alonella r.)
Cconptooereus rectirostris (C. similus)
Euryoerous lamellatus
Kurzia latissima
Leydigia quadrangularis (L. leydigil
L. acanthocevcoides
Pleupoxus denticulatus
Alona sp.
Mesooyolops edax
Cyclops vernalis
C. bicuspidatus thomasi
Eucyclops agilus
E. prionophorus
Maorooyclops albidus
copepodites
Osphvantiaum labronectwn
Diaptomus sp.
(not identified)
30.0
30.0
21.5
21.5
3.2
3.0
1.4
1.5
12.0
2.0
18.0
5.0
25
-------
4OO
40000
- 30000
-20000.
OL
Ul
CD
- 10000
MAY JUN
JUL AUG
1974
SEP OCT
APR MAY JUN JUL AUG SEP
1975
Figure 7. Total microcrustacean plankton density (numbers/m^) and dry
weight biomass (mg/m3) in a channel for the 1974 and 1975 sampling
periods. Densities of Wheeler Reservoir microcrustaceans are given
for comparison. Channel density - solid circles; Channel biomass -
open circles; and, Reservoir density - solid triangles.
26
-------
APR MAY JUN JUL AUG SEP OCT
30
UJ 20
IS
e
u
i.
5
0
50OO
4OOO
3000
20OO
1000
0
10,000
8000
6000
E 4000
2OOO
0
ZSOO
200O
1900
IOOO
5OO
1974
1975
SIMOCEPHALUS
OSTRACODStNont In 1974)
974
310
975
1975
i i i
6,530
1975
5000
40OO
3000
2000
IOOO
0
5000
4OOO
3OOO
2000
IOOO
0
IO.OOO
8000
60OO
4000
2000
0
2500
200O
1500
IOOO
5OO
APR MAY JUN. JUL AUG SEP OCT
COPEPODSlAduItt aimnwturts)
o
1974
1975
APR MAY JUN JUL AUG SEP OCT
APR MAY JUN JUL AUG SEP OCT
Figure 8. Water temperature and density of the seven dominant taxa in
one channel for the 1974 (solid circles) and 1975 (solid triangles)
sampling periods. Wheeler Reservoir densities for the three taxa
Daphnia, Bosmina, and copepods (open circles - 1974; open triangles -
1975).
27
-------
ioo-
PERCENT NUMBERS
50-
1974
MISC.
CHYDORUS
BOSMINA
COPEPOOS
CERIODAPHNIA
DAPHNIA
SIMOCEPHALUS
PERCENT BIOMASS
-KX)
4-50
I MAY I JUN I JUL I AU6 I SEP I OCTl
I MAY I JUN I JUL I AU6 I SEP I OCTl
100-
PERCENT NUMBERS
50 —
1975
MISC.
CHYDORUS
OSTRACOOS
BOSMINA
PERCENT BIOMASS
100
COPEPOOS
CERIODAPHNIA
DAPHNIA
SIMOCEPHALUS/
I
APR ' MAY ' JUN ' JUL ' AUO
0
1 APR ' MAY ' JUN ' JUL ' AU6
Figure 9. Species composition in terms of percent numbers and percent
biomass for 1974 and 1975 sampling periods.
28
-------
TABLE 5. AVERAGE PERCENT RELATIVE ABUNDANCE IN TERMS OF NUMBERS AND BIOMASS
IN ONE CHANNEL AND IN TERMS OF NUMBERS IN WHEELER RESERVOIR. THE AVERAGES
ARE FOR MAY THROUGH OCTOBER (NINE DATES) IN 1974 AND APRIL THROUGH
SEPTEMBER (ELEVEN DATES) IN 1975. 3DATA COLLECTED IN APRIL, JULY, AND
OCTOBER WERE AVERAGED FOR THE RESERVOIR PERCENT RELATIVE ABUNDANCE
Channel Microcrustacean Zooplankton
Bosmina longirostris
Simocephalus vetulus, S. serrulatus
Daphnia laevis, D. pulex
Ceriodaphnia reticulata, C. quadrangula
Chydorus sphaericus
Copepodg (adults and immatures)
Ostracods
Others
Reservoir Microcrustacean Zooplankton
Bosmina longirostris
Copepods (adults and immatures)
Diaphanasoma leuchtenbergianwn
Leptodora kindtii
Daphnia retroaurvaj D. parvula
Moina minuta
Others
Percent
Numbers
1974
47
18
3
7
15
7
-
3
79
16
3
1
1
1
1
1975
29
5
10
13
10
10
22
2
75
23
2
1
1
1
1
Percent
Biomass
1974 1975
12 13
64 21
5 25
5 9
3 2
9 12
16
2 2
Data furnished from the Nuclear Compliance Monitoring Program, Water Quality
and Ecology Branch, Division of Environmental Planning, TVA.
29
-------
SECTION 6
MACROINVERTEBRATES
SCOPE
Since summer 1974, studies of macroinvertebrates in the biothermal
channels were directed, in large part, toward identifying naturally colonizing
species and determining their rates of invasion and subsequent changes in
population size. No species were introduced artificially; all were immigrants
either by way of Tennessee River water, air, gravid-female adults, or invasion
across land. In two cases, organisms were transferred artificially from one
channel to another. Crayfish (Orconectes immunis), which initially invaded
only one channel, were distributed to other channels but did not reproduce,
and snails (Physa heterostropha) were introduced to one channel which was
lacking them.
MATERIALS AND METHODS
All twelve channels were observed and sampled, even though they differed
in presence or absence of fish, presence of the same species or numbers of
fish, or times at which they were drawn down or refilled. The sampling carried
out was indicative, nevertheless, of certain trends or lack of trends.
Three main sampling techniques were employed. These reflect the three
main habitat types present in the channels—pool areas, rock areas, and walls.
Pools were sampled with a sediment corer made of a piece of PVC pipe of 23.76
on2 cross-sectional area. Twelve cores comprised a sample in any one pool on
a particular sampling date. Rock areas were sampled with rock-filled
galvanized trays of 0.09 m2 area on which organisms were allowed to colonize
for month-long periods. Three trays were placed across each rock area to be
sampled. Rocks were scrubbed with a soft brush to remove attached organisms.
Invertebrates associated with algal growths on channel walls were sampled with
a specially constructed scraping device with an attached net bag; this device
sampled an area of 0.25 m2. Two scrapings were taken from each wall area
sampled.
All samples were washed in a No. 70 sieve and were frozen; when thawed,
organisms were sorted and counted. A representative subsample of each species
present was freeze-dried and weighed.
One experiment was designed specifically to evaluate the recolonization
of macroinvertebrates during winter, since this is the period that will be of
30
-------
particular importance in heated-water experiments. Three channels were drawn
down November 5, 1975, leaving approximately 0.5 m of water remaining in pools.
The channels were refilled two months later, at which time a six-week sampling
program was begun. Three sets of wall scrapings were taken at two-week intervals
(January 22, February 4, and February 20, 1976). On each sampling date two
scrapings each were taken from the inlet pool, the 44-m pool, and the outlet
pool of each of the three channels.
RESULTS
A list of all macroinvertebrates identified during the colonization
period is presented in Table 6. Most taxa present in the channels in October
1976 were present at least intermittently during the colonization period
(Table 7). Not all organisms present were sampled by the three standard
sampling techniques outlined. The invasion of certain taxa was observed by
simpler means. Odonates were observed emerging along the channel walls and
were subsequently seen laying eggs in the channels. Fifteen anisopteran
and one zygopteran species were identified from exuviae and netted adults.
These were identified to order in quantitative samples. Five of the
anisopteran species were present during the summer of 1974. In both 1975
and 1976, 14 were emergent, 2 species having disappeared while 2 more invaded.
The one zygopteran species was present throughout the colonization period.
Isolated Plumatella masses were found along the walls in the summers of
1975 and 1976. Two of the bivalve molluscs, Eliptio crassidens and Leptodea
fpagilis were not sampled in cores but were found on the sediment near the
inlets of drawn-down channels early in 1976. Oroonectes immunis was found
in drawn-down channels in spring 1975. Gravid females distributed to
another channel were unsuccessful at reproducing, which may be fortunate in
light of evidence of the impact of crayfish feeding and resultant competition
with fish in an aquatic system (Magnuson, et al., 1975).
The exuvium from one stonefly (family Perlodidae) was found at the outlet
end of one channel in May 1975. This was the only evidence of the presence of
Plecoptera in the channels. Certain Hemiptera and Coleoptera were captured
only by hand netting. Belastoma sp., Ranatra sp., and Mesovilia sp. were not
seen until the summer of 1976. Dytiscidae invaded in 1975. Several of the
Trichoptera were found either only at the channel outlets where the current is
swift (Chimarra obscura^ Cheumatopsyehe speci-osa, and Hydropsyche betteni), or
only as adults on the channel walls (Athripsodes caneellatus3 Oecetis -inconspicua,
and Neurecl'ips'is orepuscular-Ls). These all colonized the channels when they
were first filled. All other Trichoptera were sampled as larvae by standard
mathods. The only Diptera present that were not taken in regular samples were
the Simuliidae which inhabit the swift-flowing outlet areas and the Tabanidae
which were found in floating algal mats. Both were present beginning in 1974.
Certain genera sampled by the regular techniques were found shortly
following initial filling of the channels but were not found subsequently,
whereas the reverse was true for other genera. Two coleopterans, Ceroyon
and Tropisternus3 were collected on rock areas in summer 1974 but not since.
31
-------
The disappearance of these genera was accompanied by the introduction of
others. Gastropod mollusc genera increased from one (Physa heterostropha)
to five, with the appearance of Pyrgulopsis sp. and Pleurooera oanalioulatwn
in September 1975 and Lyrrmaea sp. and Helisoma sp. in February 1976. All of
these were collected in wall scrapings. Notoneota sp. was also first seen
in wall scraping samples in September 1975. One ephemeropteran, Baetis
bioaudatus and two trichopterans, Orthotriohia sp. and Oxyeth-ira sp. appeared
in wall scrapings in August 1976. The leech, Placobdella montifera appeared
in rock trays in late September 1976.
There was great overlap in species collected in all three habitats
sampled but certain organisms were found in only one habitat. Anodonta
•irribecilis and Corbioula manilensis were found only in pool areas. Enallagma
sp. and Libellula sp. were collected only in rock areas but could probably
have been found with more intensive sampling in pools and along the walls.
Tramea onusta was collected only in wall scrapings but probably inhabited
other areas as well. Notoneota sp., which was found in wall scrapings, is
probably also present in rock areas and is often seen in open water.
Most of the invertebrate populations in the channels reached a peak
population density followed by a decline and by subsequent leveling off
(Table 8); others showed either upward or downward trends on the final
sampling date. For pool areas, this final date was August 21, 1975, so that
estimates are not inclusive of the whole colonization period, However, with
the exception of the bivalve molluscs and Eexagenia3 abundance peaks and
population trends of all the organisms in pool areas are reflected also in
density figures of rock and/or pool areas so that all dates in the table are
accurate.
Several organisms showed downward trends in population size at the end
of the colonization period: Erpobdella punotata and Helobdella sp.,
Rexagenia b-ili,neata3 Notoneeta sp., and Covbioula manilensis. Organisms
showing population size increase were the Amphipoda, Gastropoda, and
Anodonta i-mbee-il-ls.
In the recolonization experiment certain organisms showed increased
density following channel refilling, while others showed no particular
change. Significance of change was shown by use of the Wilcoxon matched-pairs
signed-rank test. Amphipoda showed increased densities on both the second
and third sampling dates while chironomids and gastropods increased in
density between the first and third, and second and third, but not the
first and second sampling dates (Table 9). These were the only organisms
showing numerical change. There was an increase in the summer biomasses of
the invertebrates other than the Gastropoda but these changes were not
statistically significant (Table 9).
DISCUSSION
The most abundant organisms to colonize the channels as determined from
artificial substrates and core sampling were: Oligochaeta, Corbiaula
manilens-is (Pelecypoda), Erpobdella punotata (Hirudinea), Hyalella azteoa
32
-------
and.Crangonyx sp. (Amphipoda), Caenis sp. (Ephemeroptera), and Chironomidae
(Diptera). Odonates and Eexagenla bilineata (Ephemeroptera) were also common
as determined from exuviae that were collected from the channel walls and
water surfaces.
Diversity of macroinvertebrates in the biothermal channels is similar to
that in large mainstream reservoirs when both deep water and littoral zones
are considered. However, certain organisms dominating reservoir fauna are
not dominant in the channels and vice versa. Composition of pool areas in
the biothermal channels is similar to that in reservoir open water areas,
but with lower densities of Rexagenia. Rock and wall areas in the channels
show much greater invertebrate diversity than pool areas and are similar to
littoral areas in reservoirs in having a greater number of anisopteran
odonate species and greater densities of Amphipoda than open-water areas of
reservoirs.
33
-------
TABLE 6. MACROINVERTEBRATE TAXA IDENTIFIED IN BIOTHERMAL CHANNELS DURING
COLONIZATION PERIOD
Porifera
Hydrazoa
Ectopr'octa
Nematoda
Platyhelminthes
Turbellaria
Mollusca
Pelecypoda
Gastropoda
Pulmonata
Spongilla sp.
Hydra sp.
Pluma-tefLa sp.
Dugesia tigvina
Anodonta irribecilis
Eliptio arassidens
Leptodea fragilis
Corbicula manilens-is
Physa heterostropha
Lymnaea sp.
Planorbidae
Ctenobranchia
P~ieurocera aanal-icu'lata
Pyrgulopsis letsoni.
Aniielida
Oligochaeta
Hirudinea
34
-------
TABLE 6 (continued)
Helobdella sp.
Erpobdella punetata
Plaoobdella mont-Lfera
Arthropoda
Crustacea
Decapoda
Amphipoda
Orconeetes irrmunis
Hyalella azteca
Crangonyx sp.
Arachnida
Hydracarina
Insecta
Collembola
Ephemeroptera
Heptageniidae
Stenonema sp.
Ephemeridae
Hexagenia bilineata
Baetidae
Baetis bicaudatus
Callibaetis fluctuans
Caenis sp.
Odonata
Anisoptera
Gomphidae
Dromogomphus spoliatus
35
-------
TABLE 6 (continued)
Libellulidae
Epioordulia princeps
Epicordulia vegina
PaohydLplax long-ipennis
Erythemis simplicicolHs
Libellula pulchella
Libellula luctuosa
Libellula forens-is
Plathemis lydia
Perithemis tenera
Pantala hymenea
Pantala flavesaens
Tramea onusta
Maoromia taeniolata
Maaromia -ill-ino-lensis
Zygoptera
Coenagrionidae
Enallqgma civile
Plecoptera
Perlodidae
Hemiptera
Belastomatidae
Belastoma sp.
Nepidae
Eanatva sp.
Notonectidae
Notoneota sp.
Mesoveliidae
Mesovelia sp.
Trichoptera
Philopotamidae
36
-------
TABLE,6 (continued)
Chimarra obsoura
Psychomyiidae
Cyrnellue fraternus
Neurealipsis arepuscularis
Hydropsychidae
Cheimatopsyche speeiosa
Hydropsyche betteni
Hydroptilidae
Eycbcopt-ila waubes-Lana
Orthotin,ohia sp.
Oxyethira sp.
Leptoceridae
Athripsodes oancellatus
Oecet-is -Lnoonsp-Lcua
Coleoptera
Hydrophilidae
Ceroyon sp.
Berosus sp.
Tropisternus sp.
Dytiscidae
Diptera
Simuliidae
Chironomidae
Chironominae
Glyptotendipes sp.
Diorotendipes fumidus
Diarotendipes modestus
Paratany.tapsus sp.
Orthocladiinae
37
-------
TABLE 6 (continued)
Cricotopus (Isooladius) Sylvestris
group
Pseudosmitt-La sp.
Tanypodinae
Tanypus (Apelopia) neopunatipennis
Ceratopogonidae
Probeszia sp.
Tabanidae
Chrysops sp.
Blephariceridae
38
-------
TABLE 7. MACROINVERTEBRATE TAXA OBSERVED IN THREE SAMPLE AREAS ON SUCCEEDING DATES
Rocks Pools Walls
^3" •>3"
"•d". Is** LO LO iO i-O IO vO *^" r** LO lO iO LO tO to IO VO vO vO vO
Dugesia sp. ****** * * ***
Spongi-lta sp.
Hydra sp. * *
Nematoda ***** * ***
Oligochaeta ******* ******** *** *
*° Erpobdella • punotata ****** ******** ***
Helobdella sp. ******* **** *
Hydracarina * * *
Amphipodat ******** * ***
Crangonyx sp. * *
Hyalella azteca * * * * * *
Collembola * *
Eexagenia b-Llineata * * * * * * *
Stenonema sp. ** * ****
Caenis sp. ******** ******** ****
Callibaetis fluctuans ***** *
Epioordulia sp. * * * * *
-------
TABLE 7 (continued)
Rocks Pools Walls
Erythemis simplicicollis
Pantala sp.
Plathemis lydia
Tvamea onusta
°Enallagma civile
Corixidae
Notoneata sp.
Berosus sp.
Cevoyon sp.
Tropistemus sp.
Hydroptila waubesiana
Afhripsodes oanoellatus
Cyrnellus fraternus
Probezzia sp.
Chironomidae
Chrysops. sp.
* * * * *
* * * * *
*
* * * * * *
* ******
* *
* *
*
*
* * * * *
*
* . * * *
******
********
*
*
* *
*
*
* *
* * * * * * *
* *
* * * *
* * * * *
* *
******* *
******** * * * * *
-------
TABLE 7 (continued)
Rocks Pools Walls
si-
ioioiovo -3-1— 101/110101010 lovo^ovovo
r- i~~ i— r-- r-. ^^ r^i— r^-i^-r^-r^- i^.i^r~-i^r^
r~-oocriCN r^-iHrHCMiovor^oo o> 1-1 CN sf in
Belepharlceridae *
Gastropodat ******** ********
i |
Lymnaea sp. * *
Physa heterostropha *****
Pyrgulopsis letsoni * * * *
Plewcooeva canal-Loulata
Helisoma *
Pelecypodat *
Anodonta irrbecilis * * * *
Corbioula manilensis *.* * * * * * *
t Taxon used before genera were identified.
-------
TABLE 8. POPULATION TRENDS OF TAXA SAMPLED IN CHANNELS BETWEEN SUMMER, 1974 AND SPRING, 1976
to
Date of Peak
Abundance Habitat
Dugesia sp.
Nematoda
Oligochaeta
Erpobdella punctata
Helobdella sp.
Amphipoda
Hexagenia b-it-Lnsata
Stenonema sp.
Caenis sp.
Callibaet-is fluotuans
Anisoptera
Enallagma oivila
Corixidae
Notonecta sp.
Bex>osus sp.
Hydroptila waubesiana
10/74
1/75
1/75
7/75
7/75
2/76
2/75
10/74
12/74
9/75
10/74
10/74
7/75
9/75
2/75
10/74
rocks
pools
pools
pools
pools
rocks
pools
rocks
pools
walls
rocks
rocks
rocks
walls
pools
rocks
Estimated Direction of Approximate Stable
No./m2aat Population Population Density (No./m2)
Peak Density Change Spring 1976
603
420
10,276
1,192
193
3,194
35
9
3,753
45
24
14
241
9
35
340
1 cv20
1 ^ MO
1 ^ i/lOO
1
1
t
I
— »* ^
!_». ^50
I—*. ^5
1
| ^. o-10
1 ^ ^5
1 ^. %2
1
L^. ^2
1 ^. %5
-------
TABLE 8 (continued)
Date of Peak
Abundance Habitat
Cyrnellus fraternus
Pvdbezzia sp.
Chironomidae
Gastropoda
Anodonta -imbeoilis
Corbicula manilensis
8/75
12/74
5/76
5/76
8/75
7/75
rocks
pools
walls
walls
pools
pools
Estimated Direction of Approximate Stable
No./m2 at Population Population Density (No./m2)
Peak^ Density Change"3 Spring 1976
63
420
1,001
532
113
6,039
1
1— ^ ^20
t
t
t
1
Mean of all samples taken in a particular habitat on one date.
Explanation of symbols.
T = Increase
T = Decline
I ^ = Decline and leveling off
-------
TABLE 9. NUMBERS AND DRY WEIGHTS (mg) OF ORGANISMS PER m2 ON WALL AREAS ON SUCCESSIVE SAMPLING DATES
IN 1976. (1: JANUARY 22, 2: FEBRUARY 4, 3: FEBRUARY 20). DATA REPRESENT TWO SAMPLES PER WALL
AREA, AVERAGED AMONG THREE CHANNELS
a)
n)
0)
fc
H
D5
Mean numbers per m2
AMPHIPODA
Sampling Date
1
1 24
1 36
3 184
3 76
6 16
6 16
1-2*
2-3*
1-3*
2
344
468
284
184
48
96
3
888
1016
592
316
140
152
CHIRONOMIDAE
Sampling
1
- 1 92
8 1 236
< 3 363
rH 3 371
3 6 245
6 115
1-2 ns
1-3*
2-3*
2
160
169
535
701
400
256
Date
3
1180
1036
1388
2120
728
956
GASTROPODA
Sampling Date
cfl
-------
REFERENCES
Biswar, S. 1969. The Volta Lake: Some ecological observations on the
phytoplankton. Verh. Int. Ver. Limnol. 17: 259-272.
Cummins, K. W., R. R. Costa, R. E. Rowe, G. A. Moshiri, R. M. Scanlon,
and R. K. Zajdel. 1969. Ecological energetics of a natural population
of the predaceons zooplankter Leptodova k-indt-L-L Fock (Cladocera).
Oikos 20: 189-223.
Funk, W. H., and A. R. Gaufin. 1971. Phytoplankton productivity in a
Wyoming cooling-water reservoir. Pages 167-178 In G. E. Hall, ed.
Reservoir fisheries and limnology. Spec. Publ. No. 8. Amer. Fish.
Soc., Washington.
Hall, D. J., W. E. Cooper, and E. E. Werner. 1970. An experimental
approach to the production dynamics and structure of freshwater animal
communities. Limnol. Oceanogr. 15(6): 839-928.
Hutchinson, G. E. 1967. A treatise on limnology. Vol. II. Introduction
to lake biology and limnoplankton. John Wiley & Sons, Inc., New York.
1115 pp.
Hutchinson, G. E. 1975. A treatise on limnology. Vol. III. Limnological
botany. John Wiley & Sons, Inc., New York. 660 pp.
Leentvaar, P. 1966. The Brokopondo Lake in Surinam. Verh. Int. Ver.
Limnol. 16: 680-684.
MacArthur, R. H. 1972. Geographical ecology. Harper and Row, New York.
269 pp.
Magnuson, John J., Gregory M. Capelli, James G. Lorman, and Roy A. Stein.
1975. Consideration of crayfish for macrophyte control. Rept. No.
ENV 07-75-1 Univ. of Florida, Gainesville.
Odum, E. P. 1971. Fundamentals of ecology (3rd ed.). W. B. Saunders Co.,
Philadelphia. 574 pp.
Rodhe, W. 1964. Effects of impoundment on water chemistry and plankton
in Lake Ransaren (Swedish Lappland). Verh. Int. Ver. Limnol. 15: 437-443.
Wetzel, R. G. 1975. Limnology. W. B. Saunders Co., Philadelphia.- 743 pp.
Zhadin, V. I., and S. V. Gerd. 1961. Fauna and flora of the rivers, lakes,
and reservoirs of the U.S.S.R. Keter Press, Jerusalem.
45
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-78-020
3. RECIPIENT'S ACCESSION-N.0.
4. TITLE AND SUBTITLE
Browns Ferry Biothermal Research Series I.
Colonization by Periphyton, Zooplankton, and
Macro-Invertebrates
5. REPORT DATE
February 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Brian J. Armitage, Thomas D. Forsythe, Elizabeth B.
Rodgers, and William B. Wrenn
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Tennessee Valley Authority
FF&WD - Biothermal Research Facility
P.O. Box 2000
Decatur, Alabama 35602
10. PROGRAM ELEMENT NO.
1BA608
11. CONTRACT/GRANT NO.
TV-35013A
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory—Duluth, MN
Office of Research and Development
U.S. Environmental Protection.Agency
Duluth, Minnesota 55804
13. TYPE OF REPORT AND PERIOD COVERED
Interim
14. SPONSORING AGENCY CODE
EPA/ 600/03
15. SUPPLEMENTARY NOTES
Research performed in cooperation with Tennessee Valley Authority, Morris, Tennessee
37828
16. ABSTRACT
Colonization studies on a series of 12 outdoor experimental channels supplied with
water from Wheeler Reservoir (Tennessee River) were completed at the Browns Ferry
Biothermal Research Station in Alabama. Species composition, dominance, seasonal
patterns, colonization rates, and biomass estimates were determined over a 24-month
period for periphyton, zooplankton, and macroinvertebrates. In general, the
species composition and the relative densities of algal and invertebrate organisms
that colonized the channels indicated that the channels successfully simulate
reservoir ecosystems for those trophic levels.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
Zooplankton
Colonization
Experimental channels
Periphyton
Macroinvertebrates
50 B
68 D
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