H') SUGGESTED ECOLOGICAL RESEARCH
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Copies of this document are available
to the public through the
National Technical Information Service
Springfield, Virginia 22161
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A STATEMENT OF CONCERNS AND
SUGGESTED ECOLOGICAL RESEARCH
REPORT NO. 1
OF THE
LAKE MICHIGAN COOLING WATER STUDIES PANEL
THE PANEL IS SUPPORTED BY THE
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION V, CHICAGO, AND THE
POLLUTION CONTROL AGENCIES OF
ILLINOIS, INDIANA, MICHIGAN, AND WISCONSIN
EDITED BY
CALDWELL D. MEYERS
AND
KARL E. BREMER
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QUALIFYING STATEMENT
The Panel does not unanimously recognize nor endorse
all concepts and recommendations in each section of this
report.
This report is the result of many months of thought,
discussion and work by the Section authors. Their objec-
tive has been to produce a statement of concerns which
would assist in development of investigations of the effects
of cooling water use on Lake Michigan. The priority lists
are an attempt to focus further on key gaps in understanding.
It is hoped that this report will spark research, help
realize goals, and provoke discussion leading to continuing
modification of its content. Such modification is anticipated
and is a desirable result of its production. It is a working
document.
The Panel fully recognizes the many implications this
report carries to cooling water users and to those responsible
for regulation. However, this report is not intended to be
a regulatory document.
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SECTION AUTHORS
Section I Introductory Considerations of Lake Michigan
Caldwell D. Meyers
Section II Data Requirements Related to Lake Michigan Studies
Caldwell D. Meyers
Jerrold H. Zar
Andrew J. McErlean
Section III Measurement of the Effects of Cooling Water Use
on Physical Parameters
John Z. Reynolds
Wesley 0. Pipes
Howard Zar
Clifford H. Mortimer
Barton M. Hoglund
Section IV
Measurement of the Effects of Cooling Water Use
on Chemical Parameters
Wesley 0. Pipes
Carl T. Blomgren
John L. Winters
Section V Measurement of the Effects of Cooling Water Use
on Primary Producer and Consumer Communities
Eugene F. Stoermer
John Neess
Section VI
Measurement of the Effects of Cooling Water Use
on Macrozoobenthos
Carlos M. Fetterolf, Jr.
Merle H. Maass
Andrew J. McErlean
Alfred M. Beeton
Wesley 0. Pipes
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SECTION AUTHORS
(continued)
Section VII Measurement of the Effects of Cooling Water Use
on the Fishery
Thomas A. Edsall
Thomas G. Yocom
Section VIII Measurement of the Effects of Cooling Water Use
on Entrapped and Entrained Organisms
Arthur S. Brooks
James G. Truchan
John Z. Reynolds
James R. Gammon
Thomas A. Edsall
Section IX Radioecological Considerations Related to Cooling
Water Use
Phillip F. Gustafson
VI 1
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ACKNOWLEDGEMENTS
This report would not have been possible without the strength
and combined effort of the members and participants of the
Lake Michigan Cooling Water Studies Panel.
It is appropriate to recognize the wise counsel and thoughtful
help afforded the editors by Wes Pipes, Carlos Fetterolf,
Dick Herbst, Jerry Zar and Bob Otto toward this ultimate version
of Report No. 1. The Panel extends special appreciation to
Delores C. Sieja for secretarial assistance in final preparation
of the Report.
i x
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GENERAL TABLE OF CONTENTS
Qualifying Statement
Section Authors .
Acknowledgements.
List of Figures . ,
List of Tables .
General Introduction
Proposed Definitions with Application to
Lake Michigan
Section I
Section II
Section III
Section IV
Section V
Section VI
Section VII
Introductory Considerations of Lake Michigan
Data Requirements Related to Lake Michigan
Studies
Measurement of the Effects of Cooling
Water Use on Physical Parameters
Measurement of the Effects of Cooling
Water Use on Chemical Parameters
Measurement of the Effects of Cooling
Water Use on Primary Producer and Consumer
Communities
Measurement of the Effects of Cooling Water
Use on Macrozoobenthos
Measurement of the Effects of Cooling Water
Use on the Fishery
Section VIII Measurement of the Effects of Cooling Water
Use on Entrapped and Entrained Organisms
Section IX
Appendix
Radioecological Considerations Related to
Cooling Water Use
Comments of Members and Participants
of the Panel related to Report Number 1
. 111
v
ix
. xiii
xv
1
. 12
. 13
. 47
. 77
. 101
. 121
. 167
. 235
. 307
. 343
. 349
xi
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LIST OF FIGURES
Figure VII - 1. Principle problem areas associated with
power plant intakes . . 248
Figure VII - 2. Principle problem areas associated with
power plant discharges 249
Figure VII - 3. Suggested sampling stations for fisheries.
investigations of Lake Michigan 259
xiii
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LIST OF TABLES
Table I - 1. Dimensions of the Great Lakes ... 17
Table IV - 1. Water quality parameters to be considered
in site selection studies and monitoring studies. 105
Table IV - 2. Chemicals used in plant operation . . 106
Table IV - 3. Some atmospheric contaminants which
may appear in cooling tower recirculating water . 108
Table VI - 1. Estimates of abundance (number/m2), by
depth, of two benthic taxa from the central
and southern regions of Lake Michigan
1964 - 67 174
Table VII - 1. Fish fauna previously or currently
common to Lake Michigan 239
Table VII - 2. Gil 1 net specifications for various
mesh sizes 267
TableVIII - 1. Sample manipulation and comparison
to assess the effects of the power plant on
rate of primary production through the use of
14C uptake 322
xv
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GENERAL INTRODUCTION
Purpose of the Report
This report outlines scientific questions and some methods
that might be used to obtain answers regarding the ecological
effects of the intake and entrainment of water, the introduction
of waste heat, the introduction of specific chemicals, and the
release of radionuclides associated with condenser cooling. It
is anticipated that the report will produce improvements in re-
search design and a trend toward standardization of results. It
may also provide the basis for the selection of appropriate loca-
tions for more intensive research and for the possible generaliza-
tion of the results at those locations to wider areas of the Lake.
The Panel recommends priority research studies leading toward an
understanding of the whole Lake and designates specific studies
and their appropriate priorities.
Description and Objectives of the Panel^
The Lake Michigan Cooling Water Studies Panel is a technically
oriented group formed at the suggestion of representatives to
the joint public sessions of the Lake Michigan States and the U.S.
Environmental Protection Agency. In a message to the joint Federal-
State Conference of November 1972, the Regional Administrator of
EPA, Mr. Francis; T. Mayo, cited the need for development of 1)
monitoring programs to assess possible "damage to the aquatic en-
vironment of Lake Michigan attributable to existing and planned
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cooling water use, 2) criteria to trigger employment of appro-
priate corrective measures should damage become evident, and 3)
mechanisms with which to make an overall assessment of the damage
that may occur to the Lake's ecosystem from waste discharges
scattered at various points around the Lake. He then suggested
formation of a group to review these propositions and charged
them to:
-- review background information dealing with past, present
and future studies relating to thermal discharges to Lake
Mi chigan;
-- make assessments as to whether the individual studies
concerning thermal discharges will adequately assess damages
attributable to that cooling water use;
-- assess the pertinence of individual localized studies to
monitor changes in the overall lake ecosystem;
-- recommend, as necessary, additional efforts that should
be expended to assess environmental effects of the use of
Lake Michigan water for cooling.
This enjoinder and these charges have been accepted by the
Panel as objectives for its deliberations beyond production of
this report.
Actual formation of the Panel was put in motion by Mr. Mayo
in December 1972. The Panel consists of the following members,
alternates and contributors:
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Members and Alternates
State
ILLINOIS
Members:
Name
Mr. David D. Comey
Dr. Wesley 0. Pipes
(Until January 17,1975)
Mr. William V. Pye
(Until May 9,1974)
Mr. Thomas McSwIggin
Dr. Jacob Verduln
Affi liation
Businessmen for the
Public Interest,
Chicago, Illinois
Northwestern University,
Evanston, Illinois
Illinois Environmental
Protection Agency,
Springfield, Illinois
Illinois Environmental
Protection Agency,
Springfield, Illinois
Southern Illinois University
Carbondale, Illinois
Alternates: Mr. Carl T. Blomgren
Dr. John Neess
Illinois Environmental
Protection Agency,
Chicago, Illinois
University of Wisconsin,
Madison, Wisconsin
INDIANA
Members:
Mr. Gary Doxtater
Dr. James R. Gammon
Mr. John L. Winters
Aquatic Controls Inc.,
Seymour, Indiana
DePauw University,
Greencastle, Indiana
Indiana Stream Pollution
Control Board,
Indianapolis, Indiana
Alternate: Mr. Harold L. BonHomme
Indiana Stream Pollution
Control Board,
Indianapolis, Indiana
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State
Name
Af f i 1 iation
MICHIGAN
Members :
Mr. Carlos M. Fetterol f ,Jr.
Dr. John Z. Reynolds
Dr. E. F. Stoermer
Michigan Department of
Natural Resources,
Lansing, Michigan
Consumers Power Company,
Jackson, Michigan
University of Michigan,
Ann Arbor, Michigan
Alternates
WISCONSIN
Dr. Claire L. Schelske
Dr. James G. Truchan
University of Michigan,
Ann Arbor, Michigan
Michigan Department of
Natural Resources ,
Lansing, Michigan
Members: Dr. Alfred M. Beeton
Mr. Nicholas A. Ricci
(Until January 8, 1974)
Dr. Frank Boucher
Dr. Clifford H. Mortimer
University of Wisconsin,
Milwaukee, Wisconsin
Wisconsin Electric Power Co.,
Milwaukee, Wisconsin
Wisconsin Electric Power Co.,
Milwaukee, Wisconsin
University of Wisconsin,
Milwaukee, Wisconsin
Alternates
Dr. Arthur S. Brooks
Mr. Kenneth Lehner
(Until September 1, 1974)
Mr.Merle H. Maass
Dr. John Ney
University of Wisconsin,
Milwaukee, Wisconsin
Wisconsin Electric Power Co.,
Milwaukee, Wisconsin
Li nineties Inc . ,
Milwaukee, Wisconsin
Wisconsin Electric Power Co.,
Milwaukee, Wisconsin
FEDERAL"
Members:
Mr. Yates M. Barber
(Until August 30, 1973)
NOAA, National Marine
Fisheries Service,
Washington, D. C.
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State Name
FEDERAL(continued)
Members: Dr. Thomas A. Edsall
Dr. Philip F. Gustafson
Dr. Andrew J. McErlean
Affiliation
U. S. Bureau Sports
Fisheries and Wildlife,
Ann Arbor, Michigan
Argonne National Laboratory
Argonne, Illinois
U. S. Environmental
Protection Agency,
Washington, D. C.
Alternates: Dr. Donald L. McGregor
Mr. Barton M. Hoglund
(Until January 1, 1975)
Chai rman:
Techni cal
Secretary
Recording
Secretary
Mr. Karl E. Bremer
Mr. Caldwell D. Meyers
(Until October 1,1974)
Howard Zar
(Until June 1, 1974)
Ms. Marion Young
Argonne National Laboratory
Argonne, Illinois
Environmental Technology
Assessment,
Oak Brook, Illinois
U. S. Environmental
Protection Agency
Chicago, Illinois
U. S. Environmental
Protection Agency
Chicago, 111inois
U. S. Environmental
Protection Agency
Chicago, Illinois
U. S. Environmental
Protection Agency
Chicago, Illinois
Contributors
Dr. Wayne P. Alley
Mr. Jar! Hiltunen
Mr. Peter Howe
Mr. John H. Hughes
Mr. Gary MiIburn
California State University
Los Angeles, California
U. S. Fish and Wildlife
Service, Ann Arbor,Michigan
Commonwealth Edison Co.,
Chicago, Illinois
Commonwealth Edison Co.,
Chicago, Illinois
U. S. Environmental
Protection Agency
Chicago, 111inois
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Contributors
(continued)
Dr. Samuel C. Mozley University of Michigan,
Ann Arbor, Michigan
Dr. Robert G. Otto Industrial Bio-Test
Laboratories, Inc.
Northbrook, Illinois
Mr. Pete Redmon U. S. Environmental
Protection Agency,
Chicago, Illinois
Dr. James J. Reisa Council for Environmental
Quality, Washington, D. C.
Dr. Steven Spigarelli Argonne National Laboratory
Argonne, Illinois
Mr. Thomas Yocom U. S. Fish and Wildlife Service
Ann Arbor, Michigan
Dr. Jerrold H. Zar Northern Illinois University
DeKalb, Illinois
The Chairman, Technical Secretary, staff support, and fi-
nancial support for the Committee are contributed by Region V, EPA.
At the date of this writing, the Panel has had twenty-five
monthly meetings.
At the second Panel meeting on January 30,1973, the follow-
ing standing subcommittees were formed from the appointed Panel
members and alternates; Fisheries, Microbiology, Chemistry, Physical,
">*,
Benthos, Data Handling and Evaluation, Radioecology, and Entrainment
and Entrapment. Each of these Panel subcommittees consist of one to
six members permitting full use of the expertise of the individual
members to consider subdisciplinary problems, and for preparation of
this report. Alternates, observers, professional colleagues and
others interested in the future of the Lake also made substantial
contributions to the subcommittees, to the Report, and by extension,
to the effectiveness of the Panel.
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Priority Research
Most issues of water pollution resolve into conflict between
competing demands for use of a particular water resource. The issue
of thermal discharges to Lake Michigan reduces to an attempt to as-
certain the extent to which use of the Lake for cooling large stream
electric generating stations is compatible with the protection and
propagation of a desirable community of aquatic organisms and with
recreational use of the Lake. There is no doubt that Lake Michigan
will continue to be used for cooling, for aquatic life, and for
recreation; there is doubt that these uses are compatible at various
levels.
The Lake Michigan Cooling Water Studies Panel was formed as a
technical and scientific group to examine evidence relating to the
effects of cooling water use. As such, the Panel is not attempting
to determine the relative values of cooling use, aquatic life use,
and recreational use. These value judgments must perforce be made
by the citizens of the several states and their elected and appointed
representatives. The task of the Panel is to make recommendations as
to the types and value of scientific information available as an
input to the political, decision-making process.
Studies of the effects of cooling water use on Lake Michigan
have been in progress for over seven years. With few exceptions these
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studies have been oriented toward the local effects of individual
power plants. Studies commissioned and supported by individual
utility companies will, no doubt, continue to focus on local
effects. The needs recognized by the Panel provide a mechanism
for coordinating individual studies to develop information on
lakewide effects and to eliminate from individual studies those
elements either adequately explored or obviously unfruitful.
Since its inception, it was the intention of this Panel to
identify areas of ignorance which seem to be the most formidable
barriers to an adequate understanding of the effects of cooling
water use on the biota of Lake Michigan. Stated conversely, the
Panel focused on additional steps or research which, when accomplished,
would most rapidly increase our understanding of the effects of cool-
ing water use. Since it was difficult to isolate these areas of
research, the Panel used the following methodical approach:
1. Recognition of primary areas of ecological con-
cern by division of the Panel, and of its delibera-
tiWis, into eight subcommittees; e.g., Fisheries,
Physical, Chemical, etc.
2. Development of a research program to elucidate the
effects of cooling water use within those sub-
committees by discussion and deliberation based on
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knowledge, experience, published literature, and con-
sultation.
3. Development of priority lists, with appropriate
numerical values based on the availability of
relevant data, for those areas of knowledge which
are barriers to an adequate understanding of the
effects of cooling water use. (These lists have
been placed at the end of the appropriate sections)
The next step was to examine the priorities to which the Panel
has ascribed the highest degree of urgency and to attempt to select
several key issues. The criteria for selection of key issues were
that they be recognized (1) as steps facilitating the orderly use
of data for well documented answers to the remaining questions
about cooling water use or (2) as statements embodying the ultimate
goals of the Panel. The key issues identified are important to
all studies of cooling water use on Lake Michigan as a group but
all issues are not pertinent to any individual study. For instance,
the subcommittees on macrozoobenthos, plankton, and fisheries ob-
serve that although methods of identification of species and their
distribution in a local study area may be well-known, the absence
of such basic data for the Lake as a whole is recognized as a
very real barrier to the understanding of possible lakewide effects.
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The ultimate step was to obtain concurrence of the Panel in
selection of issues of highest priority and this has resulted in
the following, not necessarily in order of importance:
1. To determine the periods of time, and extremes and
average temperatures to which aquatic organisms are
exposed when they meet elevated temperatures in dis-
charge plumes and to evaluate available data to de-
termine the feasibility of detecting ecological
effects attributable to cooling water use.
2. To standardize units of measurement for each para-
meter for which environmental data are collected,
by agreement between Lake Michigan investigators
and institutions, so that information from the
large number of local studies can be expeditiously
integrated for consideration of lakewide effects.
3. To develop a taxonomic and zoogeographic characteriza-
tion of the Lake Michigan biota.
4. To facilitate organization of Lake Michigan data to
determine location and design of discharge and intake
structures to minimize important biological effects.
These are clearly issues which must be resolved before
questions of lakewide effects can be answered. This does not imply
that each utility company and governmental agency provide answers
10
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for each of these questions, for that would be redundant and
wasteful. Just as individual sections of this Report describe
studies for local and lakewide effects, these priorities refer to
broadly applicable studies useful to all interested parties. An
organizational effort is clearly needed to focus resources toward
cooperative efforts which will advance the overall understanding
of the effects of cooling water use.
11
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PROPOSED DEFINITIONS
WITH APPLICATION TO LAKE MICHIGAN
In an attempt to provide a common terminology from which to
address Lake problems, the Panel stipulates the following defini-
tions of the water zones:
Profundal Area
(Approximately 45 meters and deeper) - that area of the lake
in which the lake bed is in the hypolimnion in the summer and in
which the temperature of the whole water column does not generally
fall below 2C in the winter and over which a continuous ice sheet
forms only for brief intervals in exceptional years.
Sublittoral Area
(Approximately 10 to 45 meters deep) - that area of the lake
in which the lake bed in the summer is sometimes in the hypolimnion
and sometimes in the epilimnion depending upon the occurrence of
internal waves and upwellings.
Littoral Area
(Less than approximately 10 meters depth) - that area in which
(1) most of the surface wave energy is dissipated, in which sedi-
ments (if present) are frequently resuspended by wave action and
where the physical conditions are often suitable for growth of
attached algae and sometimes macrophytes, (2) where epilimnetic
water is the dominant medium, but, where hypolimnetic water may
occasionally intrude via upwellings or internal waves, (3) con-
taining the beach zone. The outer limits of the beach zone may be
defined as the outer limits of breaking waves in severe storms.
This limit is determined by water depth, wind fetch and exposure.
Only in the beach zone, so defined, are wave-induced, longshore
and rip currents found.
12
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SECTION I
INTRODUCTORY CONSIDERATIONS OF LAKE MICHIGAN
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Section I. INTRODUCTORY CONSIDERATIONS OF LAKE MICHIGAN
TABLE OF CONTENTS
Characteristics of Lake Michigan 16
Location and Dimensions 16
Geologic Description . . .18
Physiographic Description 19
Physical and Chemical Description . . . . . .19
General Physical 19
Thermal Characteristics . . . . . .20
Temperature . . . 20
Transparency 23
General Chemical .24
Natural Contributions 24
Cultural Contributions 24
Dissolved Solids ........ 24
Chlorides 25
Carbonates 25
Oxygen and Redox Potential 26
Phosphorous 26
Nitrogen 26
Organic Compounds 27
Calcium and Magnesium 28
Sulfur 28
Silicon 29
Iron and Manganese ^9
Trace Elements ^9
Radionuclides 31
14
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Biological Characteristics 31
Bacteria and Fungi 31
Invertebrates 33
Algae 34
Fish. . . .. . . . . . .36
Summary of Outstanding Features 38
Use of the Resource .39
Basin Growth 40
Correlation of Basin Growth to Basin Uses . . .41
Problems Resulting from Increased Use 42
Conflicts of Multi-Use Concept . . . . .42
Eutrophication. . .43
Literature Cited 45
15
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Section I. INTRODUCTORY CONSIDERATIONS OF LAKE MICHIGAN
CHARACTERISTICS OF LAKE MICHIGAN
The material in this section of the Report is drawn largely
from data presented in the Great Lakes Basin Framework Study, 1972.
Location and Dimensions
Lake Michigan is the third largest of the Laurentian Great Lakes
(Table 1-1) and the sixth largest freshwater lake in the world. It
is bordered by the states of Wisconsin, Illinois, Indiana, and
Michigan and is the only lake in the group entirely within the borders
of the United States.
The maximum length of the Lake is 307 (494 km) miles. The
maximum width of the northern basin (from Little Traverse Bay to
Little Bay de Noc) is 118 miles (190 km); the southern basin (from
Grand Haven to Milwaukee) is 75 miles (121 km) wide.
Lake Michigan is a relatively deep lake with a maximum depth of
923 feet (281 m) and a mean depth of 276 feet (84 m). The volume is
estimated to be 173 trillion cubic feet or 1,181 cubic miles
(4,919 km ) at average lake level, with an areal surface of 22,400
P
square miles (57,991 km ), and a land drainage basin in excess of
45,400 square miles (117,535 km2).
The shoreline of the Lake is regular in the southern two-thirds
of the basin but less so in the northern one-third. The total shore-
line extends 1,660 miles (2,671 km). Shoreline and shallow areas of
Lake Michigan are important to the effectiveness of the Lake as a
productive unit since a large portion of the biota depends upon
shallows for reproduction, feeding, and as nursery grounds for
immature organisms.
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Table 1-1. Dimensions of the Great Lakes.
Lake1
Superior
Michigan
Huron
St. Clair
Erie
Ontario
Length
(mi)
.350
307
206
26
241
193
Breadth
(mi)
160
118
183
24
57
53
Water
surface
(mi)
31.820
22,400
23,010
490
9,930
7,520
Drainage Avg. surf. Elev. Mean
Basin above mean sea discharge
level since 1860
(mi) (ft) (cfs)
80,000
67,860
72,620
7,430
32,490
34,800
602.20
580.54
580.54
574.88
572.34
246.03
73,300
55,000
177,900
178,000
195,800
233,900
Max.
depth
(ft)
1,333
923
750
21
210
802
Mean
depth
(ft).
487
276
195
10
58
283
from Beeton, A.M. and D.C. Chandler (1966).
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GEOLOGIC DESCRIPTION
The stratigraphy of the Great Lakes basin has determined both
land form development and the mineralogical composition of ground
and surface waters. Lithologic units range from Precambrian to
Recent and can be grouped into three time-strati graphic divisions
with unique origins and impacts: Precambrian, Paleozoic, and
Cenozoic.
Precambrian units consist of complex folded and faulted
igneous, metamorphic and sedimentary aspects; Paleozoic are largely
of marine or strand-line origin; and Cenozic are largely consolidated
sediment deposited from Precambrian and Paleozic strata from within,
and north of, the basin. Paleozoic and Cenozoic depositions, as
well as major erosional and depositional land forms, were a result
of Pleistocene glaciation during the four glacial periods (Nebraskan,
Kansan, Illinoisian, and Wisconsin). These sedimentary strata were
also subjected to regional folding resulting in outcrops such as
the Wisconsin Dome and the Findlay - Algonquin Arch, which effectively
determine the size and direction of the drainage of Lake Michigan.
The Michigan Basin has a-saucer-shaped cross-section with Precambrian
strata sloping to their greatest depth under the approximate center
of the lower Michigan peninsula. Due to this alone, and to tectonic
outcrops previously mentioned, the strata of the Eastern shore are
Mississippian-Pennsylvanian with the center of the Lake underlain
largely by a Silurian-Devonian series. Lake Huron has a similar
stratigraphic profile on the eastern side of this depositional saucer.
18
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Physiographic Description
Lake Michigan is located in the Interior Lowlands Province
which is characterized by better drainage than areas to the North,
by glacial moraines, and by outcrops of resistant, dipping, Pre-
Pleistocene strata. An example of the latter is the Niagara Es-
carpment to the north and the west of Lake Michigan. Glacial
sediments are either morainal or non-morainal debris with the
latter glacio-1acustrine, glacio-f1uvial and eolian sediment.
Due to glaciation, the drainage basin of Lake Michigan (along with
Superior and Huron) is poorly developed and the residence time of
water in the basin is extended.
Physical and Chemical Description
The physical and chemical properties of the Lake are of great
significance to its possible use as a resource, but, in light of
the number of documents on the subject, and since the purpose of
this section is introductory, the treatment here will not be ex-
haustive.
General Physical
Important properties of the waters of Lake Michigan such as
circulations, viscosity, ice formation, sedimentation, distribution
of suspended and dissolved solids, chemical reaction and interaction,
biological productivity, waste assimilative capacity, rate of eutro-
phication and many others, depend in a large part on the temperature,
pressure and density of the water. The most significant thermal
properties are: latent heats of fusion and vaporization, specific
heat, coefficient of thermal conductivity and coefficient of eddy
conductivity. Density is itself dependent on composition of the water
and varies with temperatures as affected by solar radiation and to
19
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a much smaller extent on man-influenced introductions. Composition
of the water, and especially dissolved and suspended solids, affect
transparency which in turn affects incoming radiation, temperature,
heat storage, loss of heat, photosynthetic rate, chemical reaction,
evaporation, modification of the water and, ultimately, lake circu-
lation. The dependence and interdependence of these factors on the
lake waters can easily be recognized.
Thermal Characteristics
Since temperature and the heat balance of the Lake are primary
subjects of this Report, these characteristics will be most thoroughly
covered. The specific heat of water is very high; water stores large
quantities of heat, does not give it up readily, and acts as a thermal
mediator in the atmospheric and terrestrial environments. In general,
the thermal conductivity of water is low, but since water is rarely
motionless, heat transfer is effected through turbulence and is
dependent upon mixing, circulation, stratification and climate. It
should be observed that viscosity, which is temperature dependent as
a non-linear function, also affects transport, stratification and
other aspects of circulation.
Interfacial reactions are affected largely by the latent heats of
fusion and vaporization which for water are among, the highest of all
substances.
Temperature
Lake temperatures vary with latitude and depth. Depths controls
heat storage, absorption, and transfer, but the distribution is also
strongly affected by wind driven mixing. Since winds in Lake Michi-
gan are predominately westerlies, warmer waters generally appear on
20
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the eastern shore and cold water up-wellings occur in the west.
Highest variation in mean water temperatures on the Great Lakes
occurs during mid-summer, while the range of variation is reduced
sharply in the fall during which hypolimnetic cooling is signifi-
cant; lowest variation occurs in late winter.
Vertical variation is also affected by many of the mentioned
parameters but winds are the basic mechanism of mixing. During the
spring warming phase following ice break-up, deeper waters are
colder than 4C and less than maximum density.
The following is a description of the development of the thermal
bar by Dr. C.H. Mortimer of the Center for Great Lakes Studies,
Milwaukee, Wisconsin:
"The spring warming phase first affects shallow nearshore waters,
in which stratification develops, while the offshore water mass re-
mains in its homo-thermal mixed winter condition, typically at temper-
atures well below 4C. Between the offshore water mass and the near-
shore stratified water a very narrow transition zone forms, often
marked by a nearly vertical 4C isotherm. This zone, known as the
thermal bar, is interpreted as a convergence brought about by the
mixing of the warm inshore and cold offshore masses at the conver-
gence to produce a mixture which, being close to 4C, is denser than
the parent water masses, and therefore sinks.
As the spring heat influx continues and strengthens, the volume
of nearshore stratified water increases and the "bar" (4C isotherm)
moves offshore. There are usually striking chemical and optical con-
trasts at this time, between inshore and offshore water, because in-
flows from rivers and municipal and industrial sources remain tempo-
rarily trapped inshore of the bar, and biological production is higher
21
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and starts earlier there than offshore. The offshore movement of
the bar continues until thermal stratification is established in
late June over the whole basin."
Continuing with a description of the overall seasonal stratifi-
cation of the Lake, Dr. Mortimer states:
"The form which the thermal stratification takes is determined
by the interplay of the buoyancy of the surface, heated water masses
and the mechanical mixing energy of the wind. Typically the upper
layer (the epilimnion) is mixed to near uniformity down to about 30
feet (10 m) by the end of June, at which time the lower water masses
(the hypolimnion) has warmed up to approximately 4C. The epilimnion
and hypolimnion are separated by a thermocline, a relatively narrow
zone in which temperature falls and density increases sharply with
depth. The mean level of the thermocline gradually ^psrnnr|s Huring
the summer but its actual level at any one time is strongly perturbed
by down-tiltinj (downwel1 ing) and up-tilting (upwelling) within 10
miles (16 km) of the shore and by large internal waves occupying the
whole basin. When the net heat flux to the water surface becomes
negative at the end of August, the epilimnion cools and the thermo-
cline begins to descend more rapidly, culminating in a complete mix-
ing of the water layers (the overturn) in December. Subsequent cool-
ing of offshore water during winter occurs with a more or less ho-
mogeneous water column well mixed from top to bottom, falling in
typical winters, to a temperature close to 2C by the end of March.
Ice normally forms only in bays, e.g. Green Bay, and near the shore."
Water temperatures at or near the surface respond to daily insola-
tion, diurnal heating, and cooling of surface layers. During the
22
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summer, longer days cause a net heat gain; during winter, longer
nights cause a net heat loss. The temperature interaction at the
air-water interface also causes climatic modification through over-
all temperature mediation and lake breezes.
As stated earlier, the winter minimum in offshore waters of
Lake Michigan occurs in late March at temperatures near 2C. The
shallow water near the shore is essentially freezing temperature for
a period of approximately 3 months, January through March; however,
solar insolation may warm the shallow water to 1C - 2C for a brief
period of time on bright winter days. Surface water temperatures
may reach highs of 18C to 21C in mid or late August. At any time
during the year more than half of the water in Lake Michigan is at
a temperature of 4C or less.
Transparency
In water, transparency is the ability to transmit solar, in-
direct, and artificial light. Its effects are felt on water
chemistry, biological activity including phytosynthesis, circulation,
stratification, and materials transport. It is affected by color,
dissolved solids, and suspended solids, and the penetration is
determined by intensity at the surface and angle of incidence with
the water surface. In other words, the more turbid the waters the
less the light penetration. Further, accumulations of suspended silt,
organic materials and other particles around the periphery of
Lake Michigan, particularly in the southern basin, would lead one to
expect lower transparencies there. Short term variation might be caused
by tributary inflows, storm activity, and plankton blooms.
Seasonal variation is influenced by basin physiography and
23
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cultural development. Mean transparency in late spring is highest
in the deeper portions of Lake Michigan with lower transparencies
near shore and in shallower northern portions.
General Chemical
The chemical qualities of Lake Michigan are influenced by the
biota and sediment in the Lake in addition to contributions through
natural and cultural loads from run-off and tributaries. Nutrient
loads have the greatest effects along with more general pollutional
loadings at the heavily industrialized southern portion of the Lake.
Water quality is complicated by the uncertainties of circulation, by
the great depths of the Lake and by relatively small out-flow from
the Lake which might ordinarily lead to a displacement of chemical
products.
Natural Contributions
These constituents are weathered products of soil and bedrock
along with organics derived from the biota.
Cultural Contributions
Materials that result from man's activities are e.ither associated
with run-off or are directly discharged into the Lake. The major con-
tributions include agricultural wastes, industrial and municipal
wastes, and atmospheric fallout. Nutrients, toxic metals, hydro-
carbons, pesticides, phenols and complex organics present problems
of great concern in the management of Lake Michigan.
Dissolved Solids
A useful index of the total natural and cultural inputs to Lake
Michigan is total dissolved content. Specific conductance is a common
measure of the inorganic dissolved content, and surveys of conductance
demonstrate major sources in the Chicago-Gary area and disclose
24
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maxima along the periphery of the southern basin.
Chlorides
This ion is conservative, i.e., does not readily enter into
chemical and biological reactions and may therefore be used as an
index of chemical loading and chemical build-up yielding useful
comparisons with the behavior of non-conservative material.
Chlorides originate from brines, road deicing, industrial compounds,
cleaning compounds, and natural soil and rock weathering. Lake
Michigan data indicate chloride increases from Chicago-Gary, to
Green Bay and Milwaukee, and reaches from Benton Harbor to Muskegon
and Little Sable Point to Frankfort. Major loading problems have
also occurred at Manistee and Ludington from natural ground water
concentrations there.
Carbonates
The interaction of water with carbon dioxide is significant to
living systems of the Lake due to requirements for C02 for photo-
synthesis. A complex equilibrium of C02 in the carbonate system
supplies this necessary ingredient. This equilibrium is controlled
by temperature, atmospheric C0p» pH and associations with calcium
carbonate, CaC03. Some measurement for the capacity of the water to
support life are pH, alkalinity and bicarbonate. The tendency for
change is counteracted by the buffering capacity of the water and
the most abundant mineral in the Great Lakes system which supplies
this buffering capacity is CaCO,.
O
So far, there are insufficient data to determine areal pH dis-
tribution in Lake Michigan. In addition, there is some evidence that
rises in Ph can occur as a result of algal photosynthesis and may
25
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displace the C02/carbonate equilibrium to a point at which calcium
carbonate precipitates.
Oxygen and Redox Potential
Oxygen is also essential for life support and its solution into
the water depends upon pressure and temperature. Parameters which
reflect oxygen and oxygen demand in the water are D.O. concentration,
Op activity, percent saturation, Biological Oxygen Demand, and
Chemical Oxygen Demand. Redox potential reflects the potential of
the environment to oxidize or reduce material. Although oxygen
supplies in the Great Lakes have been thoroughly studied, Lake
Michigan has not experienced serious problems except at the southern
end of Green Bay. Other data which reflect areal trends in oxygen
or redox potential are insufficient for comparison.
Phosphorus
This nutrient is essential in living systems, is readily recycled
and can be a factor limiting growth. It occurs in a number of forms,
predominately as ortho and poly phosphates, and it is removed from
lake water by organic sedimentation, by ion exchange on clays and
through uptake by algae.
The assimilative capacity of the Great Lakes for phosphorus
is high due to their water volumes but continued loading leads to
local overproduction of algae. Phosphorus removal is difficult and
control in Lake Michigan is by limitations on nutrient loading,
particularly from the sewage treatment plants discharging to the
Lake and its tributaries.
Ni trogen
This nutrient encourages eutrophication in excess, but many
26
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sources such as atmospheric and ground water inputs,are not readily
* _. & •"?•-""
controllable. It occurs as free nitrogenv*'nitrate, nitrite and
ammonia, as well as in most organic forms. The nitrogen cycle is
complex but well understood. Nitrogen is also assimilated rapidly
into the Great Lakes System but relatively high concentrations may
develop in nearshore areas receiving high loadings.
Organic Compounds
These compounds have the principal effects as oxygen demanding
compounds and as toxic substances. An attempt is made here to
introduce the problems associated with those compounds as pollutants
while recognizing that recent control measures have reduced their
seriousness to the Lake.
Chlorinated hydrocarbons are persistent, rapidly distributed,
and easily assimilated and magnified toxicants. In Lake Michigan,
DDT accumulations in Coho Salmon were determined to be unsafe for
human consumption by the Food and Drug Administration in 1969.
Discontinued use of non-biodegradable pesticides is a practical
control but physical-chemical interactions may tie up quantities
of these compounds in the environment, particularly in sediments
and degradation products. A serious problem area with respect
to chlorinated hydrocarbons exists around Green Bay, Wisconsin,
but DDT levels in many fishes from the open lake were 2 to 5 times
higher than in other Great Lakes fishes according to surveys.
Polychlorinated biphenyls also persist, are biologically magnified,
and are toxic in sufficient doses. They have been identified from
industrial sources in the Great Lakes and may be found in fish at
higher than acceptable concentrations. ^.-
27
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Phenols and phenolics are benzene derivatives which impart un-
desirable tastes and odors to water and edible biota, and which are
toxic in low concentrations. Since they are biodegradable and non-
persistent, they cause problems only near their sources.
Detergents add nutrients, usually in the form of phosphates.
These compounds indirectly reduce light penetration, and may be toxic
in quantity. Since the so called "soft detergents" containing
linear alkylate sulfonates are biodegradable, their current use is
less of a problem than the alkyl benzene sulfonate fractions formerly
used.
Petroleum can be a problem in lake waters by exerting oxygen
demand, by restricting gas exchange and by leaving unsightly slicks.
Lighter fractions may also be toxic. A recurrence of oil spills
from shore installations and loading docks has been noted on Lake
Michigan in the Chicago-Gary area and has caused considerable con-
cern and study.
Calcium and Magnesium
These are the main elements contributing to hardness and scale
formation. Their presence in water results from leaching of lime-
stone, dolomite and other minerals containing calcium and magnesium
found in the watershed. Calcium and magnesium ions are major con-
tributors to the total ionic strength in Lake Michigan. Calcite
and dolomite are important components of the carbonate buffering
system and Lake Michigan is essentially'at steady-state condition
with respect to calcium and magnesium.
Sulfur
Sulfur, important in protein synthesis and in hydrogen sulfide,
28
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sulfuric acid and its dissociation products, enters the system
through precipitation, ground and surface waters, industrial wastes
and domestic sewage. The sulfidesadd disagreeable tastes and odors
and may be toxic to certain biota.
Concentrations of sulfur compounds in the Great Lakes have been
rising in recent years. Concentrations in Lake Michigan are greatest
in areas of limited circulation such as Green Bay and Traverse Bay.
Silicon
This constituent is important as a nutrient for diatomaceous
phytoplankters, as an index of weathering of silica rocks and be-
cause of its reaction to form sedimentary silicate minerals* This
"rate of reaction" depends upon residence time of water in the
vicinity of the mineral, composition and crystal structure of the
mineral, temperature and composition of the water.
It has been concluded that the silicate system is an active
buffering mechanism in the Great Lakes. Depletion of silica levels
in the photic zone in the summer is attributed to uptake by diatoms.
Iron and Manganese
These compounds are important in the Great Lakes because of
their sensitivity to chemical changes, their buffering capacity,
their function in nutrient removal, their toxicity to plant and
animal growth under certain conditions, their role as micronutrients,
the possible presence of mineable manganese nodules, and their con-
tribution to taste and color of Great Lakes waters.
Trace Elements
When certain of the trace elements are present in sufficient
29
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quantities, they can be toxic; all can be used to identify sources
of natural and cultural inflows. Increased concentrations have
been measured within the upper few centimeters 'of the sediment -
water interface. Trace metals inputs have been measured in major
tributaries to Lake Michigan. Iron, copper, nickel, chromium,
and zinc are found in detectible quantities. Cores from southern
Lake Michigan have indicated high concentrations of arsenic near
Benton Harbor and Grand Haven, Michigan and Waukegan, Illinois.
These concentrations are supposedly derived from pesticides.
Barium, boron and bromine have not been found in Lake Michigan
waters in sufficient quantities to present a serious problem.
However, cadmium, chromium and copper have been measured in the
sediments of southern Lake Michigan in a wide range of concentra-
tions.
Iodine in Lake Michigan was measured in quantities lower than
in any other Great Lake. Lead is concentrated in the upper sediment
layer and is presumed to originate from airborne particulate com-
pounds.
Mercury has been found in the Great Lakes in alarming quantities,
Sources are clear-alkali plants, pulp and paper mills, electrical
industries and other public and industrial uses. Metallic mercury
was discharged indiscriminately to the environment prior to the
middle 1960's under the assumption that it was relatively inert, but
methylation has been shown to occur. These processes lead to con-
centrations in fish well above levels set by the USFDA and Lake
Michigan sediment cores contained concentrations from 3 to 8 times
that of the water over the sediment.
Little is known of the concentrations of silver, selenium and
30
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the uranyl 1qn in Lake Michigan. However, zinc was found in
quantities in sediment cores from the southern part of the Lake.
Radionuclides
Technological control of radionuclides has received ample
attention since the hazards of raioactivity have been recognized.
Sources are limited, but small additions accrue from atmospheric
fallout, reactor waste disposal, and accidental reactor, in-
dustrial, and research release.
Total alpha radioactivity i9 greatest on the Michigan side of
Lake Michigan but this is attributed to natural radioactivity.
Water from near Big Rock Point nuclear plant, at Charlevoix,
Michigan, has shown counts slightly higher than counts west of the
plant.
Biological Characteristics
Clearly, there is little hope that this section of the
Report can adequately treat the wealth of information on the bio-
logy of Lake Michigan. It is hoped, however, that by addressing
i
aspects; salient to the introduction of thermal effluents, the more
i
obvious gaps in understanding wfll be emphasized, and it will spur
necessary biological investigations. Floral and faunal groups des-
cribed here are the bacteria and fungi, invertebrates, algae and
fish.
Bacteria and Fungi
Routine field studies on bacteria and fungi of natural waters
such as, Lake Michigan are relatively rare in comparison to studies
of higher biotic groups. Problems in the biological and biochemical
31
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characterization of these natural populations have not been
solved due to lack of adequate methodology. However, many of the
chemical processes which comprise the major roles of these organisms
in the functioning of the ecosystem have been studied extensively.
Bacteria and fungi are decomposers, converting organic ma-
terial into simple inorganics which can be easily utilized by
heterotrophs and autotrophs alike. Some bacteria are chemotrophs,
producing energy as a result of oxidation of inorganic compounds;
and yeasts often fill a vital consumer role. Seasonal variation in
the nitrate concentration in Lake Michigan has been found to cor-
relate with changes in the rate of nitrification as well as the
uptake of nitrate by phytoplankton. Specific decomposers such as
those with affinities for starch, chitin, or cellulose may be
scarce in areas of Lake Michigan at certain times. Increases in
these and other bacterial populations may be closely dependent
upon the availability of surfaces (to which they may attach) in
the Lake and the fact that Lake conditions are often unsuitable
for the growth of aerobes from allochthonous origins. The variety
of yeasts in Lake Michigan has been related to sediment type with
evidence of only a slight relation to depth.
One of the more outstanding problems in analysis of bacterial
and fungal populations from Lake Michigan is incubation temperature.
Although these microorganisms are typified by culture at 35C, lake
temperatures rarely approach those conditions and a false estimate
of thermophils versus psychrophils may be obtained. Other bacterial
increases may be closely linked with the availability of essential
nutrients and with the compounding effect of light penetration.
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Lake Michigan is lower than Lake Erie in total counts of
bacteria used as indicators of sewage, with highest levels in
the southern periphery and in the area of Green Bay. It has been
found that Lake Michigan waters are toxic to patheogenic enteric
bacteria such as Shi gel la and certain Salmonella organisms during
certain times of the year. Toxins produced by Clostridium
botulinum are presumed to have caused large waterfowl mortalities
in the Lake in 1963-64.
Invertebrates
Knowledge of the invertebrate forms of Lake Michigan is behind
that of Lake Erie and there are still major gaps in our understand-
ing of this important component.
Although zooplankton are likely to integrate environmental con-
ditions, their passive movements through large water masses make
interpretation of both quality and quantity difficult. Early data
indicated no qualitative difference in zooplankton of Lake Michigan
and this was explained by assuming homogeneous conditions in the
Lake.
Various indices of organic pollution have been developed using
benthic organisms which seem appropriate in view of the relatively
fixed nature of the group. Insofar as fauna! gradients are con-
cerned, oligchaete populations seem to be concentrated in the
southern portions while amphipods are more abundant in the nearshore
zones of the more northerly portions. Distributional maps for pol-
lution-tolerant tubificids essentially correspond to locations of
larger cities on the Lake.
Early data on Lake Michigan also indicate little change in the
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species composition of plankton in the forty-year interval prior
to 1926. Recently a number of faunal additions have been reported.
It has been suggested that shifts in species composition may re-
flect the acceleration in eutrophication, but the picture is con-
fused by taxonomic difficulties.
Attempts have been made to generalize regarding possible cor-
relation of Lake Michigan benthos with depth, but this has been
difficult due to the variation in sediment deposits and sediment
types. It would seem certain that the combination of substrate type
and exposure to wave action exert considerable influence on the
quantity and quality of these invertebrates, but organic content
is also a significant factor. Temperature is also of importance in
several ways: as it is affected by depth, as it changes with
season, and as it is increased through human activity.
Algae
Benthic algae seem to be of lesser importance in the Great
Lakes than periphytic algae, but euplanktonic forms are more
diverse and greater in biomass. The Great Lakes flora consists of
a great number of species of phytoplankton and so considerable
difficulty exists in taxonomic discrimination.
Nuisance algae has been used as an indicator of a decline in
water quality 1n Lake Michigan. In the period, 1967-1970, both
Cladophora and Spirogyra caused problems by windrowing on the
beaches, by creating odor and color problems, by creating un-
sightly conditions, and by fouling fishermen's nets. Cladophora
and certain diatoms have also been blamed for taste and odor
problems and for clogging filters of public drinking water supplies,
34
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but these seem to have been transient problems not in current
evidence. Various other forms have been indicated in the produc-
tion of algal toxins which cause sickness and death in waterfowl
and fishes and which are capable of affecting mammalian populations,
Various types of indices to compare species and abundance have
been applied to the Great Lakes. As might be expected, it has been
found that Green Bay and a near shore Lake Michigan site were more
eutrophic than another Lake sampling station.
The timing of planktonic pulses appears to exhibit differences
between southern, more northern and mid-lake areas in Lake Michigan.
Regional differences in species have been observed and the thermal
bar has been shown to exert a profound influence on planktonic
abundance. In addition, spring phytoplankton standing crops were
higher on the shoreward side of the thermal bar than on the lake
side with the greatest standing crop at the thermal interface of
the bar.
Evidence of long-term trends of phytoplankton standing crop
taken from Chicago filtration plant records indicates an increase
in phytoplankton over the years, but evidence of taxonomic shifts
are ambiguous. Some species are apparently declining and invasion
by new species, some of a nuisance variety, has been described.
Seasonal patterns of abundance are considered bi-modal in
Southern Lake Michigan with, as has been mentioned, some variations
in timing in other lake areas. In one study, it was concluded
that the major influences on spring pulse are temperature and
35
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turbidity and that fall maxima are more limited by chemical and
physical factors. In another study, primary pulse impetus has been
attributed to temperature alone. Other workers have expressed doubt
that temperature alone can be simply correlated with phytoplankton
pulses and have attempted to relate nutrient distribution to these
phenomena.
Patterns of abundance in phytoplankton have been attributed to
a number of factors including nutrients, phosphorous, nitrogen and
carbon. Since the photosynthetic process and the rate of growth
are highly dependent on temperature and light, these factors must
also be woven into any scheme which presumes a limiting factor.
It is abundantly clear that temperature and light effects are
difficult to separate in analysis of field investigations of
phytoplankton.
Fish
Commercial and sport fisheries have probably taken place on
the Great Lakes since the arrival of man to its shores, but the
nature of the lakes has permitted a profound effect to take place
due to man-caused disturbance. Changes in species composition and
abundance have been observed in all the lakes, but particularly in
those most closely influenced by population and urban growth.
The large sizes of the lakes have not encouraged an adequate
understanding of the distribution and population of resident
species so that, in many cases, historical trends are difficult to
deduce. In addition, current records are derived from commercial
catch records which do not provide data on certain important groups,
especially, forage fishes. The openings between the lakes permit
migration, in general, but passage through the St. Lawrence River
36
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allowed Invasion by essentially foreign species and man has per-
mitted and encouraged the introduction of other exotics.
Salmonids have largely dominated in establishing goals for
management of fisheries of the lakes, including lake trout, the
coregonines and more recently the Coho and Chinook Salmon.
Other introduced fishes significant to the development of
current lake conditions have included: the smelt, carp, and gold-
fish, the alewife, sea lamprey and white perch.
In Lake Michigan, commercial fishing practices probably account-
ed for the decline of the lake sturgeon. Other changes seen in
commercial activities are the decline in the lake herring, whitefish,
lake trout, and the increasing appearance of smelt and alewives.
The decline in trout and whitefish is jointly attributed to preda-
tion by the introduced sea lamprey and by fishing; the decline in
lake herring is attributed to overfishing and competition by smelt
and alewives; decline in the chub fishery and changes in the species
composition have been attributed to overfishing and alewife
competition.
Fish are excellent indicators of environmental conditions;
both species composition and abundance reflect an integration of
cyclic and spatial environmental change; hence the environmental
interest in fish. Unfortunately changes in the fishery do not
separate direct causes from indirect causes such as those resulting
from preemption of shallows and nursery grounds, commercial and
sports fishing, damming spawning tributaries, increased sedimentation
from agriculture and deforestation, and those wrought by the intro-
duction (however, inadvertent) of predator and competitive species.
37
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It has been, in addition, of insufficient interest, or at least
very difficult to obtain and keep adequate records of fish distri-
bution and abundance to facilitate the recognition and prediction
of fisheries trends.
Summary of Outstanding Features
1. It is the sixth largest freshwater lake in the world.
2. It is extremely deep, with a mean of 276 feet (84 m) and a
maximum of 923 feet (281 m).
i
3. It has a relatively small proportion of shallow waters.
4. It is relatively regular in outline.
5. It has a relatively small drainage basin.
6. Aside from the peripheral waters, particularly in the southern
basin, and the waters at Green Bay, its transparency is high.
7. It is a relatively infertile lake and might be classsified
as somewhere between oligotrophic and mesotrophic.
8. Detention time of water in the basin is extended.
9. With some notable exceptions, the quantity of accumulated
knowledge regarding the lake ecosystem is relatively small.
10. Lake Michigan is lower than Erie, but higher than Superior and
Huron, in fish productivity and species composition and the
i
fishery has been greatly influenced by man both directly and
indirectly.
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Use of the Resource
The 13.5 million people of the Lake Michigan Basin (including
the Chicago Metropolitan Area) have at their disposal a resource
of magnificent dimension; it is an "inland ocean" of drinkable
quality. In 1970, over 2,000 mgd of water were withdrawn from
Lake Michigan for municipal use; that is projected to increase
nearly 500 mgd by 1980. Barring further degradation, over 1,100
cubic miles of drinking water are available.
Excepting the coldest months of the year, waters of the
Great Lakes are widely used for shipping; in 1972, that amounted
to over 200 million tons of cargo, largely landed at or near
Chicago. Much of this was iron ore, limestone and coal transported
from Lake Superior to the steel mills of Gary-Hammond,,
Other uses include sport fishing, boating, swimming, and bird
watching. In Chicago and Milwaukee the lake provides a pleasant
setting for the urban background and permits the inhabitants an
escape to open space. During warmer h.onths, the shores of the Lake
are widely used for biking, walking, swimming, and visual relief.
The Lak." mediates domestic sewage and industrial wastes and
these introductions probably have had greatest impact on the
other uses. The effects are felt largely in the peripheral areas
of the Lake since economics encourages disposal close to shore.
It is also true that the littoral zone is ecologically of greatest
i -V"»
value and of greatest concern in protection of drinking water
quality. Treatment at municipal sewage plants around the lake in
the 1970's was in excess of 660 mgd with capital costs exceeding
350 million dollars. These costs may double by 1980, and operation
39
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and maintenance is rising,, Industrial wastes, largely in the
southern basin, are unestimated but contribute substantially to
water quality problems. Lake waters are also used to mediate
the effects of waste heat produced in the process of electrical
generation. Power demands from both the domestic and industrial
sectors in the future will probably increase pressures for this
use.
Lake Michigan also has an important role in the total commer-
cial fisheries catch of the Great Lakes Basing Preliminary data
indicate that 47.4 million pounds, worth 5.2 million dollars were
landed in 1973. These landings account for 76 percent of the
total weight taken in the U.S. Great Lakes and 61 percent of the
dollar value with the discrepancy between percent weight and
percent value explained by alewife harvest.
v
Sports fishing in the Great Lakes has increased in value,
due in part to massive stocking programs of state and federal
agencies, to an estimated 350 million dollars per year (not
including capital equipment), with the value in Lake Michigan
estimated at 73 million dollars per year. These numbers are
estimated due to the difficulty in determining the value of a
resources so highly dependent on services of a diverse nature,
such as the fuel, baits, lodging, food, boats and equipment,
required to participate in the sport.
Basin Growth
The total Great Lakes Basin population accounted for 14 to 15
^Personal Communication, 1975. Great Lakes Fisheries Commission,
Ann Arbor, Michigan,
40
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percent of the U. S. population in the decades 1940-60 with the
Lake Michigan Basin containing 46 percent of that total during
the same period. In the decades 1980 to 2020, this Basin total
is projected to decrease slightly to 13.5 percent of the national
by 2020 with Lake Michigan maintaining a relatively steady 45 to
46 percent. Absolute numbers in the Lake Michigan Basin are ex-
pected to increase nearly threefold (U. S. Army Corps of Engineers,
1972) and this addition will cause water uses to increase. Ex-
tended concern for the well being of the Lake is anticipated.
Correlation of Basin Growth to Basin Uses
Development of data which would indicate trends of water or
lake use is difficult. Increases (from 1940 to 2020) from ap-
proximately 8.5 million to nearly 25 million total Lake Michigan
Basin population can be surmised to add to uses of the Lake for
recreation, domestic consumption and for waste disposal. Certain
aspects of use for transportation might also increase but would
require a detailed breakdown of cargo.
Employment projections indicate that the total workers in
the fields of agriculture, forestry and fisheries will decrease
from 267,216 in 1940 to 49,700 in 2020, repeating a decrease of
81 percent. For workers employed in manufacturing industries,
projections are for 1,085,201 workers in 1940 to increase 149
percent to 2,705,000 workers in 2020. Clearly, since these are
projections and since the respective impacts of these jobs are
not known, these number's must be used with caution.
National trends of surface water use for recreational activities
are increasing. This is due to the increased urbanization of the
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population and a tendency to desire escape or change, along with
an Increase In leisure time due to a shortened work week. This
indicates that water quality must continue to be upgraded for
water contact, and that management of fisheries must take sport
fishing into greater consideration than has been done previously.
PROBLEMS RESULTING FROM INCREASED USE
Conflicts of Multi-Use Concept
Designation of a water body for multi-use either formally
or informally means that the most stringent water quality demands
must be met on a total basis. For Lake Michigan, use for drink-
ing requires that the water be oil and grease free, that organisms
which might impart unacceptable tastes and odors be absent, that
organisms which would clog filters be absent, and that bacterial
levels be acceptably low. The level of required quality for use
of Lake Michigan waters for industrial processes, for waste
disposal, for shipping, or for power boating are rather low and in
fact, these latter purposes are likely to contribute to poor quality
unless controls are exacting. The possible conflicts between
these intended uses can be great.
This is especially true in a water body like Lake Michigan
with its oligo-mesotrophic characteristics of cold, transparent,
relatively infertile waters. The conflict becomes exaggerated
since the human population which aesthetically desires transparent
i
blue water causes the lake to attain a progressive degree of greenness
merely through its existence on the shores. Furthermore, the
Lake is most green within sight of shore and more pristinely
42
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blue nearer the center of the Lake, out of sight and reach of the
majority of the inhabitants.
The simplest answer is to insist on maintenance of the entire
Lake at a level of quality appropriate to all uses. Such
uniformity cause it to be most easily monitored and regulated,
and certainly most acceptable for the variety of uses, but it is
also clearly the most expensive. It may even be an unwise use
of the resource. The alternative of zoning or use designation
where controlled disposal or use for shipping, for example, may
be limited to certain areas, is a possible answer, but this
solution is not in consonance with the national trend to clean
up our surface waters. It is also more difficult to monitor and
regulate, and by natural forces, difficult to control and limit
the areas of effect. However, it may be more in keeping with
the notion of wise use in contrast to the purest conservation.
It is not the purpose of this document to rule or decide on
these questions, but rather to discos them. The technical
expertise available to us, as a nation, may, in fact, permit us
to understand what are the costs, the techniques, and the efficacy
of a return of this Lake to a "blue or a greenish color" but it
is a social decision as to what that color should be. It is
worth noting that this is a group decision and not one for a
select few, whether they are scientists or informed citizens.
Eutrophication
In the current ecological movement, the term "eutrophication"
has been widely used to mean a deterioration in water quality
and excessive productivity due to man's activities. In a
43
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scientific context, it is a term describing the aging process
undergone by all lotic waters. Scientifically, it has been used
most extensively in reference to small upland lakes; this con-
tinuum of aging has been designated by three terms and charac-
terized as follows:
1. oligotrophic - deep, abundant oxygen, low
nutrients, few individuals of the biota
from a large number of taxa.
2. mesotrophic - characterized similarly but
with an increase number of individuals of
the biota from a decreased number of taxa.
3. eutrophic - shallow, lower oxygen (especially
at depth), high nutrients, large numbers of
individuals from a relatively few taxa.
Lake Michigan is certainly undergoing these changes in the
process of aging, but the vast quantities of water involved
tend to slow the process. The lake' s depth provides a buffer
against the tendency to become more shallow, and the great water
mass resists seasonal warming, and dilutes the effects of
nutrients that cause increase in productivity. It is probably
true, as mentioned previously, that the more peripheral, littoral
waters in the southern basis of Lake Michigan are exhibiting the
symptoms of eutrophy and this is more certainly true in Green
Bay. This is primarily caused by land run-off and contributions
from smaller municipalities, and in the southernmost part of the
Lake,to industrial discharge. The limited literature suggests
that subtle, though not necessarily irreversible degradation of
the Lake has already taken place; retardation of these processes
is a desirable end.
44
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Literature Cited
Beeton, A.M. and D.C. Chandler. 1966. The St. Lawrence
Great Lakes. Pages 535-558 In; Frey, D.G. (ed)
Limnology in North America. University of Wisconsin
Press, Madison, Wisconsin.
Great Lakes Basin Framework Study. 1972. Limnology of
lakes and embayments. Appendix No. 4, Draft No,. 2,
Volume I (Parts I and II). Great Lakes Basin
Commission, Ann Arbor, Michigan 658 pp.
45
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SECTION II
DATA REQUIREMENTS RELATED TO LAKE MICHIGAN STUDIES
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Section II. DATA REQUIREMENTS RELATED TO LAKE MICHIGAN STUDIES
TABLE OF CONTENTS
Introduction 49
Declaration of Intent 50
Sampling Considerations 51
Sample Collection and Processing 55
Data Handling 61
Data Evaluation 62
Scientific Acceptability ......... 66
Introduction to Priority Needs . 69
Priority Needs 70
Literature Cited .73
48
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Section II. DATA REQUIREMENTS RELATED TO LAKE MICHIGAN STUDIES
Introduction
This section of the Report presents recommendations toward
the objective quantification of the effects of cooling water use
on surface waters. Many environmental studies have suffered from
insufficient statistical confirmation of ecological conclusions.
This can best be remedied by more thorough statistical planning
during early stages of program design. Objective statistical
support of ecological conclusions can be achieved through adequate,
informed planning of the number of stations, intervals, frequency,
and replicates. Suggestions are also made regarding study design,
data collection and some fundamental statistical analysis.
Concern has also been expressed with the great amount of
data on Lake Michigan which are scattered widely in formal and
informal publications and accumulated in files unavailable for
comparison and analysis. Lake Michigan investigators are
encouraged to make all Lake data available for review and analysis
through central data storage. The answers to many current
questions regarding the ecological status of the Lake lie within
reach through data which have already been collected; this
section of the Report proposes efficient utilization of those
data. •
49
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Declaration of Intent
It is important to define the goals of each proposed
research project and the relationship of that project to the
overall goals of assessing the effects of cooling water use.
This should be accomplished in a written proposal of study prior
to actual data collection. Such proposals should be carefully
developed and closely scrutinized by the funding agency, since
it serves as a basis for both the quality and the usefulness of
the proposed work. Submission of the proposal to the funding
agency should be preceded by a critical external review by
colleagues and other professionals to increase utility of the
study.
Collection of data on each environmental parameter should be
justified. The collection of data and samples "which might be
useful later on" can be very compelling. Clearly, data collec-
tion can save time, effort and money as long as future use is
not only anticipated, but is an integral part of the program plan,
The collection of data and samples with no planned purpose should
be discouraged.
The types of measurements which should be made are defined
in later sections by suggesting standard techniques for the
subject organisms or parameters. A study proposal should include
a detailed description of the type and desired precision of those
measurements selected, with justifications. In addition, the
study area and areas of concentration and a rationale for those
limits should be indicated.. The duration of the research project
should be stated with some realistic estimate of the possibility
of meeting target dates.
50
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Sampling Considerations
After problem selection, an explicit statement of that
problem should be drafted to relate the proposed sampling scheme
to it. For example, if an attempt is made to determine changes
in water chemistry caused by the introduction of heat, the
possible reasons for an expected change should be stated, based
upon the physics of the system and the chemicals in question.
Sampling plans should provide details of suspected spatial and
temporal changes (or differences) and the manner in which these
will be statistically quantified so as to leave no reasonable
doubt of the magnitude of Qhange (or difference). Extensive
and statistically sound use should be made of reference locations
and times.
After the problem is defined and the measurements are
selected, the associated assumptions must be made and clearly
stated; for instance, it could be assumed that release of biocides
into a cooling water discharge is not time dependent, i.e.,
with neither diurnal or seasonal variation, since power plants
operate more or less continuously. These assumptions affect the
economics of the proposed work to a great extent; sampling may
be conducted during working hours and in seasons of comfortable
ambient conditions. If later information indicates that plant
operators apply reduced quantities of biocides in winter months
when fouling of the coolant system is less likely, or should
biocides be applied at specific daily periods, the statement of
these assumptions become valuable. They may cause data to be
discarded or at very least, reevaluated, and effect new
experimental design. Further, and perhaps most importantly,
statement of the most trivial assumptions forces the investigator
51
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to more critically examine the precise nature of his problem
and proposed methods of investigation.
Prior to the problem statement, a review should be con-
ducted of existing data and studies which bear on the proposal.
This should be done in a form suitable for publication. Should
previous data or studies be unavailable, a modest pilot study
should be conducted to develop information on which to base an
informed proposal. Both literature reviews and pilot studies
are used for justification of the proposed studies, for forming
a data base upon which to build, to serve as a source of
appropriate techniques, methods and tools (including statistical
considerations) for comparison with new data, and as an indication
of careful proposal preparation. The intent of both literature
survey and pilot study is to estimate the magnitude of central
tendency and the magnitude of variation of each parameter, and
to determine the potential for discrimination of environmental
differences.
In its final form, the sampling design should reflect the
full range of each parameter, to differentiate human influences
from natural variability due to climatic, seasonal, daily and
other periodic and aperiodic changes. This necessitates random,
or other statistically sound sampling. Replication and the
provision of reference data, reference samples and reference
stations are also required. The number of replicates needed for
statistical treatment is dependent upon the variation in the
parameter of interest, the accuracy with which one desires to
describe the parameter and the magnitude of difference one desires
to detect (See Cochran and Cox, 1957). Careful selection of this
52
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number will assure a sound comparative base without collection
of excessive or redundant data. The number of replicates need
not be regarded as fixed but rather subject to adjustment on the
basis of periodic review and analysis.
In cases where the number of replicates required for
statistical validity is too great due to economic or physical
limitations, the desire for statistical acceptability must be
balanced against practical considerations. The investigator
must also consider if:
(a) the question is valid,
(b) the question is sufficiently important to
justify possible upheaval in the subject
population, and
(c) the effort and expense which the investigator
must expend to achieve statistical validity
are warranted.
To serve these desired ends, benefit/cost analysis may be
appropriate.
When these costs, both economic and environmental, have been
balanced, the information and measurements may be designated as
"special studies" for intensive investigation at a single site.
When this occurs, the investigator should select a site with
broad characteristics that could apply to several sites or to an
entire system.
Although the emphasis in this section of the Report is
toward meeting satisfactory statistical goals, it should be noted
that statistical significance does not imply ecological signifi-
cance and vice versa.
53
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The proper order for development of the statistical
rationale should be:
(1) observation or proposal of a change or
difference,
(2) preparation of an hypothesis which is a
statement of that change or difference,
(3) preparation of a test for that hypothesis
which would tend to verify the existence of
change or differences and would establish
their magnitudes,
(4) preparation of a statistical framework for
the test which verifies that observed
differences are not due to random chance and
which establishes the probability that the
changes or differences in collected samples
reflect actual changes or differences in the
environment,
(5) review of tests and statistical requirements
to determine feasibility within physical,
biological, temporal, and spatial constraints.
It is clear that the state of knowledge of organism groups
and the available investigative techniques and tools strongly
influence testing, sampling, and the ability of the investigator
to draw conclusions regarding ecological significance. Any
ecological significance perceived should be declared, with
specific limitations of the tests.
The great number of variables in the lake makes the attain-
ment of true ecological "controls" virtually impossible. However,
54
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this does not preclude the demonstration of meaningful differences
between areas of suspected effect and reference stations.
Reference stations might be considered sampling locations at
which measurements are made which typify natural or ambient
conditions in a given time and space.
When the decision has been made to collect data, a sampling
schedule should be developed to facilitate field study.
Frequently, biological data are separated from physical, chemical,
geological and meteorological data due to the relative difficulty
of collection. In many cases, the measurement of biological
parameters in situ is not possible, and laboratory time may be
greater than field collection time by a factor of 20. Therefore,
it is usually easier to collect chemical and physical in situ
data which more accurately reflect ambient conditions, and there
is a reluctance to collect biological data simultaneously.
However, biological, chemical and physical data should be
collected concurrently insofar as is possible.
Sample Collection and Processing
The absence of comparative data is frequently a major
problem in environmental study. Regardless of the nature of the
study, temporal and spatial changes, rates and instantaneous
magnitudes are measured only against data collected expressly to
provide background. Data collected for other studies are rarely
directly comparable to proposed work for one or more of the
following reasons:
(1) the time frame is not comparable; e.g.,
previous data were collected in winter,
or during the night, or were not collected
55
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with the desired frequency;
(2) the location is not comparable; e.g.,
previous data were collected two miles
further from shore, only at the surface,
or were all collected across the Bay which
has been filled in with dredging spoil;
(3) unusual ecological conditions prevailed
during the previous collection that cannot
be duplicated; e.g., mean temperatures
exceeded the 20 year average, flows exceeded
the 100 year expected high, or water level
was less than the predicted lows for that
water body.
These variations are usually impossible to control and dif-
ficult to predict. However, some variation in design and data
collection can be standardized through agreement. This sub-
committee recommends careful review and standardization of the
following wherever possible:
(a) Collecting gear and other equipment
This includes nets, seines, dredges, pumps,
water samplers, traps, and instrumentation
and pertains to overall dimensions, orifice
sizes, net apertures, rates of water
passage, sizes and location of supporting
structures, and methods of suspension and
deployment. •
(b) Techniques of collection, processing, and analysis
This includes methods of cal ibrat.ion; field collection
56
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period, distance, or volume; sequence of deployment,
sample removal, gear cleaning, sample sorting, sample
treatment and preservation, and sample storage; lab-
oratory sequences of sample removal, washing, treat-
ment, examination, sorting, enumeration, and
recording; and a basic series of analyses which may
be applied to the data.
(c) Reference collections of permanently preserved samples
which are entire, or aliquots representative of the
original sample
This requires specification of storage facilities
recognized by investigators for routine deposit of all
preservable field samples. These reference collections
permit examination, identification, emuneration and
analysis subsequent to the original treatment, for
confirmation of the original results, or to permit
application of analyses not considered at the time c ;•
original treatment.
(d) Standard and accepted biological keys
This presumes that, (1) texts exist which permit
organism identification through comparison with a
series of recognized characteristics, and (2) that those
characteristics, organisms, and keys have the sanction
of authorities in the field or discipline, and have
applicability and the desired accuracy for use in a
limited geographic area.
57
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(e) Methods and forms for reporting
Development of recognized and accepted forms for field
and laboratory data recording permitting immediate
transfer to computer/storage and processing.
(f) Units for reporting environmental data
Metric units are preferred for all parameters; English
units are included in this report as supplements to
metric units only where they were collected in earlier
studies.
(g) Accuracy of reported data (i.e., significant figures)
Precision should meet the objectives of the project
for which the measurements are being obtained. When
limitations to precision are built in, as in the use
of instruments that are calibrated to, for instance,
the second decimal place (0.01), there is no advantage
in attempting to interpolate between the lines nor is
there reason to read multipliers of that second decimal
place to an accuracy greater the' that which is real or
justified.
(h) Horizontal positioning and mapping
Measurements of distance are used in nearly all phases
of environmental sampling and monitoring. In general,
the greatest accuracy is required for mapping horizon-
tal distances for locating discharge plumes and
obtaining accurate current measurements. Systems
for obtaining distance measurements with varying degrees
of precision are readily available. Methods of de-
58
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termining distance should be routinely reported with
the precision of the instruments, and where appropriate,
with the observed variability of repeated measurements
of the same distance.
As a special case, the location of the near-field iso-
therms to thermal discharge structures dictates that
the position of the temperature measurement be known
with an accuracy of no less than 10 percent of the
width of the discharge orifice. For geometrical reasons,
the error in position will always be equal to or greater
than the error in the distance measurements that define
that position. Therefore the maximum error for dis-
tance measurements when mapping the near-field region
of the plume should be about 5 percent of the width of
the discharge.
In trapping the far-field region of the plume, accuracy
of position is less critical. Inaccurate distance
measurements will produce inaccurate areal measurements
within isotherms but the major source of inaccuracy
results from the artistic freedom assumed in drawing
isotherms through widely scattered data points.
Accuracies of +_ 10 to 30 meters are reasonable in
mapping far-field regions of the plume.
(1) Vertical distance
Depth is usually measured relative to the water surface
elevation at the time of sampling but, in some instances
59
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a fixed vertical distance should be used. For example,
accurate depths are essential in studies involving physi-
cal effects such as erosion, sediment deposition or
organisms on the bottom of the Lake. The precision
for depth measurements for most studies is +_ 0.5 m
(+_ 2 feet), but studies in the beach zone require pro-
portionately greater precision. A precision of +_ 0.01 mm
(+_ 0.25 inches) or better may be required for studies
of erosion or sediment deposition.
(j) Level of statistical significance
Five percent, unless otherwise justifiable.
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Data Handling
Modern computers permit investigators to collect and analyze
large amo.unts of data. In a system as large as Lake Michigan,
and with investigators widely scattered in academic and govern-
mental institutions, universal access to data collected on the
Lake is imperative. Data released by a scientist subsequent to
collection, computation and even publication should be placed in
recognized, accessible storage for possible use by others. Thus,
the original collection becomes even further justified, redundancy
is decreased and conclusions regarding the environmental state of
the Lake become more widely known. In view of recent national
constraints regarding access to data collected through public
funds, sharing may be mandatory once the information is released
by the original investigator.
Universal access to shared data requires development of a
compatible format for collection and storage among investigators
and institutions of Lake Michigan. In addition, provisions should
be made for translation and transfer of data and analyses
packages between different computer systems.
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Data Evaluation
In the section of the environmental proposal or report des-
cribing material and methods there should be a statement of
minimum acceptable standards for data treatment. This state-
ment should express not only the form for data presentation
(e.g., the arithmetic mean, the median, standard error, etc.), but
should also state confidence limits acceptable to all investi-
gators and describe the statistical treatment in detail. This
initial commitment will permit the reviewer to judge the rigor
with which the data were or are to be evaluated and will provide
the investigator with some targets at which to aim.
When describing the effects of environmental difference or
alteration, numerically, through species counts, biomass estimates,
or density, or when physical or chemical values are stated, the
following values should be presented, using data transformations
when appropriate:
(1) arithmetic mean,
(2) standard error.
(3) sample size, and
(4) confidence limits for the mean.
Reference to these values and other statistical procedures may
be found in Snedecor and Cochran, 1967; Sokal and Rohlf, 1969;
Steel and Torrie, 1960; and Zar, 1974. In circumstances where
nonparametric analysis is appropriate, the investigator should
present the median, sample size and nonparametric measure of
di spersion.
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When describing the effects of environmental difference or
alteration through an evaluation of the structure of the biotic
community, the following forms of expression are appropriate:
(1) species diversity, with the specific form dictated
by convention of the biological group (see Dorris
and Wilhm, 1968; Lloyd, Zar, and Karr, 1968; Pielou,
1966),
(2) equitability indices (e.g., "evenness"; see Pielou,
1966),
(3) species richness, an indication of the number of species
accounting for a specified portion (e.g., 95 or 99 per-
cent) of the community.
The results of a study of suspected environmental alteration
or difference should be evaluated to determine the extent of
difference, and to determine statistically whether the differences
observed are greater than those which could reasonably be expected
to have occurred through random variation.
For an assessment of spatial and temporal differences, the
following statistical procedures are recommended:
I ne procedure known as "analysis of variance" is a widely
applicable method of statistically analyzing lake data. By
analysis of variance one may, for example, infer from samples
taken at different locations (or times) whether the lake means
at these locations (or times) are the same or different.
63
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Strictly speaking, analysis of variance requires certain
mathematical assumptions (e.g., an underlying normal distribution
of data) be met, although moderate departures from these assump-
tions are not serious. Howeyer, there are many cases where such
departures from the assumptions of normality are not only pre-
dictable, but may be corrected for by transforming the raw data.
This is the case when dealing with percentages or with frequencies,
for example, in counts of biological entities. Therefore, data
transformations should be considered wherever appropriate.
If the transformation of data does not correct for severe
violations of the statistical assumptions for analysis of variance,
then techniques of non-parametric statistical analysis should be
considered to answer questions regarding spatial or temporal
differences in the lake.
Following analysis of variance, multiple comparisons are
often desirable when more than two means are compared. Procedures
commonly employed are:
(1) Student - Neuman - Keuls' test,
(2) Tukey's test,
(3) Scheffe's test.
Similarity indices might be used to indicate uniformity of
biological assemblages between season or area (Grieg - Smith, 1964;
Horn, 1966; Whitaker, 1967). Cluster analysis may also be utilized
to indicate similarities among biological assemblages (Cairns and
Kaesler, 1969, 1971; Cairns, Kaesler and Patrick , 1970; Kaesler
and Cairns, 1972; Kaesler, Cairns and Bates, 1971; Roback, Cairns
and Kaesler, 1.969; and Sneath and Sokal , 1973).
64
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Interrelationships among biological and physical parameters
may be examined by simple or multiple regression and coefficients
of correlation.
In the visual presentation of data by tables and figures,
planning and clarity of expression are paramount. It can also
help to have the aid of someone trained in graphics or with a
practiced eye for visualization. Tables should be fully self-
explanatory and the units for each numeric variable should appear
on each table or group of tables. When measures of central
tendency are depicted in tabular form they should be accompanied
by an indication of sample size and a measure of variability (e.g.,
standard error). Where numerical entries are zero, they should
be explicitly written rather than indicated by a dash or a dotted
line, and a numeric entry should never begin with a decimal point.
Figures should also be self-explanatory and should tend to
clarify data trends rather than to confuse or complicate them.
Overcrowded graphs and figures cause the reviewer to lose
interest and perhaps miss a major point of emphasis. Both verti-
cal and horizontal scales should be clearly labeled (including
units of measurement) on all figures or groups of figures and
samples sizes should be identified.
65
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Scientific Acceptability
It is apparent that, faced with serious gaps in basic infor-
mation, it is neither possible nor desirable for the Lake
Michigan Cooling Water Studies Panel to compose "cookbook" or
pro forma exercises which would result in approval to discharge
heat into Lake Michigan. A more fruitful approach is to cast
recommendations in the form of criteria of performance. Such
criteria are common to all scientific investigations and rest on
the following points:
Adequacy - Is the investigation of sufficient scope
and intensity to answer the questions
posed?
Reliabi1ity - Does sampling and measurement quantify
answers with a degree of certainty which
would support meaningful conclusions?
t
Accountabi1ity - Will basic measurements and determinations
stand inspection by independent experts?
V a 1i d i ty - Do the measurements actually relate to
the quantity sought and are they indepen-
dent of other variables?
Following is a further elaboration of these points:
Adequacy
Clearly, the adequacy of studies is crucial in determining
effects of thermal pollution on biotic communities in Lake
Michigan. In simplest terms, several desirable or undesirable
consequences may be envisioned:
66
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1. extirpation of native populations through intol-
erable habitat modifications,
2. introduction of exotic populations through
modification of existing habitats,
3. change in the community structure or abundance
of existing biotic assemblages,
4. changes in process rates of individual popu-
lations or of integrated biotic communities.
The overall objectives of studies to evaluate the effects of
cooling water use include demonstration of the ecological changes
induced by a small temperature increase in a limited area of the
receiving waters. If changes are found through comparative stud-
ies, ultimately causes must be ascribed to those changes through
comprehensive laboratory experiment on individuals and populations.
Such experiments, in and of themselves, are not sufficient dem-
onstration of acceptability unless they relate findings back to
the field. In order to support the criterion of adequacy, investi-
gators should demonstrate that they have-performed studies both
before and after the construction and operation of a licensed
faci1ity whi ch:
1. have determined biological populations occurring
in the body of water under consideration,
2. have determined abundance of populations,
3. present meaningful indices of the structures of
biological communities, '
4. have obtained valid estimates of basic process rates
associated with biological communities present,
67
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5. have extended over a time interval sufficient
to detect and quantify both existing trends
and cyclic natural variations within the system,
6. have been coordinated with physical and chemical
studies such that a comprehensive description of
the environmental mil ieu has been presented.
In the last analysis, the most convincing demonstration of
the adequacy of studies is repetition and confirmation by indepen-
dent experts. It is therefore strongly recommended that corrobora^
tive studies be sponsored by agencies responsible for the pro-
tection of the public interest.
Re!iabi1i ty
1. Accuracy: The accuracy of tests, measurements, or pro-
cedures should be supported by known standard samples
and evaluation by independent methods. Estimates of the
magnitudes of inaccuracies should be clearly defined and
included in data reports.
2. Precision: Tests, measurements and procedures should be
replicated to provide clear estimates of uncertainties
in precision, and those estimates should be included in
all reports.
3. Acceptable levels of uncertainty: The investigator
should routinely provide estimates of uncertainties
which may exist in all aspects of his work.
4. Independent review and verification of evidence by
recognized experts should be encouraged.
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Accountabi 1 ity
1. Where techniques permit, voucher specimens should be
permanently preserved in a recognized repository for
possible taxonomic or qualitative verification.
2. Copies of original data on destructive analysis (chem-
ical and biochemical measurements) and measurements of
transient phenomona (physical and meteorological) should
become part of the public record. "Original data" is
construed to mean the first digital output in standard
measures.
3. For analyses using both qualitative identification and
enumeration (analysis of biological assemblages), orig-
inal data (as defined above) should become part of the
public record and should be permanently preserved in a
recognized repository.
4. For all determinations requiring interpretation or expert
opinion, all authors of interpretations and opinions should
be clearly identified and qualified.
5. Independent review and verification of supporting evidence
by recognized experts should be encouraged.
Introduction to Priority Needs
The term priority research is inappropriate to the purpose
of this section of the Report which would seem to be more to
recommend corrective measures to improve the usefulness of
current and future data, than to propose further development of a
methodology or of data. Priority numbers assigned therefore re-
flect the relative values of those steps which, in the best judg-
69
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ment of the Panel, would tend to push forward the goal of data
improvement with greatest possible speed. Priority values have
been ranked according to the following scheme:
1 - highest priority consistent with achieving
primary goals of the Panel,
2 - high priority studies supporting priority 1
items,
3 - intermediate priority but ultimately providing
support to both 1 and 2.
Since tried and acceptable techniques exist for these
analyses, categorization based on current status of the data is
unnecessary.
PRIORITY NEEDS
1. To standardize units of measurement for each parameter for
which environmental data are collected, by agreement between
Lake Michigan investigators and institutions.
Priority 1
2. a. To develop uniform specifications for environmental data
which render them appropriate for computer storage.
b. To investigate the feasibility of, and to adopt where
feasible, standardized data forms which would facilitate
transfer and computer storage.
c. To adopt standardized coding for environmental data which
would permit computer storage.
70
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d. To arrange for a central data bank to contain, analyze and
distribute raw and analyzed data on thermal problems and
their associated effects.
Priority 1
3, To negotiate for, and to designate specific public libraries
as repositories for all reports to assure the availability
of Information on Lake Michigan thermal problems.
Priority 1
4. To determine the levels of statistical significance necessary
for routine analysis of the various types of environmental
data (acceptable levels depend on the depth of knowledge of
the sub-discipline or organism-group, the frequency and number
of species and the base of experience in testing the effects of
environmental perturbation on the population and community
structure).
Priority 2
5. To recommend revision, production and uniform acceptance by
Lake Michigan investigators and institutions of biological keys
which are inadequate or which do not now exist.
Priority 3
6. To determine from available data the within-sample variation
which might be expected from biological, chemical and physi-
cal parameters of interest in determining the effects of the
introduction of waste heat into Lake" Mi chigan.
Priority 2
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7. To estimate, based on data on within-sample variability, the
numbers of replicate data necessary to detect various magni-
tudes of difference between groups of data.
Priority 2
8. To specify descriptive statistics and accompanying confidence
limits to be reported for each type of environmental data col-
lected.
Priority 1
9. To specify measures of biotic diversity (if any) which are
appropriate for each biological parameter.
P r i o r i ty 1
10. To specify the analytic procedure or procedures to be used
to assess each type of spatial or temporal environmental
difference. If alternative analyses are available, the
criteria through which a choice may best be made should be
clearly stated.
P r i o r i ty 1
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Literature Cited
Cairns, J., Jr. and R.L. Kaesler. 1969. Cluster analysis
of Potomac River survey stations based on protozoan
presence-absence data. Hydrobiologia 34:414-432.
\
Cairns, J0, Jr. and R.L. Kaesler. 1971. Cluster analysis
of fish in a portion of the upper Potomac River.
Trans. Amer. Fisheries Co. 100:750-756,,
Cairns, J., Jr., R.L. Kaesler, and R. Patrick. 1970.
Occurrence and distribution of diatoms and other algae
in the upper Potomac River. Not. Natur. Acad. Natur.
Sci. Philadelphia. No. 436. 12 pp.
Cochran, W.G. and G.N. Cox. 1957. Experimental Designs.
Wiley, New York. 617 pp.
Dorris, T.C. and J.L. Wilhm. 1968. Biological parameters
for water quality criteria. BioScience 18:477-480.
Grieg-Smith, P. 1954. Quantitative Plant Ecology.
Plenum Press, London. 256 pp.
Guenther, W0C0 1964. Analysis of Variance. Prentice-Hall,
Englewood Cliffs, N0J. 199 pp.
Horn, H.S. 1966. Measurement of "overlap" in comparative
ecological studies. Amer. Natur. 100:419-424.
Kaesler, R.L. and J. Cairns, Jr. 1972. Cluster analysis
of data from limnological surveys of the upper
Potomac River. Amer. Midland Natur. 88:56-67,,
73
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Kaesler, R.L., J. Cairns, Jr. and J.M. Bates. 1971.
Cluster analysis of non-insect macro-invertebrates
of the upper Potomac River.
Hydrobiologia 37:173-181.
Lloyd, M., J.H. Zar, and J.R. Karr. 1968. On the
calcuation of information-theoretical measures of
diversity. Amer. Midland Natur. 79:257-272.
Pielou, B.C. 1966. The measurement of diversity in
different types of biological collections.
J0 Theoret. Biol. 13:131-144.
Roback, S.S., J. Cairns, Jr., and R.L. Kaesler. 1969.
Cluster analysis of occurrence and distribution of
insect species in a portion of the Potomac River.
Hydrobiologia 34:484-502.
Scheffe, H. 1959. The Analysis of Variance.
Wiley, New York. 477 pp.
Sneath, P.M.A. and P.K. Sokal. 1973. Principles of
Numerical Taxonomy.
W.H. Freeman, San Francisco. 573 pp.
Snedecor, G.W. and W.G. Cochran. 1967. Statistical
Methods. Iowa State University Press,
Ames, Iowa. 593 pp.
Sokal, R.R. and F.J. Rohlf, 1969. Biometry.
W.H. Freeman, San Francisco. 776 pp.
Steel, R.G.D. and J.H. Torrie. 1960. Principles and
Procedures of Statistics.
McGraw-Hill, New York. 481 pp.
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Whittaker, R.H. 1967. Gradient analysis of vegetation.
Biol Rev. 49:207-264.
Zar, J.H. 1974. Biostatistical Analysis. Prentice-Hall,
Inc. Englewood Cliffs, N.J. 620 pp.
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SECTION III
MEASUREMENT OF THE EFFECTS OF COOLING
WATER USE ON PHYSICAL PARAMETERS
-------
Section III. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
PHYSICAL PARAMETERS
TABLE OF CONTENTS
Definition of Physical Parameters 80
Objectives of Measurement of Physical Parameters ... 81
Questions Answerable Through Physical Measurement ... 81
Natural Physical Conditions 81
Predictive Information 82
Monitoring Discharge Plumes 83
Distribution of Chemicals Added to the Discharge. . 83
Physical Sampling Sites 83
Intake 83
Discharge 84
Littoral Area 84
Profundal Area 85
Iterative Sampling Changes 86
Physical Parameters of Interest 86
Water Temperature 86
Lake Currents ..... 87
Turbulent Diffusion 89
Wave Height and Wave Length 90
Turbidity 90
Light Intensity in the Water 91 •
Related Meteorological Variables 91
Other Physical Measurements 92
78
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Determination of Ambient Temperature 93
Physical Data and Ecological Effects 94
Introduction to Priority Research 96
Priority Research . .... 97
79
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Section III. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
PHYSICAL PARAMETERS
Definition of Physical Parameters
The physical parameters considered significant to this
program are variables which may be changed from their natural
values by the use of lake water for once-through cooling, and
related meteorological variables which affect mass movement of
the lake water and heat exchange between the lake and the atmo-
sphere .
The direct effect of a condenser cooling water discharge is
to change the values of some physical variables such as tempera-
ture, gas solubility, etc., in a relatively small area of the
lake. The biological effects of the discharge itself (as
differentiated from intake or condenser passage effects which
are considered in a separate section of this report) are indirect
effects resulting from the physical changes. In order to
determine both the immediate and persistent biological effects of
the discharge it is necessary first to determine the area in which
measurable physical perturbations occur. These man-made physical
changes should be related to the averages and extremes of the
natural physical variables in the lake. Designation of the
physical measurements to be made depends upon the study objectives.
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Objectives of Measurement of Physical Parameters
1. To describe the distribution through time and space, parti-
cularly in the littoral area, of those physical variables
influencing water quality and the biota of the lake;
2. to provide adequate physical data to improve prediction of
variations in physical aspects of the water mass caused by
discharge plumes;
3. to verify thermal plume models which aid in describing the
variability of plume behavior in the lake;
4. to collect data for monitoring the physical effects of
condenser water discharges.
Questions Answerable Through Physical Measurement
Natural Physical Conditions
1. To what extent is the water of the sublittoral and littoral
area and water inshore of a thermal bar restricted in inter-
change with the remainder of the lake?
2. What is the rate of dispersion of pollutants away from the
shoreline and what physical parameters influence this rate?
3. What is the relative importance of the wind and of density
differences induced by solar heating in driving the circu-
lation of the lake?
4. Can the heat added by condenser water discharges significantly
increase the volume of water in the epilimnion in the summer
and/or significantly affect the vertical distribution- of''.
* .
temperature and dissolved material?
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5. How frequent, extensive, and persistent are upwellings and
what role do they play in bringing nutrient laden waters
into the euphotic zone?
6. What is the normal, and what are the extremes of, light
penetration in the lake?
7. What is the normal, and what are the extremes of, winter
temperature distribution in the lake?
8. To what depths are sediments disturbed by wind induced mixing
of the lake in different seasons of the year?
9. What, if any, is the influence of ice on shore erosion?
Predictive Information
1. From what strata of the lake is the intake water withdrawn?
2. For what periods of time and to what extremes and average
temperatures are aquatic organisms exposed when they meet
elevated temperatures in discharge plumes?
3. What is the extent and temperature range of a sinking plume?
4. What is the velocity field around the intake?
5. To what extent can a discharge plume be confined to the shore-
line by lake motion?
6. What are the appropriate methods for predicting the size and
location of a discharge plume under natural conditions of
lake variability?
7. Where and how should discharge and intake structures be lo-
cated and designed to minimize important biological effects?
8. What influence does bottom configuration have upon the dis-
persion of thermal discharges?
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Monitoring Discharge Plumes
1. Can discharges significantly influence turbidity and light
penetration?
2. To what extent do discharges erode and transport bottom
sediments?
3. To what extent might a discharge plume prevent or destroy
the formation of ice and result in additional shore
erosion?
Distribution of Chemicals Added to the Discharge
1. How do physical forces act upon additives to the discharge and
what is the distribution of additives in the discharge itself?
Physical Sampling Sites
The following sections identify those locations where physical
parameters should be measured to answer questions related to
physical and biological effects of use of the lake for cooling
water. Details of how the measurements and frequency relate to
the study objectives are discussed in a later section. Meteorologi-
cal variables apply to all locations; however, they can usually be
grouped as relating either to inshore or offshore conditions.
Intake
Temperature and water currents are important physical parameters
in the area of the intake. Preoperational studies can determine
ambient water temperatures and, if recirculation from the discharge
does not occur, help in prediction of intake temperatures during
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operation. During plant operation, intake temperatures can be
monitored routinely in the plant. Preoperational current studies
at the intake can be used to identify the permanent effects of
currents caused by plant operation. Measurements for verifica-
tion may be made during plant operation.
Discharge
Temperature and currents should also be studied at the dis-
charge. Discharge water temperature can be monitored in the
plant. Current and turbidity measurements can be made from the
point of discharge into the lake to points beyond the expected
zone of influence. Pre-operational studies of ambient conditions
near the discharge will determine physical characteristics of the
receiving waters before plant operation. During operation these
data may be used for comparison with reference areas outside the
zone of plant influence.
During plant operation, physical variables are measured to de-
fine (1) temperature distribution of the thermal plume, (2)
currents in the plume as compared to ambient conditions, (3) mean
and maximum residence times of entrained organisms, (4) relative
mixing and dispersion of the discharge water into ambient lake
waters, and (5) changes in turbidity resulting from the other
identified changes.
Littoral Area
All cooling water withdrawal and discharge occurs in what would
be classified as the littoral areas. Extensive measurements of
physical parameters at numerous littoral sites are required for
an adequate categorization of uses currently made in the nearshore
water of Lake Michigan.
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These comparative measurements are useful in evaluating alterna-
tive locations for new cooling water uses as for evaluating the
differences in physical effects of existing uses. The Physical
Subcommittee offers a tentative selection of five areas based on:
1. Similarities in the nature of shoreline, bottom material
and depth contours.
2. Similar biological characteristics.
3. Distribution of power stations and other sites at which
data are regularly collected.
AREAS INCLUDED:
a. Kewaunee-Point Beach
b. Waukegan-Zion
c. Michigan City-South Haven
d. Ludington
e. Northern Rocky Shoreline
Profundal Area
Measurement of physical variables in the profundal area is
much more difficult than in the intake, discharge or littoral
areas. Consequently, sampling programs for measurements at offshore
locations require justification. The only questions linking the
characteristics of offshore waters with cooling water in a physical
sense relate to the rate of interchange between the offshore and
inshore waters. Special programs (involving temperature, current
or dispersion measurements) should address this question. A
sampling program designed for long-term or routine monitoring of
physical variables of profundal areas does not seem germane.
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Iterative Sampling Changes
The physical sampling program will necessarily change as
biological problems are identified. For instance, if it is
determined that the far field region, where temperatures are less
than 2C (3F) above ambient, is biologically unimportant, physical
measurements of the energy exchange coefficient at the surface of
the lake becomes relatively unimportant. If this far field
region is unimportant, ambient lake turbulence is also relatively
unimportant for predicting plume behavior.
Physical Parameters of Interest
The physical variables of interest for study of cooling water
effects on Lake Michigan include water temperatures, lake currents
ambient turbulence defining dispersion (eddy diffusivities,
entrainment coefficients), turbidity, light penetration, surface
heat exchange coefficients, and meteorological variables such as
wind speed and direction, air temperature, relative humidity, and
incident and reflected radiation.
Water Temperature
Temperature is the most significant physical variable to
these studies because it determines the buoyancy field and relates
directly to the physiological responses of the biological organisms
Fortunately, it is also one of the easiest variables to measure.
Using water temperature, or its increase, as a conservative label
it is possible to trace cooling water passing through the plant.
Unfortunately, temperature is not a unique tag or tracer and at
times temperature increases due to added heat can become confused
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with natural temperature variation. Using temperature as a tag
often leads to problems in defining the plume due to local
differences in ambient water temperatures.
The temporal and spatial characteristics of ambient water
temperatures in Lake Michigan are not well known. Data are needed
on the temporal and spatial variations of ambient water temperature
at specific sites, to compare operational biological data with
natural conditions. Specifically, data are needed to define and
describe (1) spatial and temporal variations in surface temperature,
and (2) temperature variations with time and depth, providing
information on upwellings, natural stratification, thermal bar
phenomena, sinking plumes, and possible recirculation of plume
water into intakes. Preferred units of expression are degrees
Celsius (degrees Fahrenheit). Water temperature measurements for
most studies should be made to the nearest 0.1C (0.2F). When
the change in heat content is to be calculated over a short time
period, a precision of 0.01C (0.02F) may be required.
Lake Currents
A number of parameters are associated with the dispersive
mechanisms that act upon the cooling water plume. Some of these
are actual physical variables (currents) and some are mathematically
defined parameters (eddy diffus1vities) depending upon the parti-
cular mathematical formulation used to describe the situation.
Lake current is the primary mechanism transporting heat into
the lake from the point of discharge. Currents affect the tra-
jectory of the plume, and the intensity of turbulence. Very
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little is known about the speed, direction and persistence of
near-shore currents (within 10 km). Data of this type are not
only essential for thermal plume predictions, but also 1n under-
standing erosion problems in the lake. To describe and interpret
near-shore currents, information is also needed on wave heights
and periods, offshore currents, wind speed and direction, atmos-
spherlc stability, 1n addition to data on near-shore currents
themselves.
There are two types of currents directly associated with the
thermal plume Instrumental 1n dispersing heated water: those in-
duced by the initial momentum of the discharge and those induced
by density differences (buoyant spreading).
One of these effects usually dominates, depending upon the
location of that point where momentum dissipates and buoyant
forces become dominant. Currents induced by momentum effects are
relatively well understood for simple configurations, but more
data are needed for an understanding of boundary effects such as
those caused by the bottom and the interactions with ambient lake
currents; specifically, how are forces exerted on the plume by the
ambient current and the bottom? Currents produced by buoyant
forces are less well understood and no mathematical models avail-
able for predicting plume behavior in large lakes specifically
include this phenomenon, even though it is Important in producing
the sharp Interface observed on the upcurrent side of the plume.
Data are especially needed on the temperatures and currents at
this interface.
The flow of the water is a function of current speed and direc-
tion. Preferred units of expression are cm/sec (ft/sec) for cur-
rent speed, and degrees of the compass for direction. The
88
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precision needed for current speed is embodied in a current meter
with a threshold of 3 cm/sec (0.1 ft/sec) and an accuracy of 10
percent; and +_ 5 degrees in direction.
If current measurements are to be made in areas where the
orbital wave velocities affect the currents, a current meter must
be chosen that is insensitive to orbital motion. (Current meters
with Savonious rotors as sensing elements are not recommended.)
Properly designed drogues and suitable position location
techniques are an acceptable and inexpensive method of obtaining
current data. The cross sectional area of a drogue exposed to
underwater drag should be at least 100 times the area above water
that is exposed to wind forces.
Turbulent Diffusion
Turbulent diffusion is an hydrodynamic process related to flow
and turbulence which describes the distribution of suspended ma-
terial, solutes, and heated waste as by measuring velocities,
temperatures, and/or tracer concentrations and fitting mathematical
models to the data. Values are therefore dependent upon the model.
It is not feasible to specify precision for measurement of diffu-
sion because there is no clearly defined reference value. Turbulent
eddies, the mechanism by which energy is provided to produce mixing,
occur over a wide spectrum of eddy sizes. Thus, measurements of
turbulent dispersion (eddy diffusivities) must include eddies that
are at least as large as the largest dimension of the plume. Values
of turbulent diffusion coefficients are usually several orders of
magnitude greater in the horizontal than in the vertical direction,
particularly under stratified conditions. Dye dispersion is a
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technique used to measure diffusion, however, erroneous results
may be produced where buoyant forces are significant.
Wave Height and Wave Length
Height, frequency and directional characteristics of surface
waves determine their effects on water motion at various depths
and their effect on turbidity and sediment movement. A number of
waj/es are always present at any location or time so that repre-
sentative wave height, wave length, and period would normally be
obtained from a time-varying record. Suitable measurements might
be obtained visually or may require a lengthy and accurate time
series record for power spectrum analysis. Additional approaches
may use wave prediction techniques through meteorological data
and airborne sensors.
Wave heightmeasurements should be expressed in meters (feet).
Calculated values for wave length and direction should be ex-
pressed in meters (feet) and degrees of the compass (true), re-
spectively. Desired precision of wave height measurement depends
on the purpose, though an accuracy of 10 cm or 2 percent of full
scale is readily attainable.
Turbidi ty
Turbidity may be determined roughly from Secchi disc depths or
more precisely from photometric attenuation. Turbidity is a biolog-
ically important parameter that can have a profound effect on
primary productivity. Turbidity can also be a measure of turbulent
mixing for it is this turbulent energy that lifts the sediments
from the bottom and holds them in suspension. Turbidity can also
be used as a tracer to identify various water masses. Measure-
ments would be.limited to the relatively shallow water areas.
\
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Light Intensity In the Water
The objective of the measurement of light intensity is usually
the measurement of the depth of the euphotic zone, the principal
zone of energy conversion by green plants. In this context pre-
cise depth measurements are more important than precise light in-
tensity measurements. The instrument preferred for light intensity
measurements in the water is a submarine photometer. Photometer
readings at various depths in the lake can be converted to extinc-
tion coefficients and related to turbidi ty readings made on water
samples in the laboratory. Photometric techniques lend themselves
to spectral analysis, should this be required. Secchi disc
readings are difficult to relate to measurements made with other
instruments or to models of primary production and are therefore
of limited value.
Related Meteorological Variables
Thermal energy introduced into the lake is eventually given
up to the atmosphere and to outer space. Various mass and energy
exchange phenomena that take place at the air-water interface are
important in the rates of exchange. Analyses of existing plumes
indicate that most of this energy is lost from the plume regions
that are less than 2C (3F) above ambient. If the peripheral region
of the plume, where the temperature differential is less than
2C (3F) above ambient, is important from a biological point of
view, then measurements of the factors influencing surfacing heat
exchange must be made» These factors include gradients in the air
temperature, velocity and humidity above the water surface, water
91
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temperature, solar and atmospheric radiation and reflected and
emitted radiation from the surface of the water.
Meteorological measurements are needed as mentioned above, to
evaluate surface energy exchange rates, and these measurements are
desirable to correlate near-shore surface conditions to parameters
more easily measured than near-shore currents. These measurements
are readily made with existing equipment and techniques. The
major difficulty that may occur is in obtaining suitable towers or
sites for measurement over the water. Related meteorological
variables are those influencing temperature, flow, turbulence,
dispersion rates, exchange of heat between the lake and the
atmosphere, and local water turbidity. The following variables
may be measured, though not necessarily at each site.
1. Air temperature in C (F), +_ 1C (2F).
2. Lake surface water temperature (for determination of
atmospheric stability) should be measured with a precision
of +_ 1C (2F).
3. Relative humidity in percent, +_ 5 percent.
4. Wind speed in km per hour (miles per hour), +_ 3.0 km per hour
(+_ 2.0 miles per hour).
5. Wind direction in degrees (true) of the compass, to +_ 10
degrees.
6. Net radiation balance in langleys per day (Btu/ft2/hr), + 10
langleys per day (+_ 1 Btu/ft2/hr.).
Other Physical Measurements
Two specific phenomena, occurring in Lake Michigan and important
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to thermal plume dispersion, are development of a thermal bar during
spring (and sometimes in early winter) and possible occurrence of
sinking plumes. Both occur when water above 4C mixes with water
below 4C. Observations of both phenomena are made primarily by
temperature measurement. Development of a thermal bar is a dynamic
process and, in general, is easily measured by instrumentation
located on a boat or be infrared overflights. Sinking plume data
can be obtained through fixed sensors on the lake bottom or measure-
ments taken from a boat; both methods have advantages and disadvan-
tages. Unfortunately weather sometimes prevents research vessels
from obtaining sinking plume data during cooler months when the
sinking condition is most likely to exist.
Determination of Ambient Temperature
Water Quality Standards for temperature proposed for Lake
Michigan by the U.S. EPA and adopted at least in part by all four
states (Illinois, Indiana, Michigan, Wisconsin) are based upon
an allowable mixing zone of approximately 72 acres in area for
those waters with temperature greater than 3F above the "natural"
temperature or less than a specified maximum temperature for the
month. "Natural" is defined as the temperature that would exist
in the absence of artificial heat inputs. • At present there is
not clear definition of how "natural" temperature is to be
determined.
"Ambient" temperature, the temperature that would exist in
,1
the absence of heat input, must first be determined. Attempts to
define ambient temperature have created considerable difficulty
in the reduction and interpretation of field data acquired over
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the last four years. For instance, natural surface temperature
measurements have shown changes greater than 1C (2F) over a
distance of 180 meters (600 feet) in a direction parallel to the
beach. Moving in a direction perpendicular to the shoreline, data
have shown differences as much as 3C (5-1/2F) in distances of
600 meters (2000 ft.). This was a case of shoreline heating where
temperature decreased moving away from shore; a completely natural
process. With upwelling conditions, which occur rather frequently,
differences of as much as 4C (7F) in 910 meters (3000 ft.) have
been observed. Under these conditions ambient temperatures also
vary with time. Data have shown that the ambient surface tempera-
ture increases as much as 3C (5-1/2F) over a 2 hour period during
a calm day with a large solar energy input. This layer of warm
water was less than 1 ft. deep.
This questions the point in time and space at which a tempera-
ture to be called "ambient" can be identified. Both cooling water
users and regulatory agencies need a clear definition of the method
of identifying the ambient temperature. Should a method be considered
that uses measurements at greater depths than the upper few microns,
infrared scanning cannot be used as a monitoring tool.
Physical Data and Ecological Effects
Collection of physical information is intended to assess the
ecological effects of the use of Lake Michigan for cooling. Con-
tributions fall into two main, interrelated categories, which
provide: (1) a description of the influence of natural variables
operating on physical characteristics of the lake, over both long
and short time scales (e.g,, both seasonal and episodic during
94
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storms or upwelling, and on the life history, growth, and mortality
of lake organisms which live or migrate within the influence of
cooling water); and, (2) a description of the intensity, extent,
and direction of the mechanical and thermal perturbations imposed
on living organisms by the cooling water in its passage through the
intake, pumps, and condensers and continuing during its dispersion
from the outfall.
It follows that an adequate description of category (2), this
panel's ultimate objective, is not possible without substantial
knowledge of the natural variation under category (1). It also
follows that the program of physical measurement must be designed
using the best information biologists can provide on the life
histories, distribution, movement, and thermal and mechanical
tolerances of those groups of organisms which either represent
a direct resource (e.g., fish and fish food), or which contribute
in a more subtle way to a healthy ecological situation in the
lake.
The scale of time, distance and the frequencies over which
tolerances and physical variables are measured must match the
scales and frequencies of exposure of the organisms to the
perturbation in question. However, these scales and frequencies may
differ among organisms; for example, planktonic organisms making
a single passage through the plant and plume differ from organisms
entrained only in the outer plume, or from sessile groups only
occasionally or remotely influenced by a plume. However, it seems
that the assessment of ecological effect on these
95
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relatively local scales is a prerequisite for any reliable assess-
ment of lakewide effects.
Introduction to Priority Research
The following research is identified in the body of the
discussion on physical parameters which are considered necessary
to adequately assess environmental changes resulting from the
introduction of waste heat into Lake Michigan. These questions
have been selected as possible keys to a more rapid accomplishment
of research, resulting in a better understanding of lake
conditions. Assigned priorities represent the judgement of the
Panel as to the relative importance of these key topics balanced
against the availability of data. The need for physical measure-
ment by other subcommittees committed to assessment of the
aquatic environment through chemistry or through the biota have
been used to adjust these priorities. Priority values may be
ranked according to the following scheme:
1 - highest priority consistent with achieving primary
goals of the Panel,
2 - high priority studies supporting priority 1 items,
3 - intermediate priority, but ultimately providing support
to priori ty 1 ,
4 - low priority, supporting other programs but not of
critical importance in itself,
5 - deferred priority of a general supporting nature.
These research topics have also been placed in categories
96
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which reflect the current status of the data, and the assigned
values may be interpreted in the following way:
1 - as soon as possible using available data,
2 - using data currently being collected,
3 - by means of individual research projects not now under-
way. N-
Priority Research
A. Toward Assessment of Natural Physical Conditions
1. To determine the extent to which the littoral and sub-
littoral area, or water inshore of a thermal bar is
restricted in interchange with the remainder of the Lake.
Priority 2, Category 3
2. To determine the rate of dispersion of pollutants away from
the shoreline, and physical parameters which influence
this rate.
Priority 2, Category 3
3. To determine the relative importance of the wind and of
density differences induced by solar heating in driving
the circulation of the Lake.
Priority 2, Category 3
4. To determine the effects of water exchange on epilimnetic
volume and/or vertical distributions.
Priority 5, Category 1
5. To determine the frequency, extent and persistence of
upwellings and the role they play in bringing nutrient
laden waters into the euphotic zone.
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Priority 2, Category 2
6. To determine the normal and the extremes of light
penetration into the waters of the Lake.
Priority 3, Category 3
7. To determine the normal, and the extremes of, winter
temperature distribution in the Lake.
Priority 5, Category 1
8. To determine to what depths sediments are disturbed by
wind-induced mixing of the Lake in different seasons of
the year.
9. To determine what, if any, is the influence of ice on
shore erosion.
Priority 4, Category 2
B. Toward Development of Predictive Information
1. To determine from what strata of the Lake intake water
is withdrawn.
Priority 5, Category 2
2. To determine the periods of time and extremes and average
temperatures to which aquatic organisms are exposed when
they meet elevated temperatures in discharge plumes.
Priority 1, Category 2
3. To determine the extent and temperature range of a sinking
plume.
Priority 1, Category 2
4. To determine th.e velocity field aroirnd an intake.
Priority 1, Category 3
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5. To determine the extent to which a discharge plume can be
confined to the shoreline by lake motion.
Priority 3, Category 1
6. To determine appropriate methods for predicting the size
and location of a discharge plume under natural conditions
of lake variability, and the influence of bottom configura-
tion on thermal dispersion.
Priority 2, Category 2
7. To determine where and how discharge and intake structures
should be located and designed to minimize important bio-
logical effects.
Priority 1, Category 3
C. Toward Monitoring Discharge Plumes
1. To determine the extent to which discharges erode and
transport bottom sediments.
Priority 3, Category 2
2. To determine the extent to which a discharge plume might
prevent or destroy the formation of ice and result in
additional shore erosion.
Priority 4, Category 1
D. Toward a Determination of the Distribution of Chemicals
1. To determine the action of physical forces upon additives
to the discharge and distribution of additives in the
discharge itself.
Priority 2, Category 3
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SECTION IV
MEASUREMENT OF THE EFFECTS OF COOLING WATER
USE ON CHEMICAL PARAMETERS
-------
Section IV. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON CHEMICAL
PARAMETERS
TABLE OF CONTENTS
Introduction 103
Definitions Of Chemical Parameters 104
General Water Quality . . . • . . 104
Additions From Plant Operation 104
Air Pollutants 104
Precision and Units of Expression 104
Objectives of The Measurement of Chemical Parameters 110
Questions Answerable Through Chemical Measurements 110
Chemical Sampling Sites Ill
Method of Sampling 112
Frequency of Sampling 113
Site Evaluation Studies 113
Monitoring 114
Operational Monitoring 114
Replication of Samples 115
Changes in Operational Monitoring Program 116
Chemical Data and Ecological Effects 116
Priority Research . . 117
102
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Section IV. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
CHEMICAL PARAMETERS
Introduction
The chemical parameters considered in this section are those
used in definition of water quality. In many instances, chemical
analyses are considered a part of or a supplement to biological
studies; these analyses might be more appropriately considered
an integral part of the biological studies. This section is
concerned with those studies needed to determine the changes in
water quality which might result from cooling water use.
There are several committees addressing problems in the water
quality of Lake Michigan. These include the Laboratory Directors
of the Calumet Area-Lake Michigan Conference, the Monitoring
Committee and Toxic Substances Committee of the Lake Michigan
Enforcement Conference, the Environmental Quality Committee of
of the Great Lakes Commission, and the Upper. Lakes Reference Group
and the Great Lakes Water Quality Board of the International Joint
Commission. The Lake Michigan Cooling Water Panel is concerned
with the effects of cooling water use on water*quailty and on its
effects on the biota. It is anticipated that lines of communi-
cation will be established with these other committees, so that
information on chemical parameters can be easily exchanged.
103
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Definitions of Chemical Parameters
Cooling water use may produce changes in water quality by
changing the solubility of dissolved gases, by changing the rate
of biological processes which produce water quality changes, and by
the addition of materials used in plant operation. In coal fired
power plants, drainage or leachate from fly ash holding ponds may
reach the cooling water discharge. In a plant where cooling
towers are used, the evaporation of water causes increases in
the concentrations of substances already in the cooling water.
Chemicals used for slime and corrosion control and air pollutants
scrubbed from the atmosphere may also be discharged.
General Water Quality
The parameters used to describe water quality in general are
listed in Table IV - 1.
Additions from Plant Operation
Representative substances which might be used in plant operation
are listed in Table IV - 2.
Air Pollutants
Representative substances which might be scrubbed from the atmo-
sphere and appear in cooling tower blowdown are listed in Table IV-3
Precision and Units of Expression
The preferred units of expression for chemical parameters are
metric, usually milligrams per liter (mg/1) for chemical substances
dissolved or suspended in the water. Occasionally micrograms per
liter is the appropriate unit of expression. The units of expres-
sion used in reporting for the results of chemical analyses should
conform to those of the USEPA STORET System.
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Table IV-1. Water quality parameters to be considered In site
selection studies and monitoring studies
Wastewater Components
Bacteria, Fecal Coliform*
Biochemical Oxygen Demand*
Chemical Oxygen Demand
Cyanide
Hexane Soluble Materials
Nitrogen, Organic*
Phenols
Total Organic Carbon
Plant Nutrients
Nitrogen, Ammonia*
Nitrogen, Nitrate*
Nitrogen, Nitrite*
Phosphorus, Soluble*
Phosphorus, Total*
Silica*
Water Supply Parameters
Alkalinity*
Color
Chloride
Fluoride
Hardness
Iron
Manganese
Oxygen, Dissolved*
pH*
Solids, Total Dissolved*
Solids, Total Suspended
Sulfate
Turbidity
Potentially Toxic Materials
(examples)
Arsenic
Boron
Chromium
Lead
Mercury
PCBs
Nickel
Selenium
Si 1ver
Zinc
Pesticides
Phthalates
* Parameters which should be a.part of all water quality evaluation;
other parameters are suggested for consideration when there is
reason to believe that they may be present in unusual concentrations
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Table IV- 2. Chemicals used in plant operation.
Name
Use
Form to be Monitored
Al urn
Chlorine
Lime
Phosphates
Sodium Carbonate
Sodium Hydroxide
Sodium Sulfite
Sulfuric Acid
Boric Acid
Hy d r a z i n e
Morpholine
Phosphates
Chromates
Phosphates
Organic Phosphates
Zinc
Chlorine
Silt control, poly-
mers
acrylamide
polyacrylate
Water Treatment
Water Treatment
Water Treatment
Water Treatment
Water Treatment
Water Treatment
Water Treatment
Water Treatment
Reactor
Reactor
Reactor
Reactor
Cooling Tower
Cooling Tower
Cooling Tower
Cooling Tower
Cooling Tower
Cooling Tower
Al ion
Free and combined chlorine
Ca ion, hardness, alka-
linity, pH
Total and orthophosphate
Na ion, alkalinity, pH
Na ion, pH
Na ion, oxygen
S04 ion, pH
Boron
Ammonia - N
Ammonia - N
Total and orthophosphate
Trivalent and Hexavalent
Chromi urn
Total and orthophosphate
Total and orthophosphate
Zinc ion
Free and combined chlorine
Ammon.ia - N
Organic - f!
BOD •
106
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Table IV - 2. Chemicals used in plant operation.
(continued)
Name
Use
Form to be Monitored
polyethyleneamine
Dispersants Cooling Tower
sodium lignosul-
fonate
Organic biocides Cooling Tower
sodium polychl-
orophenol
quaternary amines
methylene bis-thi -
ocyanate
etc.
Oxygen inhibitors Cooling Tower
sodium mercapto-
benzothiozole
benzotriazole
etc.
BOD
Phenols
Organic - N
Ammonia - N
etc.
BOD
Organic sulfides
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Table IV - 3. Some atmospheric contaminants which may appear in
cooling tower recirculating water.
Iron
Lead
Copper
Nickel
Vanadi urn
Zinc
Phosphorous
Chromi urn
Cadmi urn
Mercury
Arseni c
Ammonia
Sulfite
108
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The precision and accuracy required for each individual
determination depends upon the objective of the measurement,
the natural variation in ambient concentration, and the availa-
bility of analytical techniques and instruments with appropriate
precision. The laboratory responsible for the analysis should be
prepared to demonstrate that the sample collection, sample
handling, and laboratory methods are adequate to provide the
required precision and accuracy for the parameter. As a part of
this demonstration, Standard Samples prepared in EPA laboratories,
should be analyzed. Samples should occasionally be replicated to
demonstrate that the methods give reproducible results. Other
uncommitted laboratories should analyze aliquots of the same
sample.
The regulations, 40 CFR, Part 130, TEST PROCEDURES FOR THE
ANALYSIS OF POLLUTANTS, of the Federal EPA should be followed in
making the chemical analyses except when greater sensitivity than
provided by those techniques is required by the objectives of the
analyses. In those instances where alternative analytical
techniques are required, approval should be requested through the
Regional Director of EPA Region V or the State Pollution Control
Agency.
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Objectives of The Measurement of Chemical Parameters
To monitor cooling water to determine:
a. if the cooling water use produces changes in water quality or,
b. if there are changes in water quality from other sources
which might produce biological changes.
Questions Answerable Through Chemical Measurements
1. Does cooling water use result in dissolved gas super-saturation
to the extent that it is a threat to organisms in the discharge
piume?
2. Does cooling water use result in loss of significant amounts
of dissolved oxygen from the discharge plume?
3. Does cooling water use result in increase in Biochemical Oxygen
Demand in the discharge plume?
4. Does cooling water use result in an increase in total quantities
of algal nutrients or an increased availability of algal nutri-
ents?
5. What chemical substances are present in the drainage or leachate
from a fly ash holding pond?
6. What chemical substances are present in the blowdown from a
cooling tower which is introduced into the discharge?
7. Does cooling water use increase taste and odor problems in the
lake water?
«
8. Are there substances present in the water whose rate of
uptake, accumulation and toxicity might be changed by a temper-
ature change?
9. Are power plants a source of toxic, persistent organic compounds?
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Chemical Sampling Sites
NOTE: Whenever possible, stations should be located at sites pre-
viously occupied or logically selected to maximize continu-
ity of data.
1. Measurements of chemical water quality should be made at in-
take and discharge to determine changes in water quality
occurring in the plant and long-term water quality trends of
the lake water.
2. Point sources (including tributary contributions) of waste-
water discharge in the area of the power plant (within 5 miles)
should be monitored to determine effects on the local aquatic
comnium' ties.
3. Water quality should be monitored in the discharge plume to
determine the concentration gradients of materials discharged
and to determine possible biological effects of the discharge
on water quali ty.
4. Special studies of chemical water quality should be conducted
at shallow and deep water stations to define quality differences
between these two areas.
5. Special studies of water quality should be conducted at refer-
ence stations near and at some distance from power plants to
determine long terms trends of water quality in Lake Michigan.
6. Special studies should be undertaken to answer questions raised
under item 3.
Ill
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Method of Sampling
A wide spectrum of sampling methods is required for water
quality analyses as a part of the studies of cooling water use.
Continuous recording instruments and composite samplers are needed
for monitoring intake and discharge while a Kemmerer or Van Dorn
sampler may be appropriate for lake samples. Careful attention
should be given to containers used in transporting samples and
appropriate methods for preserving and handling samples so that
alteration or contamination is minimized.
It is not feasible to specify methods and special considera-
tions for sample handling and preservation required for each of
the possible water quality analyses. The laboratory responsible
for the results should demonstrate that the methods provide the
precision and accuracy required by the objectives.
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Frequency of Sampling
Sampling frequency depends on the type and the objectives of
the study and availability of background data. The types of studies
considered here are site evaluation studies, plant monitoring studies,
and special studies.
Site Evaluation Studies
Site evaluation studies should provide data to aid in selection
among alternative sites and determination of problems particular to
a specific site. Water quality factors are usually less critical
to site evaluation than are physical or biological factors.
Water quality surveys similar to sanitary surveys should be
considered part cf site evaluation studies: sources of waste
water within five miles of the proposed site should be located and
characterized, rivers discharging to the lake within the area
should be evaluated, surface runoff within five miles of the pro-
posed site should be surveyed, and specific sources of waste
materials in the runoff (animal raising operations, fertilized
agricultural fields, highways which contribute oils and'salt, etc.)
should be identified.
Use of water in the area of the proposed site should also be
identified; withdrawals for either domestic or industrial water
supply, and the extent of recreational water use in the area of
particular interest.
Water quality samples should be collected from the area of
proposed intake and discharge and analyzed for the parameters
listed in Table 2. Preferably these samples should be collected
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and analyzed once each season for at least one year. Where there
are severe time limitations, at least one set of samples should
be collected and analyzed.
Unusual findings obtained during the site evaluation survey
should be related to specific inputs of materials.
Monitoring
This program shoald be a continuation of the site evaluation
study and should provide a basis for evaluating the results of opera-
tional monitoring. The location of sampling sites depends on plant
design and the expected operational monitoring program.
Operational Monitoring
This program should include parameters measured continuously,
weekly, seasonally, and semiannually. Measurements should be made
in the intake and discharge to determine the direct effect of plant
operation on water quality and on areas unaffected by the discharge
plume to provide data on the rate of dispersion of chemicals dis-
charged and to identify other inputs in the area.
1. Continuously
The following should be monitored continuously in the plant
intake and discharge: temperature, dissolved oxygen, specific
conductivity, and turbidity. In addition, if chlorine is used
for disinfection in any part of the plant operation, the dis-
charge should be sampled for total residual chlorine at the
time of introduction.
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2. Weekly
The following should be measured weekly in the intake and
discharge: alkalinity, ammonia nitrogen, fecal coliform,
biochemical oxygen demand, chloride, color, hardness, nitrate,
nitrite, organic nitrogen, orthophosphate, pH, total dissolved
solids, total suspended solids, and sulfate.
3. Seasonally
The following chemicals should be measured in the intake,
discharge, and the discharge plume once per season:
aluminum, arsenic, boron, cyanide, chloride, hexane-soluble
materials, magnesium, phenols, sodium, and strontium.
4. Semi annually
The following should be measured in the intake and discharge
on a semiannual basis: barium, beryllium, cadmium, chromium,
copper, lead, mercury, molybdenum, selenium, silver, stronti-
um, tin, vanadium, and zinc.
Replication of Samples
Replication of samples and analyses should be built into these
programs to define the range of variability. A minimum of two
replicates should be taken at each sampling. Additional replicates
may be required for those parameters which show high variability
in the intake water and for which detection of small changes in con-
centration may be of significance to the measurement of biological
effects.
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Changes In Operational Monitoring Program
Changes in the sampling programs could be considered when:
1. the concentration of a given chemical parameter does not
change significantly over a one year period, or
2. the concentration of a parameter is in a range in which the
cooling water use would have no effect, or
3. the range of variability is so great that detection of
changes in the value of the parameter is excessively difficult, or
4. there is a process change in the plant which would alter the
characteristics of the discharge.
Chemical Data and Ecological Effects
Chemical water quality data are of value primarily for
determining mechanisms of ecological changes. For example, a
sudden decrease in photosynthetic rate in the area of the dis-
charge might be due to excessive temperature, mechanical damage
during condenser passage, toxic chemicals, or a combination of
all three. If such an effect is measured, then its cause should
be determined. An investigation would include chemical analyses
of the samples in which the effect was noticed.
The relationship of chemical data to ecological effects de-
pends first upon measurement of the ecological effect and then
the use of chemical analyses to determine the cause. Thus, it
is not possible to.specify a_ priori what chemical analyses are
needed. Hypotheses describing the mechanisms by which changes in
116
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chemical water quality could cause the observed ecological effect
must be formulated and tested using appropriate chemical procedures
However, well known changes in chemical water quality can cause
large ecological effects for example: a depletion of hypolimnetic
oxygen for several weeks completely changes the benthic communi-
ty, or an increase in the concentration of soluble orthophosphate
from levels below the limiting concentration greatly increases the
likelihood of nuisance algal blooms. Monitoring water quality
changes due to cooling water use should detect types of water
quality changes which cause these predictable ecological changes.
Priority Research
Research priorities identified here are questions which were
developed while describing studies to increase understanding of
the effects of thermal introduction on water chemistry. The
selection itself, and the assigned priority values were determined
by a demonstrated need for answers in these areas and because
other, perhaps more far-reaching research, depends upon the
results of these studies. In addition, the available data, or the
relative ease with which data may be obtained, has been used as
a factor for selection and for categorization. Adjustments have
been made in priorities and categories originally assigned by the
subcommittee based on best judgment and needs of the entire Panel.
Priority values have been ranked according to the following scheme:
1 - highest priority consistent with achieving primary goals
of the Panel ,
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f
2 - high priority studies supporting priority 1 items,
3 - intermediate priority but ultimately providing support to
priority 1 ,
4 - low priority supporting other programs but not of critical
importance in itself,
5 - deferred priority of a general supporting nature.
Since this subcommittee chose to arrange these studies by category,
categorical criteria are self-explanatory.
Category 1. Answers to these questions should be developed as soon
as possible using available data.
1. To determine dissolved oxygen at the intake and discharge of
representative Lake Michigan power plants and the extent to
which cooling water use results in the loss of dissolved
oxygen from the discharge plume.
Priority 1
2. To determine the extent to which cooling water use results in
an increase in biochemical oxygen demand.
Priority 1
Category 2. Answers to these questions should be developed using
data currently being collected.
1. To determine if cooling water use results in an increase in
total quantities of algal nutrients or in an increased availa-
bility of algal nutrients.
Priority 1
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2. To determine chemical substances present in the drainage or
leachate from fly ash holding ponds at representative Lake
Michigan power plants.
Priority 3
Category 3. Answers to these questions should be developed by
means of individual research projects not now underway.
1. To determine chemical substances in cooling tower blowdown.
Priority 2
2. To determine if cooling water use results in dissolved gas
supersaturation to the extent that it is destructive of
aquatic life.
Priority 2
3. To determine substances present in the water whose toxicity
is significantly altered by a temperature change.
Priority 4
4. To determine the toxicity of chemicals used in plant
operation or in cooling tower operation.
Priority 1
5. To determine if increased temperature results in a significant
increase in the rate of uptake of materials injurious to fish.
Priority 3
6. To determine the rate of oxygen demand by benthic organic
deposits in Lake Michigan and the effect of increased tempera-
ture on that rate.
Priority 4
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SECTION V
MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
PRIMARY PRODUCER AND CONSUMER COMMUNITIES
-------
Section V. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
PRIMARY PRODUCER AND CONSUMER COMMUNITIES
Table of Contents
Introduction 123
Principal Problems 123
Objectives of the Measurement of Microbiota .... 126
Measurement of Environmental Provinces 127
Phytoplankton 128
Introduction 128
Questions to be Answered 132
Approaches 135
Field Observations 135
Measurements 137
Evaluation 139
Zooplankton . 141
Introduction 141
Field Studies: Questions 148
Field Studies: Implementation 149
Laboratory Studies: Questions 155
Microbenthos 157
Introduction 157
Approaches . . . 158
Particulate Fallout ..... 159
Benthic Respiration . . '. . 160
Priority Research 161
Literature Cited .... - 163
122
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Section V. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
PRIMARY PRODUCER AND CONSUMER COMMUNITIES
Introduction
It should be recognized at the outset that a good deal more
quantity and quality of information is necessary to assess the
effects of thermal effluents on communities of microscopic organisms
in Lake Michigan than that which is presently available. Insuf-
ficient attention has generally been given to some or all of these
communities in available studies on thermal effects. In many cases,
it is necessary to pose questions which have not yet been asked of
the Lake Michigan system to provide a basis for management deci-
sions. Some of the problems particular to microbiological com-
munities are discussed briefly below.
Principal problems
Perhaps the most fundamental problems with microbiological
communities is their extreme complexity. Hundreds of species may
be found in a single sample from certain primary producer com-
munities in Lake Michigan and many more may be expected to fall
within the thermal effect of any single facility.
Unfortunately, the composition of such communities is poorly
known at even the fundamental level of identification. Taxonomic
i
treatises which comprehensively Itreat many of the important groups
are unavailable. Even basic historic works are scattered and scarce
Detailed investigations of thermal effects at the community level
will frequently require development of a taxonomic base during the
study. In addition, there is a paucity of investigators with
training and background necessary to approach these problems in
Lake Michigan. Perhaps because of this lack of fundamental
123
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knowledge, there are potentially important types of communities
for which practically no information exists. This is true of all
indigenous bacterial communities and of most benthic primary
producer communities, particularly those occurring in deeper
parts of the Lake.
Another characteristic of microbiological communities which
impeded an understanding of their responses is the variation in
abundance and composition in a single season, at any given sampling
station (Vol1enweider et al., 1974). Any microhabitat may be
occupied by several associations during a season. Natural seasonal
succession is responsible for a large part of this variation but
it is strongly suggested that succession is increased by environ-
mental disturbance. This means that to detect natural patterns
of change, more replicate samples of microorganisms should be
collected per unit time than for larger organisms, especially in
disturbed areas such as the nearshore zone of Lake Michigan. It
is also true that the grand growth period for many associations
occurs during the late autumn and early spring when field operations
are most difficult on Lake Michigan.
Many microbiological communities in Lake Michigan contain repre-
sentatives of fundamentally different biochemical divisions: This
causes serious problems in sampling and preservation for population
ii
studies (Uterir.ohl , 1958) and equally serious problems in designing
and implementing quantitative experimental studies. In many in-
stances, it is necessary to preserve and/or analyze multiple. •
aliquots using different methods to insure that all important group's
124
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are adequately treated.
Rapid turnover and specific responses of the microbiota to
heat also causes difficulty in the study of thermal addition on
microbiological communities. Doubling times of the species,
where known, range from hours to days and significant population
changes may be effected by short exposure to a stress. (Goldman and
Carpenter, 1974). In the Great Lakes, the change may be extirpation
of native populations and/or introduction of'exotics (Stoermer and
Y2ng, 1959; Hchn, 1959). Unlike higher organ i 317,3, the dispersal
of most primary producer species is relatively rapid (Rosowski and
Parker, 1971). It appears, for example, that the phytoplankton flora
of Lake Michigan is presently changing quite rapidly (Stoermer,1972).
It also appears that benthic primary producer communities have
changed drastically in the past 100 years, although this situation
is not as well documented as changes in the phytoplankton.
The rapid response time of microbiological communities hinges
on the fact that most communities are self-regulating to at least
some degree either through biochemical antagonisms or by sequester-
ing nutrients (Schelske and Stoermer, 1972; Fogg, 1965). Exposures
to increased temperatures have been known to select for populations
which pre-empt space, nutrients or both and which become widespread
in the system through those mechanisms (Foerster etal., 1974). Cer-
tain species of blue-green algae which are both favored by relatively
high temperatures (Cairns, 1972) and known to excrete antagonistic
fractions, may constitute a serious potential nuisance in Lake -
Michigan.
125
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Unlike higher organisms, these organisms have little or no
avoidance capacity. Effects of multiple passage or relatively
long thermal exposure in plumes can be expected to be more severe
in the microbiological communities than with organisms with suf-
ficient mobility to escape. It is basically understood that in
the trophic dynamics of an aquatic ecosystem, measurable effects
on the primary producers are manifested throughout the system.
Changes in the abundance or composition of carbon reserves fixed
at low trophic levels are important in the growth and mainten-
ance of fishes and other higher forms (Benson and Lee, 1975). It
is also apparent that changes in microbiological communities may
have direct effects on human welfare in Lake Michigan. Since
primary uses of the Lake include requirements for high quality
potable water and utilization of the Lake and its shore zone for
recreation, biological over-productivity or changes in the qual-
ity of the communities are of immediate and substantial public
interest (Vaughn, 1961).
Objectives of the Measurement of Microbiota
Operationally, studies should proceed in several distinct phases:
1. The first should be a background study providing an assessment
of spatial and temporal distribution, and baseline numbers
in populations occurring in the region of the proposed facil-
ity, and existing trends in such populations. Although some
of this information may be available from the literature,
exploratory field studies are strongly recommended-:
126
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2. Based on the above, detailed study of the waters in the im-
mediate region of the proposed facility can then be designed.
The output from the latter study should provide a detailed chart
of the populations occurring or passing through the region
of probable measurable thermal effect, and the seasonal vari-
ations in such populations. Reference stations should be in-
cluded for comparison with stations in the regions of imme-
diate effect, and fnr nnc^ihlp He term i na t i nn nf 1 a |c o uiirjo effects.
This study should be initiated well in advance of initial con-
struction when possible and should extend through at least five
years of the full operation of the facility.
3. If changes in population abundance, community structure, or
process rates are detected, experimental studies should be de-
signed and initiated to isolate and quantify any causes which
can be ascribed to cooling water use, directly or indirectly.
Measurement of Environmental Provinces
Studies should recognize and treat with biological provinces with-
in Lake Michigan:
A. The nearshore zone (ca. 8 miles from shore)
1. Milwaukee - Michigan City
2. Michigan City - Little Sable Point
3. Little Sable Point - Pyramid Point
4. Pyramid Point - Mackinac
5. Grand Traverse Bay
6. Northern Islands areas
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7. Mackinac - Point Detour
8. Bay de Noc and Green Bay north of Chambers Island
9. Southern Green Bay
10. Deaths Door - Algoma
11 . Algoma - MiIwaukee
a. The vicinity of any major stream or other effluent of
any of the above regions.
b. The open water zone
1. South of 42° 30'N
2. 42° 30'N - 44° 30' N
3. Grand Traverse Bay
4. North of 44° 30' N
5. Bay de Noc and Green Bay north of Chambers Island
6. Southern Green Bay
These geographic regions do not precisely delineate habitat types;
however, communities in these regions are sufficiently different
that caution is necessary in making a direct comparison of results
appropriate for another. In addition, it is suggested that there
is a consistent difference in plankton assemblages in the eastern
vs. western portions of the open water zone and the effects of cool-
ing water use must be determined as it pertains to those assemblages
in a further attempt to measure lakewide effects.
Phytoplankton
Introduction
Phytoplankton are microscopic plants -which are suspended in water
128
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In large lakes, such as Lake Michigan, most of the species which
comprise the phytoplankton complete their entire cycle free floating;
others exist on solid substrates. Such communities are quite complex.
At least ten major divisions of the Plant Kingdom are represented
in phytoplankton communities of Lake Michigan. Because of fundamental
differences in morphology, life histories, and physiological require-
ments in representatives of these divisions, few generalizations
can be made at the community level. Even generalities regarding the
representatives of any one of the major divisions are apt to be mis-
leading. Individual species belonging to some of the major divisions
have been reported from almost every conceivable aquatic situation.
Something on the order of 2000 individual species are now known to
occur in the Lake and undoubtedly others will be reported in the
future.
The majority of these organisms are either passive, or so feebly
motile that they cannot overcome water movements even when velocities
are low. Some respond actively to physical and chemical stimuli in
the environment but their capacity for avoidance is essentially nil.
Phytoplankton organisms known to occur in Lake Michigan range
in size from 1.0 micrometer in greatest dimension to something over
500 micrometers. The great majority are functionally unicellular,
although colonial aggregations are common in most of the divisions
represented.
Both the abundance and composition of phytoplankton communities in
129
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Lake Michigan, particularly in the nearshore waters, is highly vari-
able. Depending on location and season, numbers may range from
200 cells/ml to over 30,000 cells/ml (Stoermer,1972). Composition
in different localities ranges from domination by species usually
considered to be indicative of very high water quality, to domina-
tion by species which are abundant in highly eutrophied waters in
the Great Lakes system (Stoermer and Yang 1970).
Perhaps the most outstanding characteristic of primary producer
communities in general, and the phytoplankton in particular, is
their rapid and total response to environmental change. Most
phytoplankters have generation times ranging from several hours to
several days so that perturbations of the system may cause rapid
reactions. Most of these microorganisms are cosmopolitan in dis-
tribution and when conditions are significantly changed indigenous
or existing species associations may be rapidly replaced by other
organisms. Changes of this type have occurred in Lake Michigan
and elements of the present phytoplankton community probably were
not present in the Lake before the intervention of man (Stoermer and
Yang, 1969).
The principal role of phytoplankton in the aquatic ecosystem
is primary production. In a sense, these organisms operate at the
interface between the physical and chemical milieu and organisms
at higher trophic levels, since they utilize radiant energy to fix
essential chemical elements into metabolically useful substances.
In large lakes, such as Lake Michigan, the habitat-aval Table, to
phytoplankton far exceeds that available to'other primary producer
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communities requiring solid substrates for their growth, and energy
fixed by phytoplankton is the primary controlling factor in total
productivity of the ecosystem. A fact often overlooked is that
while the abundance and physiological condition of phytoplankton
controls the amount of material available to higher levels in the
food chain, the kinds of phytoplankton also determines the type of
material available. If changing environmental conditions result in
a change in phytoplankton composition from dominance by one division
to dominance by another with greatly different biochemical charac-
teristics, serious impact may be observed in the consumer communities.
It should be observed that such changes occur with increasing intro-
ductions of domestic and industrial waste. Because characteristics
of the drainage basin of Lake Michigan and its considerable thermal
inertia, indigenous phytoplankton populations still existing in the
Lake were adapted to conditions of low nutrients and low temperature.
The primary factor controlling productivity was the availability of
phosphorus. The characteristic seasonal cycle of phytoplankton
abundance has consisted of a spring and autumn maximum and rather
uniformly low populations during the rest of the year. (Stoermer and
Kopezynski, 1967). The indigenous flora was dominated by diatoms
(Bacillariophyta) and microflagel1ates belonging to several divisions
(Chrysophyta, Pyrrophyta, Cryptophyta) with relatively small numbers
representing other divisions (Cyanophyta, Chlorophyta) which are
usually important in smaller lakes in the regions(Ahlstrom, 1936).
Most of these organisms are perennial and appear to be cold steno-
thermal although experimental evidence regarding temperature require-
ments of species native to Lake Michigan is almost entirely lacking.
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It is suspected that their requirements for low temperatures were
met during the summer months by a vertical adjustment to the area
of the thermoclineal 1 owed by the high transparency of the offshore
waters of Lake Michigan.
At present, phytoplankton communities in the Lake are under-
going substantial change. Changes in the ecosystem, apparently
human induced, have caused replacement of the indigenous flora of
the inshore waters by introduced species particularly during the
spring period of maximum productivity (Stoermer, 1972). Productivity
levels have been substantially increased and there is growing evi-
dence that phosphorus is no longer the limiting element (Schelske
and Stoermer, 1972). Depletion of available silica is of particular
concern during the summer stagnation when it is reduced to levels
which will not support diatom growth. Since species belonging to
other divisions which do not require silica for growth, particularly
the Cyanophyta, and Chlorophyta, are favored under such conditions,
it is believed that nuisance conditions caused by the proliferation
of green and blue green algae may arise in Lake Michigan as they have
in Lake Erie and Lake Ontario. Most nuisance species of blue-green
algae (Cyanophyta) apparently require relatively high temperatures,
so that addition of heat to nearshore waters may contribute to such
undesirable conditions.
Questions to be Answered
The following general questions should be addressed both in
the context of the system as it is now (pre-operational), and after
the addition of heated effluents and other facts associated with
132
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operations of a facility with a thermal discharge.
1. What populations are present?
a. What are the seasonal differences in occurrence and
abundance?
b. What are the spatial differences in the region of the
facil ity?
Comment;
Clearly it will be necessary to develop information regarding
. . ...
ui u I u i u ^ I *~ a I
response such as species diversity ordination analyses. Specific
identifications may pose considerable difficulties for reasons al-
luded to earlier, however taxa encountered should be identified
to the species level.
2. What is the characteristic population structure of such
assemblages?
a. Are there characteristic seasonal changes?
b. Are there regional differences?
Comment;
It is suggested that comparative measures of .assembl age com-
position and abundance, such as ordination analysis or similar
techniques, be employed. Simpler indications of assemblage struc-
ture, such as the various diversity indices, are notoriously dif-
ficult to interpret for phytopl ankton.
3. What are the measurable process rates associated with such
assemblages and how are they affected by thermal additions
and other factors connected with cooling water use?
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a. Growth rates of abundant populations.
b. Productivity rates.
c. Nitrogen fixation rate. (Vanderhoef et al., 1972).
d. Uptake of key nutrient elements.
1. Phosphorus
2. S i 1 i c a
3. Nitrogen
Interpretation of the answers to these questions may be
difficult since the historic data base for the phytoplankton is
weak and certain informational links between species and numbers
are lacking except on a local and recent basis. To close these
gaps, it is important that answers to the following questions be
developed by water users as a group, for use in individual site
investigations:
1. What was the composition of the plankton populations which
were present in earlier years? Phytoplankton communities in
most areas of Lake Michigan are already severely perturbed
and the indigenous fauna and flora, in the strict application
of the term, no longer exist. Efforts should be made to re-
construct the original composition through review of literature,
preserved collections, or by paleolimnologic methods. This
historical perspective is necessary to establish the background
of acute and chronic change which has occurred in the Lake's
flora and fauna through time, caused by human influence. This
background would permit comparisons with current data by pro-
viding a standard against which to measure more recent effects.
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In addition, a better understanding of the changes which have
transpired in plankton populations may permit prediction of
future trends and guard against permanent exclusion of the
indigenous fauna and flora by thermal pollution.
2. What are the ranges of spatial and seasonal variation within
such a system? Since, in phytoplankton , extreme variations
in total assemblage abundance and equally significant changes
in community structure may occur in lateral distances of a few
cooling water requires extremely sensitive measurement and analy-
sis methods. Program designs should demonstrate this capability
and explicitly state limits of detection of modifications which
occur.
3. What are the trends and causes of trends of phytoplankton
abundance and species composition now present within the system?
Since thermal effects are largely synergistic, it is important
to demonstrate that additional thermal loading will not in-
tensify problems resulting primarily from other types of pertur-
bation (Beeton and Barker, 1974). If information is inadequate,
studies should be focused on explanation of these trends.
Approaches
Field Observations
An extremely comprehensive program of field sampling is
necessary to answer the questions posed. Some principal aspects,
including sampling location and frequency, should be determined
' o. ' .
through knowledge of the discharge characteristics of the plant
(e.g., shoreline, submerged jet, length of canal or. conduit,
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velocities, etc.) and the regional characteristics of the
lake environment (e.g., water quality, location of signifi-
cant pollution introduction, location of spawning or nursery
grounds, etc.). Fixed stations will be necessary for develop-
ment of comparative data and it is believed that, for initial
determination, the sampling area should be equal to an area
encompassed by twice the radial distance from the cooling
water discharge to the most extreme 1C isotherm. Since the
position of this isotherm is extremely variable, and perhaps
undefinable, the suggested distance is arbitrary and is certain-
ly subject to enlargement or diminution depending upon sound
evidence. In any event, sampling intensity should concentrate
in the vicinity of the discharge on the assumption of greatest
effect. It should be incumbent on the plant operator to demon-
strate valid estimates of microbiota (abundance and species
composition) to the 95 percent confidence level for the area
sampled in order to detect the extreme of possible effects of
cooling water use. In view of variation found in the micro-
biota through space and through time, the exact number of stations
cannot be specified but initial arrays of 64 stations may be
justi fied.
Accompanying physical and chemical data should parallel
logical sampling. Again, in view of variability previously
found in the microbiota through time (Holland and Beeton, 1972)
monthly sampling frequency is a minimum effort. Weekly or bi-
weekly samples are desirable during periods of expected seasonal
pulses.
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Measurements
Measurements which should be made on samples include:
1. Estimates on standing crop biomass should be made from all
samples. Method of choice is assay of extracted chlorophylls
(Strickland and Parsons, 1968). Results should be validated
by independent methods such as assay of total organic carbon
or total organic nitrogen.
2. Estimates of rate of primary productivity should be made from
all surface samples and from all depths at not less than ten
stations strategically located with respect to depth and dis-
tance from thermal source. Method of choice is measurement of
14C uptake rate (Strickland and Parsons, 1968).
3. Estimates of nitrogen fixation should be obtained from all
surface samples. Method of choice is acetylene reduction
technique (Stewart et al., 1967).
4. Estimates of species composition and abundance of phytoplankton
assemblages should be obtained from all samples by microscopic
identification and enumeration of organisms in suitable prepared
whole water samples. Because of diversity of biochemical groups
present, care should be taken to employ techniques of identification
suitable for particular groups to insure accuracy. These measure-
ments should be made in a temporal sequence which permits
calculation of growth rates for predominant populations.
5. Estimates of concentration of both particulate and dissolved
major nutrients (Phosphorus, Nitrogen and Silica) should be
*
made on all samples.
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In addition to sampling in the vicinity of the facility, at
least one array of stations, consisting of a line transect at dis-
tances of 1/8, 1/4, 1/2, 1, 2, 4, 8, and 16 statute miles from
shore should be established within the same biological province
as the primary grid, but as far removed as possible from human
effects. These stations should serve as a reference for near-site
studies and as a monitor of possible whole lake effects. These
stations should be sampled in the same manner, and at the same
intervals as the primary grid stations and this same suite of
analyses should be performed.
After discharge, a much larger volume of water is heated by
the mixing and dilution of the plume with surrounding water than
the volume of water which actually passes through the plant. Al-
though the temperature elevation is not as great as in the plant,
the small increase may have a great effect on the microbial community.
Whereas large temperature increases in the plant may result in
mortality, inhibition of various metabolic processes or, a short-term
stimulation of metabolism, lower temperature elevation in the mixing
area may cause a prolonged stimulation of metabolic activity, growth
and reproduction.
In addition to a program to measure metabolic rates in the field,
experimental studies should be included. Measurement of the rate
of carbon fixation by a series of ^C experiments on samples incubated
at temperatures artificially elevated above -ambient conditions is
appropriate. Experimental temperatures bracketing those existing or
c
predicted for a given power plant will reproduce the seasonal response
of phytoplankton to increased temperature. This information may then
v 138
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be evaluated for Isothermal areas to predict overall response of
phytoplankton to thermal elevation.
Evaluation
Experimental procedures should evaluate the following:
1. Effects of temperature elevation o,n carbon uptake. Rates
should be measured at small temperature increments above
ambient, conditions up to and exceeding maximum temperature
observed or expected for the power plant. For example,
if the particular power plant has an expected cooling water
temperature rise of IOC and the ambient lake temperature
is 8C, samples collected from an area not influenced by
the plant should be incubated at 8, 10, 12, 14, 16, 18,
and 20C.
2. The effect of exposure to elevated temperatures through
time.
Samples from reference areas should be exposed to similar tem-
peratures for similar lengths of time. After exposure, samples should
be returned to ambient temperature and the rate of carbon uptake de-
termined to assess the effects of exposure to elevated temperatures
through time.
Metabolic processes such as respiration, nitrogen fixation and
uptake of other nutrients could also be observed in a similar manner
to assess thermal effects.
These studies could be extremely valuable for providing design
139
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engineers with some of the numbers necessary to design more ecologi-
cally compatible systems. By knowing temperature response of the
plankton, appropriate condenser temperatures can be selected. In-
formation on temperature response of the plankton and the effects
of exposure to elevated temperatures through time could aid in
designing discharge structures to minimize harmful effects.
Development of predictive models of the metabolic response of
phytoplankton or other microbial groups to elevated temperatures would
be an extremely valuable aid in design, or assessing the effects of
operating plants. Such models could not be applied to all areas of
the Lake due to differences in species composition, nutrient condi-
tions, and other factors, but might provide estimates of impact on
the microbial metabolism. Modelling would also reduce repetitions
of experiments at proposed power plant sites.
Another experiment which should be considered is observation of
natural phytoplankton cultures following exposure to elevated tem-
peratures. Large cultures held at elevated temperatures or eleva-
ted for short periods of time and returned to ambient should be
observed through time for changes in species composition and abun-
dance. These observations could provide clues to the effects of
thermal elevation on the composition of the phytoplankton community
at a particular site or in the Lake as a whole.
Each of the experimental procedures outlined above should be
conducted at least six times per year during all seasons of the year
for at least three years. After evaluation of the results, it may
be possible to discontinue the work.
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Zooplankton
Introduction
Zooplankton are animals characteristically spending a sig-
nificant part of their life-cycles suspended in water. Most
prominent or quantitatively significant species in the zooplank-
ton of typical continental fresh waters are holoplanktonic, that
is, no life stage is spent outside the plankton. Marine zooplank-
ton by contrast includes a significant number of meroplanktonic
forms, where suspended egg or larval stages later give rise to
sedentary ones. In typical fresh water, including Lake Michigan,
this link between planktonic and benthic communities is tenuous,
although there are exceptions of possible importance. There is
also a blurring of the distinction between planktonic and seden-
tary or benthic organisms in some inshore waters, since there are
organisms which more characteristically attach to bottom materials
or surfaces of rooted higher plants and which briefly enter the
plankton when migrating vertically (there are examples among the
Cladocera, Ostracoda, Mysidacea, Amphipoda, and Insecta). The
same phenomenon occurs in waters adjacent to the bottom at dis-
tances from the shore. It is one factor distinguishing inshore
and offshore zooplankton assemblages.
Exceptions of possible importance in Lake Michigan are the
fol1 owing:
1. Numerous species of insects occurring in a large lake spend
only the egg and pre-adult periods there, leaving it as adults
(e.g. many Diptera, Trichoptera, Plecoptera). Some are planktonic
141
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for short but well-defined stages (Diptera: Tendipedidae, some
species during very early and very late larval, and entire pupal
stages; Culicidae, Chaeoborus, during entire larval and pupal
stages).
2. Most of the species in some of the major zooplanktonic groups
(Cladocera, Rotifera, Copepoda; see below) have an encysted, dia-
pausal stage (e.g. the mictic egg in Cladocera and Rotifera)
which is highly resistant to damage from mechanical injury, desic-
cation, or unfavorable chemical conditions, and which can leave
the water to be distributed as a dust particle by the wind or other
agent. This characteristic gives a species-population the means
to avoid unfavorable conditions, and may also explain the nearly
cosmopolitan distributions of many planktonic forms.
3. Certain macrozoobenthic species, in Lake Michigan most strikingly
Pontoporeia affinis and Mysis relicta, regularly migrate vertically
through a sufficient distance to carry them well beyond the benthic
biotope and into the zooplankton, at least at certain seasons or
certain time of day.
The bulk of the Lake Michigan zooplankton, as of most inland
waters of reasonably large size, is composed primarily of individuals
of four major animal groups, the Cladocera and Copepoda (Arthropoda,
Crustacea), the Protozoa, and the Rotifera (Aschelminthes).
Under most conditions, members of these groups account for
more than 90 percent of the total zooplankton biomass, and probably
do so in Lake Michigan. Animal groups contributing less to the
plankton biomass in Lake Michigan are Arthropoda: Insecta, Crustacea
(Mysidacea, Amphipoda), Arachnoidea (Hydracarina): a few platyhel-
142
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minths, nematodes, and annelids. Fish eggs and larvae, more
properly meroplanktonlc, are discussed in the fisheries section.
Among the major groups of Crustacea, there is a general ten-
dency for the Cladocera to become relatively less prominent as
lakes become colder and more oligotrophic (and, because of
correlations between these factors and size, as lakes become
larger); rotifers remain about equal in importance in relation
to crustaceans in all cases. Thus, the zooplankton of Lake Michi-
§ u u COPiS'iSi.S pi'lmai'liy O i prOtOZOanS, C i a u G C c i* a il 3 , COpcpOuS, 5 i"i u
rotifers, with the largest fraction of the biomass normally made
up of copepods (Wells, 1960).
Within all groups, there is great taxonomic diversity, a
character that distinguishes the zooplankton from, for example,
the macrozoobenthos. Each major zooplankton group contains a
large number of species with very different responses to environ-
mental conditions and of very different quantitative significance
locally and seasonally. For these reasons, it is as difficult to
characterize zooplankton of the Lake as having a general response
to environmental disturbance, such as discharge of waste heat, as
it is phytoplankton. It is worth noting that many of the principal
zooplankton forms are complex, advanced metazoans. Because of
highly adapted and responsive sensory systems, and because of their
advanced degree of organization, they are highly responsive to,
and easily injured by changes in their environment.
The majority of zooplankton in Lake Michigan range in size
between about 50 micrometers (smaller rotifers and protozoans) and
1 cm (larger cladocerans) in length or greater diameter. Unlike
143
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phytoplankton, they are all capable of independent motion, although
this is not usually vigorous enough to enable them to resist water
currents in the Lake itself, or in the vicinities of intakes and
discharges. Within a water mass, independent movement of zoo-
plankton may cause considerable change in density with time. For
example, vertical displacement of single plankters over distances
of several meters in 24 hours is possible. Changes in local
density or organisms complicates sampling, and may mean that the
effects of an environmental change, such as a change in water
temperature, are removed from the original site of the insult.
Although the capacity of typical zooplankters to avoid un-
favorable environmental conditions has very clear limits imposed
by their limited mobility, it is not as restricted as it is for
phytoplankton.
'Because of small size and, in many cases, high reproductive
capacities, some zooplankton respond rapidly to environmental
change through changes in abundance. In a favorable environment,
certain parthenogenetically reproducing cladeocerans can achieve
an 8 - to 10 - fold increase in population in a matter of a few
days (i.e., doubling times may not be less than those for the
more rapidly reproducing phytoplankton). Others, requiring longer
periods for development through successive larval stages (e.g.
copepods), show slower and even delayed responses. As with phy-
toplankton, the cosmopolitan distributions of many characteristic
species (and the existence of resistant, easily dispersed stages
in their life cycles) make possible the replacement of "native"
species with "exotics" having competitive advantages under the
144
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altered conditions. Such changes have apparently occurred 1n
parts of the Lake Michigan system (Beeton, 1965; Robertson, 1966).
Such replacement is possibly unlikely to be as striking for
copepods as for cladocerans or rotifers: although the reasons
are not well understood, the former show a much higher degree
of geographic specificity than the latter, which may mean that
one species of copepod is less likely to be rapidly replaced by
another as environmental conditions change (Hutchinson, 1967,
r. fiRfi ff \
r • - — — ••./.
With the exception of one group of planktonic copepods
(Cyclopoida) and a few specialized calanoid copepods and clado-
cerans (Leptodora and Polyphemus), the food of major zooplankton
is primarily suspended particulate organic matter —living cells
of phytoplankton, or at least organic detritus originating from
phytoplankton biosynthesis. Most zooplankton feed with highly
specialized mechanisms for filtering, concentrating, or sedimen-
tingsuspensoids, each of which depends on a high degree of phy-
siological coordination. Feeding rate and efficiency are strongly
affected by food density, temperature, oxygen supply, and other
chemical conditions.
Zooplankton are, in turn, food for a wide variety of higher-
order consumers, including fish, insects, and other invertebrates
depending on size and availability to the predator.
The primary role of the zooplankton community is as the major
link between the blosynthetic and energy-fixing function of the
phytoplankton and the remainder of the Lake's ecosystem. Dis-
turbance of this function results in disturbance of secondary
145
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productivity^ in the entire Lake, most significantly to produc-
tivity of various economically valuable populations of fish.
All species of fish occurring in Lake Michigan probably de-
pend upon zooplankton for food at least during early develop-
mental stages. Those which feed extensively on zooplankton
through the adult stage include the alewife, yellow perch, small
centrarchids, such as bluegills and sunfish, most forage species
of small size (members of the family Cyprinidae), sticklebacks,
and darters, and members of the genus Coregonus, such as the
whitefish, lake-herrings, bloaters, and ciscoes.
Probably few species of zooplankton are entirely indifferent
to the quality of their food, and most of those that have been
carefully studied are selective, favoring certain species or
materials derived from phytoplankton and rejecting others. The
nutritional welfare, composition, and productivity of the zooplankton,
therefore, very strongly reflect quality as well as quantity of
photopl ankton food, and respond strikingly and quickly to environ-
mental changes that affect the composition and abundance of their
food (see, for example, Pacaud, 1939; Lowndes, 1935; Fryer, 1954).
Species composition of zooplankton of Lake Michigan and
seasonal changes are imperfectly known, and it is difficult to
'The term "secondary productivity" will be used throughout this
section to refer to productivity of all heterotrophs, without
making distinctions among the so-called primary, secondary,
tertiary, . . . consumers. Such distinctions are useful in
certain contexts, but not here.
146
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separate natural changes in the character of the community from
those resulting from human alteration of the Lake's environment.
There is some indication that "native" oligothermal species,
such as Diaptomus (Leptodiaptomus) minutus, are being replaced
by more euthermal ones, such as Diaptomus (Skistodi aptomus)
oregonensis. and that certain species characteristic of oligo-
trophic waters, such as Eubosmi na (Bosmina) coregoni , are being
replaced by those characteristic of more eutrophic waters (not
nas*aecav*41t« K a /* a n c o f\ -P + amnŁiv»a^iiv*o K 11 +• -fnv* v*o a c n n c a + n v*o c a n +"
I • N. W * I • W Wt w « • • ** Wt W f* . w w _ . . —
unknown), such as Bosmina longirostris (Beeton, 1965, 1966, 1969)
Such changes, if permanent, may reflect quality of the food
supply or changes in water chemistry. The composition of the
rotifer component of the zooplankton is, with the exception of
a few large or prominent forms, almost entirely unknown.
Studies of species-composition and abundance of zooplankton
are complicated by annual and diel cycles of abundance. Annual
cycles of abundance appear to be correlated with factors such as
temperature, food supply, and predation (as the spring-fall
pulses of Daphnia in many inland lakes), diel cycles (as in 24-
hour changes in depth-distribution of populations of Daphnia)
with changes in light intensity or quality. Whatever the cause,
cycles are well known and sampling programs should take them
into account (Wells, 1960; Gushing, 1951).
The importance of zooplankton for monitoring cooling water
effects follows from two characteristics of the community:
1. Ecological status. It is a central trophic element and
quantitatively significant factor in the Lake ecosystem. If
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affected directly, secondary effects will ramify in two directions,
upwards, toward the primary productivity of the phytoplankton, on
which it exerts a complex regulatory effect through grazing, and
downwards, toward fish and other animals and the secondary pro-
ductivity of the entire ecosystem.
2. Sensitivity results from small size and high reproductive po-
tential. (High reproductive potential may also negate sensitivity
by permitting rapid replacement of individuals destroyed by con-
denser passage.)
On the other hand, it is not an easy community to study because
of taxonomic confusion in some of the groups, because of the dif-
ficulty of maintaining most species under laboratory conditions,
and because of numerous problems in estimating abundance in field.
Environmental changes affect zooplankton by altering certain
physiological rates: of respiration, digestion, reproduction, and
other similar processes, probably in age-specific ways. These
changes are then reflected in properties of the entire community,
such as total respiration, total productivity, rate of change in
biomass, and species composition. Individuals are suitably
studied primarily under laboratory conditions; communities pri-
marily in the field.
Field Studies: Questions
The following general questions should guide field studies
of the effects of thermal discharges on zooplankton populations:
1. What changes have occurred in the species composition of the
affected community?
148
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a. In the relative biomasses of the various species com-
posing it?
b. In the p.atterns of seasonal change that characterize
its species composition?
2. What changes have occurred in the productivity of the affected
community? What changes in fractional units of productivity
furnished by the major components? What changes in the
seasonal distribution of productivity?
3. How are the above changes related to changes in the character
or behavior of the phytoplankton community? How, for example,
has the food supply of major elements in the zooplankton
community been affected?
4. What is the character and behavior of the zooplankton community
in the Lake as unaffected by man, or, what was the condition
of that part of the Lake prior to thermal discharge? Two sub-
sidiary questions are implied here:
a. Is the discharge a factor that disturbs the stabilized
state of the Lake, if indeed its state is stabilized?
b. How does the discharge interact with other control 1able
impacts, such as chemical pollution, to modify or amplify
the effects?
Field Studies: Implementation
1. Standard Samples
a» Location and number of samples (see sections on
phytoplankton).
b. Collection and treatment of samples
1) For species determination and enumeration, evaluation of
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biomass by dry weight, settled volume, total carbon,
total nitrogen, or any other destructive analysis,
samples are best collected with a metered townet (or
isokinetic pumping of water') to obtain an integrated
sample from the top to the bottom of the water column
(except where vertical distribution is the subject of
study) so that results can be expressed as quantity
per unit area of lake surface. If several kinds of
gear are used, they should be standardized by compari-
son at a given location and time.
2) Townets (or strainers for pumped samples) have a mesh
size too coarse to capture smaller zooplankton, such
as most of the rotifers, copepod nauplii, and smaller
cladocera. Smaller forms are probably best studied
quantitatively in whole water samples; zooplankton may
range down to diameters of the order of 50 micrometers,
as noted above.
3) For specific analyses, the catch should be subsampled.
The best technique for handling standard zooplankton
samples is to preserve the entire sample so as to main-
tain the identity of all animals. This may be a two-step
A properly used townet may come close to being isokinetic at the
orifice, although it probably will never achieve that ideal; a
townet often results in damage to the organisms. Volumes can be
controlled better with pumped samples, but the apparatus is more
complicated, subject to malfunction, and intake avoidance may
still be a significant problem.
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process (anesthesia plus fixation) and varies depending
upon the kind of zooplankters in the sample. This is
followed by a preliminary concentration of the catch and
removal of a true aliquot for species determination and
enumeration (by age-class if possible: see below). Re-
moval of material from this aliquot (for counting, for
diagnostic purposes—dissection, making mounts for micro-
scopic examination, etc.) must not change its composition,
because the residue 1s preserved as a voucher. Correct
determination of field abundance and composition of zoo-
plankton may require additional collection of specimens
at the same locality, based on data from the aliquot (some
organisms require examination in the living condition, and
some require fixing or preservation with special precautions
for competent determination).
After removal of the aliquot, the residue of the sample
should be dried at low temperature or under vacuum, and pul-
verized for storage and destructive analyses. Data should
be accumulated for eventual calculation of conversion
factors (and their variances) relating total carbon, total
nitrogen, total dry weight, and counts by species, to save
effort in later similar studies.
Dry material retained will be useful for additional
••
destructive analysis, for example, for radioactivity, heavy
metal content, or chlorinated hydrocarbon content. Useful-
ness will be maximized if careful attention is given to
conditions of preparation and storage.
151
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4) Sampling errors. When developing data over areas using
large integrated samples (hundreds of liters), replica-
tion at a station is probably unnecessary because:
a) true errors of sampling for large samples will be
insignificant;
b) errors due to horizontal nonhomogeneous plankton dis-
tribution ("patchiness") will not be correctly esti-
mated by simple replication of long tows or pumping
runs. Major sampling errors in counts, determina-
tions of dry weight, carbon content, etc., will ori-
ginate primarily in aliquotting or subsampling, and
here replication is required. The degree of replica-
tion is determined by variation in the samples and
by rigorous testing of the subsampling procedures;
c) other errors will originate in poor calibration of
the sampling equipment as it measures sample volume.
Calibration should be performed regularly to insure
a high level of precision;
d) 95 percent confidence limits for means, based on sub-
sampling replication should be presented with all results
However, if stations are to be compared to stations in
order to detect changes which may have occurred over a
more limited geographic distance, or to substantiate
possible vertical variation, replication at sampling
stations may be required, depending upon the sizes and
nature of the samples.
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c. As soon as possible, the above scheme should be implemented
with regular sampling along 16-mile transects in unaffected
areas in each of the geographic regions of the Lake (as
listed in the section on phytoplankton) on a regular monthly
schedule and maintained indefinitely to provide a baseline
for evaluation of future conditions.
d. Such techniques should generally apply to on-site
studies and monitoring programs.
2. Productivity.
No single measure equivalent to 14C-uptake (primary pro-
ductivity) is currently available to provide information on
productivity in a population of consumers. Techniques involving
use of ATP ("adenosine tri phosphate) are currently under develop-
ment to provide this important information.
Secondary productivity of a single-species population can
be laboriously computed through data on birthrates, mortality
rates, growth rates, respiratory rates, age-structures, etc. in
various combinations. Most of these data are exceedingly diffi-
cult to obtain. In the absence of direct determination of
secondary productivity, indices from standard samples will
provide some information on some of the components of the zoo-
pi ankton.
153
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Faithfully through time, at all stations on the Lake, a
picture of the normal seasonal pattern of zooplankton productivity
characteristic of each of the various geographic regions will be
obtained, which will serve as background or standard of comparison
against which changes produced by thermal discharges can be
evaluated.
These indices are ratios of numbers of individuals at two
different stages of the life cycle (thus at two different ages).
They are related to rates of change in population size, or to
turnover rates. In conjunction with information on absolute popula-
tion size, and compared within a species through space and through
time, the following routine measurements may shed light on zooplankton
productivity:
a. Average number of broodpouch eggs per parthenogenetic female
in many cladocerans (especially species of Daphnia). In most
cladocerans, there are no strikingly distinct juvenile stages,
and ages can only imperfectly be inferred from size. The
broodpouch egg, however, is a well-defined age'category, and
the number of eggs carried is related to the rate of addition
of new individuals to the population.
b. Proportions of adult females (or of all females) carrying
ephippial eggs (agains, in Cladocera, especially Daphnia). The
significance of production of ephippial eggs in cladocerans is
not well understood. Poor nutrition is thought to stimulate
production, and appearance of ephippial eggs is thought to be
an indication of overcrowding and incipient population decline
(Hutchinson, 1967, p. 597 ff.).
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c. Relative number of female (copepods) carrying egg sacs. As
in a., this is a measure of the rate of addition of new
individuals to the population.
d. Average number of eggs per sac(female copepods). There 1s
little information on the significance of the number of eggs
per sac, but along with the frequency of gravid females in
the population, it 1s a measure of the potential rate of
increase.
e. Ratio of copepoditss tc numbers of adults in a cupepod popu-
lation. This is related to mortality rate between the
average copepodite and average adult age, and may provide in-
sight into the rate of predation on the population.
Ratios of numbers of nauplii to copepodites to adults serve
a similar purpose, except that, at present, it is not generally
possible to identify copepod nauplii to species; it is neces-
sary to work with the entire population of copepods without
regard to possible specific variation. Wherever the popula-
tion consists of more than one dominant species, unambiguous
interpretation of changes in ratios of nauplii to later stages
of the reproductive cycle will be impossible.
f. Similar indices should be developed for populations of plank-
tonic rotifers; rotifers, depending on species, produce both
parthenogenetic and sexual eggs, which are often distinguish-
able and countable.
Laboratory Studies: Questions
The principal objectives of a program of laboratory investi-
155
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gations of zooplankton are to improve understanding of the re-
sponses of the organisms to unnatural patterns of temperature
elevation, both the momentary ones of relatively great magnitude,
such as are experienced by organisms passing through the condensers
of a plant, and those more prolonged but of lesser magnitude, as
may be experienced by organisms entrained in a discharge plume.
Study of entrainment effects is discussed in another section.
Aside from injury from direct exposure to. heat, a variety of
indirect effects might be expected on zooplankton, such as those
that would follow from direct effects on the phytoplankton, af-
fecting the source of food. Until the effects of thermal dis-
charges on phytoplankton are more clearly understood, it is not
possible to propose specific guidelines for laboratory investiga-
tions of the responses of zooplankton to changes in the quality
of food.
1 . Food Preference
a. What is the principal food for zooplankton species
seasonally and throughout development? What preferences
or requirements are revealed by differences in the compo-
sition of the zooplankton species?
b. What replacements among species, or shifts in dominance,
are likely to follow changes in the composition of the
phytoplankton (such as a shift from dominance by one
species of diatom to dominance by another)?
156
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Mi'crobenthos
Introduction
This term is applied to communities of microscopic organisms
which exist on the lake bottom or at the interface between the lake
and land. Such communities are complex and composed of primary pro-
ducers belonging to several major algal divisions and consumer organ-
isms including Protozoa and representatives of several invertebrate
groups, characteristic communities tend to develop on substrate types
and are often designated as: epiphytic (occurring on plants),
epilithic (on rocks), epipelic (on soils), psammonic (among sand
grains). The general term periphyton is often applied to coarser,
more obvious forms.
Due to difficulties in quantitatively sampling these communities,
they have remained rather poorly known with the exception of nuisance
causing periphyton growths. Limited observations indicate that such
communities occur to depths of at least 30 m in Lake Michigan. Many
species are present which are apparently obligate cold stenotherms
(Stoermer, in press). Certain elements of this "glacial relict"
flora and fauna apparently find refuge in Lake Michigan below the
level of the thermocline during the summer months.
Because the primary producer component of these communities is
much more concentrated than the plankton, they provide a rich food
source for invertebrate animals. The importance of these communities
to the total ecology of the Lake has not been adequately investigated.
Observations, however, indicate that areas of benthic algal growth
157
-------
are favored feeding regions for adult fish of many species, furnish
a place of refuge for the young of some species, and are nesting
grounds for others.
Primary concerns regarding thermal effects are damage to indigenous
stenothermal communities by plume impingement and facilitation of
growth of nuisance periphyton, C1adophora in particular, in the
eutrophied nearshore zone (Neil, 1974; Griffiths, 1974).
Approaches
Because of the present inadequate state of knowledge, extensive
preliminary reconnaissance is necessary followed by detailed observa-
tion of characteristic community types. Suggested phases of this
process include:
1. An intensive visual survey should be made of the region which
could conceivably come under the influence of heated plumes.
This survey should include shoreline, and bottom to a depth of
at least 20 m. Sampling of communities should be accomplished
at this time. It is imperative that personnel sampling are
thoroughly familiar with community types and appropriate sampling
methods. At most sites, work will be accomplished by SCUBA divers.
Output should be detailed maps of substrate types and comprehen-
sive lists of the fauna and flora characteristic of substrate
types and depths.
>. On the basis of this information, a detailed study plan should be
designed and submitted to appropriate agencies for review. A
study plan should demonstrate adequate sampling of community
types with depth and distance from the effluent. Sampling inter-
val should be not less than monthly. Certain habitats may be
closed to sampling by ice during the late winter season.
158
-------
Parameters should include:
a. Population abundance and community structure estimates
similar to those developed for plankton communities.
b. Standing stock biomass estimates.
c. Productivity and growth rate estimates.
It is suggested that measurements of biomass and productivity
be obtained from naturally occurring communities rather than from
those developed on artificial substrates. Such estimates require
innovative sampling techniques and the use of in si tu enclosure
experiments best accomplished by SCUBA divers. Artificial sub-
strates may be used as a measure of trends, but should not be re-
garded as quantitative or representing natural conditions in the
Lake.
Another problem is transfer of materials from the plankton to
benthic habitats. This problem is also important to investigations
on macro-invertebrates and fish as well as microbiological communities
Since certain of the studies are best accomplished with the work
outlined above, they are discussed in the following sections.
Particulate Fallout
Planktonic organisms which pass through or are influenced by
the thermal effluent from a power plant eventually die and sink to
the bottom of the Lake as do plankters in undisturbed areas of the
Lake. Many of these organisms are consumed or decomposed during
theirdescentwhi le others complete the fall to the bottom and become
part of the sediments. If the effects of a power plant effluent
result in death of planktonic organisms, one might expect dead
organisms to rain down from the plume in greater numbers in the
159
-------
vicinity of the plant, than in undisturbed areas. This could
result in an accumulation of organic matter on the bottom which
could either enhance the bottom fauna or create an oxygen demand
and subsequent depletion, limiting bottom organisms. If the pro-
duction of planktonic forms is stimulated by the effluent, deposi-
tion might not occur in the immediate vicinity of the plant, but
may be shifted further downstream. In either case, measurement of
the fallout of particulate matter from the water column would pro-
vide useful information concerning the influence of the power plant
on the planktonic community and, in turn, its influence on the
benthic community.
It is suggested that a series of sediment collectors be deployed
to measure the rate of particulate fall from the water column. Col-
lectors could be placed at the ten stations proposed above for
detailed study of phytoplanktonic productivity and, should also be
near stations sampled for benthic organisms. Sediment collectors
could be deployed and retrieved on a regular basis coincident with
monthly plankton sampling. Analyses should be performed on the
particulate material to determine the substance collected and or-
ganic carbon content.
Benthic Respiration
Another measurement closely allied with particulate fallout is
rate of oxygen consumption in bottom sediments. Whether the oxygen
is consumed by macrobenthic forms or by microbial organisms is of
minor concern. What is important is a comparison of the rate of
consumption to re-oxygenation. In areas that have been organically
enriched, oxygen consumption generally occurs at a rate greater
160
-------
than In an unenriched area. Furthermore, in an area organically
enriched either naturally or from power plant stimulated fallout,
and, warmed by a thermal effluent, oxygen consumption may be in-
creased as a result of both stimuli.
Measurement of benthic respiration yields information on the
problems discussed above. Technique for rn_ si tu respiration ap-
propriate for this study have been described in the scientific
literature. The apparatus could be set out with the sediment
m A v»<\^v»4/\»/rt/^ a ^ +• *•
I I %•* I W W I I V« * W V4 IA I W V
rates combined with the particulate fallout data would yield valuable
information to evaluate effects of a power plant on the benthic
ecology of Lake Michigan.
Priority Research
This subcommittee has expressed its ideas regarding research
necessary to understanding the effects of thermal introduction into
Lake Michigan in the preceeding sections. From their knowledge,
they do not believe that existing data will get at some of the more
serious fundamental problems in this area. They therefore suggest
that the following research be strongly considered and that it be
categorized as follows:
Category 1 . Basic research necessary to implement or fortify ongoing
and/or essential studies.
1. To develop standard reference works in English which
address the taxonomic aspects of algal communities.
2. To develop quantitative knowledge of the physiological
requirements of planktonic species native to Lake Michigan.
161
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Category II. Basic research necessary to interpretation of results
of ongoing and/or essential studies.
To develop, from historical collections and from paleo-
1imnological studies, temporal and spatial trends of
populations of plankton which existed in Lake Michigan.
Category III. Special interest questions answerable by further
treatment of existing data or by minor modifications of presently
planned programs.
To develop, through proposed environmental monitoring
programs and through the generation of special field
measurements, information on planktonic populations of
the following nature:
a. mass transport of biomass,
b. food chain perturbations.
Category IV. General regional support items necessary to facili-
tate cooling water studies.
To develop basic facilities support (ships, buoys, computer
systems, etc.,) for the collection, identification and
analysis of planktonic populations, especially platform
and large instrument package support.
162
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Literature Cited
Ahlstrom, E, H. 1936. The deep water plankton of Lake Michigan,
exclusive of the Crustacea. Trans. Amer, Mlcrosc. Soc. 55:
286-299.
Beeton, A.M. 1965. Eutroph1cat1on of the St. Lawrence Great
Lakes. Llmnol. & Oceanog. 10:240-254.
1966, Indices of Great Lakes Eutroph1cat1on.
Great Lakes Res. D1v. Univ. M1ch. Publ . 15:1-5.
1969. Changes In the environment and biota of
the Great Lakes, pp. 150-187. ln_: Eutrophication: Causes,
consequences, correctives. Washington, D.C. U.S. Nat. Acad.
Sci.
Beeton, A.M. and J. M. Barker. 1974. Investigation of the in-
fluence of thermal discharge from a large electric power
station on the biology and near-shore circulation of Lake
Michigan - Part A: Biology. Univ. Wisconsin - Milwaukee,
Center for Great Lakes Studies, Spec. Rep. No. 18. 26 pp.
Benson, A.A. and R. F. Lee. 1975, The role of wax in oceanic
food chains. Scientific American, 232: 76-86.
Calrnes, J. 1972, Coping with heated waste water discharges
from steam-electric power plants. Bioscience, 22: 411-420.
Gushing, J. H. 1951. The vertical migration of planktonic
Crustacea. Biol. Rev. 26: 158-192.
Foerster, J, W., F. R. Trainor and J. D. Buck. 1974. Thermal
effects on the Connecticut River: Phycology and Chemistry.
J. Water Poll. Control Fed. 46: 2138 - 2152.
Fogg, G. E. 1965. Algal cultures and phytoplankton ecology.
Univ. Wisconsin Press, Madison. 126 pp.
Fryer, G. 1954. Contributions to our knowledge of the biology
and systematics of the freshwater copepods. Schwelz. Z.
Hydrol. 16: 64-77.
Goldman, J. C, and E, J. Carpenter. 1974. A kinetic approach
to the effect of temperature on algal growth, Llmnol.
Oceanogr. 19: 756-766.
Griffiths, J, S. 1974, Aquatic biological studies Pickering
Generating Station, 1970-1973. Report #74-78-H, Hydro-
Electric Comm. of Ontario, Research D1v. (Privately
163 .
-------
published; see Neil (1974) loc. cit.)
Hohn, M. H. 1969. Qualitative and quantitative analyses of
plankton diatoms, Bass Island area, Lake Erie, 1938-1965,
including synoptic surveys of 1960-1963. Ohio Biol.Surv.,
N. S., Vol. 3, No. 1. 211 pp.
Holland, R. E. and A.M. Beeton. 1972. Significance to eutro-
phication of spatial differences in nutrients and diatoms
in Lake Michigan. Limnol. Oceanogr., 17: 88-96.
Hutchinson, G. E. 1967. ATreatiseon Limnology, Vol. II. New
York, N.Y. John Wiley & Sons. Xi + 1115 pp.
Lowndes, A. G. 1935. The swimming and feeding of certain calan-
oid copepods. Proc. Zool. Soc. Lond. 1935:687-715.
Neil, J. H. 1974. Cladophora in the Great Lakes. Limnos Ltd.
Report DSS Contract #OSS4-0171. 62 pp.
Pacaud, A. 1939. Contribution a 1' ecologie des cladoceres.
Bull. Biol . Fr. Beige., Suppl. 25. 260 pp.
Robertson, A. 1966. The distribution of Calanoid copepods in
the Great Lakes. Great Lakes Res. Div. Univ. Mich. Pub!.
15:129-139.
Rosowski, J. R. and B. C. Parker. 1971. Selected papers in
phycology. University of Nebraska, Lincoln. 876 pp.
Schelske, C. L. and E. F. Stoermer. 1972. Phosphorus, silica,
and eutrophication in Lake Michigan, pp. 157-171. In:
Nutrients and Eutrophication, Li kens, G. E. (ed.).Amer. Soc.
Limnol. Oceanogr., Special Symposium Vol. No. 1.
Stewart, W. D. P., G. P. Fitzgerald and R. H. Burris. 1967.
I^n situ studies on N2 fixation using the acetylene re-
duction technique, Proc. Nat. Acad. Sci.(Washington),
58: 2071-2078.
Stoermer, E. F. (in press). Comparison of benthic diatom communities
in Lake Michigan and Lake Superior. Verh. Int. Verein. Limnol.
Stoermer, E. F. 1972. Statement. p. 217-254.
In: Conference on Pollution on Lake Michigan and its tributary
basin, Illinois, Indiana, Michigan, and Wisconsin. Fourth
Session, Vol. I. U.S. Environmental Protection Agency.
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Stoermer, E. F. and E.E. Kopczynska. 1967.
Phytoplankton populations in the extreme southern basin of
Lake Michigan, 1962-1963. lr^: Ayers, J. C. and D. C.
Chandler, Studies on the environment and eutrophication of
Lake Michigan. Univ. Michigan, Great Lakes Res. Div. Spec.
Rep. No. 30. 415 pp.
Stoermer, E. F. and J. J. Yang. 1969. Plankton diatom assemblages
in Lake Michigan. Univ. Michigan, Great Lakes Res. Div. Spec.
Rep. No. 47. 268 pp.
Stoermer, E. F. and J, J. Yang. 1970. Distribution and relative
abundance of dominant plankton diatoms in Lake Michigan.
Univ. Michigan, Great Lakes Res. Div., Publ . No. 16. 64 pp.
Strickland, J. H. D. and T. R. Parsons. 1963. A practical handbook
of seawater analysis. Bull. Fish. Res. Bd. Canada, No. 167.
311 pp.
Utermtihl, H. 1958. Zur Vervolkommung der quantitativen Phytoplankton
Mitt. Int. Verein. Limnol. 9: 1-38.
Vanderhoef, L.N., B. Dana, D. Emerick, and R. H. Burris. 1972. Acety-
lene reduction in relation to levels of phosphorus and fixed
nitrogen in Green Bay. New Phytol. 71: 1097-1105.
Vaughn, J. C. 1961. Coagulation difficulties at the south district
filtration plant. Pure Water 13: 45-49.
Vol1enweider, R. A., M. Munawar, and P. Stadelmann. 1974. A com-
parative review of phytoplankton and primary production in
the Laurentian Great Lakes. J. Fish. Res. Board Canada,
31: 739-762.
Wells, L. 1960. Seasonal abundance and vertical movement of plank-
tonic Crustacea in Lake Michigan. U. S. Fish & Wildlife
Service. Fishery Bull. 60: 343-369.
165
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SECTION VI
MEASUREMENT OF THE EFFECTS OF COOLING WATER
USE ON MACROZOOBENTHOS
-------
Section VI. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON MACROZOOBENTHOS
Table of Contents
Foreword . . . . . • • • • • • • .171
Introduction 171
Macrozoobenthos of Lake Michigan 171
Biology of Selected Lake Michigan Benthos 173
Pontoporeia affinis 173
Oligochaeta 175
Chironomids 177
Fingernail clams 178
Opossum shrimp 179
Role of Zoobenthos in The Ecosystem 181
Benthos As Indicators of Environmental Qualtiy 184
Response of Benthic Animals To Environmental Stimuli . . .187
Physical Factors 187
Depth 187
Substrate 188
Water Movement 190
Temperature .191
Light 193
Chemical Factors 194
Concerns For The Macrozoobenthos As Related To Cooling Water Use.195
Experimental Questions 197
On-site Pre-operational Studies 197
On-site Operational Studies 199
168
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Table of Contents
Off-site (Lakewide) Studies Related to Macrozoobenthos 200
Principal Problem Areas in Understanding Effects of Cooling
Water Use on Benthos 201
Natural Environmental Factors 202
Effects of Other Discharges 203
Sampling Problems 204
Determination of The Role of Benthos At Study Sites 206
Objectives of Measuring Environmental Conditions and Responses . . . .206
Benthic Study Field Methods 207
Collection 207
i
Separation 208
Sediments 209
Mapping of Sediments 210
Laboratory Analysis of Sediment 212
Sediment Chemistry 213
Supporting Information 214
Sampling Design 215
Establishing Stations 215
Fixed Grid 216
Selection of Reference Area(s) 216
Station Identification 216
Station Distribution and Spatial Interval 216
Sampling Frequency 217
Number of Sampl es 217
169
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Table of Contents
Laboratory Techniques 218
Data Presentation 219
Generic and Specific Identification 219
Biomass 220
Diversity Indices 220
Research Needs And Controlled Experiments 221
Priority Needs And Research 223
Literature Cited 228
170
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Section VI. MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
MACROZOOBENTHOS
Foreword
All comments received regarding this paper during the period of
solicited review have been incorporated into the text.
Introduction
In some lakes zoobenthos is sparse and therefore its role
in the lake's ecosystem appears insignificant. However, the zoo-
benthic standing crop of Lake Michigan is extraordinarily large
(179 kg/ha) compared with other large and deep lakes in North
America (Alley and Powers, 1970) or with lakes all over the
world (Hayes, 1957). Zoobenthos are important in energy transfer
and serve two major functions: food conversion and nutrient
recycling.
Macrozoobenthic organisms are characteristically less mobile
than many aquatic organisms and therefore integrate environmental
stress over time. Their relative abundance and community structure
are indications of the quality of their environment: water and
sediments. Changes in benthic communities often are more easily
measured than in communities or populations of other aquatic
organisms.
Macrozoobenthos of Lake Michigan
The profundal macrozoobenthos of Lake Michigan is made up
largely by members of five taxonomic groups:
171
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1. Amphipods (Amphipoda)
2. Segmented worms (01igochaeta)
3. Midge larvae (Chironomidae)
4. Fingernail clams (Sphaeriidae)
5. Opossum shrimp (Mysidacea)
These groups are also dominant in the sublittoral zone, but
other taxa are found with them. These five groups are of greatest
importance in the benthos because the largest area of the lake is
the profundal zone. The oligochaete, midge and sphaeriid fauna
include several species, but Pontoporeia affinis is the overwhelm-
ingly important amphipod and Mysis relicta is the only representa-
tive of the Mysidacea found in the lake. These two species, which
occur naturally in relatively few lakes in North America and are
relicts of the glaciation which formed Lake Michigan, are very.
important to the support of fish fauna of the lake.
The littoral areas in general, and especially rocky shorelines,
embayments, island areas, river mouths and unusual structures,
provide habitats for many other animals such as crayfish, snails,
and the immature forms of mayflies, stonefiles, and caddisflies.
Since cooling water is usually withdrawn and discharged into the
littoral zone, inhabitants of these areas are most likely to be
affected. Littoral zone benthos is often locally important to
adult spiny-rayed fish and may be especially important to the
juveniles of many fish species which frequent shallow water. The
contribution of the littoral zone to the lakewide benthic biomass
is far overshadowed by that of the sublittoral and profundal zones.
172
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A perspective on the abundance, depth distribution and
dominance of amphipods and oligochaetes in Lake Michigan is pro-
vided by Mozley and Alley (1973), who report these animals made
up over 80 percent by number of those collected in extensive
surveys of the central and southern basins during 1964-67 (Table VI-1.)
Biology of Selected Lake Michigan Benthos
Pontoporeia affinis.
Adult Pontoporeia range from 6 to 9 mm in size in Lake Michi-
gan (Alley, 1968). Peak mating occurs in mid-winter and the
female carries the fertilized eggs and embryos within a marsupial
pouch beneath her abdomen. When released, the young are slightly
less than 2 mm long. Just after the young are released,the popu-
lation reaches a maximum (Mozley and Alley, 1973). Newly released
amphipods can pass through screening devices which retain adults.
Size frequency histograms indicate that Pontoporeia living
at a depth of 10 m in Lake Michigan mature in one year; those
living between 20 - 35 m require two years to mature; and those
living at depths greater than 35 m possibly require three years or
more to mature (Alley, 1968). Amphipods at 10-35 m depths repro-
duce in the spring, while those living at greater depths reproduce
intermittently throughout the year.
While Pontoporeia frequently inhabit depths less than 8 meters,
large populations are not normally found there. Populations gener-
ally increase with depth to the 35 m contour where populations
f\
average 8,500/m (or more) and then taper gradually to populations of
1,000 or less/m at depths exceeding 180 m (Powers and Alley,1967).
173
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Table VI - 1. Estimates of abundance (number/m2), by depth, of two benthic taxa
from the central and southern regions of Lake Michigan. 1964 - 67.'
Taxon
Depth
m
Amphipoda 0- 20
21
41
61
Oligochaeta 0
21
41
61
- 40
- 60
-140
- 20
- 40
- 60
-140
Mean
Ani
6,
8,
6,
3,
1,
1,
2,
Central
Number of
mal s
380
477
876
353
389
460
509
520
Basin
Number of
Grap Samples
12
199
116
286
10
196
91
227
Southern
Mean Number of
Animals
2,
4,
4,
3.
2,
3,
2,
544
264
858
137
898
411
171
720
Basin
Number of
Grap Samples
235
160
164
250
229
157
163
248
]After: Mozley and Alley, 1973.
-------
Pontoporeia occur over a wide range of sediment types, but
largest populations are found in silty-sand sediments that permit
easy burrowing and access to organic detritus. Marzolf (1963)
demonstrated a correlation between numbers of amphipods and numbers
of bacteria contained on detrital organic substrate. Several
investigators theorize that the major nutritional source is bacteria
which decompose detritus, rather than detritus itself. Vertical
migrations of several meters into the water column are common for
a small percentage of the Fontupureia population during hours cf
darkness and to a lesser extent during the daylight hours (Marzolf,
1965; and Wells, 1968).
01i gochaeta
Several species of segmented worms are abundant in Lake
Michigan. In general, the ratio of amphipods to oligochaetes
shows a north to south gradient, with oligochaetes more abundant
to the south. The dominant oligochaete of Lake Michigan is
Stylodrilus heringianus in the profundal and transitional zones
(Howmiller, 1972 a). Limnodrilus hoffmeisteri is most abundant in
river mouths, deltas, and shallow water areas (Hiltunen, 1967:
and Howmiller and Beeton, 1970). Moderate numbers of Potamothri x
mol dav iens is, P_. vejdovskyi and Peloscolex f reyi occur in shallow
water and transitional areas and Tubi fex tubi fex are often rather
common lakewide at a depth of 40 m (Hiltunen, 1967). Brinkhurst
(1969) points out that distribution maps for the pollution tolerant
tubificids, Peloscol ex mul ti setosus , Limnodri 1 us cervix, and L_.
175
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maumeensis essentially correspond to the locations of the largest
cities on the Great Lakes with the exception of Chicago. In Chicago,
sewage is discharged to the Illinois River and is diverted away
from Lake Michigan. Other oligochaetes locally important in
Lake Michigan are Limnodri 1 us spiral is, Aulodrilus pluriseta,
Limnodrilus claparedeianus, Peloscolex variegatus and P_. superiorensis
(Mozley, 1974). Forty species of microdrile Oligochaeta are known
from Lake Michigan (Hiltunen, 1967). Eleven of these species were
not found in Green Bay by Howmiller and Beeton (1970). They found
two species not reported by Hiltunen.
Many species of oligochaetes breed over a wide seasonal range
with a peak in the summer months. Fertilized eggs are deposited
in cocoons in the sediments and a life cycle is complete in 12 to
18 months. This pattern can be modified by local conditions
(Kennedy, 1966), hence time of recruitment will vary from place
to place.
Recent Russian work (mentioned in Mozley, 1974) indicates
possible generation times of two months for Tubifex tubifex and
Limnodrilus hoffmeisteri, while other tubificid species require
more than one year for sexual maturation. Peak numerical popu-
lations undoubtedly occur in different months and there is a lag
between emergence of the embryos and growth to sizes retained on
screening devices. Various investigators have reported peak counts
from February to October. Oligochaete biomass in Saginaw Bay of
Lake Huron fluctuated from 3.0 g/m2 in June to 8.4 g/m2 in August,
to 0.5 g/m2 in October of 1969 (Schneider et al., 1969). To date,
176
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the data on seasonal oligochaete population fluctuations do not
lend themselves to generalization, e.g., a fall maximum has been
reported in Lake Michigan littoral zones while November minima
have been reported for S_. heringianus.
Attempts to correlate oligochaete populations with sediments
on the basis of particle size alone have usually failed. Organic
content may be more important than particle size and the incom-
pletely understood relationship between the tubificid species and
the microbial flora of the organic material may be the key to dis-
tribution and abundance.
Chironomids
Heterotrissocladius and Prod ad i us are the only midges found
in important numbers in the profundal zone of Lake Michigan. They
are also found in the sublittoral zone where Heterotrissocladius
is represented by at least two species. In the littoral zone and
areas to 20 m depth the midge fauna is dominated by Potthastia,
Cryptochironomus, Monodiamesa tubercul ata, Paracl adopelma, Procl adius.
Tanytarsini, Chironomous attenuatus. Ł. antharacinus and other
Chironomus. Polypedi1 urn and Parachironomous can be important
locally. Generally, members of the Orthocladiinae become more
numerous in the northern part of the lake, but Psectrocladius cf.
simul ans is numerous in the southern part. Procladi us and other pre-
daceous midges often occur in company with large oligochaete popu-
lations.
According to species preference and water temperature, midges
emerge as adults to mate from very early spring to as late as
October for Heterotrissocladius. Midges of the deeper waters are
177
-------
probably limited to one cycle or less a year, while those 1n
the shallows may go through more than one cycle. Most commonly,
eggs are laid 1n gelatinous masses which sink to the bottom. The
first larval Instar 1s usually planktonlc and later Instars oc-
casionally leave the sediments or substrate to swim above the
bottom, especially at night.
Considering Lake Michigan as a whole, midges are far less
numerous than amphlpods and ollgochaetes and make up a small part
of the blomass. However, at depths less than 10 m, chironomid
larvae may be the dominant macrobenthic animals. Heterotrissocladius
may be 100 to 300 times less abundant than amphlpods and ollgo-
chaetes In an average sample taken from the profundal zone.
The Ch1ronom1dae exhibit the most pronounced seasonal abundance
of the major taxa. The times of emergence of each species and
recruitment of early Instars Into the size retained in sieving de-
vices are variable and little information is available. A July
maximum has been reported 1n littoral areas, probably because
several small species reach screenable size only just before summer
metamorphosis.
Fingernail Clams
Twenty species of Sphaeriidae are known from Lake Michigan
(Heard, 1962). Generally, Pisidium numerically dominate the
sphaeriid fauna at all depths. Sphaerium nitidum and S^. striatinum
forma acunrlnatum occur with Plsidlmn, but only in local areas do
178
-------
the numbers of Spharerlum exceed the numbers of Pisidium in any
sample. Maximum spaeriid populations are found between 30 and
60 m. Pisidium is commonly observed carrying its young in the
mantle cavity during late summer, but there is no firm information
on population fluctuations with season (Heard, 1960). If the young
were released concurrently, large increases in numbers should occur
over short periods because the young are large enough to be retained
in the most commonly used sieve sizes.
Opossum Shrimp (Mysis relicta)
Mysids are considered epibenthic. In shallow and intermediate
depths they spend daylight hours on or just above the sediments
and in deep water some of the animals may be considerably above
the sediments. At night large numbers (probably all) move upward
into the plankton. Apparently their sensitive eyes and backward-
darting escape reaction enable the animal to elude capture by
benthic grabs most of the time. Because of their habits and
mobility, methods, to determine the effects of pump entrainment on
the populations would be similar to methods suggested in Section VIII,
Entrapped and Entrained Organisms.
Reynolds and DeGraeve (1972) reported monthly estimates of
mysid density in southeastern Lake Michigan. Using a plankton net
attached to a benthic sled, animals were not captured at depths
of 9 m. Density was usually low at depths between 18-37 m,
moderate between 46-55 m and relatively high at 64 m and deeper.
Average population density at depths from 18-73 m ranged from
^Hiltunen, J., 1974. Personal Comm. Great Lakes Fishery Laboratory,
U.S. Fish and Wildlife Service, Ann Arbor, Michigan.
2Beeton, A.M., 1975. Personal Comm.
University of Wisconsin, Milwaukee, Wisconsin.
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0.3/n)2 in December, to 64.2/m2 in August. Maximum density was
2
228/m . These estimates are most likely too small as the water
stratum from the bottom to a height of 10-15 cm was not sampled.
Reynolds and DeGraeve (1972) also suggest that sizeable numbers of
adults apparently move from the deep water areas to relatively
shallower water (18-64 m) in winter where they breed and subsequently
release their young in April and May. At greater depths there ap-
pears to be some breeding and recruitment throughout the year.
General population abundance was lowest in December and highest in
mi d-summer.
Mysis from Lake Michigan range in length from about 3 to
27 mm. Incubation time of the young in the marsupium may be no
longer than 2 or 3 months. Brood size declines with development
from egg (mean, 14.1/female). At release, young are 2-3 mm
in length.
Mysids are reported to feed on organic detritus and pelagic
diatoms in Lake Michigan (McWilliam, 1970). This differs in part
with observations from Char Lake, N. W. Territories, where feeding
on inorganic particles and diatoms on a moss substrate was reported
by Lasenby and Langford (1973). Apparently the microbiota or
absorbed film of colloidal organic matter attached to the inorganic
s
particles are gleaned in the gut. The authors reported that mysids
feed on Daphnia, other cladocerans, and components of plankton
while in the water column at night.
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Role of Zoobenthos In The Ecosystem
The macrobenthlc invertebrates of Lake Michigan are part of
the energy transfer system and serve two major functions: recycling
nutrients from the sediments and deep water areas into the photo-
trophic zone, and converting lower organisms into a food form
available to higher organisms.
Oligochaetes (and other invertebrates), burrowing and feeding
in sludges and sediments, pass the converted materials upward to
the sedimsr.
t-watsr interface where they are more susceptible to
breakdown and assimilation by other processes. Without such re-
cycling, nutrients and other chemical elements deep in the sediments
would be essentially unavailable.
Mysids remain on or near the bottom part of the time and at
other times migrate vertically many meters into the water column.
During migration their fecal pellets redistribute minerals derived
from the bottom materials. To a more limited extent this same
phenomenon occurs with Pontoporeia and some midge larvae. Fish,
feeding on these migrating organisms, contribute to the same
cycling phenomenon.
The more obvious energy transfer role is that of converting
organic detritus (or the microflora and fauna associated with it)
into a form directly available to fish of recreational and com-
mercial importance, or for smaller fish which in turn are food
for the larger species of value to man.
Oligochaetes are rarely reported as important fish food, but
because these animals breakdown rapidly during digestion, their
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importance may have been overlooked. Midges are well recognized
as food for small fish and have been reported by Rolan (1972) as
food for at least 19 species of fish found in Lake Michigan. His
listing did not include many species of Lake Michigan fish known
to consume midges. Rolan also reported six species of Lake Michigan
fish as known sphaeriid feeders; his list did not include spottail
shiners, alewives, deepwater and slimy sculpins, or Catastomidae,
all known sphaeriid feeders. Wells and Beeton (1963) recorded
fingernail clams (Sphaerium nitidum) in the stomach of Lake
Michigan bloaters (Hiltunen, J. K. 1975, Personal Communication).
Pontoporeia affinis and Mysis relicta are, for several reasons,
the most important macroinvertebrate food for fishes of commercial
and recreational value in Lake Michigan: their abundance, wide dis-
tribution, high percentage of benthic biomass, availability to fish,
and the preference of many fish species for these organisms at
some stage of the fish's development.
Henson et al., (1973) summarized much of the literature
dealing with the food habits of the important fish in Lake Michigan
Important forage species such as smelt and sculpin. depend heavily
on Pontoporeia. The diet of longnose suckers can be as high as 63
percent Pontoporei a and the intake of the white sucker is about
30 percent Pontoporeia. Both fishes are commercially important.
Young lake trout'and burbot feed on this amphipod as do the deep
water chubs which are in turn eaten by the larger trout. The
diet of whitefish is comprised of as much as 63 percent Pontoporeia.
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Mysis relicta is the dominant food organism for the deep-
water bloater chub and the average occurrence in stomach was 48.2
percent. Mysis is important in the diet of smelt and whitefish
and ranks first in volume of food for young lake trout (28-30 cm)
in Lake Superior. Mysids are eaten also by burbot.
Sphaeriid clams have been reported by several investigators
as important in the diet of migrating waterfowl, particularly
scaup. Over-wintering old squaw ducks on Lake Michigan feed
heavily on Pontoporeia to depths of 20 m.
The two major benthic energy pathways in Lake Michigan involve
Pontoporeia and Mysis. The first pathway, based on nutrient input,
goes through the phytoplankton, the zooplankton, Mysis , the chubs
and other forage fish, to the large salmonids. Because of the cur-
rent abundance of alewives in Lake Michigan and the lesser importance
of Mysis in their diets, Mysis is partially bypassed in this energy
transfer. The second pathway begins with energy derived from the
organic matter and microbenthos , leads through Pontoporeia. the
chubs, and numerous other forage fish including the alewife, to the
large salmonids. Collapse of either the Pontoporeia or Mysis popu-
lations would result in an energy shunt with added stress on the
remaining cornerstone. The ecological outcome would be difficult
to predict. Current information and knowledge of cooling water use
on Lake Michigan does not suggest that such use has affected popu-
lations of these organisms.
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Benthos As Indicators of Environmental Quality
The relative abundance, species composition and community
structure of benthos are reflections of the quality of their en-
vironment as characterized by chemical, biological, substrate, and
other physical conditions. Benthic animals are characteristically
less mobile and therefore are better indicators of stresses over
time than pelagic organisms. Environmental stresses are often
reflected in changes in benthic assemblages. These changes are
often more easily measured than in communities or populations of
other aquatic organisms.
Oligochaetes have perhaps been more misused as indicators of
aquatic environmental quality than any other single group. Upon
discovery of very abundant populations of Oligochaetes, various
investigators, especially those representing enforcement agencies,
have proposed over-simplified and perhaps naive schemes of popula-
tion detection and assessment. An eminent authority on North
American Oligochaetes, Dr. Ralph Brinkhurst (1965), has stated
categorically, "there is no simple numerical relationship between
the numbers of unidentified worm species, or the proportion of all
worms in the fauna, and pollution of any but the most obvious, and
demonstrably extreme types." Identification of the worms is
essential because the presence of a particular species and community
structure reflect environmental conditions much more accurately
than simply the presence of "oligochaetes" alone.
Brinkhurst, et al. (1968) suggest the indicator value of some
Oligochaetes in the Great Lakes based on many years of observa-
tions and taxonomic work:
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1. Species restricted to grossly polluted areas:
Limodri 1 us hoffmei steri, L^. cervi x, and Peloscol ex
multisetosus.
2. Species often present in grossly polluted areas:
Branchiura sowerbyi, L^. maumeensis, and L^ cl aparedianus.
3. Present in mesotrophic or eutrophic areas (in the
classical sense): Aulodri1 us. Potamothrix. and
Peloscolex ferox.
4. Characteristic of oligotrophic areas: Rhyacodri1 us,
Tubi fex k e s s1e r i americanus , Peloscolex variegatus,
and Stylodrilus heringianus.
The problem with such lists is that contradictory opinions
or modifications continually emerge. This subcommittee feels
the categorization "restricted to grossly polluted areas" is too
rigid and a more appropriate category would be "present in a
wide range of environments, but not abundant outside polluted
areas". Tubi fex tubi fex, Limnodri1 us hoffmeisteri and Peloscolex
multi setosus for example, could be included in that category.
Brinkhurst, et al. (1968) also suggest the use of some species
of chironomid larvae as indicators of trophic conditions in lakes,
as have other scientists. The subcommittee endorses efforts to
also Howmiller and Beeton (1971); Hiltunen (1967, 1969),
and Kinney (1972).
185
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develop this concept further, especially as it would refer to
specific sites and stresses. However, local conditions do not
often reflect lakewide conditions in large bodies of water.
There is universal agreement that such animals as Pontoporei a,
Mysi s , Heterotrissocladius and Sty!odri1 us heringianus are in-
dicative of oligotrophic situations. On the other hand populations
of oligochaetes composed of Limodri 1 us cervix, J^. maumeensi s , and
high numbers of _L. hoffmei steri, indicate saprobic conditions.
Generalizing on the significance of the presence of species where
preference is less clear meets with disagreement. Similar relation-
ships are recognized for many other benthic organisms. It is ac-
knowledged that the presence or absence of certain species and
population trends of certain species can be meaningful information
on environmental quality, provided such information is interpreted
by an expert thoroughly familiar with the ecosystem.
Total numbers of individuals or biomass of benthic populations
or communities have also been used as evidence of organic enrichment
of lakes (Alley and Powers, 1970, and Robertson and Alley, 1966).
Biomass measurements should be employed only with careful attention
to technique since preservation of animals and measurement of
weight have been so varied that comparison of results with other
studies may be misleading (Howmiller, 1972b).
In summary, at the present time the use of all macrozoobenthic
information in Lake Michigan as an indication of environmental
quality is not an exact science. However, reproducible results and
reliable, generalized judgments are often possible. While con-
troversy exists over which populations or assemblages indicate what
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environmental conditions, there is much agreement on most worm
species-communities as well as on Pontoporeia relationships.
Response of Benthic Animals to Environmental Stimuli
Physical Factors
Depth
Most benthic species in Lake Michi gan,.do not thrive in the
shallowest water areas or deepest areas of the profundal zone,
but between those two extremes their depth distribution is not
sharply limited. There is general agreement as to whether a
species is typically shallow water, transitional, or deep water
in habit, but depth range is normally broad. Rolan (1972) reviewed
the work of several investigators and combined their information
into graphs clearly illustrating these generalizations.
Such depth-related factors as temperature, light intensity,
chemistry, turbulence, sediment composition and availability of
food appear to be more important than hydrostatic pressure. Certain
chironomids, dependent on ability to secrete gas for buoyancy before
emerging, may be limited by hydrostatic pressure.
Shallow areas of unstable sediments subject to wave action and
turbulence generally have low macrozoobenthos populations. However,
recent work (Mosley, S.C. 1974. Personal communication) using a #10
net indicates that, at least in midsummer, extremely large populations
of meiobenthos (>micro- and
-------
collected greacci
been thought to inhabit such areas.
The data of Mozley and Alley (1973) showing depth distributions
of Amphipoda and Oligochaeta (which made up over 80 percent of the
organisms captured) appear to be representative of the depth dis-
tribution of a number of benthic organisms in Lake Michigan. Other
investigators (Cook, et al., 1965; Schuytema and Powers, 1966)
have reported peak numerical populations in Lakes Michigan and
Huron occurring at depths less than 10 m. These data include
samples from bay and harbor areas not typical of exposed shorelines
and open waters. Their data for depths =>20 m are representative
and show numbers peaking at about 35 m, dropping rapidly to depths
of 80 m, and then leveling off.
On the sandy, exposed shorelines of eastern Lake Michigan
populations of macrobenthic animals are comparatively sparse at
depths less than 7 m, however chironomids are most abundant there.
Amphipods, sphaeriids and oligochaetes increase between 7 and 13 m
and amphipods and oligochaetes increase further between 22 and 25
meters. These changes correspond to changes in sediment type and,
most likely, to accompanying changes in organic content.
Substrate
Substrate is one of the most important factors influencing
distribution and abundance of benthic fauna. Changes in type and
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abundance of benthos with depth, as described previously for a
sandy exposed shore, corresponded with changes in sediment type.
At depths less than 7 m, coarse and medium sands predominate; be-
tween 8 and 22 m, fine sands with some silt are most frequent; and
between 22 and 25 m, gelatinous silt and clay generally become
dominant. Underwater observations show that sediment types do not
change smoothly with increasing depth. Patches of silt and muck
occur in zones where clean fine sand predominates (Mozley and Alley
1973).
Many species occur over a broad range of sediment types and
substrates. Laboratory experiments have determined a preferred
substrate composition for some species. Other factors equal, the
species will be found in greater numbers in association with their
preferred substrate in a natural situation.
Median particle size is often reported in benthic studies
(See section following on "Sediments and Sediment Chemistry").
Brinkhurst (1967) feels that such studies have not been helpful
in explaining the occurrence of oligochaete species. However,
Henson (1962) found that the abundance of oligochaetes in the Straits
of Mackinac region, when plotted against median particle size, was
nearly a normal curve with the mean (050) at 3.9, which is fine to
very fine sand. Several authors have generalized that oligochaetes
prefer finer sediments to coarse ones. Henson and Herrington (1965)
plotted the distributions of 25 species of fingernail clams in the
Straits region against depth and particle size. They established
the preference of several species for median particle sizes.
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Evidence from a number of recent studies supports the con-
tention that organic content of sediments may have more influence
on benthic distribution than sediment size. Brinkhurst (1967) has
found Ilyodri1 us tempTetoni positively correlated with organic
content of sediments, while Peloscolex ferox, another oligochaete
species, is negatively correlated. Schneider et al. (1969) found
that Hexagenia sp. and Chironomus plumosus are positively corre-
lated and Cryptochironomus and Pseudochi ronomus negatively correlated
with organic content of sediments in Saginaw Bay of Lake Huron.
Fenchel (1972) provides insight into the relationship of interstitial
bacterial populations to sediment particle size and nutrient content
of water.
In general, sorting of the lighter organic sediments following
resuspension by a variety of factors tends to keep the littoral
sediments low in organic content, while sublittoral and profundal
sediments are higher. Organic content and the associated microbial
fauna may be more important than particle size or other factors
such as depth in governing the distribution and abundance of macro-
zoobenthos.
Water Movement
A few benthic species whose usual habitat is quiet water can
adapt to turbulent conditions provided a stable substrate to burrow
into or cling to is available. Amphipods, certain midge larvae and
snails have such adaptive ability since they can be found, along with
immature stoneflies and certain mayflies and caddisflies, in shallow
areas subject to great turbulence, such as exposed rocky shore or
breakwaters. Rheophilic organisms adapted to life in flowing streams,
such as caddisflies (Hydropsyche), may colonize the riprap of power
190
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plant intake and discharge areas in the lake. Currents have a role
in bringing food to sessile filter feeders and also in distributing
the eggs and early instars of several benthic insects.
Movement of unstable sediments appear to limit the shoreward
distribution of many species. Grinding action may limit microbio-
logical and diatom development on such sediments, eliminating a
food source. Such action can also injure the animal directly.
Resuspensions of sediments by wave action and redistribution of
the lighter organic fractions to deeper water also deprives organ-
isms living in the shallows of this food source.
Discharge of cooling water may produce a scouring action on
the bottom precluding benthos colonization around the discharge
structure. Farther from the discharge, populations of lacustrine
benthic organisms will increase. These animals may benefit from
fallout of crippled or dead zooplankton and broken algal cells
caused by p-assage through the pumps, condensers and discharge
structure.
Temperature
The species composition of aquatic communities at all trophic
levels depends in part on the temperature characteristics of their
environment. Each species has upper and lower thermal limits (both
short and long-term), optimum temperatures for growth, preferred
temperatures in thermal gradients, normal temperature ranges, and
temperature limits for various activities such as mating, ovipositing,
egg incubation, hatching, pupating and emerging. Aquatic inverte-
brates are without internal mechanisms for thermal regulation and,
191
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since their surface area is large in proportion to their mass,
their body temperature quickly conforms to the temperature of the
surrounding water. Thermal conditions are rarely optimal, as
natural variations create conditions either above or below optimum
within a tolerable range.
Lake Michigan is one of the southernmost lakes possessing an
oligothermic fauna characteristic of colder lakes. This is possible
since the hypolimnlon is insulated from surface warming by a well-
marked thermocllne and remains cold and well-oxygenated at tempera-
tures near 5C throughout the summer, although surface layers may
warm up to 20C or more. The warming of the main water mass in
spring and early summer lags the air and watershed temperature to
such an extent that warm water rivers entering the lake may be
10 - 15C warmer than the lake surface waters.
The glacial marine relicts Pontoporeia affinis, Mysis relicta,
Heterotrissocladius subpilosus Kieffer (Henson et al., 1973); a
possible glacial marine relict, Pisidium conventus (Henson, 1966);
and other oligothermic fauna thrive in the thermal regime of the
hypolimnion and thermocline.
The southern half of Lake Michigan is generally warmer than
the northern half and because prevailing winds from the sector
south to west produce more frequent upwellings along the western
shore than on the eastern shore, surface temperatures are generally
higher on the eastern side. During the spring warming phase pre-
viously described, the region of nearshore thermal stratification
with surface temperatures rising above 4C is separated from off-
shore homothermal water at temperatures below 4C by a narrow
outward-moving transition zone (the thermal bar) in which water
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at maximum density Is actively sinking (vertical 4C Isotherms).
The offshore transport of heat therefore takes place not only at
the surface as the thermal bar moves outwards but also 1n the form
of heat addition to deeper layers, gradually warming the hypolim-
nlon from its March minimum near 2C to its summer value near
4C.
These several phenomena Influence the lake's thermal regime
and tfiu'3 determine ir. part the species present, their abundance.
distribution, reproductive activities and productivity.
The addition of heat to Lake Michigan by cooling water dis-
charges has the potential for changing the structure and metabolism
of aquatic biological communities. Such changes may be detrimental
or beneficial. While the great majority of published investigations
on effects of thermal discharges to the Great Lakes, and Lake Michigan
in particular, demonstrate negligible environmental effects,
especially for the benthos, scientific prudence dictates caution in
presuming that the effects of all current and proposed thermal
discharges to Lake Michigan will be negligible.
Light
Cooling water discharges may scour bottom sediments and create
increased turbidity locally. Littoral currents transporting sediment
can provide fresh materials for resuspension by scour. The extent
to which the resulting decreased light transmission influences
benthos has not been reported. Light intensity Influences the distri-
bution of some benthlc species directly, regulates the vertical migra-
tions of Pontoporeia (Marzolf, 1965) and Mysis (Beeton, 1959) and limits
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the water depth to which benthic flora, a food source, can grow.
Segerstrale (1971) demonstrated photoregulatory dominance over
thermoregulation in maturation of Baltic populations of Pontoporeia.
Chemical Factors
Few investigations have been conducted to quantify the influence
of chemical contaminants in the sediments on benthic macroinverte-
brates. Gannon and Beeton (1969, 1971) carried out a series of
laboratory tests with benthic animals using sediments from nine
Great Lakes harbors. - Sediments from five harbors were toxic to
Ponotoporeia. Test animals displayed selectivity for the less
contaminated sediments when offered choices. The U.S. EPA used
data from these tests to establish criteria for identification of
sediments which should be dumped only in confined areas (U.S. Army,
1971). Contaminants of general concern are volatile solids, phos-
phorus, ammonia, organic nitrogen, chemical oxygen demand, oil and
grease, iron, lead and zinc. Oily sediments have been identified
• ifc.
by many authors as influencing benthic communities.
Johnson and Matheson (1968) associated direct iron toxicity, or
COD associated with iron oxidation, with a lack of tubificid worms
in Hamilton Bay in the vicinity of steel mill discharges.
Changes in dissolved gases caused by heated discharges may be
more important than currently recognized. J"h«re are documented in-
cidents of gas bubble-Disease of fish in heated effluents (Demont
and Miller, 1972) and the laboratory occurrence of gas bubble disease
in three species of bivalve mollusks held in heated running sea-
water during the winter (Malouf et al., 1972). Any effects on
benthos would probably be limited to the immediate vicinity of the
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discharge.
Biocides, such as chlorine used to prevent fouling in con-
denser tubing are known to kill fish (Truchan and Basch, 1974).
Benthos can be similarly affected when they are resident in the
zone of residual biocides and time-toxicity relationships exceed
their tolerance.
Concerns For The Macrozoobenthos As Related To Cooling Water Use
Mechanisms by which cooling water use causes, significant
effects on the Lake Michigan macrozoobenthos community have not
as yet been demonstrated unequivocally. The possible potential
effects of use of Lake Michigan waters for cooling lead to the
primary concern that the macrozoobenthos may be so altered, reduced
or eliminated that an energy shunt is created which would result
in lower production of desirable forage, game and commercial fish
or increased production of undesirable fauna and flora, or both.
Mechanisms which could contribute to this primary concern are:
A. Thermal
1. Shortened incubation periods resulting in a reduced
hatch of smaller and less physically-capable animals,
2. Premature hatching when food sources are not avail-
able ,
3. Premature emergence into unfavorable climatological
conditions,
4. Chronic conditions exceeding temperature tolerances
of desirable organisms,
5. Conditions favorable to organisms of less value as
food to macrozoobenthos and higher trophic levels,
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6. Conditions favorable to parasitic or disease
organisms,
7. Conditions favoring abnormally high predation, and
8. Stress induced by intermittent thermal shocks as
plumes shift or units go on and off line.
B. Physical, other than thermal
1. Substrate alteration during construction,
2. Substrate alteration by physical interruption of
littoral drift,
3. Creation of uninhabitable environment due to velocity
of discharge, and
4. Increased turbidity by scour.
C. Chemical
1. Direct toxicity by chlorine,
2. Direct toxicity by discharge of boiler cleaning
materials,
3. Direct toxicity by cooling tower maintenance materials,
and
4. Accumulation of toxic metals in sublethal concen-
trations.
D. Intake
1. Impingement of large organisms such as crayfish on
screens ,
2. Pump entrainment and condenser passage, and
3. Deposition of organisms killed or crippled by entrain-
mento
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Experimental Questions
i
In response to the-concerns enumerated above there are experimental
questions to be answered or addressed during investigations into
effects of cooling water use on macrozoobenthos. The questions are
grouped into on-site preoperational , on-site operational, and
off-site lakewide studies. While this encourages redundancy, there
are advantages to the reader. There is an inherent responsibility
in planning or evaluating any study to be sure investigative resources
are allocated wisely so that the aspects which have the greatest
potential for impact at the specific study site receive an appropriate
share of the effort. Thus some aspects may be addressed only through
literature search while others should be investigated in minute detail.
In responding to these questions, the investigator should
establish the relationship to the macrozoobenthos. The questions are
not all-inclusive, nor exclusive of site-specific considerations.
On-site Pre-operational Studies
1. What are the bottom contours within the study area prior
to construction or operation?
2. What are the substrate types within the study area prior
to construction or operation?
3. Are the contours and substrates known to an extent which
would permit detection of changes caused by construction
or operation?
4. Are the substrates unique to the site or critical to the
survival and well-being of important indigenous
macrozoobenthos?
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5. Is the littoral drift known?
6. Will the littoral drift be physically altered by
construction or operation?
7. Were the littoral drift, bottom contours, and substrate
types altered by construction?
8. What are the preconstruction or preoperation
macrozoobenthic populations and communities in the
study area? Species? Densities? Diversity?
Community biomass? Important species biomass?
9. Are the macrozoobenthos communities known to an extent
which would permit detection of change? Were they
altered by construction?
10. Are the macrozoobenthic organisms of importance in the
diet of local fishes?
11. Are the local macrozoobenthos unique or critical to the
ecosystem of the water body segment or lake?
12. Are any of the macrozoobenthos present in nuisance
quantities?
13. Are the seasonal behavior patterns and life cycle
activities of the important animals known?
14. What food sources are important to the macrozoobenthos?
15. Based on plume modeling and anticipated operational modes,
what macrozoobenthic organisms will be impacted and over
what area?
t
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On-site Operational Studies
1. What changes have occurred in the bottom contours due to
construction and operation? Are the changes important
to the macrozoobenthos?
2. What changes have occurred in the littoral drift due to
construction and operation? Are the changes important
to the macrozoobenthos?
3. What changes have occurred in the substrate type due
to construction and operation? Area"! extŁ"t? Are the
changes important to the macrozoobenthos?
4. What are the post-operation macrozoobenthos populations
and communities?
5. What changes have occurred in the macrozoobenthos due to
construction and operation? Were the changes statisti-
cally significant? Areal extent? Are the changes
ecologically significant to higher trophic levels?
6. Are any of the macrozoobenthos present in nuisance
quanti ties?
7. Are macrozoobenthic organisms impinged or pump-entrained?
In sufficient numbers to threaten appreciable harm to
populations or communities? If so, what is fate of
entrained organisms?
8. What is reaction of macrozoobenthos to biocide applications?
To other chemicals associated with plant operation? Is
reaction sufficient to threaten appreciable harm?
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9. Do macrozoobenthos accumulate toxic materials for potential
transfer to higher trophic levels?
10. Are there indications of gas-bubble disease in the dis-
charge area?
11. If changes have occurred in the macrozoobenthic community
what mechanism or combination was responsible? Pump-
entrainment? Biocide reaction? Reproductive synchrony?
Velocity? Scour? Substrate shifts? Littoral drift
shifts? Food source? Predation? Parasitism? Disease?
Intermittent thermal excusions? Chronic thermal
conditions?
Off-site (Lakewide) Studies Related to Macrozoobenthos
It should be noted that investigation of lakewide effects
are not the responsibility of a single user, or group. There are
many stresses on the waters of Lake Michigan and separation of those
caused by cooling water use is difficult.
1. What are the substrate types and their areal extent?
2. What are the habitat types and their extent?
3. What benthic fauna occupy these substrates and habitats?
In what densities? Community biomass? Important species
biomass? Can these be generalized?
4. What roles do the benthic animals have in the lake's
ecosystem?
5. Which benthic animals are of primary importance to this
system and why?
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6. To what extent would elimination (destruction) of a
habitat type (or portion of a type) and its associated
biota affect the lakewide ecosystem?
7. What is the effect, real or potential, of local effects at
one site or all combined local -effects on the lakewide
ecosystem?
8. Can long-term chemical changes in the lake have an effect
on benthic animals and to what extent will the chemical
additives from a number of power plants amplify this effect?
Major investigative effort should be directed toward field
studies at present. Clearly, many of the experimental questions
posed are more research than baseline surveys. However, it should
be obvious to the investigators that when perturbations occur in
the field, the causative factors can often be isolated only in
the laboratory. Controlled experiments and research needs are
discussed later in this chapter.
Principal Problem Areas In Understanding Effects of
Coojing Mater Use on Benthos
The problems associated with understanding the results of
benthos investigations as a part of studies of cooling water use
fall into four categories: a) regulation of benthos abundance and
community structure by natural environmental factors, b) separation
of the effects due to other water uses from the effects of cooling
water use, c) obtaining precise estimates of abundance and communi-
ty structure, and d) demonstration of the significance of the
benthos in the over-all lake ecosystem.
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Natural Environmental Factors
From previous investigations it seems reasonable to assume
that the off-shore benthos community of Lake Michigan (exclusive of
Green Bay and many near-shore areas) 1s essentially a single
community. However, it has been found that abundance and community
structure of the benthos change with certain natural environmental
factors, chiefly depth and sediment composition. Macrozoobenthos
abundance is usually very low at depths less than five meters and
increases with depth to a maximum at a depth of 30 to 60 meters.
At depths greater than 60 meters, benthos abundance decreases. Near-
shore sediments with a high percentage of small particles and/or
a high organic content support large populations of tubificid worms
which are less abundant in other types of sediments.
Normal turbulence due to wave action can move bottom sediments
i
in areas shallower than about 15 meters and redistribute the benthos
and small particle size material. This material settles in depths
ranging from 15 to 60 meters with the heaviest deposition of organic
matter derived from the disturbed sediments occurring between
15 to 25 meters.
Condenser cooling water intakes and discharges usually are
located in water less than 15 meters deep. This is not the region
of maximum macrozoobenthos abundance but is the region in which
the abundance and composition of the benthos may change quite
significantly due to natural factors: depth, sediment composition,
and perhaps others. These natural variations in benthos compound
the problem of demonstrating effects of cooling water use,,
Careful selection of areas for sampling will avoid this
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problem. Test areas in which cooling water use effects might be
observed should be selected with adequate consideration of the
natural effects of lake currents and wave action. Reference areas
should be selected to permit comparison with the test areas in
depths, sediment types, and as many other environmental factors as
possible.
The benthic community in any given area changes seasonally
and annually. Due to these changes comparison of preoperational
data from a test area only may not provide a very clear picture
of the effects of cooling water use. Comparisons of changes in
the benthic community of the test area with changes in the
reference area(s) provide the best approach for measuring effects.
Such comparisons will be of greatest value when preconstruction
and preoperational data from test and reference areas are avail-
able.
Effects of Other Discharges
Discharges of waste materials to Lake Michigan have caused
changes in the benthic community in some areas. Some of these
changes are obvious and highly localized such as the increased
abundance of leeches and reduced abundance of other benthos near
the discharge from a steel mill. Some changes are more widespread,
such as the increases in tubificid populations in the 15 to 25 meter
depth range in association with inputs of organic wastes at
several points around the lake. When changes in the benthos in
areas of cooling water use are found, it must be determined whether
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the changes are due to cooling water use or to inputs of waste
materials.
The best approach to this problem which can be suggested at
present is again careful selection of test and reference areas.
Particular attention should be given to distance from influential
discharges such as municipal wastewater treatment plants and
mouths of large rivers. Selection also involves knowledge of pre-
vailing currents. If both the reference and test areas are sub-
jected to the same environmental influences except for the single
factor of cooling water use, the differences in changes between
the test and reference areas should be due to the cooling water use,
Once a difference in the changes in benthos occurring in the
test area is found, this should provide verification for one of
the concerns expressed previously. If it appears that one of the
mechanisms is actually operating in the lake, it should be further
tested by laboratory experiment. Data from the laboratory experi-
ments, if properly designed and conducted, should be quite helpful
in separating the effects of cooling water use from the effects of
the input of waste materials. Further information on the response
of benthos to various stresses should also be quite helpful for
sorting out effects.
Samp!ing Problems
An objective of any program of benthos sampling is to obtain
samples giving a quantitative estimate of the abundance and species
composition of the benthic community or a representative fraction
thereofo In any area the faunal assemblage is likely to
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vary considerably from one sample to the next. Thus replicate
samples are needed to estimate the mean and variability of indivi-
dual samples. Samples from test and reference areas must be
collected in a manner so that they provide comparable data. Each
replicate sample in both areas should consist of organisms
collected over an equal area and occupying an equal volume of
sediment. Since sampling devices are imperfect (i.e., any sampler
is somewhat selective) and do not collect equal volumes from
different sediment types, each sample should be examined immediately
after collection and rejected if the sampler does not contain an
appropriate volume or if there is evidence that the sampler is
not functioning properly.
Benthos tend to have different distributional patterns at
different depths. While the expected distribution is random in
areas where sediments are disturbed by wave action and aggre-
gated in deeper areas, the benthos of some nearshore areas
may contradict this by exhibiting strong aggregation. In cases
of animals with territorial behavior (e.g., crayfish) the distri-
butional pattern may be regular. Statistical distributions which
may correspond to the various patterns of benthos dispersion are
Poisson for random, negative binomial for clumped, and positive
binomial for regular. Sampling an area to fully document patterns
of dispersion may require a prohibitive number of samples. For
statistical treatment, mathematical transformations of the data
should be used only where there is valid justification. The normal
distribution should be assumed only when it can be shown that the
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data fit. When the data are inadequate either to demonstrate the
distribution or to provide precise estimation of the parameters
of the distribution, non-parametric procedures should be used, as
for data from different areas.
Determination of the Role of Benthos at Study Sites
As previously indicated, the benthic community is of major
importance to the lake ecosystem as a source of fish food. Since
it is important to design a benthic sampling program which defines
(
the role of the benthic community in the study area, stomach
contents of fish of a variety of species and ages should be
analyzed to determine the importance of benthic organisms in their
diet. Such analysis should be related to the seasonal benthos
communities.
Objectives Of Measuring Environmental
Conditions and Responses
In general terms, the objectives of site-specific benthos
investigations are to quantify the on-site effects of cooling
water use, to establish the spatial limits of benthic effects, to
determine the extent to which such effects are cause for concern,
and to relate measurable perturbations to the water body segment
or the Lake Michigan system as a whole.
Some specific objectives of preconstruction or preoperational
studies are establishment of the baseline environment for com-
parison with conditions during operation. For comparison of
macrozoobenthos,the bottom contours, sediment types, normal seasonal
benthos abundance, distribution and community structure should be
determined. Knowledge of the important species (e.g. reproductive
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behavior and time, migration, thermal tolerance) and their role in
the system is highly desirable.
Some specific objectives of operational studies are to
determine changes in bottom contours, sediment type and benthos
distribution, abundance, community structure and behavior (as
distinguished from normal changes) caused by construction and
operation of cooling water intake and discharge. If changes in
benthic populations are observed, the question of the significance
of these changes to higher trophic levels should be addressed.
Benthic Study Field Methods
Col 1ection
Benthic samples should be collected using appropriate and
recognized sampling devices and methods. The choice of sampler is
dictated in part by the substrate, depth, and organisms. When
various techniques are employed at one study site, a mechanism
should be adopted to compare techniques on a quantitative basis
after careful consideration. There are great differences in sampling
efficiencies among grabs. In granular substrates the following
devices may be used:'
1. Grab samplers (Ponar, Petersen, Ekman, Smith-McIntyre)
2. Core samplers (single and multiple)
3. Sleds and dredge nets
For discussion of relative sampling efficiencies and appropriate-
ness see Powers and Robertson, 1967; Mozley and Chapelsky, 1973;
Beeton, Carr and Hiltunen, 1965; Flannagan, 1970, and Howmiller,
1972.
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In areas of rock outcrops, large rocks and gravel, or hard
packed clay, the following sampling devices may be used:
1. Pumps
2. Scuba divers (direct observation, in situ collecting, or
photography)
3. Artificial substrates approximating natural substrates
4. Sleds
Separation
Organisms should be separated from the sediment by sieving or
elutriation or both. Meshes should not be larger than those of a
U.S. Standard No. 30 sieve (589 microns). Samples should be placed
in labeled containers and preserved with 10 percent buffered for-
malin or 70 percent ethanol.
A U.S. Standard No. 60 sieve (246 microns) may be used
when the substrate allows. This size is more efficient at re-
taining smaller macroinvertebrates such as early instar chironomids
and minute ol igochaetes. Varying sieve sizes affects comparabili-
ty of the stations and the advantages of sieve sizes must be
considered against the effort of extracting and identifying these
small animals. There is a possibility that samples of larger
animals from a larger surface area may be more valid statistically.
For more complete community estimates, two sample sizes and sieve
meshes might be used together.
If organisms are not separated from the substrate in the
field, the entire sample can be placed in a labeled container and
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kept cool and unpreserved until it is separated, preferably the
same day. However, the organisms are subject to predation and
also to death from anoxia or abrasion (followed by decomposition).
Since differences in numbers and sizes of animals recovered could
result from inconsistent methodology, trials should be conducted
with known numbers of live animals to determine (a) the relation-
ship of holding time to percentage recovery and (b) the numbers
and sizes of animals recovered by field separation techniques com-
pared with laboratory techniques. It is preferable not to vary
collection and separation techniques on a study area.
Sediments
Although bedrock exposures are found in Lake Michigan, most
of the bottom is covered with glacial deposits overlain by more
recent sedimentary materials. Descriptions are provided by Hough,
1935; Ayers and Hough, 1965; Ayers, 1967; Powers and Robertson,
1968; Somers and Josephson, 1968; and Mozley and Alley, 1973.
These sediments play an important role in abundance and composi-
tion of the benthos since they provide the physical habitat for
all and the food supply for many. Variations in the benthic
community with sediment type and composition must be known in
detail before it is possible to ascertain the effects of other
environmental variables (such as temperature). Some of the
possible effects of cooling water use upon the Lake Michigan
ecosystem are related to possible changes in the sediment such as
the patterns of sediment erosion and deposition near discharges,
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or increased organic content in the sediments due to "fall-out"
of plankton killed during condenser passage.
Mapping of Sediments
Sediments in the areas of actual or potential cooling water
use should be mapped for selection of sampling sites for field
studies of the benthic community and for estimating potential
effects on the habitat. Five methods used for sediment mapping
are applicable to benthos work: grab samples, core samples, use
of divers, underwater television or photography, and seismic
profi1es.
1. Grab samples are useful since the surface layer in-
habitated by most of the benthos makes up a large
portion of the sample. However, the layered character-
istics are often disturbed by the action of the grab.
When grab sampling an area of approximately 500 cm^, the
volume of each sample should be at least one-half liter
to assure adequate representation. If this amount cannot
be collected by a single grab, a core sampler should
be used. However, in well-sorted, fine sand some grabs
are inefficient and core samplers do not retain the
sample.
2. Core samplers penetrate deeper, but usually cover less
surface area than grabs. They collect a smaller amount
per sample of the critical upper layer mainly inhabited
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by benthos, but the sample Is relatively undisturbed.
Core samplers are particularly useful In areas of hard
clay where a grab will not penetrate to collect an
adequate sample. Examination of the •edlment from a core
sampler may be confined to the upper 2 cm for surfldal
sediment mapping, although the deeper sediments may be
important to certain benthic animals.
3. Divers trained in scientific observation and using
techniques for random or design sampling can be useful
in mapping sediment characteristics. Divers are
especially valuable for locating such features as rock
outcrops, patches of silty or organic sediments, or i
areas of macrophyte growth missed by other sampling i
techniques.
4. Underwater television or photography are alternatives to
the visual observations supplied by divers.
5. Seismic profiles provide data on gross distribution of
sediments over large areas but cannot provide the detailed
information on the upper layer of sediment over a small
area needed for evaluation of benthic habitats. Sediment
profiles based on seismic data and some core samples are
available from the Illinois Geological Survey for the
entire southern basin of Lake Michigan.
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Sediment mapping should extend at least 2 kilometers along
the shore in either direction from the point of discharge and at
least 2 kilometers away from shore. These distances vary with
the site and size of the anticipated area of influence. For
initial mapping, at least 10 samples should be collected over each
km2. These could be supplemented by visual surveys by trained
divers to identify significant features of the bottom which may
be missed by random sampling. Sediment mapping should also be
involved in selection of reference areas to insure comparability.
Laboratory Analysis of Sediment
Sediment type is identified by laboratory analysis. Since
there is no way at present to relate sediment mineralogy to
benthic communities, mineralogical analyses are not recommended.
However, it is highly important to have information on organic
content and the particle size distribution. See Substrate Section,
page 188, for comments on quality of sediments.
1. Organic content should be measured by total organic
carbon determination (TOC) and reported as percent dry
weight (+_ 1 percent).
2. The particle size distribution of dry sediment should be
determined by shaking it through a series of 7 sieves
with the following separation sizes (Inman, 1952):
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Separation
size (mm)
2.00
1.00
0.5
0.25
0.125
0.0625
0.0039
Phi
(-Iog2d)
-1 .0
0.0
1.0
2.0
3.0
4.0
8.0
Class
very coarse sand
coarse sand
medium sand
fine sand
very fine sand
silt
clay
The Phi number (-log2 diameter in mm) of the mean particle
size and the standard deviation in Phi values should be
reported. It is also useful to report the percent (by
weight) of particles less than 0.0625 mm in diameter.
Sediment Chemistry
Sediment chemistry of particular interest in evaluating
cooling water use describes the exchange of materials between the
sediments and water of the lake. Specific elements often are, or
become, insoluble and are deposited in the sediments. If toxic,
and biologically available, they may reach concentrations high
enough to alter composition of the benthic community. It is also
significant that benthic organisms sometimes recycle nutrients
and other materials from the sediments into the water and back
into other trophic levels.
Where cooling towers are used, evaporation increases chemical
concentrations in the blowdown. Toxic materials may be used in
cooling tower maintenance. Therefore, materials in blowdown
discharged into the lake have potential for accumulating in sedi-
ments over a relatively small area. In view of the wide range of
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blowdown contaminants, it is not possible to make general recom-
mendations on the types of analyses which should be performed,
however, investigators should be alert to the possibility that
changes in benthic communities may be due to changes in sediment
chemistry.
Corrosion or erosion in circulating water systems may contri-
bute toxic metals to once-through cooling water discharges or to
cooling tower blowdown. Metals of concern include copper, zinc,
and chromium. Concentrations of these materials in the discharge
and physical models of their distribution over the receiving
area are needed before it is possible to specify the analyses
and precision.
Supporting Information
The following information should be collected (concurrently,
and with appropriate periodicity) to assist in interpretation of
benthic ecological patterns which may emerge from the survey:
1 . Water Chemi stry
a. dissolved oxygen immediately above or in sediments
b. suspended organic matter
c. C:P:N ratio
2. Water depth (in meters)
3. Date and standard time
4. Temperature (Celsius) of bottom waters. The relationship
to overlying temperatures may be of value, as would be
the temperature at the sediment-water interface or in
the sediments at critical sites. If the area of the
bottom impacted by increased temperatures and the frequency
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and amplitude of such increase is not well known,
interpretation of direct thermal effects will be
difficult at best.
5. Transparency, by photometer or Secchi disc
6. Visual examination and description of the sediment at
the time of sampling. The sediment type or combination
of layered sediments may be encoded by a single number
or combination of numbers. Example: medium sand
layered over hard clay - 10, 2/6, or silty fine sand =
5, 4/3.
1 - Coarse sand 7 - Clay-soft
2 - Medium sand 8 - Gravel
3 - Fine sand 9 - Rock
4 - Silt 10 - Layered sediments
5 - Mixed 11 - Gelatinous
6 - Clay-hard
Sampling Design
A statistician familiar with environmental sampling should
be consulted during the design stages of the program.
Establishing Stations
Sampling stations in the test and reference areas should be
established in a similar manner, either in a grid system or by
random selection along transects. The number of stations and
number of replicate samples depends on the degree of variability
in the habitats. To determine the extent and detail of the pro-
gram, preliminary sampling should be done to evaluate variability
in depths, sediments, water quality and benthos. For statistical
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analysis of areal differences, stations from similar habitats may
be grouped.
Fixed Grid
Areal extent of the grid and proximity of the stations should
fit the size and the expected area of influence. The grid should
be modified to account for special situations as outlined below.
Selection of Reference Area(s)
The reference area(s) should be sufficiently remote from the
test area to be unaffected by the plant operation. They should be
as similar as possible to the test area in topography, sediment
types, distribution of sediments, and water quality. Differences
will create difficulties in interpretation of results and identi-
fication of changes in the test area. Considerable effort
should be expended in making as careful and knowledgeable choice
as possible. (See Principal Problem Areas in Understanding
Effects of Cooling Water Use on Benthos, page 201.)
Station Identification
Stations should be located with precision and either marked
by a buoy or located using a transit with fixed shore points or
distance measuring equipment. Far field or open lake stations
can be accurately established and relocated with ships' radar
and other navigational aids.
Station Distribution and Spatial Interval
Stations should be distributed so results of sampling can be
related to the frequency of occurrence of the discharge plume
in the test area. Spatial interval depends upon the extent and
homogeneity of the area over which the target effects are to be
evaluated. Establishment of stations in the area where heated
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water will contact the bottom 1s Important. Additional stations,
if necessary, should be located to measure and evaluate: 1)
erosion by disturbance of bottom sediments; 2) winter sinking
plume; 3) areas of increased fish predation; 4) areas of "fall-out"
of organisms killed by condenser passage. Additional sampling
sites may be needed to document special situations.
Sampling Frequency
Ideally, sampling should be done every other month (six times
per year) for the calendar year and more often during periods of
rapid change such as late spring or summer at a critical site.
Minimum sampling frequency should be four times per year,
seasonal.
Number of Samples
The number of replicates collected at each sample site in
the test and reference area on each sampling date should be
adequate for statistical treatment as discussed in the Date Require-
ment Section (page 47) and Sampling Problems, page 204. Generally,
at least three replicates should be collected each time and at
least four replicates may be required if non-parametric statistical
tests are used. The number of replicates required may be much, much
greater than three or four if it is desirable to detect significant
differences in species abundance in the presence of the variability
usually found in benthic populations. A key to the amount of
benthos sampling and detail desirable is associated with the
severity of impact experienced at the site and importance of the
site specific and water body segment of the benthic community.
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An approach to detect differences in abundance which is not
generally satisfactory is to assume that the Poisson distribution
(random distribution) model can be used to describe the data.
The square root transformation is used to "stabilize the
variance" and analysis of variance is applied to the transformed
data.
There are good biological reasons to believe that benthic
population data should fit distributional models other than the
Poisson, such as the binomial or negative binomial. If the
incorrect distributional model is used, then the incorrect data
transformation is used and analysis of variance will be less
likely to detect differences. However, the number of replicates
required to examine detailed distributional properties of the
data may be beyond the resources of any particular study group.
There should be a special study to determine the appropriate
distributional models for analysis of benthos data. Until such
a study is carried out, non-parametric tests are recommended.
When data distributions are not known, non-parametric tests often
have greater sensitivity to detect differences than analysis of
variance. Design of sampling should be decided with the advice
of a statistician.
Laboratory Techniques
Sorting, identification and enumeration of benthic samples
should be performed using standard laboratory equipment, pro-
cedures, and techniques. All identifications should be performed
with appropriate magnifiers and microscopes using recognized
taxonomic keys or publications.
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Data Presentation
Generic and Specific I-denti fication
In general, dominant organisms should be identified to
species if possible and all other organisms should be identified
at least to genus, counted and quantified in units/m^. Fol^owin-g
-t-hi.s-g=u-i del-4-ne-, -my si ds , decapods, amphipoxls , aird mo:st_-o3-jg*DŁiHffiabes
s^hor3'd~~be -i-denti f.i-ed to species. Sphaeri i dae s-ho u W-"fce-H d-e=n
-------
and Whipple (1959) is useful for other forms.
Since use of the recommended sieve mesh size (589 microns)
will probably result in escape of the majority of Nematoda,
Ostracoda, Harpacticoidea, Platyhelminthes and benthic Cladocera,
identifying representatives of these groups to specific levels is
of little quantitative value. Identification becomes important
when refined collection and separation techniques are used and
greater community description is desired.
Biomass
1. Dry weight determinations should be made on unpreserved
organisms since preservatives cause weight loss (Howmiller,
1972b). Organisms should be oven dried at 60C for 24
hours and weighed.
2. For ash free determinations, dried organisms should be
placed in a muffle furnace at 600C for 30 minutes.
Ash free weight equals oven dry weight less final weight
after ashi ng.
Diversity Indices
Depending on the level to which the organisms have been
identified, species diversity analysis may be conducted. The
usefulness of species diversity indices with Lake Michigan
zoobenthos is questionable (See Mozley, 1973). Species "richness"
and "evenness" are of interest, but sampling and taxonomic problems
severely limit their use. They are an optional means of
presenting data, if justifiable.
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Research Needs and Controlled Experiments
Although this chapter focuses on a very practical field
problem, the evaluation of the effects of cooling water use on
Lake Michigan macrozoobenthos, solutions to the mechanisms which
control the undesirable effects may be most efficiently pro-
vided by basic research. Field studies provide estimates of
effect, but often do not bear on causative mechanisms. While
no attempt will be made to provide an endless list of laboratory
studies, carefully chosen laboratory research projects can
provide guidance for operational protocols that could minimize
environmental impact. It is possible to identify areas of
laboratory investigation on benthic organisms of immediate
practical use. One of the first questions concerns the simple
effect of heat on the benthos, that is, temperature bioassays of
ecologically important benthic species to provide estimates of
effects of chronic and acute exposure to heat.
Laboratory bioassays have been justifiably criticized for
the following reasons:
1. Such studies may have limited transfer value.
2. Test conditions in the laboratory may not adequately
simulate simple field situations.
3. Bioassays tend to treat a single factor at a time,
making it difficult to predict multiple effects,
synergisms, or modifications that might occur under
natural conditions.
4. More complex field situations are difficult and expensive
to simulate in the laboratory.
In view of the foregoing, laboratory studies should consider
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the following factors and their interactions: temperature,
biocides, cooling tower blowdown products, dissolved gases.
In general, the physiological requirements of most species
of lake macrozoobenthos are poorly known, including even their
basic temperature and dissolved oxygen requirements. Bioassay
and characterization of toxicity should characterize normal
requirements and develop criteria to identify responses to
changes from normal. This knowledge is fundamental to under-
standing the results of environmental change. As a partial
remedy, the following steps are proposed:
1. Have competent specialists select key, dominant, or
representative species, both site specific and water
body segment specific;
2. Subject selected species to intensive laboratory study
to determine oxygen and temperature tolerances at
various life history stages;
3. Standardize procedures, design variables, and reporting
procedures for the testing; and
4. Perform toxicity and uptake tests for biocides and
heavy metals only on species for which oxygen and
temperature tolerances have been developed.
By standardizing bioassay protocols, information developed
for one site is more applicable to work related to other sites.
The effect of intermittent heat or discontinuous generation
on benthic organisms is a second area of concern which can be
profitably studied in the laboratory. Irregular generation and
shifting plumes can cause unseasonal thermal environments which
222
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may have significant ecological effects even though absolute
temperature differences created may be small. Many physiological
and behavioral activities, such as reproduction and migration are
keyed to normal seasonal and daily temperature patterns.
Priority Needs and Research
Relatively immobile benthic and sessile organisms may be
subject to continuous or intermittent stress in the vicinity of
facilities using Lake Michigan as a source of cooling water.
Stress may be caused by discharge velocity, thermal differences
or exposure to chemicals used in plant operation. This may re-
sult in a difference in benthic communities in the vicinity of
such facilities from those remote from the facility.
Minimum stress to benthic organisms is achieved by minimizing
the bottom area exposed to harmful conditions. This may be
accomplished by careful discharge location and design, and by
cooling water and wastewater treatment before discharge. Such
measures may entail additional use of other resources and an
economic penalty to the discharger, which is ultimately passed
to the consumer. Therefore, a decision should be made on a case-
by-case basis as to how the benthos are to be protected. The
bottom area in the vicinity of thermal discharges may represent
a living space denied to benthic organisms and this space may
or may not be of significance to the biological community.
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The need for biological judgment requires that this sub-
committee recommend some general and specific studies which
would compare the effect of environmental alteration to natural
situations. Since some of these studies take precedent over others,
a system of priority has been established based on need, and
categorization has been accomplished based on the availability
state of the data, as follows:
Priority - 1 - Highest priority consistent with achieving
primary goals of Panel;
2 - High priority item directly supporting
priority 1 items;
3 - Intermediate priority.
Category - 1 - Solution available from existing data;
2 - Solution available from ongoing studies;
3 - Solution requires additional research.
(A) The discussion introducing this section identifies high
priority need for biological information applicable to the
regulation and/or modification of thermal discharges: determi-
nation of the importance of macrozoobenthos in the vicinity of
the discharge to the biological community of the receiving system.
The most obvious approach is through field food chain studies on
site to aid in answering the question of whether elimination or
alteration of macrozoobenthos in areas of varying size would
affect fish or their populations.
224
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Priority 1, Category 3.
(B) The second high priority information need is the
ability to distinguish the effects of cooling water use on
macrozoobenthos from contemporaneous changes due to other causes
Priority 1, Categories 1 and 2.
(C) Because cooling water use represents only one of a
number of stresses on the Lake Michigan ecosystem and because
the macrozoobenthos of the vast profundal and sublittoral areas
are of established importance to the biological community, base-
line measurements of lakewide zoobenthos populations are needed
in sufficient detail that trends may be recognized at an early
date. These base!ine measurements should be accompanied by a
seasonal biological map incorporating activities of important
species.
Priority 1, Categories 1, 2 and 3.
To provide the above three information needs, other studies
and activities of a supportive nature should be initiated.
(D) Macrozoobenthos species lists with synonyms and known
spatial and geographic distribution.
Priority 2, Category 1 and 2.
(E) Determine and list species of special significance and
specify reasons for significance, i.e.:
a. Benthic environmental quality indicators
b. Energy transfer in food chains
c. Recycling of nutrients, toxins and radioactive materials
d. Accumulators of materials of concern (metals, organics,
and radioactivity)
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e. Nuisance producers
Priority 2, Category 1 and 2.
(F) Determine sampling design and sampling devices necessary
to ensure minimum capability for identification of change.
Intensive review of exiting data should yield conclusions on
such factors as:
a. Replication and limits of statistical error
b. Spatial distribution of sampling efforts
c. Criteria to establish reference locations
d. Seasonal distribution of sampling effort
e. Data reporting criteria and format
f. Sampling devices
Priority 2, Categories 1 and 2.
(G) Identification of the degree of influence on benthic
populations by such factors as:
a. Chemicals (algacides, cleaning agents, chlorine blow-
down products)
b. Thermal effects (intermittent, acute and chronic ex-
posures, sinking plumes)
c. Riprap
d. Fish predation
e. Scour and velocity
f. Enrichment (organism "fall-out" from plumes)
Priority 1, Categories 1, 2 and 3.
Items D, E, and F above relate to the basic problem of benthos
investigation on any body of water on which several academic,
enforcement, industry, and consultive entities are working:
non-uniformity of methods. This leads to a low degree of data
226
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comparability. Utility of results and efficiency of the total
effort would be increased greatly by adopting compatible,
if not uniform, methods. Therefore, a recommendation is made
for two workshops: the first on taxonomy and nomenclature and
the second on sampling and data analysis. No priority has been
established, but these workshops are considered highly signifi-
cant to an orderly assessment of thermal effects on the macrozoo-
benthos of Lake Michigan.
227
-------
LITERATURE CITED
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Henson, E.B. 1962. Notes on the distribution of benthos in the
Straits of Mackinac region. Proc. 5th Conf. Great Lakes Res.
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Henson, E. B. 1966. A review of Great Lakes benthos research.
Univ. of Mich. Inst. Sci. and Tech., Great Lakes Res. Div.,
Publ. No. 14, pp. 37-54.
Henson, E. B. and H. B. Herrington. 1965. SpaerHdae (Mollusca:
Pelecypoda) of Lakes Huron and Michigan in the vicinity of
the Straits of Mackinac. Proc. 8th Conf. on Great Lakes
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Henson, E. B., E. C. Keller, A. J. McErlean, W. P. Alley, and
P. E. Etter. 1973. The ecological effects of taconite
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18, 1973: pp. 1161-1319 (mimeo).
Hiltunen, J. K. 1967. Some oligochaetes from Lake Michigan.
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Hiltunen, J. K. 1969. Distribution of oligochaetes in western
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Hiltunen, J. K. 1973. A laboratory guide: Keys to the tubificid
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Hough, J. 1935. The bottom deposits of southern Lake Michigan.
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Green Bay, 8-14 July 1971. Univ. Wise. - Milwaukee, Center
for Great Lakes Studies, Spec. Rept. 13.
Howmiller, R. P. 1972b. Effects of preservatives on weights of
some common macrobenthic invertebrates. Trans. Am. Fish.
Soc. 101: 743-746.
Howmiller, R. P. and A. M. Beeton. 1970. The oligochaete fauna
of Green Bay, Lake Michigan. Proc. 13th Conf. Great Lake
Res., pp. 15-46.
Inman, D. 1952. Measures for describing the size distribution
of sediments. Journ. Sed. Petrol. 22: 125-145.
Johnson, M. G. and D. H. Matheson. 1968. Macroinvertebrate
communities of the sediments of Hamilton Bay and adjacent
Lake Ontario, Limnology and Oceanography, 13: 99-111.
Kennedy, C. R. 1966. The life history of Limnodri1 us
hoffmeisteri, Chap. (Oligochaeta: Tubificidae) and its
adaptive significance. Oikos 17: 158-168.
230
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Kinney, W. L. 1972. The macrobenthos of Lake Ontario. Proc.
15th Conf. G_reat Lakes Research, Int. Assn. Great Lakes
Research, pj> . 53-79.
Lasenby, D. C. and R. R. Langford, 1973. Feeding and assimila-
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:es Basin Framework Study, Great Lakes Basin
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Occurrence of gas bubble disease in three species of bivalve
mollusks. J. Fish. Res. Bd. Canada. 29: 588-589.
Marzolf, G. R.--1963. Substrate relations of the
amphipod, Pontoporeia affinis Lindstrom. Ph,
Univ. of Mich. , 92 pp.
burrowing
D. thesis,
Marzolf, G. R. 1965. Vertical migration of Pontoporeia affinis
(Amphipoda) in Lake Michigan. Proc. 8th Conf. on Great
Lakes Res.
Mason, W. B., Jr. 1973. An introduction to the identification
of chironomid larvae. National Environmental Research
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McWilliam, P. S. 1970. Seasonal changes in abundance and
duction in
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repro-
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to
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Pennak, R. W**. 19.53. Fresh-Water Invertebrates of the United
States. Ronald Press Co., N. Y.
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of the macrobenthos of Lake Michigan. Proc. 8th Conf. Great
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Powers, C. F. and W. P. Alley. 1967. Some preliminary
observations on the depth distribution of macrobenthos in
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Spec. Rep. No. 30.
Powers, C. F. and A. Robertson. 1967. Design and evaluation
of an all-purpose benthos sampler. In: J. C. Ayers and D.
C. Chandler (eds.), Studies on the environment and
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Res. Div. Spec. Rep. #30.
Powers, C. F. and A. Robertson. 1968. Subdivision of the benthic
environment of the upper Great Lakes, with emphasis on Lake
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Rains, J. H. and T. V. Clevenger, 1974. Benthic macroinverte-
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Lake Michigan macrobenthos. Limnology and Oceanography 11:
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Saether, Ole A. 1973. Taxonomy and ecology of three new species
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Schuytema, G. S. and R. E. Powers. 1966. The distribution of
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233
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234
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SECTION VII
MEASUREMENT OF THE EFFECTS OF COOLING WATER USE
ON THE FISHERY
-------
Section VII, MEASUREMENT QF JHE EppECTS pp COOLING WATER USE
ON THE FISHERY
Table of Contents
Introduction. ......... .238
Historical Description of Great Lakes
Fish Stocks ....... .238
Utilization by Man . 242
Effects of Pollution and the Electric Power
Generating Industry on F1sh Stocks .... .244
Principal Problem Areas . . . . . . .247
Program for Measurement of Effects . . . . . .254
Introduction and Research Priorities . . . .254
Priorities 255
Categories ....... .255
Quantifying Statement on Program Orientation . . .256
Methods of Investigation ....... .258
Before and After Studies ....... .258
Questions to be Answered ...... .258
Materials and Methods ...... .260
Trawl Sampling of Juvenile and Adult Fish . -260
Gill net Sampling of Juvenile and Adult Fish .266
Seine Sampling for Juvenile and Adult Fish. .269
Plankton Net Sampling for Fish Fry . . .271
Pump Sampling of Fish Eggs .... .272
Tagging or Marking of F1sh .... .273
Intensive Plume Studies ....... -276
236
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Table of Contents
Questions to be Answered . . . . . . . . . -?77
Materials and Methods
On-s1te Bloassays .
Questions to be Answered 287
Materials and Methods 288
Laboratory Studies 289
Questions to be Answered 289
Materials and Methods 290
Lakewlde Studies 292
Questions to be Answered 293
Materials and Methods 294
Trawl Sampling of Juvenile and Adult F1sh . . .294
6111 net Sampling of Juvenile and Adult F1sh . . -295
Seine Sampling for Juvenile and Adult F1sh . . -295
Plankton Net Hauls for F1sh Fry Assessment . . .295
Pump Sampling of F1sh Eggs 297
Literature Cited 298
237
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SECTION VII MEASUREMENT OF THE EFFECTS OF
COOLING WATER USE ON THE FISHERY
Introduction
Historical Description of Great Lakes Fish Stocks
The Great Lakes and their tributaries and connecting waters
contain an extensive fish fauna which includes representatives
of most of the important families of North American freshwater
fishes. Hubbs and Lagler (1958) described 20 families and 173
species in the Great Lakes drainage basin and stated that
theirs was undoubtedly an incomplete list. Although nearly all
of the fish native to the drainage basin had access to Lake
Michigan, relatively few species became established in the Lake
proper, and most of these were cold water species.
A complete list of the fish fauna of Lake Michigan is not
available, but according to Wells and McLain (1973), a number of
of species were, or are now common (Table VII-1).
The fish fauna of Lake Michigan, as the early settlers
found it, was dominated by salmonids of which the whitefish,
lake herring, and lake trout were the most abundant. Since that
time, several species of coregonines have become rare or have
disappeared from the Lake. The lake sturgeon is now rare, the
native lake trout population was exterminated and the Michigan
grayling, apparently an anadromous species, is now extinct
(See Wells and McLain, 1973 for a detailed description of these
and other changes in the fish stocks of the Lake).
238
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Table VII - 1. Fish fauna previously or currently common
to Lake Michigan.1
COMMON NAME
SCIENTIFIC NAME
Sea lamprey2
Lake sturgeon
Alewife2
Lake whitefish
Blackfin cisco
Deepwater cisco
Longjaw cisco
Shortjaw cisco
Bloater
Kiyi
Shortnose cisco
Lake herring
Round whitefish
Lake trout
Brook trout
Rainbow trout (steelhead)2
Brown trout2
Coho salmon2
Chinook salmon2
Petromyzon marinus
Acipenser fulvescens
Alosa pseudoharengus
Coregonus clupeaformis
Coregonus nigripinnis
Coregonus johannae
Coregonus alpenae
Coregonus zenithicus
Coregonus hoyi
Coregonus kiyi
Coregonus reighardi
Coregonus artedi i
Prosopium cylindraceum
Salvelinus namaycush
Salvelinus fonti nali s
Salmo gairdneri
Salmo trutta
Oncorhynchus kisutch
Oncorhynchus tshawytscha
1
According to Wells and McLain (1973).
2Species that have gained access to the lake and have become
abundant during the period of historical record.
239
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Table VII - 1 Continued.
Rainbow smelt2
Northern pike
Carp
Emerald shiner
Spottail shiner
Longnose sucker
White sucker
Channel catfish
Bullheads
Trout-perch
Burbot
Ninespine stickleback
Smallmouth bass
Yellow perch
Waileye
Freshwater drum
Slimy sculpin
Spoonhead sculpin
Fourhorn sculpin
Osmerus mordax
Esox 1u c i u s
Cyprinus carpio
Notropis atherinoides
Notropis hudsonius
Catostomus catostomus
Catostomus commersoni
Ictalurus punctatus
Ictalurus spp.
Percopsis omiscomaycus
Lota 1ota
Pungitius pungitius
Micropterus dolomieui
Perca flavescens
Stizostedion vitreum vitreum
Aplodi notus grunniens
Cottus cognatus
Cottus ricei
Myoxocephalus quadricornis
2Species that have gained access to the lake and have become
abundant or common during the period of historical record.
240
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While many of the native fishes of the Lake were declining
in abundance, several exotic species became established and
reached high levels of abundance. In some instances, these
exotic species caused or hastened the decline of native stocks
by preying on them or competing with them for food or space.
The carp was one of the earliest deliberate introductions to
the Great Lakes basin. It is mainly a fish of the tributaries
and the shallow inshore waters and its effect on the native fish
populations of the Lake, although probably detrimental, has not
been adequately measured. The rainbow smelt, another deliberate
introduction, has become a food, sport and forage fish; however,
it is also credited speculatively with causing major declines in
the lake herring population. The sea lamprey, a marine species
that apparently migrated into the Great Lakes through man-made
canals in the 1800's, became abundant in Lake Michigan in the
middle 1940's. This species was largely responsible for the
decline in abundance of a number of desirable native species and
the extinction of the native lake trout and several species of
large coregonines. The alewife, a marine invader, was first
seen in moderate numbers in the Lake in the middle 1950's after
the lamprey had eliminated the larger predators. The alewife
reached peak abundance in the fall of 1966, but following a
massive die-off that occurred in 1967, the population seems to
have stabilized at a substantilly lower level of abundance. The
alewife competes for food with many native species and has
apparently caused major changes in the zooplankton composition
241
-------
of the Lake (Wells, 1970). The alewife is also the most
important food item in the diet of trout and salmon in Lake
Michigan.
Control of the sea lamprey and the relatively stringent
restrictions placed on the commercial fishery in Lake Michigan
since the late 1960's have permitted the recovery of various
lake spawning species including the whitefish. Control of the
sea lamprey and the presence of a large forage stock of alewives
set the stage for the rehabilitation of the lake trout and
other anadromous stocks of trout in the Lake. Coho and chinook
salmon were successfully introduced in 1966-1967 followed by the
apparent successful establishment of the Atlantic salmon in the
Lake in 1972.
Utilization by Man
A commercial fishery has existed in Lake Michigan at least
since 1843. According to Wells and McLain (1973) the earliest
fishery was conducted for whitefish, which were abundant in the
inshore waters of the lake. Total commercial fish production
for Lake Michigan in 1879 (the first year of record) was nearly
24 million pounds, of which about half was whitefish. Pro-
duction increased to about 41 million pounds annually in 1893-
1908 due primarily to increases in the catch of lake herring.
Production fell to about 24 million pounds annually in 1911-1942,
Total production averaged 26 million pounds annually during
1943-1965, but the period was one of marked instability and
242
-------
change in the fishery. During those years the lake trout
disappeared from the commercial catch. Whitefish stocks de-
clined to very low levels and the species virtually disappeared
from the catch for several years. The catches of smelt and
walleye rose briefly to record levels, and the alewife made
its first appearance as a species of commercial importance in
the lake.
Total production averaged about 51 million pounds annually
in 1966-1970 and 46 million pounds annually in 1971-1973. Of
the total production, alewives averaged 42 million pounds
annually in 1966-1970 and 32 million pounds in 1971 -
1973.
Because of the depleted condition of some fish stocks and
the need to reserve other stocks for the rapidly growing sports
fishery, the future of the commercial fisheries of Lake Michigan
can at best be called uncertain.
Angler interest in Lake Michigan is now at an all time high
because of the trout and salmon management programs, and there
is every indication that this interest will continue to grow and
be a major determinant for management of the fish stocks of the
Lake. Angler catches, which in the 1950's and early 1960's
probably reached a record low for the Lake, began to climb with
the partial rehabilitation of the lake trout and steelhead
stocks, the establishment of stocks of lake-dwelling brown
trout, and the successful introduction of Pacific salmon. In
1972, the most recent year for which published records are
243
-------
available, the angler catch In the State of Michigan's waters
of Lake Michigan was 347,000 steelhead trout, 311,000 lake trout,
610,000 coho salmon, and 234,000 Chinook salmon (Michigan De-
partment of Natural Resources, 1973). Few statistics are
available on the sport fishery for other species in the Lake,
but the once productive inshore (pier) fishery for yellow perch
is again attracting large numbers of anglers in some areas and
daily catches of up to 100 fish per angler are being reported.
Effects of pollution and the electric power generating industry
on fish stocks
In the early days of settlement, untreated sewage and sawmill
wastes were problems in river and harbor mouths and adjacent
areas and the major effect on the fish populations of the-Lake
was probably felt by anadromous species. Large pockets of heavy
pollution from municipal and industrial sources exist today.
The absence of desirable species and the lowered fishery pro-
ductivity in Southern Green Bay, for example^ can be attributed
to pollution. Pollution of the entire Lake by DDT, mercury,
PCBS and other conservative or long-lasting contaminants from
point and nonpoint sources is also a matter of great concern.
A number of species in the Lake have contaminant levels that
exceed safe levels set by the FDA for human consumption.
Recently the effects of electric power generation on the
Great Lakes and their biota have come under scrutiny. Serious
inquiry into these effects was initiated in the 1960's when it
244
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was recognized by resource agencies in the basin that future waste
heat discharges to the Lake might become large enough to pose
a threat to water quality and to the fisheries of the lakes.
Present concern over the adverse effects of once-through cooling
includes not only the effects of waste heat discharges on the
Lake and its biota but also losses that occur when fish and
other organisms are drawn into plant cooling systems. The kinds
of damage that may occur to fish and other organisms as a result
of electric power generation at steam electric stations have
recently been summarized by Edsall and Yocom (1972) and by Clark
and Brownell (1973).
An adequate and reliable demonstration of the effects of
electric power generation with once-through cooling on the fish
populations of Lake Michigan has not been made. Utility company
records show that large numbers of fish are killed at plants now
operating with once-through cooling on Lake Michigan, but infor-
mation on the distribution,abundance,and dynamics of the fish
stocks of the Lake needed to assess the significance of these
measured mortalities at power plants is not yet available. Con-
sequently, the present basis for concern over the adverse effects
of existing power plants on the fishery productivity of the Lake
is partly conjectural.
y
-/
Lack of an empirical assessment of the impact of cooling
water use at existing power plants on the fishery productivity
\
4
245
-------
of the lake makes 1t Impossible to accurately predict the con-
sequences of future increased use of the lake water for cooling.
Nevertheless, the available Information suggests that the elec-
tric power generating Industry will have a serious impact on the
fishery productivity of the Lake in the future unless alternatives
to open-cycle cooling are employed (Great Lakes Fisheries Lab,
et al.1970). For example, withdrawals of cooling water and all
discharges of wasteheat by power generating plants on the shores
of Lake Michigan occur within the littoral area. In Lake Michigan,
these littoral waters are equal in volume to only 0.4 percent of
the volume of the whole lake. If projected power demands were met
only with plants using once-through cooling, the cooling water
withdrawals by the electric power industry on Lake Michigan in
the year 2000 would be about 91,000 cubic feet per second. This
rate of withdrawal would require passing a volume equivalent to
one percent of the littoral water of the entire lake through the
cooling systems of power generating plants daily (Great Lakes
Fisheries Lab, et al»1970). Because damage is probably proportion-
al to the cooling water use rate, extremely high mortalities of
fish in the littoral waters of Lake Michigan could be expected
if these waters were used for cooling at a rate of one percent
per day.
Although the littoral waters of the lake are only a small
fraction of the total lake water,these littoral waters are vital
to the existence of almost every species of Great Lakes fish.
246
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Only the deep water sculpin and a few species of deep water chubs
are absent from the littoral waters. Fishes such as yellow perch,
smallmouth bass, northern pike, and walleyes, are all relatively
permanent residents of the littoral waters. Other species such
as the lake trout and most of the whitefishes..use the littoral
waters during the colder portion of the year as feeding and
spawning grounds and as nursery areas for their young. Fishes
that spawn in tributaries of the lake must pass through the
littoral waters on their way to and from the spawning grounds
and their offspring must pass through these waters when they
migrate to the Great Lakes for the rapid growth phase of their
lives. Thus the littoral waters exert considerable influence on
the fishery productivity of the Great Lakes and there is a great
need to provide protection for fish and their food organisms in
this important area of the lake.
Principal Problem Areas
Steam electric generating plants operating with once-through
cooling create both intake and discharge "problem areas" for Lake
Michigan fish (see Edsall and Yocom 1972 for a review). Although
the Fisheries Section of this panel report was restricted to con-
sideration of only the effects of power plant cooling system dis-
charges, it is necessary to present at least a general outline of
both intake (Fig. VII - 1) and discharge (Fig. VII - 2) problem
areas because the intake and discharge problems at most plants on
Lake Michigan are not clearly separated. Many of the fish taken
247
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Figure VII - 1. Principle problem areas associated with power plant intakes.
FISH ENTER INTAKE
FISH TOO LARGE TO
PASS THROUGH TRAVELLING SCREEN
FISH SMALL ENOUGH TO PASS
THROUGH TRAVELLING SCREEN
AND ARE PASSED THROUGH PLANT
ro
4k
03
FISH KILLED IMMEDIATELY OR
ULTIMATELY BY IMPINGEMENT
FISH REMOVED FROM
FOREBAY ALIVE
DISPOSAL
ON LAND
DISPOSAL
IN LAKE
[FISH UNHARMED | [SUBLETHAL EFFECTS
FISH RELEASED
IN DISCHARGE
POSSIBLE ADVERSE
EFFECTS ON
WATER QUALITY
FISH RELEASED
IN DISCHARGE
t
FISH RETURNED
TO LAKE REMOTE
FROM DISCHARGE
1
FISH RELEASED
IN DISCHARGE
t
-------
Figure VII - 2. Principle problem areas associated with power plant discharges.
10
FISH EXPOSED TO DISCHARGE
FISH DRIFT INTO DISCHARGE
FISH SWffl INTO DISCHARGE
FISH CARRIED INTO
DISCHARGE FOLLOWW8
PLANT PASSAGE
FISH ENTRAINED
DIRECTLY FROM
RECEIVING WATER
FISH UNHARMED
NO FURTHER
EXPOSURE TO PLANT
FISH ENTRAINED
NO FURTHER
EXPOSURE TO PLANT
FISH ENTRAINED
AT INTAKE
FISH NOT
EXPOSED
AGAIN
-------
in at the intake may pass into the discharge, and fish present in
the discharge may be drawn into the intake when the effluent is
accidentally or deliberately recirculated.
Although recirculation is recognized as undesirable because
it may result in increased entrainment and impingement of fish,
the seriousness of the problem in Lake Michigan appears to be
virtually unknown. However, it is clear that all of the fish
large enough to be impinged on the traveling screens of existing
power plants on Lake Michigan a're killed when they are drawn into
these plants because none of these plants are now equipped with
devices that would permit returning these entrapped or impinged
fish to the lake alive and unharmed.
The problem of the combined effects of plant passage and
subsequent exposure to adverse conditions in the discharge plume
is one that has received general recognition. However, until the
level of mortality caused by plant passage alone is determined,
it is impossible to state whether the additional exposure obtained
in the discharge plume is important to these fish. The available
information (see Coutant and Kedl 1975, Beck and Miller 1974,
Marcy 1973, 1974, and Clark and Browne!! 1973) suggests that
fish small enough to pass through the traveling screens will
probably experience high to very high mortality during passage
through the plant because of exposure to high lethal temperatures,
hydraulic or physical mauling (caused by the pumps and collision
with internal surfaces of the cooling system) and lethal concen-
250
-------
trations of chlorine.
A more thorough discussion of intake problem areas is pre-
sented in Section VIII of this report.
Fish that are entrained at the discharge and those that sur-
vive passage through the plant cooling system are exposed to
various conditions that may threaten their survival. These
include:
1) hydraulic mauling, particularly at plants with a high
velocity discharge (Clark and Brownell 1973),
2) elevated temperatures (Coutant and Kedl 1975, Clark and
Brownell 1973, Edsall and Yocom 1972),
3) chlorination (Basch and Truchan 1973, Stober and Hanson
1974),
4) gas embolism (Coutant and Kedl 1975),
5) predation: those that are incapacitated to some extent,
even temporarily, may have reduced ability to avoid
predators and have an increased probability of being eaten
by predators concentrated in or near the plume (Coutant,
etaK 1974, Yocom and Edsall 1974, Coutant 1973, Hocult
1973, Sylvester 1972, Gritz 1971), and
6) displacement: discharge currents may interfere with move-
ments of young fishes and prevent them from reaching
required or favored habitat (see Houde and Forney 1970,
Houde 1969b).
251
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The discharge of heated water from a power plant will cause
marked changes in the distribution of fish in the vicinity of the
plant. Most Lake Michigan species appear to be attracted toithe
heated discharge during a portion of the year and are absent from
or avoid the discharge during the rest of the year (Romberg and
Spigarelli 1973,Edsall and Yocom 1972). Fish attracted to and
residing in a heated plume in Lake Michigan could be killed or
damaged in a number of ways. For example:
1) fish encountering a sharp thermal gradient may be unable
to respond and may be killed by high temperature (Gall-
away and Strawn 1974, Meldrim and Gift 1971, Van Vliet
1956),
2) fish acclimated to high discharge temperatures, especially
in winter, die or are debilitated by cold shock if the
plant heat output is interrupted (Coutant, eta!0 1974,
Clark and Brownell 1973, Edsall and Yocom 1972),
3) high gas saturation of the discharge waters, especially
in winter, may create conditions in which fish would be
killed by gas bubble disease (Otto 1973, DeMont and Miller
1971),
4) chlorination of the cooling water may kill fish, or drive
them from the discharge area (Basch and Truchan 1973);
those driven from the discharge in winter could suffer
cold shock (see 2 above), or experience reduced repro-
ductive success (Arthur and Eaton 1971),
5) fish residing at elevated discharge temperatures will
252
-------
concentrate pollutants, including mercury and DDT, more
rapidly than those living at lower temperatures (Reinert,
et al.1974, MacLeod and Pessah 1973),
6) toxicity of some pollutants is higher at higher temper-
atures (Stober and Hanson 1974, MacLeod and Pessah 1973,
Macek, et al.1969, de Sylva, 1969).
7) the incidence and lethality of various fish diseases may
increase with temperature (Fryer and Pilcher 1974, Plumb
1973, Ordal and Pacha 1963),
8) reproductive success of yellow perch and possibly
other species may be reduced by exposure of mature adults
to overwintering temperatures exceeding those found in
nature (Brungs 1971, Hubbs and Strawn 1957, unpublished
data, National Water Quality Laboratory, Duluth, Minn.).
9) reproduction times may be altered significantly (Adair
and Demont 1970, DeVlaming 1972),
10) demersal eggs spawned in areas with even small temperature
increases (including those areas impacted by winter sinking
plumes) may die (Powles 1974) or will have accelerated
embryonic development and hatch early (Colby and Brooke
1973, Brooke unpublished MS, Berlin eta!0 unpublished MS);
the fry may be out of phase with their planktonic food
supply and a larger than normal percentage may be lost
to starvation,
11) during the winter months, fish residing in heated ef-
fluentsmay lose weight because their metabolism will be
high and their food supply may be low (Kelso 1972, Brett
253
-------
et al.1969, Marcy 1967),
12) migratory fishes may spend a great deal of time at
various thermal discharges thereby altering migration
patterns or schedules and substantially increasing their
exposure to abnormal temperatures (Spigarelli and Thommes
1973).
Program for Measurement of Effects
Introduction and Research Priorities
The research program is divided into five major subsections:
Before and After Studies, Intensive Plume Studies, On-site
Bioassays, Laboratory Studies, and Lakewide Assessment Studies.
The research activities described in these sections are complemen-
tary and are intended (collectively) to provide the basis for
measuring a portion of the effects of power plant discharges on
the fish of Lake Michigan. (A complete description of the effects
of power plant operation on Lake Michigan fish and the assessment
of the biological significance of these effects requires that data
also be obtained on intake damage to fish and on intake and discharge
damage to the organisms that serve as food for these fish.)
In each of the five sections we present a list of questions
that we believe should be answered for each cooling water use
site. It may be possible to answer some of these questions
adequately with information that already exists in the literature
(for example, published information on the low temperature
tolerance of yellow perch suggests that the species would not be
254
-------
susceptible to cold shock death at Lake Michigan power plants)
or from information collected at nearby sites. Questions that
cannot be-adequately answered with existing information define
the research needs for that site. These questions are grouped
and assigned numerical priority rankings to reflect a logical
order for programming research efforts. Some reordering may be
necessary when these guidelines are put into practice at a par-
ticular site because these priorities must be to some extent site
specific.
Definitions of numerical rankings are as follows:
Priorities
1 - Highest priority consistent with achieving the primary
LMCWSP goal of determining the effect of cooling water
use on the Lake Michigan ecosystem.
2 - High priority item directly supporting priority 1 items.
3 - Intermediate priority item generally supporting priority
2 items.
Categories
1 - Questions which are answerable with currently available
data; additional research is not needed.
2 - Questions which may be answerable with data currently
available.
3 - Questions which are not answerable with currently avail-
able data; additional research is needed.
255
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Qualifying Statement on Program Orientation
This section of the report provides specific methodologies
for use as guidelines in the demonstration of the possible adverse
effects of once-through cooling on the fish populations of
Lake Michigan. Because of the specific nature of these recommen-
dations, it is appropriate to preface them with some qualifying
remarks.
Answers to many of the questions posed in the following
sections of this subcommittee report can be best obtained through
the use of conventional time-tested sampling gear and methods
that are of universal acceptance among professionals and resource
agencies with long histories of experience with the Lake Michigan
fishery. Adoption by the electric power generating industry of
these methods and types of sampling gear recommended in the guidelines
will provide continuity of record and permit direct comparison of
fishery data with data collected over the past several decades by
fishery resource agencies.
Despite the need for standardization of gears and methodologies,
differences among sites and differences in the design, capacity,
and operating characteristics of the power generating plants on the
Lake, may make it impossible to carry out identical fishery sampling
procedures at all sites. Studies initiated before these guidelines
were developed may not conform to these guidelines, but data
from these studies may prove to be adequate for the evaluation
of certain local effects at the study site. It is also
256
-------
clear that methodologies needed to answer some of the questions
posed in the following text (see for example the section dealing
with Intensive Plume Studies) have not been developed and consid-
erable latitude in approach toward answering these questions is
desirable and necessary. Deviations from prescribed procedures
and criteria of performance, however, should not be made without
clear justification, nor should they be made in a manner that
prevents acquisition of data directly comparable and equivalent
to data that would be obtainable following the methodologies set
forth herein.
The level of field sampling effort required to reliably
describe fish stocks will vary greatly among species and life
stages of each species, and it is virtually impossible to specify
the level of effort required at a given site without knowledge of
the kinds and numbers of fish found on the site and the uses they
make of the site. Generally, the level of field sampling effort
expended to answer the questions posed in the methods section of
this report should at least be high enough to permit detection of
true minimum differences of 20 percent at the 5 percent probability
level. The amount of field sampling effort specified herein may
require adjustment to achieve this degree of sampling precision.
257
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Methods of Investigation
Before and after studies
This section describes methodology to determine the size
and composition of the fish stocks at the study site before plant
operations begin and following the onset of plant operation,
and to determine the uses fish make of the site and the extent to
which these uses are altered by plant operation. The recommended
period of study is at least three years prior to, and three years
subsequent to full plant operation. The sampling grid (Figure VII - 3)
is scaled for use at a site occupied by a plant with a cooling water
use rate of 3,000 - 4,000 cfs and a temperature rise across the
condenser of approximately 11C.
A rescaling of this grid and a change in the effort would be
necessary at sites where the amount of cooling water used or the
amount of waste heat rejected was markedly different.
Questions to be Answered
1. What kinds and numbers of fish are found in the vicinity
of the plant site and how does this change diurnally, seasonally,
annually, and as a result of plant operation? (Priority 1, Category 2)
a. what is the age, size, and sex composition of these
populations and how does it change diurnally, seasonally,
annually, and as a result of plant operation? (Priority 2,
Category 2)
b. what use is made of the site as a spawning, nursery,
feeding or over-wintering ground or as a migration route
258
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(36.4m)
ro
(Jl
Depth Contour
Discharge on Centerline
Figure VII - 3. Suggested sampling stations for fisheries investigations
of Lake Michigan.
-------
by fish, and does this change as a result of plant
operation? (Priority 1, Category 2)
q. what are the age-specific food habits of each species
in the vicinity of the site and how do they change
seasonally and annually, and do these change as a result
of plant operation? (Priority 2, Category 2)
Materials and Methods
Trawl sampling of juvenile and adult fish
a. Sampling Location - All stations shown in Figure VII - 3.
b. Gear
1) Sixteen-foot semiballoon bottom trawl for stations
0-10 feet; 16-ft headrope, 19-ft footrope (actual
spread approximately 12 ft), net made of nylon
netting of the following size mesh and thread;
1-1/2" stretched measure No. 9 thread body, 1-1/4"
stretched measure No. 15 thread cod end, 1/2" stretched
measure No. 63 thread knotless nylon inner!iner, head
and foot ropes of 3/8" diameter Poly-dac net rope
with legs extended 3 ft and wire rope thimbles spliced
in at each end with shackles attached to fasten net
onto doors. Six 1-1/2" x 2-1/2" Ark floats spaced
evenly on center of headrope. 1/8" galvanized chain
hung loop style on footrope. Net treated in green
copper net preservative. Trawl is available from
Marinovich Trawl Co., Inc., 1317 East First Street,
260
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Biloxi, Miss. 39533*.
2) Thirty-nine foot bottom trawl for all other stations
in Figure VII - 3: 3/4 size Yankee standard No. 35.
Headropes, 39 ft; sweep, 51 ft; wings and squares,
3-1/2 inch stretched, 21 thread nylon; belly, 2-1/2
inch stretched, 21 thread nylon; cod end 1/2 inch
stretched nylon seine netting, 12 ft in length.
Trawls are available from Gloucester Grocery and Boat
Supply Co., Inc., 17-21 Rogers Street, Gloucester,
Mass. 01930*. ;.
c. Sampling frequency
1) Collect at all stations monthly.
2) Make duplicate 10-minute trawl tows on the bottom
parallel to the bottom contour at each station. Make
all tows for each depth on the same day.
3) Record vertical temperature profile with a bathythermograph
and record other pertinent physical data at the time of
each trawl haul.
d. Sample processing
1) Separate catch into groups by species and when possible
into subgroups by age (young-of-the-year, yearlings,
and over-yearlings) on the basis of size.
2) Count all fish in each subgroup and obtain a total y
weight for the subgroups; exception: when the catch of
any subgroup is too large to make enumeration
practical, obtain a total weight of the subgroup,
*This does not constitute an endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
261
-------
withdraw a subsample and obtain a total weight and
count, so as to permit determination of total number
of Individuals in the subgroup by simple proportion.
3) Process the catch made during each visit to each
station as needed to reliably determine the length,
weight, sex, state of sexual maturity and age of
individuals in each subgroup.
a) Length - Record total length (distance from tip
of snout to tip of caudal fin with lobes compressed)
in mm (inches) to nearest whole mm (0.1 inch).
b) Weight - Record fresh (wet) weight in grams
(ounces) to the nearest gram (0.1 ounce).
c) Sex and state of sexual maturity.
d) Age determination - The age of the younger sub-
groups can often be estimated from the length
frequency distribution for the species. Scale
samples provide a reliable method for determining the
age of most fish.
Remove 10-20 scales from the left side of a
representative number of fish in each subgroup
below the origin of the dorsal fin and midway
between the insertion of the fin and the lateral
line. Although this should be the best location
for obtaining scale samples for age and growth
studies, it is recommended that this be
verified for the species and stocks being sampled
262
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in each geographic area, before large numbers of
the scale samples are collected.
Place the scales from each fish in an indi-
vidual envelope and record on the envelope the
species sampled, the location, date, method of
capture, and the individual length, weight, sex,
and state of sexual maturity.
A plastic impression of the scale can be made
in the laboratory to facilitate age determination
(Smith, 1954). A roller for producing plastic
impressions is available from Wildlife Supply Co.,
301 Cass Street, Saginaw, Mich. 48602*.
Pack calculation of body length in earlier
years of life can be accomplished using the scales
(Hile 1941, Tesch 1968).
4) Routine observations
a) Record any occurrence of disease or infestation
by parasites.
b) Examine all trout and salmon (and other fishes
for which tag and release studies are being con-
ducted) for fin clips, tags, or other marks, and
record mark, size and conditions of each marked
fish.
5) Preserve samples for laboratory analysis as needed,
after gathering the data prescribed in previous
rThis does not constitute an endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
263
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sections.
a) Feeding habits
Kill fish selected for analysis and preserve
stomach contents immediately in 10 percent
formalin. Small fish can be preserved whole in
formalin. These fish should have the body cavity
punctured or slit or injected with formalin to
facilitate preservation (retard digestion) of
their stomach contents. For specimens too large
to preserve and store conveniently, record length and
weight and assign a code number. Remove the stomach
and preserve it in 10 percent formalin after labeling
with the code number.
Examine stomach samples, and record the frequency
of occurrence and the total volume of each kind of
organisms eaten, following the methods of Windell
(1968), or Wells and Beeton (1963).
b) Determination of contaminant level
Kill fish selected for analysis and preserve by
freezi ng.
Perform analyses for PCBs , pesticides, heavy
metals, etc., as needed, according to methods
described in Section IV of this report.
c) Fecundity estimates
Small fish can be preserved whole in 10 percent
formalin and the ovaries can be removed and ex-
amined in the laboratory. Large fish should be
264
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weighed, measured, and given a code number. The
ovaries can then be removed, weighed fresh, and
preserved in 10 percent formalin or in Gilson's
fluid (Bagenal and Braum, 1968).
Determine fecundity according to methods
given in Bagenal and Braum, 1968.
The use of fecundity data (in conjunction with
information on the total number of eggs spawned
and the size and sex composition of a population
may be used to estimate fish stock abundance
(Saville 1964) .
Sample analysis
1) Population size estimate
a) The catch statistics from trawl samples (together
with those from gi 11 net, seine , plankton net, and
pumped samples — see later sections) can be applied
toward an estimate of total population based on
estimates of catch per unit effort. Some methods
of estimating population from catch statistics
are given by Ricker (1958), Chapman (1961),
Saville (1964), Robson and Regier (1968), Beverton
and Holt (1957) and Gulland (1969).
b) Other analyses concerning biological interrelations
will be outlined in later sections.
2) Use data collected from trawling (and from gill netting,
plankton netting, seining, pumping, and tagging — see
later sections) to determine the importance of the study
265
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area as a spawning and nursery ground, and to determine
the seasonal size distributions of the resident fish
populations and some of the interrelations of these
populations.
2. Gill net sampling of juvenile and adult fish
a. Sampling location
1) Bottom gill net sets at all stations 15 ft and deeper
as shown in Figure VII - 3.
2) Oblique sets along center line of Figure VII - 3 at
30' , 60' , and 120'.
b. Gear
1) Standard bottom gill net gangs each including 50 linear
feet of 1-1/2-, and 100 linear feet each of 1-1/2-,
2-, 2-1/2-, 3-, 3-1/2-, 4-, 4-1/2-, 5-, 5-1/2-, and
6-inch mesh. Each mesh size is a separate net and all of
the nets are joined end-to-end, with nets of different
mesh sizes interspersed randomly.
2) Two oblique gill nets. One gang with 1-1/2 inch mesh
and one gang with 4-1/2 inch mesh. Lengths will depend
upon the water depth where fished.
3) Specifications
a) Net specifications are those proposed for
standard bottom gill nets by the Great Lakes Fishery
Commission and currently used by the Michigan
Department of Natural Resources. The net is
6 ft deep (float line to lead line). Table
VII - 2 contains specification for each mesh size.
266
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Table VII - 2. Gill net specifications for various mesh sizes
Stretched mesh
size (inches)
1-1/2
2
2-1/2
3
3-1/2
4
4-1/2
5
5-1/2
6
Net length
(feet)
50
100
100
100
100
100
100
100
100
100
Twine Size
110/3
110/3
210/2
210/2
210/2
210/3
210/3
210/3
210/3
104 thread
No. of meshes
deep
55
41
33
27
23
20
18
16
15
nylon 13
267
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b) All thread to be used in making this gill netting
shall be nylon of American manufacture. Thread must
withstand scalding process without injury. Stretched
measure is in inches when wet, as measured with an
8-ounce sliding weight gauge. Measurement is to
be made after webbing has been soaked in water for
one-half hour or longer. Webbing is to be pre-
shrunk and heat set, and knots must hold without
slipping. Measurement shall be made of at least
10 different meshes chosen at random, but well away
from the selvage for each piece of netting. Mesh
sizes shall not vary over 1/32 of an inch. All
netting must be double selvage top and bottom.
The netting is hung on No. 6 Starlite braided
nylon maitre (or equivalent) with No. 9 t-spun
nylon seaming twine (or equivalent). The nets are
hung on the one-half basis, i.e., 200 feet of
netting are hung on each 100 feet of unstretched
maitre. Use regular aluminumgill net floats, and
space 7-1/2 feet apart. Attach a 1/3 pound lead
directly under each float.
All specifications refer to the nets after
they are constructed. When the nets are being
hung, the maitre should be under a tension of
about 100 pounds; allowance therefore needs to be
made for the stretch of the maitre so that when
the tension is released 200 feet of netting will
be on 100 feet of maitre, and the floats will be
268
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spaced properly.
c. Sampling frequency
1) Collect at all stations monthly.
2) Make three replicate sets at each depth (overnight
sets) on successive days.
3) Measure water temperature and other pertinent
physical factors at the time of each net set.
d. Sample processing
1) Separate catch by species and mesh size and
whenever possible by age (young-of-the-year,
yearlings, and older); for oblique sets separate
catch by depth also.
2) Determine age composition, length, weight, state of
sexual maturity and fecundity, and stomach contents
of each subgroup or an adequate subsample of each
age group.
If necessary preserve subsamples in 10 percent
formalin for processing at a later date.
3) See previous section on sample preservation.
e. Sample analysis - See previous section on sample analysis
3. Seine sampling for juvenile and adult fish
a. Sampling locations - All shoreline stations shown in
Figure VII - 3.
b. Gear
1) Gear should include a nylon bag seine, 1/2 inch
269
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square mesh, TOO feet long and 8 feet deep with an
8' x 8' x 8' bag of 1/4 inch mesh in the center.
Seine should be constructed of strong (50 - 80 Ib.
test) mesh. The bottom line should be weighted to
hold the net on the bottom while the net is being
pulled; floats should be numerous enough to prevent
sections of the top line from submerging. A lead
line of 30 strands of "Regal Rope" around a polypro-
pylene core will conform to most bottom types. One
supplier of such nets is: The Nylon Net Company,
P.O. Box 592, Memphis, Tenn. 38101*.
2) Larger seines (12' x 1000') should be used where the
capture of large salmonids is probable.
c. Sampling frequency
1) Collect at all stations monthly.
2) Make triplicate seine hauls across contours at each
station on the same day.
3) Estimate wave heights and measure water temperature,
turbidity, and other pertinent factors at the time
of each seine haul.
4) Sample processing - See previous sections.
5) Sample analysis - See previous sections.
*This does not constitute endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
270
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4. Plankton net sampling for fish fry
a. Sampling locations
All stations on the 15 foot depth contour should be
sampled as shown in Figure VII - 3, plus one station at
the intersection of the centerline and each of the follow-
ing depth contours: 15, 30, 45, 60, 75, 90, 105, and
120 feet.
Sample the 0 (surface), 1-, 2-, 4-, 6-, 8-, and
10-meter depth levels within the water column at each of
the above stations, as water depth permits.
b. Gear
Gear should include a one-half meter nylon plankton net,
351 micron Nitex with 1/2-m ring diameter, 'nylon covered
stainless steel bridle, and PVC bucket 5" in diameter
and 8" long with 351 micron stainless steel bolting cloth
window. Length of the net is 2.5 meters. One source of
nets of these specifications is: Wildlife Supply Company,
2200 South Hamilton Street, Saginaw, Michigan 48602. The
approximate cost is $130.00*.
c. Sampling frequency
1) Sample all stations weekly from May through September.
2) Make duplicate 5-minute tows at each depth at each
station on the same day.
3) Measure water temperature and other pertinent physical
factors at the time of each plankton net tow.
*This does not constitute endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
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d. Sample processing
1) Rinse organisms adhering to inside surface of net
body into bucket and preserve them in 10 percent
formal in.
2) Sort by species and developmental stage (prolarvae,
larvae, post larvae, or juvenile).
3) For each developmental stage: enumerate, measure
an adequate sample of individuals (total length in
mm), and obtain a total dry weight.
e. Sample analysis - See previous section.
5. Pump sampling of fish eggs
a. Sampling locations
All stations shallower than 75 feet shown in
Figure VII - 3.
b. Gear
Centrifugal lift pump passing bottom water through #30
screen with a flow meter to record volume of water
samples.
Specifications - None available at this time.
c. Sampling frequency
1) Make duplicate 5-minute pumpings on the bottom
along the depth contour at each station.
All stations must be sampled on the same day.
2) Sample weekly, May 1 - August 1 and again on
December 15 and March 1.
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3) Measure water temperature and other pertinent
physical factors at the time of each pumping.
d. Sample processing
1) Sort eggs into major size (species) groups separating
live (translucent) eggs from those that are dead
(opaque, fungused, etc.) and record the number in each
subgroup.
2) Measure the diameters of an adequate sample in each
subgroup of live eggs.
3) Record the developmental stage of live eggs in each
subgroup, if possible.
e. Sample analysis - see previous sections.
6. Tagging or Marking of Fish
Fish captured at the site can be tagged (or marked) to pro-
vide information on the local movements and lakewide migra-
tion patterns. Although some species, including the Pacific
salmons, are known to range widely throughout the lake, the
extent to which many important native species undertake local
and lakewide movements is poorly known. Knowledge of whether
the fish found at a cooling water use site are permanent
residents of the site or simply migrants passing through the
area is important in evaluating the impact of the plant on
the fish populations of the lake.
a. Sampling location
Capture, tag and release fish at any of the stations
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shown in Figure VII - 3, but concentrate on those
stations shallower than 75 feet.
b. Gear
1) Tags and marks.
a) Fin clipping may be suitable for short term
population size data on fish other than trout
and salmon (these salmonids are already being fin
clipped for various studies by state agencies;
further clipping would cause confusion).
b) Anchor spaghetti tags (FLOY tags*) or other
commercially available tag where recognition of
individual fish is necessary (i.e., growth and
movement studies), or where fin clipping is
not recommended (Rounsefell and Kash, 1946).
c) Dyes or pigments
Specifications:
Imbed biologically inert fluorescent pigment in
fish scales or integument with compressed air.
This method permits simultaneous marking of large
numbers of fish with a minimum of fish handling;
the method may be suitable for fish that are
sensitive to handling or are too small for tags
or fin clips. Pigments persist for over one year
and fluoresce under black (ultraviolet) light.
Pigments and spraying apparatus are available from:
:This does not constitute an endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
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Wildlife Supply Co.*, and Day-Glo Color Corporation,
4732 St. Clair Avenue, Cleveland, Ohio 44103*.
See Arnold (1966) and Jessop (1973).
d) Hot or cold branding - See Moav et al. (1960) and
Raleight et al. (1973).
e) Radio or ultrasonic transmitters - See studies of
residence time in thermal plumes discussed on
Page 280 (Intensive Plume Studies).
2) Capture and recapture equipment - Fish may be taken
by any means that does not reduce their viability.
a) Seine - 30 ft seine (61 deep) with knotless mesh
(1/2" or less) to reduce abrasion to capture fish.
One source of such nets is the Nylon Net Co.,
P.O. Box 592, Memphis, Tenn. 38101*.
b) Trap or fyke net - Nylon net with 8' diameter
mouth with 2 funnel-shaped throats on 2nd and 4th
hoop. Wings 50' long. Whole net tarred. Mesh
size 1". Such nets are available from Nylon Net
Co., P.O. Box 592, Memphis, Tenn. 38101*. The
approximate cost is $100.
c) Electrofishing - We can make no specific recommen-
dations at this time.
d) Hook and line - As appropriate.
c. Sampling frequency
1) Tag and release fish as frequently as is needed to
permit adequate description of the movements of fish
using the site. Record data and location of release
* This does not constitute an endorsement by the Lake Michigan
Cooling Water Studies Panel or the authors.
275
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and if possible length and weight of each fish.
2) Recapture as part of general survey.
d. Sampling processing
1) Record any marked fish taken, the date and location
of capture, and their lengths, and weights if possible,
2) Minimize handling; anaesthetize fish if necessary to
prevent injury to fish during handling.
3) Release fish at capture site unless site-specific
requirements indicate displacement studies of marked
fish are also desirable.
e. Sample analysis
Data on time and location of recapture should give
indications of patterns and rates of movement or migration
and thus help determine whether populations found at each
site are local or transient. Further information on
analytical procedures is found in Spigarelli and
Thommes (1973).
Intensive Plume Studies
These studies are designed to describe the fish community in
the discharge plume and the area immediately surrounding the plume
and will determine the behavioral and pathological responses of
fish to the physical, chemical, and biological environments that
exist in the plume.
276
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It is difficult to present a detailed sampling plan that per-
mits a reliable characterization of the fish populations of heated
plumes, because adequate physical plume measurements (including
data on sinking plumes) are not available for most of the plants
now operating (or under construction) on Lake Michigan; further-
more, fish populations in and around these plumes have received
little study until relatively recently. In general, the sampling
gear and methodologies described elsewhere in this report can be
successfully adapted to local conditions for use in sampling the
plume populations; new approaches such as electronic plume mapping
and fish locating and radio tracking may also be needed.
Questions to be answered
1. What kinds and numbers of fish are residing in the dis-
charge plume; and what are the diurnal, seasonal, and
annual patterns and trends? (Priority 1, Category 3)
a. What is the age, size, and sex composition of each
species composing the resident population and what
are the diurnal and seasonal trends? (Priority 2,
Category 2)
b. What are the residence times within specific iso-
therms in the plume, of these fish (i.e., to what
temperatures are these fish acclimated) and what are
the diurnal, seasonal, and annual trends? (Priority 1,
Category 3)
c. What percentage of the fish residing in the plume
during the colder months of the year are killed or
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made susceptible to predation when plume temperatures
rapidly decrease to receiving water temperatures, be-
cause of plant shutdown? (Priority 2, Category 3)
d. What percentage of fish killed by cold shock float
on the surface where they are visible? (Priority 1,
Category 3)
e. What percentage of the fish residing in a discharge
plume are killed, incapacitated, or driven out of the
plume during chlorination? (Priority 2, Category 3)
f. What percentage of the fish resident in the plume
during the colder months of the year develop gas
bubble disease symptoms and are killed, made suscep-
tible to predators, or driven out of the plume?
(Priority 2, Category 3)
g. What percentage of the fish driven out of the plume
during the colder months of the year suffer cold
shock and death or are made more susceptible to
predators residing outside the plume? (Priority 2,
Category 3)
h. What percentage of the fish residing in the plume
during the warmer months of the year, are killed
or are shocked and made susceptible to predation
when plume temperatures drop suddenly because of
an upwelling that reduces intake water temperatures?
(Priority 2, Category 3)
i. Do fish residing in a discharge plume accumulate a
significantly higher level of contaminants such as
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mercury, PCBs, pesticides, etc., than fish in adja-
cent unheated lake water? (Priority 2, Category 3)
j. Does the discharge of waste heat into Lake Michigan
lower the reproductive success of the lake's desirable
species of fish, and/or increase the reproductive
success of less desirable species of fish? (Priority 1,
Category 3)
k. Are any of those species with low temperature or
"winter chill" requirements (as determined by lab-
oratory studies) found in heated plumes, and is their
timing and duration of residence in the plume ade-
quate to cause a reduction of reproductive success?
(Priority 2, Category 3)
1. What kinds and numbers of fish spawn in areas im-
pacted by the heated discharge? (Priority 2, Category 3)
m. What is the reproductive success of these fish and
does it compare favorably with the success of members
of the same stock that spawned outside the heated
discharge, or that spawned in the area before the
plant was constructed and waste heat was released?
(Priority 2, Category 3)
n. What kinds and numbers of fish are prevented from
spawning in their "ancestral" spawning areas by the
heated discharge? (Priority 2, Category 3)
o. Will those fish that are prevented from spawning on
an "ancestral" spawning ground (by the discharge of
i
waste heat) be able to locate other suitable spawning '
279
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grounds, or will their reproductive contribution be
lost because they spawn in areas where the survival of
eggs and fry will be low? (Priority 2, Category 3)
p. Will the addition of heat to spawning grounds
accelerate embryonic development and cause premature
hatching? (Priority 2, Category 1)
q. Will fry that hatch prematurely and out of phase
with their normal food supply be able to find
sufficient food to permit good growth and survival?
(Priority 2, Category 3)
2. What effect does cooling water use have on the availability
of suitable food and feeding conditions for Lake Michigan
fishes? (Priority 2, Category 3)
a. Do fish inhabiting heated plumes in winter lose sig-
nificant amounts of weight due to the unavailability
of food? (Priority 2, Category 3)
3. Do heated effluents or intake flows serve as barriers to
fish movements? (Priority 3, Category 3)
4. Does the discharge plume affect the numbers and types of
fish trapped at the intake? (Priority 2, Category 2)
5. How does winter deicing by recirculation of heated
effluent influence patterns of residence or entrapment
of fishes at the intake? (Priority 2, Category 2)
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Materials and Methods
Conduct simultaneous plume mapping and echolocation of
fish in the plume and in the unheated water surrounding
the plume to determine the abundance of fish within spe-
cific isotherms. The methodology for a study of this
type is currently under development at the Point Beach
nuclear plant site by Argonne National Laboratory
(Spigarelli, et al.,1973a; Romberg and Spigarelli, 1972)
a. Sampling location
The heated plume and surrounding unheated lake waters;
sampling stations will not be geographically fixed
because plumes change shape, size, and location in
response to wind and lake currents and level of plant
operation.
b. Sampling gear
Data are collected continuously by electronic means
with shipboard equipment.
c. Sampling frequency
1) Conduct one or more complete plume mapping and
fish echolocation surveys each month for at least
one year until the seasonal patterns of distri-
bution and abundance of the major fish species
relative to stable plume isotherms are reliably
established.
2) Conduct additional surveys as needed to deter-
mine the effect of upwellings, plant shutdowns
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and chlorination on the distribution and movements
of the fish populations of heated plumes and
adjacent waters.
d. Sample processing
See Spigarelli, et al. (1973a) and Romberg and
Spigarelli (1972).
2. Conduct intensive fish sampling with nets (in conjunction
with plume mapping and fish echolocation studies) to
determine the size, density, composition, and condition
of the fish populations in heated discharges.
a. Sampling location
Collect samples in the heated effluent and in the
surrounding waters where temperatures are not
elevated; whenever possible collect samples within
discrete isotherms.
b. Sampling gear
Bottom trawls, gill nets (anchored and drifted),
seines, lift and dip nets may be employed as the
situation demands.
c. Sampling frequency - see previous sections
d. Sampling processing
1) Sort catch into subgroups by net mesh size,
species, and life stage or age group (young-of
the-year, yearling, and over-yearling) and obtain
and record a total weight for each subgroup.
Count and record all individuals in each subgroup
when number is small, otherwise count and weigh
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and record data for a representative sample of
the subgroup to permit later expansion of the
data by simple proportion.
2) Collect the following according to procedures
outlined in Materials and Methods Section of
Before and After Studies (Page 260).
a) Scale samples (to permit estimates of age
composition and growth in length and weight;
includes length-weight-sex data).
b) Stomach contents (to establish food habits
and general level of feeding).
c) Whole fish (for analyses of concentrations
of pollutants such as DDT, PCBs, heavy
metals, etc.); uptake and concentration of
some pollutants is higher at elevated
temperatures and fish in heated plumes may
be accumulating these materials more rapidly
than those in unheated lake water.
3) Examine fish and record:
a) Any brands, tags, fin clips or other
identifying marks
b) Incidence of infectious diseases or parasites
c) Symptoms of gas bubble disease.
3. Conduct studies to determine residence time of individual
fish in the plume, and temperatures to which these fish
are acclimated under stable plume conditions.
2.83
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Residence time data for individual fish will permit
estimation of the turnover rate of the populations in
the plume. Data on residence time and acclimation tempera-
ture will also permit more precise judgments concerning
temperature dependent effects of cooling water use. For
example, when the acclimation temperature of the plume
population is known, data from laboratory temperature
tolerance studies can be used to predict whether an
interruption of the discharge of a heated effluent would
cause low temperature mortality among the plume residents.
It will also be possible to estimate the degree of repro-
ductive impairment occurring among populations of yellow
perch that overwinter in heated plumes (due" to their
winter chill requirements not being fully met), when
both the population turnover time and acclimation temper-
ature are known.
No single method is entirely suitable for determining
residence time and acclimation temperatures of fish
inhabiting the heated discharge plume and several
complementary methods may have to be applied.
Deep body temperature measurements (Spigarelli et al.,
1973b) made on fish immediately after capture and
removal from the water give some idea of the temperatures
experienced immediately prior to capture. Deep body
284
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temperatures can be measured by inserting the tempera-
ture sensing probe of an electronic thermometer into the
rectum or muscle tissue of the fish; if the former method
of insertion is used, the fish can also be tagged or
marked and released. Body temperature measurements
have been made at the Point Beach nuclear plant by the
Argonne National Laboratory (Spigarelli et al., 1973b).
Marking fish by branding, removal of fins, spraying with
fluorescent pigment or the application of an external
tag may yield information on length of plume residence
and migration tendencies (See discussion of tags and
marks on page 273).
Thermoluminescent dosimeter tags (Romberg et al., 1972)
appear to have promise for use as short-term integrating
temperature recorders; they can also trace long-term
movements of the tagged fish.
Temperature sensitive transmitters implanted in fish and
monitored by radio-tracking systems offer perhaps the
greatest potential for obtaining precise, detailed thermal
histories of individual fish. Data can be collected
continuously to determine residence times of individual
fish within specific isotherms. A system using shore
based receivers and capable of tracking several fish
285
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simultaneously is under development by University of Wisconsin
researchers for use at the Point Beach nuclear plant.
4. Conduct studies to determine behavioral responses of fish
populations to upwellings of water from the hypolimnion,
plume shifts, and chlorination.
All of these events can result in sudden exposure of the
plume fish population to temperatures considerably lower
than those to which they are acclimated. During upwelling,
the temperature of the water entering the plant cooling
system intake may drop as much as IOC (18F) in a few
hours, causing the discharge temperature and the inshore
water temperature to fall by a similar amount. Plume
shifts in response to wind and lake current changes occur
relatively frequently and may cause portions of the plume
population to drift away from the discharge in isolated
"lenses" of heated water that can be observed when plume
shifts occur.
Although very low concentrations of chlorine are lethal
to some fish (trout and salmon and possibly others),
studies have shown that fish may be able to detect and
avoid even sublethal concentrations. As a consequence,
chlorination of cooling waters, especially during the
colder months of the year, may force fish residing in
the plume to leave the heated plume waters, thereby
286
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risking cold shock and low temperature death; those that
remain in the plume may receive lethal exposures to chlor-
ine.
No single method is entirely suitable for documenting
behavioral responses of plume fish populations to sudden
changes in water temperature or to chlorination (which
may result in the population moving out of the heated
plume to areas with lower temperature). A combination
of the methods detailed in the section on plume mapping
and fish location and those which propose to determine
plume residence time and acclimation temperatures will
be adequate to the task (see also Kelso, 1974).
On-site Bioassays
These studies are required to produce data of a site specific
nature. For example, chlorine toxicity may vary widely with water
quality, which in turn may vary widely among sites. Therefore,
chlorine toxicity studies should be conducted at each cooling water
site where chlorination is practiced.
Questions to be Answered
1. What are the acute and chronic effects of intermittent
chlorination on fish in the thermal discharge area and
how do these effects vary with species, life stage,
water temperature and other seasonal changes in lake
water quality? (Priority 2, Category 2)
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2. What are the acute and chronic effects on fish in the
thermal discharge area of cold shock caused by plant
shutdown? (Priority 2, Category 2)
3. Is there a higher incidence and virulence of infectious
of contagious diseases among fish in the plume than
among fish in unheated areas of the lake? (Priority 2,
Category 3)
4. Do fish in the plume exhibit symptoms of gas bubble
disease and if so, what are the consequences to the fish
that are displaying those symptoms? (Priority 2, Catego-
ry 3)
Materials and Methods
1. Effects of intermittent chlorination on caged fish held
in the thermal discharge. Recommended procedure: see
Basch and Truchan (1971).
2. Acute and chronic effects of continuous and intermittent
chlorination and temperature on fishes found in power
plant thermal plumes. Recommended procedure: Arthur
and Eaton (1971).
3. Effects of plant shutdown on caged fish held in the
thermal discharge. Recommended procedure: see Basch
and Truchan (1971) for details on cage construction and
installation; see Brett (1952) and Fry, Hart, and Walker
(1946) for details on conducting thermal bioassays and
interpreting results under conditions of constant and
changing temperature.
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4. Effects of plume residence on incidence of gas bubble
disease. Recommended procedure: No specific procedure
has been developed that appears totally satisfactory for
direct application to all Lake Michigan situations; but
see Bouck etal. (1970), and Ebel (1969) who provide
background information on GBD; DeMont and Miller (1971)
who report the first incidence of GBD among fish in a
thermal plume and Otto (1973) who provides information on
the tolerance of Lake Michigan fishes to GBD.
5. The rate and severity of infection of contagious diseases
among caged fish in a thermal plume. Recommended pro-
cedure: None developed at this time but see Plumb
(1973).
Laboratory Studies
Laboratory studies produce information on the physiological
and ecological requirements and tolerances of organisms, that can
be used for independent interpretation and verification of field
observations and field bioassay studies. It is our intent that
these laboratory studies be broad in scope and applicability of
results so that the necessity for repetition as part of the demon-
stration of effect at each plant is precluded.
Questions to be Answered
1. What are the preferred and avoidance temperatures of
Lake Michigan fishes? (Priority 2, Category 2)
2. How are fish fry and eggs affected by the shear forces
289
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generated by turbulent cooling water? (Priority 3,
Category 3)
3. What are the temperature tolerances of the egg, larvae,
juvenile, and adult life stages of the fishes of the
lake? (Priority 1, Category 2)
4. What are the effects of sublethal exposure to elevated
temperatures and rapid temperature drops on fish repro-
duction and predator avoidance? (Priority 2, Category 2)
5. What are the effects of temperature on the feeding
requirements and on the growth and conversion efficiency
of fishes? (Priority 3, Category 2)
6. What are the swimming capabilities of larval and juvenile
Lake Michigan fishes relative to power plant intake current
velocities? (Priority 2, Category 2)
7. What are the effects of temperature on the uptake of
pesticides and other contaminants by fish residing in the
plume? (Priority 3, Category 2)
Materials and Methods
1. Preferred and avoidance temperatures of Lake Michigan
fishes. Recommended procedure: See McCauley and Tait
(1970), and Meldrim and Gift (1971).
2. Studies of the deformation and disruption of fish fry and
fish eggs in turbulent, shear-flow conditions. Recommended
procedure: No procedure for experimentation has yet
been developed. The problem was discussed by Goodyear
290
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and Coutant (U.S. Atomic Energy Commission, 1973);
see also Cox and Maxon (1971), Csanady (1973), Coutant
and Kedl (1975), and Pommeranz (1974).
3. Temperature and tolerance of larval, juvenile, and
adult fish. Recommended procedure: Use method of Brett
(1952) for sudden continuous exposure to an elevated
constant temperature.
4. Effect of sublethal thermal shock on the ability of larval
and juvenile fishes to avoid predation. Recommended
procedure: See Yocom and Edsall (1974), Coutant
et al. (1974).
5. Swimming speeds of juvenile and larval inshore fishes of
Lake Michigan. Recommended procedures: Methods are
currently under development by T.G. Yocom at the Great
Lakes Fishery Laboratory, Ann Arbor, Michigan; see also
Houde (1969a).
6. Effects of temperature on food intake, conversion effi-
ciency, and growth of juvenile and adult Lake Michigan
fishes. Recommended procedure: See McCormick et al.
(1971 ), and Brett et al. (1969) .
7. Effects of temperature on maturation, spawning, fertili-
zation, and embryo survival of fishes. Recommended
procedure: See Hokanson et al . (1973), and Colby and
Brooke (1970). The National Water Quality Laboratory,
Duluth, Minnesota has also developed a procedure for
determining temperature requirements for the maturation
of the gonads and reproductive success of the yellow
291
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perch (MS in preparation) that should be suitable for
investigating these temperature requirements of other
Lake Michigan fishes.
8. Effects of elevated temperatures on the rate of uptake
and concentration of toxic materials directly from lake
water by fish. Recommended procedures: See Reinert
etal. (1974), Reinert (1970), Willford etal. (1973), and
MacLeod and Pessah (1973).
Lakewide Studies
Lakewide fish stock assessment is needed to determine the
distribution and abundance of fish in Lake Michigan and to obtain
the vital statistics including the age composition and age-specific
birth, death, and growth rates of the populations. These data, wheiy
treated according to currently accepted methods for the analysis
of fish population dynamics will permit an evaluation of the lake-
wide effect of cooling water use on the fish populations of Lake
Michigan.
Lakewide studies of the scale needed to evaluate the effects
of cooling water use on Lake Michigan fish will require careful
planning and execution if useable results are to be obtained.
Studies to assess the fish populations of the lake are already
underway by the various state and federal resource protection and
management agencies with proprietary interest in the lake. Any
additional studies designed to describe these populations for the
purpose of determining cooling water use effects should be closely
coordinated with these ongoing efforts.
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We have not attempted to present a review of the ongoing
fish population assessment activities on the lake, but reports of
these studies may be seen in the minutes of the annual Lake Michi-
gan Lake Committee Reports of the Great Lakes Fishery Commission.
Recently completed estimates of biomass for several Lake Michigan
fish populations are available in Fisheries Report No. 1813 of
the Michigan Department of Natural Resources (1974) and in Edsall
et al. (1974).
The sampling program presented in the "Materials and Methods"
Section that follows, if conducted independently of ongoing
assessment studies, is the minimum effort that would permit
adequate description of the areal and depth distribution and rela-
tive abundance of the populations of important fish in the lake
(Item 1 in the "Questions to be Answered" Section). Coordination
of the Lakewide Studies program with those of the various resource
agencies may permit a reduction in the effort required of the
Utilities as outlined in the Materials and Methods Section that
follows.
Questions to be Answered
1. What are the areal and depth distributions and relative
abundance of the various fish populations of the lake
throughout the year? (Priority 1, Category 2)
2. What is the absolute size (age specific numerical
abundance and biomass) of each of the populations of
fish in Lake Michigan? (Priority 1, Category 3)
3. What are the age specific rates of growth, reproduction,
mortality (including fishing mortality) and the food
habits for each population of Lake Michigan fish
293
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(Priority 2, Category 3)
4. What magnitude of age specific loss or damage caused
by cooling water use can each population sustain without
a significant decline in productivity and in the ability
of each of these populations to recover to former levels
of importance and abundance if the cause of loss or
damage from cooling water use is removed? (Priority 1,
Category 3)
Materials and Methods
Trawl sampling of juvenile and adult fish
a. Sampling location - Cross-contour sampling transects, at
least every 50 miles of lakeshore. Trawl hauls at 2.5,
5, 7.5, 10, 12.5, 15, 17.5, 20, 25, 30, 35, 40, 45, 50,
60, 70, and 80 fathoms across each transect (parallel to
the bottom contours).
b. Gear - See Materials and Methods in Before and After
Studies (Page 260).
c. Sampling frequency
1) Visit all stations in spring and in fall for at least
one year.
2) See additional notes on frequency in Materials and
Methods Section of Before and After Studies (Page 261).
d. Sample processing - See processing information in Materials
and Methods Section of Before and After Studies (Page 261).
e. Sample analysis - See Materials and Methods Section of
Before and After Studies (Page 265).
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2. Gill net sampling of juvenile and adult fish
a. Sampling location
Cross-contour sampling transects, every 50 miles of
shoreline.
1) Bottom gill net sets at 1, 5, 10, 15, 20, 30, 40,
50, 60, 70, and 80 fathoms across each transect
(nets set parallel to bottom contours).
2) Oblique gill nets set at 5, 15, and 30 fathoms across
each transect (parallel to bottom contours).
b. Gear - See gill net specifications in Materials and
Methods Section of Before and After Studies (Page 266).
c. Sampling frequency
1) Visit all stations in spring and in fall.
2) See discussion of frequency in Materials and
Methods Section of Before and After Studies (Page 269).
d. Sample processing - See processing in Materials and Methods
Section of Before and After Studies (Page 269).
e. Sample analysis - See analysis of samples (Page 265).
3. Seine sampling for juvenile and adult fish
a. Sampling location
Cross-contour sampling transects, every 50 miles
of lakeshore.
Seine hauls in beach zone water (0-10 ft).
b. Gear - See Materials and Methods of Before and After
Studies (Page 269 ).
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c. Sampling frequency
1) Visit all stations in spring and fall for at least
one year.
2) See sections on sampling frequency in Materials and
Methods of Before and After Studies (Page 270).
d. Sample processing - See discussion of processing in
Materials and Methods of Before and After Studies
(Page 261 ).
e. Sample analysis - See analysis of samples in Materials and
Methods of Before and After Studies (Page 265).
Plankton net hauls for fish fry assessment (see Wells. 1973).
a. Sampling locations
Cross-contour sampling transects, at least every 50 miles
of lakeshore.
Sampling stations at 15, 30, 45, 60, 75, 90, 105, and
120 feet.
Sample the 0 (surface), 1-, 2-, 4-, 6-, 8-, and 10-meter
depth levels within the water column at each of the above
stations, when water depth permits.
b. Gear - See Materials and Methods of Before and After
Studies (Page 271).
c. Sample frequency - See Materials and Methods of Before
and After Studies (Page 271). Sampling to continue for
at least one year.
d. Sample processing - See Materials and Methods of Before
and After Studies (Page 272).
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e. Sample analysis - See Materials and Methods of Before
and After Studies (Page 265).
5. Pump sampling of fish eggs
a. Sampling locations
Cross-contour sampling transects, at least every 50
miles of lakeshore.
Make triplicate 5-minute pumpings on the bottom along
the contour at each station at 0.5, 1, 1.5, 2.5, 3,
3.5, 4, 4.5, 5, 7.5, and 10 fathoms.
b. Gear - See Materials and Methods of Before and After
Studies (Page 272).
c. Sample frequency - See Materials and Methods of Before
and After Studies (Page 272). Sampling to continue for
at least one year.
d. Sample processing - Materials and Methods of Before and
After Studies (Page 273).
e. Sample analysis - Materials and Methods of Before and
After Studies (Page 265).
297
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301
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302
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305
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SECTION VIII
MEASUREMENT OF THE EFFECTS OF COOLING WATER USE
ON ENTRAPPED AND ENTRAINED ORGANISMS
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Section VIII MEASUREMENT OF THE EFFECTS OF COOLING WATER USE
LON ENTRAPPED AND ENTRAINED ORGANISMS
*i 1
Table of Contents
Introduction 310
Entrapped Organisms. 311
Introduction 311
Monitoring Program for Existing Water Intakes 312
Objectives . 31.2
Sampling Frequency 313
Sampling Methods 313
Sampling Data Required 313
Monitoring Program for New and Proposed Water Intakes 314
Objectives . 314
Methods of Investigation 314
Entrained Organisms 314
Introduction 314
Phytoplankton 316
Introduction 316
Objectives 317
Methods of Investigation k .... 317
Methods of Sampling 1 • 323
Sampling Interval I .... 324
Sampling Frequency 1 324
Sampling Site Selection '/.... 324
Special Problems 325
308
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Zooplankton and Entratnable Benthos. , . . . . . . ... . . . .325
Objectives . . . . . . .... . . . . . . . . .326
Methods of Sampling . . . . . . . . .326
Sampling Frequency and Interval 328
Ftsh . . . 328
Introduction. . 328
Objectives 328
Questions to be answered. 329
Methods of Investigation and Sampling 331
Plant Entrainment 331
Plume Entrainment 335
Priority Research 337
Literature Cited 341
309
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Section VIII, MEASUREMENT OF THE EFFECTS OF COOLING WATER USE ON
ENTRAPPED AND ENTRAINED ORGANISMS
Introduction
The possible ecological effects of entrapment and en-
trainment of Lake Michigan organisms in water intake systems are
of significant concern. Entrapment is defined here as the trap-
ping or confinement of organisms within an intake system, or im-
pingement of organisms on screening devices such that the organ-
isms are unable to return to their natural habitat. Organisms
with potential for becoming entrapped are of a size sufficient to
preclude passage through a 3/8 inch screen mesh and whose swim-
ming ability is insufficient to permit them to swim against in-
ward moving intake currents. Fish are of primary concern although
larger invertebrates may also become entrapped or impinged.
Entrainment is defined as a process whereby small organisms
in the lake water are passively carried with the cooling water
into an intake structure, through a cooling system and thence back
to the lake. Entrained organisms are small organisms drawn into
an intake system whose size does not preclude their passage through
a 3/8 inch screen mesh and on through a cooling water system.
Planktonic forms entrained in the effluent plume by mixing processes
are also included within the category of entrained organisms. These
310
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two types of entrainment are referred to as plant and plume entrain-
tnent, respectively. Entrainable organisms include members of the
phytoplankton and zooplankton communities, small fish, fish eggs
and larvae and small benthic forms periodically in the water column.
The published literature does not contain an abundance of
information relating to the problems of entrapment and entrainment.
However, a considerable amount of information has been collected
at operating power plants and is made available in published reports.
A report prepared by the Lake Michigan Cooling Water Intake Technical
Committee, 1973, specifically relates to water intakes on Lake Michi-
gan. This contains an excellent review and discussion of intake
structures, and entrapment problems on Lake Michigan. Others of
more general context include Sonnichensen, et al., 1973; Sharma,
1973; and U.S. EPA, 1073; these are excellent review documents on
cooling water intakes and entrapment problems. A recent publica-
tion edited by Jensen (1974) contains 35 papers dealing with both
entrapment and entrainment research at power plants and other
water intake facilities. Papers in this report cover the entire
spectrum of concern from phytoplankton entrainment to fish entrap-
ment and include current bibliographic citations for further
reference.
Entrapped Organisms
Introduction
The entrapment of organisms in a water intake system depends
on the area of the lake from which the water is withdrawn, the
311
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physical arrangement and hydraulics of the particular system and
the specific location of the intake, whether it is onshore, off-
shore at the surface or submerged. The proximity of an intake to
aruds highly populated with lake organisms, spawning grounds, etc.,
are also important in determining the numbers of organisms which
may be entrapped.
Before the impact of intake systems on populations of Lake
Michigan organisms can be evaluated, information is needed on the
numbers of species, and life history stages currently being en-
trapped. The program outlined below is designed to document the
numbers of organisms which are or may be entrapped or impinged
at intakes. It is suggested that these data be evaluated in terms
of such factors as intake location and type to determine if certain
areas of the lake or specific intake designs contribute dispro-
portionately to the entrapment of organisms. This information is
essential to the evaluation of the impact of entrapment on Lake
Michigan populations. If design and location factors are signifi-
cant, it will also be necessary for the proper evaluation of exist-
ing intake systems and for the design of future intake structures.
Monitoring Program for Existing Water Intakes
Objectives
The primary objective of this program is to determine the
daily and seasonal variations in numbers, size and weight of all
species entrapped in intake systems. This monitoring scheme is
adapted from that suggested by the Lake Michigan Cooling Water In-
take Technical Committee, 1973.
312
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Sampling Frequency
Sampling should be conducted through one calendar year.
Data on organisms which become impinged on the intake screens
should be collected daily.
Sampling Methods
Collection of large invertebrates, juvenile and adult fish
impinged on screening devices can be accomplished using collection
baskets in the backwash sluiceway. Mesh size of the collection
baskets should be equal to or smaller than the intake screen mesh.
Sampling Data Required
1. Plant operating data required during monitoring period:
a. Flow rate
b. Temperature - intake and discharge
c. Time started, duration and amount of warm water
recirculated for intake deicing.
d. Total residual chlorine contained in recirculated
water during condenser cleaning.
e. Current velocity at intake(s) over the range of
water volumes used in plant operation.
f. Number of times screens are operated between sampling
intervals.
2. Data required from biological collections:
a. Species, life stage, number and size of each organism
collected from the screens.
b. Volume of water sampled.
c. Number, length, weight, and age group (young-of-the-year,
yearlings ar.J older) of all fish collected from
screening devices.
313
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d. Representative samples of each species for determina-
ion of sex and breeding condition.
e. Numbers of naturally occurring dead fish in the area
ahead of the intake screening system should be estimated.
Monitoring Program for New and Proposed Water Intakes
Objectives
The primary objective for preoperational biological sampling
is to determine the abundance of potentially entrappable organisms
in the area of proposed intakes and to determine if fish are using
the area as spawning, nursery or feeding grounds, and/or as migra-
tion routes.
Methods of Investigation
1. Field studies to obtain this information are discussed in
the fisheries, benthos, and microbiology sections of this
report.
2. Model studies may be necessary to determine the optimal de-
sign of intake structures which would reduce potential loss
through entrapment or impingement.
3. Initial operation: When a new intake system becomes operational
it should be closely monitored for one year as prescribed above
for existing intakes.
4. Design modification: If a new intake system entraps an un-
acceptable number of organisms, design modifications should
be considered, tested as per 2 above, and implemented.
Entrained Organisms
Introduction
Organisms in the intake water not stopped by the plant screens,
diverted, or otherwise removed from the circulating water intake
flow, pass through circulating water pumps, steam condensers and,
314
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related appurtenances and back into the receiving water. Passage
through the cooling system may place stresses on the organisms
including: mechanical abrasion due to turbulence and irregular
surfaces in the sys.tem, pressure effects caused by pumping and
head losses, temperature effects caused by heat transfer in the
condenser and, on occasion, toxic effects caused by addition of
biocides to control fouling.
Because of the small size of entrained organisms, and their near
neutral buoyancy, it is assumed that each organism behaves hydrody-
namically as a water parcel during passage through pumps and conden-
sers. Organism travel paths are probably dissimilar, so effects may
also differ. For instance, the position of organisms relative to
pump impellers and the vertical distance an organisms must be raised
to reach the level of a given condenser tube in a system can result
in slightly different pressure histories. Hence, it is necessary
to deal with averages rather than individual organisms,, This is
consistent with physical measurements made in circulating water
systems, such as pressure, velocity and temperature gradients which
are also described in terms of averages. Pressure through a system
typically varies from one atmosphere to positive pressures of about
20 psig after passage through the pumps. Negative pressures may
also be encountered. The temperature conditions experienced by a
hypothetical organism passing through a cooling system are more
uniform than pressure. The temperature history may be determined
by assuming a linear increase in temperature through the length
315
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of a condenser tube equal to the average temperature rise through
the condenser. The effluent temperature rise can be quite variable,
depending on the amount of water circulated, and variations in plant
load. Typical temperature rises through a condenser range from
about 0C to 15C with flow velocities in the condenser tubes
ranging from 1.5 to 3.0 m/sec.
The following sections describe investigations necessary to
determine effects of entrainment on phytoplankton, zooplankton
(including entrainable benthos), and fish (including fish eggs and
larvae). Specific sampling techniques are suggested for use at
power plants on Lake Michigan. In addition, suggestions for labora-
tory studies are included which could be instituted if necessary
to isolate causes of entrainment effects.
The results of these studies should be carefully evaluated
with information on lakewide populations of entrainable organisms
to determine the impact of entrainment on the lake ecosystem.
Phytoplankton
Introduction
The phytoplankton of Lake Michigan (described in the Micro-
biology section of this report) are susceptible to entrainment
and possible damage in cooling water systems. Two major concerns
regarding the effects of entrainment on the phytoplankton are:
1. Does entrainment affect the rates of mortality, growth,
reproduction, and primary production?
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2. Do the effects of entrainment influence lakewide populations
of phytoplankton and other species dependent on them?
If the answers to these questions indicate that there is a
significant effect on the ecology of the lake resulting from en-
trainment, additional questions may be asked to isolate the causes
1. Is the effect caused by thermal, mechanical or chemical
perturbations?
2. Where does the effect occur, at the intake, in the plant,
at the discharge, or in the discharge plume?
3. What corrective measures could be employed to reduce adverse
effects.
Objectives
1. Determine the effects of entrainment on phytoplankton.
2. Determine if these effects influence local and lakewide
phytoplankton populations.
3. If warranted, based on answers from 1 and 2 (above) determine
the causes of observed entrainment effects within the cooling
system.
Methods of Investigation
Studies to determine the effects of entrainment on phytoplank-
ton should involve one or more basic types of observations:
1. microscopic examination of phytoplankton,
2. measurement of chlorophyll concentrations,
3. measurement of rates of primary production, and
4. observations of cell growth and division.
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Without elaborating on specific procedure, the following re-
search outline is presented to answer basic questions concerning
phytoplankton entrainment. Procedures involve both field and
laboratory studies.
Effects of Plant Entrainment on Phytoplankton Mortality
Immediate Effects
It is extremely difficult, if not impossible to de-
termine living or dead cells from visual observation of a sample of
phytoplankton. It is necessary therefore to rely on an indirect
physiological measurement. Following are some measurements that
might be made:
1. Rate of Carbon Uptake
Measurement of carbon uptake rates using an isotope
of carbon ^C is a sensitive indicator of the general
viability of the algae. A comparison of uptake
rates at the intake and discharge of a power
plant may be used as a measure of the effects of
plant entrainment on the phytoplankton.
2. Chlorophyll measurements
Chlorophyll "a" is a plant pigment common to all
phytoplankton. It is easily and accurately measured,
and it degrades rapidly when a phytoplanker dies.
A comparison of the concentration of chlorophyll
"a", and its degraded forms at the intake and
discharge of a power plant provides another indirect
measure of plant entrainment effects.
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3. Other physiological measurements
Other physiological-biochemical techniques,
such as ATP determination, have been employed to
assess entrainment effects on phytoplankton.
These techniques are not specific for phytoplankton
and are not acceptable for this purpose without
careful control.
'Long-Term Effects
The long-term effects of entrainment on phytoplankton
may be more important to the lake than immediate effects.
What happens to a phytoplankter several hours or days
after it has been discharged? Is it dead when it leaves
the plant only to decompose 1n the lake? Is it living
when discharged but unable to reproduce? Or, is its
rate of growth and division accelerated as a result of
entrainment? Are some species affected more drastically
than others?
The following are techniques which could be used in an attempt
to answer these questions:
1. Observation of cultures
Intake and discharge water maintained at ambient
temperature over a period of several days provides
one means for answering these questions. Subsamples
from such cultures may be periodically examined for
changes in species composition and abundance, chloro-
phyll content, and carbon uptake rates.
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2. The effect of plant entrainment on phytoplankton
growth, division and primary productivity
Studies outlined under "Immediate Effects," coupled
with No. 1 above, are also suitable for determining
the influence of entrainment on growth, division,
and primary productivity of the phytoplankton.
3. The effect of plume entrainment on phytoplankton
Although organisms entrained in the plume do not
pass through the plant, they may be exposed to
turbulence, elevated temperatures, and residual
biocides. Comparisons of phytoplankton samples
collected in the plume with samples obtained from
the intake of the plant and from a reference area
may provide insight into plume entrainment effects.
Studies similar to those outlined above for plant
entrainment effects are suitable here for compara-
tive purposes. In addition, samples of intake and
discharge waters may be mixed in various proportions
to simulate the dilution of effluent water in the
plume to observe plume entrainment effects under
more controlled conditions.
4. Determination of the cause of observed plant entrain-
ment effects
If preliminary studies of plant and plume entrain-
ment demonstrate a significant adverse effect, the
following studies should be initiated to isolate
the cause:
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a. Carbon uptake studies
Through a series of sample manipulations and com-
parisons it is possible to assess the total
effect of plant entrainment on carbon uptake
rates and to discern the individual effects of
temperature evaluation, biocide addition,
mechanical action and the duration of exposure
to elevated temperatures. Table VIII-1 summarizes
these manipulations and the effects measured.
b. Phytoplankton growth and cell division studies
Observations of chlorophyll concentrations, and
species composition and abundance on a series
of cultures manipulated as shown in Table VIII-1
would yield information concerning plant effects
on these parameters.
c. Experiments of opportunity
When a power plant is out of service for mainte-
nance, the plant often has the capability of cir-
culating cooling water without the addition of
heat. During these periods information may be
obtained on the mechanical effects of the cool-
ing system and the addition of biocides exclusive
of thermal effects.
d. Preoperational studies
A complete assessment of entrainment effects on
phytoplankton cannot be made prior to startup,
but tests which simulate entrainment conditions
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Table VIII - 1. Sample manipulation and comparison to assess the effects of the power plant on rate of primary
production through the use of C uptake.
1
Effect
Measured
Total
Plant entrainment
(temp. .pressure,
pumps, turbulence)
Mechanical
CO
Ł (pumping, pressure,
turbulence, cavitation)
Temperature
(thermal elevation)
Biocide addition
Duration of exposure to
elevated temperature
Sample
Collected At
Intake
Discharge
Intake
Intake
Intake
Intake
Intake
Incubation Compared
Temperature With
Intake
Discharge
or
Intake
Intake
or
Intake
Intake
Intake
Sample
Col lected At
Discharge
Intake
Discharge
Intake
Intake
Discharge
and
Biocide
Intake
Incubation
Temperature
Discharge
Discharge
Intake
Discharge
Other tempera-
ture increases
above and be-
low discharge
temperature
Intake
Various elevated
temperature for
various lengths
of time
Adapted from Brooks et al., 1974.
-------
can be conducted before final plant design.
Similar tests may be conducted to those discussed
above for operating power plants but which simu-
late expected plant condition.
A thorough literature review and a series of well-
designed experiments could provide preoperational
information applicable to the entire lake which
could then be used to design cooling systems to
minimize ecological impact.
Methods of Sampling
Each of four basic types of observations (carbon uptake,
chlorophyll, microscopic examination and culturing) should be made
on subsamples of a larger, well-mixed sample to assure that all
measurements are performed on the same water mass. It would be
beneficial if a subsample could also be taken for chemical analysis
of plant nutrients and toxic substances. Subsampling a single
large sample maximizes the amount of information for interpretation
and minimizes sample collection.
All samples of water for phytoplankton investigations should
be collected in non-metallic, non-toxic vessels such as a plastic
bucket or Van Dorn bottle. The use of pumps and nets which may
damage organisms or which are size selective are not acceptable
for the collection of phytoplankton. Samples should be held in
glass or non-toxic plastic containers. Transferring samples
through rubber or Tygon-type tubing, which are toxic to phytoplank-
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ton, must be avoided.
Sarapi ing Interval
During the initial phases of study, samples should be collected
and observations made monthly for a period of at least one year.
One sampling site such as the intake should be monitored weekly to
note sudden changes in the phytoplankton populations. Drastic
population shifts in the weekly samples should trigger full-scale
investigations described above.
Sam pi ing Frequency
During monthly sampling, phytoplankton should be collected
at least three times during 24-hours: early morning, midday,
and late evening. This schedule could be reduced to one collec-
tion per day when diuvnal patterns for the area have been deter-
mined.
Sampling Site Selection
The exact point of collection is difficult to designate in
general guidelines since nearly every power plant has a different
cooling system design. The following points in the cooling system
are appropriate for sample collections:
1. at the intake, ahead of any pumps or screens,
2. at the point of discharge, and
3. in the discharge plume.
If more detailed investigations are necessary to determine
the causes of entrainment effects, additional samples may be ob-
tained within the cooling system i.e., before and after pumps and
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condensers.
Special Problems
For valid comparison of two points in the cooling system, it
is imperative to collect samples from the same well-mixed water
mass as it flows through the plant. Preliminary studies should
be conducted with tracers to determine travel times through the
cooling system from intake to discharge. It is also extremely
important to make sure that samples collected at the intake, for
example, are representative of the water actually entering the
plant. Stratification and nonhomogeneous conditions have often
been observed in what appear to be turbulent well-mixed waters.
The same caution would hold for the discharge of the plant.
Zooplankton and Entrainable Benthos
The zooplankton of Lake Michigan, described in another section
of this report, are susceptible to entrainment and possible damage
in cooling water systems. Primary concerns regarding the effects
of entrainment on the zooplankton are: 1) Does entrainment affect
the rates of mortality, growth, reproduction? 2) Do the effects
of entrainment influence lakewide populations of zooplankton and
other species dependent on them? If the answers to these questions
indicate that there is a significant effect on the zooplankton popu-
lation of the lake resulting from entrainment, additional questions
may be asked to isolate the causes:
1. Is the effect caused by thermal, mechanical or chemical
perturbation?
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2. Where does the effect occur, at the intake, in the plant,
at the discharge or in the effluent plume?
3. What corrective measures could be employed to reduce any ad-
verse effects?
Objectives
1. To determine the kinds and numbers of zooplankton entrained.
2. To assess the effect of entrainment on survival and repro-
duction of zooplankton.
3. To describe the seasonal and diurnal patterns of entrainment.
4. To relate research findings to lakewide studies.
5. If warranted, to distinguish between mechanical and chemical
damage and thermal effects in relation to plant design.
Methods of Sampling
1. Pumped samples are more desirable than net samples provided
the pump does not damage the organisms. A pump which will
transfer small fish without harm is satisfactory for zoo-
plankton and benthos. Non-toxic material should be used
throughout the sampling system.
Nets used to concentrate zooplankton and benthos from the
pumped sample should have a maximum mesh size of 160 microns
and should be metered, or the pumping rate should be timed
to provide an accurate determination of the volume filtered.
2. Samples should be taken in duplicate. If no vertical strati-
fication of organisms occurs, duplicate mid-depth or integrated
samples may be taken.
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3. Sampling sites should be established in the forebay, immediately
ahead of the traveling screens, and as close as possible to the
point of discharge. Sites for plume entrainment studies are
dictated by plume characteristics.
4. Samples should be carefully concentrated in non-toxic containers
»
and inspected microscopically for mortality and damage as soon
as possible after collection. (See 1 below).
The following studies could be undertaken at one or two sites
to answer the questions pertaining to the entire lake, or major
regions.
1. Special studies should be conducted to establish criteria
for damage and to examine the relationships of motility,
vital dye uptake, or other indices to long-term effects.
2. Time-temperature studies should be conducted to establish
thermal tolerances of important species and to permit an
estimate of plume entrainment effects.
3. Zooplankton and benthos entrained in the plant and/or the
plume may experience a non-lethal thermal shock that will
adversely affect normal reproduction. Special studies should
be conducted in which zooplankton and benthos are exposed to
a thermal regime through time for observations of growth and
reproduction.
4. If biocides are added to the cooling water, special studies
should evaluate effects on zooplankton and benthos.
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Sampling Frequency and Interval
Samples should be taken in the forebay and at the discharge
during a 24-hour period at least monthly. Duplicate samples
should be taken every 3 to 4 hours during the 24-hour survey.
Fish
Introduction
Entrainment of fish, fish eggs, and larvae has been observed
in once-through cooling systems of plants located on the Lake Mich-
igan shoreline, but the species and numbers of these organisms and
their fate have been poorly documented. The potential for damage
to the lake fish populations by entrainment depends on the numbers
of organisms that pass through the condenser system and on the
conditions experienced during passage. Fish, fish eggs, and larvae
also can be entrained directly in the effluent plume from the
receiving water when the effluent is discharged into the lake,
especially at plants where diffuser systems are used to enhance
mixing for rapid temperature reduction.
Objecti ves
Plant Entrainment
1. Determine the species and numbers of fish, fish
eggs, and larvae drawn into and discharged from
cooling systems using Lake Michigan water.
2. Determine the immediate and delayed effects of
cooling system passage on these organisms.
Plume Entrainment
1. Determine the species and numbers of fish, fish
eggs, and larvae entrained directly into the
discharge plume from the receiving water.
2. Determine the immediate and delayed effects of plume
entrainment on these organisms.
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Questions to be Answered
Plant Entrainment
1. What species and numbers of non-screenable fish, fish eggs,
and larvae are drawn into and discharged from cooling water
systems?
2. Are there statistically significant differences in the
species and numbers of non-screenable fish, fish eggs, and
larvae drawn into cooling water systems on a diurnal,
seasonal and annual basis?
3. Assuming 100% mortality of the fish, fish eggs and larvae
that are entrained, is it reasonable to expect that this
loss in itself, or when added to the other losses resulting
from cooling water use will significantly affect fish popula-
tions? If so, the following questions should be answered to
more clearly identify the specific causes of the entrained
losses.
4. Is there a statistically significant difference between the
numbers of viable, non-screenable fish, fish eggs, and larvae
drawn into a power plant and the numbers discharged from the
cooling system?
5. Is there a statistically significant correlation between
densities of non-screenable fish, fish eggs, and larvae in
the area of the lake near the cooling system intake and the
species and numbers in the cooling water drawn into the
plant?
6. Will eggs that survive plant passage be able to complete
development; will fish and fish larvae that survive plant
passage be mobile and able to locate and capture food
effectively?
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7. Will fish and fish larvae surviving plant passage be more
susceptible to capture by predators concentrated in or near
the discharge plume?
3. Will the simple physical transport of undamaged fish, fish
eggs, and larvae from the intake area into the discharge plume
reduce survival?
9. If the answers to the above questions confirm the potential
for significant detrimental effect on lakewide fish populations
caused by entrainment, to what extent are the following factors
responsible: pressure changes; elevated temperatures, changes
in gas saturation; chlorination; collision with screens, pump
impellers and other internal surfaces of the cooling system;
and shear forces created by turbulence?
Plume Entrainment
1. What kinds and numbers of fish, fish eggs, and larvae are en-
trained directly into the discharge plume from the receiving
water?
2. What are the diurnal, seasonal, and annual discharge entrain-
ment patterns?
3. What percentages, if any, of the entrained fish, fish eggs,
and larvae are killed because of the conditions encountered?
4. If the answers to questions 1 - 3 above demonstrate a signi-
ficant detrimental effect on the fish populations caused
by plume entrainment, to what extent are each of the following
factors responsible: gas saturation; chlorination; shear
forces created by turbulence; probable decrease in ability to
avoid predators concentrated in or near the plume; displacement^
of entrained organisms from one habitat to a second, perhaps
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less favorable habitat?
Methods of Investigation and Sampling
Plant Entralnment
Sampling with a Pump Sampling System
A pump sampling system is recommended as the primary method
for determining species and number of non-screenable fish, fish eggs,
and larvae of each species passing through plant cooling systems. A
pump sampling system is preferred because a standardized system can
be built that can be used at most if not all plants, thereby providing
a basis for comparability of data collected among plants. Pumped
systems also are easier to automate than systems in which sampling
is done with nets suspended directly in the mainstream of the cooling
water flow. (An automated pump sampling system is under develop-
ment at the Great Lakes Fishery Laboratory.)
Continuous pumped sampling is recommended as the primary method
for determining species and numbers of fish, fish eggs, and larvae
of each species entrained and passing through power plant cooling
systems, because (a) the numbers of these organisms, even in areas
known to be good spawning and nursery areas, are typically low, and
(b) their distribution in time and space is usually either changing
rapidly or patchy as a result of natural conditions. Therefore,
adequate representation of these organisms can only be obtained
with continuous sampling.
The actual volume of water to be pumped to provide an adequate
sample is dependent on the densities of fish, fish eggs, and larvae
in the water surrounding the cooling system intake structure. If the
maximum recorded density of 6.4 alewife larvae per cubic meter at the
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Cook Plant intake on July 20, 1973 (see Wells, 1973) is taken
as an example, a continuous pumping rate of 0.75 cubic meters per
minute or about 1,090 cubic meters per day would have to be main-
tained to obtain a sample of approximately 7,000 larvae. By the
same logic, reducing the larval density in the influent water by
two orders of magnitude (to 0.064 per cubic meter) would reduce the
number captured .to about 70 per day — probably still an adequate number
from which to estimate the daily larval entrainment rate. However,
reduction of larval density by 3 orders of magnitude (to 0.0064 per
cubic meter) would require a higher pumping rate to insure adequate
representation of this species in the sample.
Alewife larvae are probably more abundant in the lake than those
of any other species of fish, e.g. perch never exceeded 0.071 per
cubic meter and most samples had less than 0.047 perch larvae per
cubic meter (Wells, 1973). Smelt were even less abundant (0.038 per
cubic meter) than perch, and few if any larvae of other important
species were captured at all. The available data, therefore, indicate
that continuous sampling at a pumping rate of at least 0.75 m^/min.
would be needed to detect the entrainment of these species.
Sampling Location
Pump intake ports of the sampling system should be located:
1. Immediately behind the traveling screens, if possible; other-
wise, immediately ahead of the traveling screens.
2. At a suitable point in the discharge system.
3. One sampling port should be located near the surface, one
near the bottom, and one at mid-depth. If uniform mixing can
332
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be demonstrated, one sampling depth may suffice.
Sampling Frequency and Duration
Sample continuously for one year to determine the kinds and numbers
of non-screenable fish, fish eggs, and larvae that pass through the
plant; sample for at least one additional year during periods of
peak entrainment to provide a measure of year-to-year variability.
The 24-hour sampling day should be divided into four parts
corresponding to the four major diel periods (dawn, daylight, dusk,
darkness) and a single composite sample should be obtained daily
for each of these periods.
Sample Processing
1. Preserve each sample in 10 percent formalin. (Note: It is not
necessarily intended that every sample collected under this
continuous sampling routine be examined and analyzed; rather
the sampling objectives, the sample variance, and the required
level of precision will dictate which of the preserved samples
are to be subjected to the following additional processing).
2. Sort preserved fish by species and by developmental state
(prolarvae, larvae, post-larvae, or juvenile) within species,
enumerate each subgroup separately, and measure an adequate
sample (total length in mm).
3. Sort eggs by size group or species; measure diameters of an
adequate sample in each group.
Sampling with Anchored Plankton Nets
These experiments are designed to provide data for comparison
of sampling efficiency of pumped and non-pumped sampling methods
and to provide data on the number of non-screenable, live and dead
333
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fish, fish eggs, and larvae that are drawn into and discharged from
the plant. Note: The need for estimates of in-plant mortality of
these non-screenable fish, fish eggs, and larvae depends on the
answers obtained to questions 1 - 3 above for Plant Entrainment.
Sample Location
Suspend one plankton net immediately downstream from each of
the intake ports of the pumped sampling system, in the traveling
screen well or at another plant location upstream from the con-
densers, where comparative studies can be made.
Sampling Gear
A conventional 1/2 meter oceanographic plankton net with a
maximum mesh aperture of 351 microns and with a flow meter in-
stalled in the net opening, and a large "non-flow through" collecting
chamber in .the apex is the gear of choice.
Sampling Frequency and Duration
Collect net and pump samples simultaneously for as long as
necessary to permit comparison of the effectiveness of the two
methods and to provide the needed data on in-plant mortality of
non-screenable fish, fish eggs, and larvae. Note: It will be
necessary to determine the filtering efficiency of the suspended
nets by comparing the flow rate recorded by the net flow-meter for
the complete net (net frame, flow-meter, net bag, and collecting
vessel) fished in the normal sampling location, with the flow rate
recorded by the net flow-meter after the net bag and collecting
vessel have been removed. Flow rates obtained under the latter
conditions also will provide information needed to expand the
catches obtained by the pump sampling system.
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Sampling Process
1. Sort eggs by size group or species, measure diameters of
an adequate sample in each group, and record the condition of
f
each egg (live or dead).
2. Preserve the entire catch in 10 percent formalin after live
examination.
3. Sort fish by species and by developmental state (prolarvae,
larvae, post-larvae, or juvenile) within species, and enumerate
each subgroup separately; record the condition of each fish
(1ive or dead).
4. Measure an adequate sample (total length in mm) of each
subgroup.
5. Preserve the entire catch in 10 percent formalin after live
examination.
6. Methods should be developed to permit rapid distinction
(under field conditions) between live and dead fish, fish eggs
and larvae, and between live, damaged individuals and those
that have suffered subtle but irreversible damage that will
directly or indirectly cause their death, or otherwise prevent
them from completing their normal life cycle. Vital staining
techniques currently under development may prove helpful in
making these determinations.
Plume Entrainment
Determine the species and numbers of fish and fish eggs
and larvae entrained directly into the discharge plume, and the
effects of the entrainment on these organisms by sampling with
335
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towed plankton nets in and around the discharge plume.
Sampling Locations
Collect samples simultaneously at the discharge, in the
plume, and in unheated waters adjacent to the plume. If a physical
plume model can be developed to show the amount of receiving water
that is mixed with the heated effluent at various points along the
longitudinal axis of the plume, only information on the density of
the entrainable fish, fish eggs, and larvae in the receiving waters
adjacent to the plume is needed to estimate the kinds and numbers
of these organisms that may be entrained. Sampling at intervals
on the longitudinal axis of the plume within discrete temperature
isotherms permits evaluation of the condition of fish and fish eggs
found there, so their condition can be related to the effects of
plant and plume entrainment.
Sample Gear
The gear of choice is a conventional one meter, 351 micron
mesh, oceanographic plankton net with a flow meter installed in
the net opening and a large non-flow through collecting chamber
installed in the apex of the net. When towing these nets at the
appropriate speed to capture small fish (maximum of about 4 mph,
true net-speed through the water) a steel towing cable (about 1/8
inch) and a heavy metal "net depressor" (about 45 pounds) will
be required.
Sampling Frequency and Duration
No estimates of sampling frequency can be made until reliable
descriptions are obtained of the species and numbers of fish,
336
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fish eggs and larvae entrained fr,om the receiving water.
Sampling Process
See above section for processing live fish, fish eggs, and
larvae on page 335.
Priority Research
The research priorities listed below are designed to provide
answers to questions concerning the local and lakewide effects of
entrapment and entrainment at cooling water intakes and discharges
on the biota of the lake.
1. What are the effects of entrainment on the phytoplankton
and zooplankton populations of Lake Michigan?
2. What are the effects of the entrainment of fish and fish
eggs and the entrapment of fish on the Lake Michigan
fishery?
An adequate answer to each of these questions clearly demands
a rather complete understanding of the spatial and temporal aspects
of the populatio.n dynamics of Lake Michigan phytoplankton, zoo-
plankton, and fish. Distinguishing the effects of entrainment and
entrapment on the biota of the lake from natural background
variation will be difficult and expensive but will be necessary
if we are to predict the effects of cooling water use.
The following is a list of priority research topics of a
more specific nature. Priority values have been ranked according
to the following scheme:
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1. - highest priority, consistent with achieving primary goals
of the Panel ,
2. - high priority studies supporting priority 1 items,
3. - intermediate priority, but ultimately providing support
to priority 1,
4. - low priority supporting other programs but not of critical
importance in itself,
5. - deferred priority of a general supporting nature.
Categorical values may be interpreted in the following way:
Answers to these questions should be developed:
1. - as soon as possible using available data,
2. - using data currently being collected,
3. - by means of individual research projects which
are not now underway.
A. Entrapment
1. To evaluate the data on the numbers of fish currently
entrapped at Lake Michigan cooling water intakes and
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determine if this loss is detrimental to the local
and lakewide fish populations.
Priority 1, Category 1 and 2
2. To evaluate fish entrapment data to determine which
of the existing intake designs entrap the fewest
fish.
Priority 2, Category 1 and 2
3. To investigate alternate intake designs of fish
diversion devices to minimize fish entrapment.
Priority 2, Category 3
B. Entrainment
1. To evaluate existing data concerning the effects of
plant and plume entrainment on the phytoplankton,
zooplankton and fish populations of Lake Michigan.
The following sequence should be followed:
a. Determine the species and numbers of each species
entrained.
b. Determine percentage mortalities resulting from
entrainment, based on available data. Where
data are lacking for specific groups of organisms,
339
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assume 100 percent mortality.
c. Gather existing data on concentrations of en-
trainable organisms in representative zone around
the lake, and estimate the size of the local and
lakewide populations.
d. Obtain data on flow rates of cooling water through
selected plants within these zones and the volumes
of water entrained by the effluent plume within
the l.OC isotherm.
e. Calculate percentage loss of the local and lakewide
population of each organism group within the
representative zone.
f. Determine whether these losses will significantly
affect the local and lakewide populations of these
organisms and what effects will be manifest in the
overall Lake Michigan ecosystem.
Priority 1, Category 1 and 2
2. If significant data gaps are found or if adverse effects
are predicted from the analyses outlined above, proceed
with the monitoring program suggested.
Priority 3, Category 3
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Literature Cited
Brooks, A.S., R.A. Smith, and L.D. Jensen. 1974
Phytoplankton and Primary Productivity. In: Environ-
mental responses to thermal discharges from the
Indian River Station, Indian River, Delaware. Ed. by
L.D. Jensen. Rept. No. 12. Cooling Water Discharge
Research Project (RP-49). The Johns Hopkins Univ.
205 pp.
Jensen, L.D. 1974. Entrainment and Intake Screening
Proc. of the Second Entrainment and Intake Screening
Workshop,, Report No. 15. The Johns Hopkins Univ.
Cooling Water Research Project. Electric Power
Research Institute, Palo Alto, California. 347 pp.
Lake Michigan Cooling Water Intake Technical Committee, 1973,
Lake Michigan Intakes: Report on the best technology
available. U.S. EPA, Region V, Chicago. 152 pp.
Sharma, R.K. 1973. Fish Protection At Water Diversion and
Intakes: A bibliography of published and unpublished
references. ANL/ESP-1. Argonne National Laboratory,
Argonne, Illinois. 33 pp.
Sonnichsen, J.C., Jr., B.W. Bentley, G.F. Bailey and
R.E. Nakatani, 1973.
A Review of Thermal Power Plant Intake Structure
Designs and Related Environmental Considerations.
HEDL-TME 73-24 UC-12. Hanford Engineering Development
Lab., Richland, Wash. 93 pp.
U.S. Environmental Protection Agency. 1973.
Development Document for Proposed Best Technology
Available for Minimizing Adverse Environmental Impact
of Cooling Water Intake Structures. EPA 440/1-74/015.
175 pp.
Wells, L. 1973. Distribution of fish fry in nearshore
waters of southeastern and east-central Lake Michigan,
May - August 1972. Great Lakes Fishery Laboratory.
Ann Arbor, Michigan Administrative Report. (processed)
24 pp.
341
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SECTION IX
RADIOECOLOGICAL CONSIDERATIONS RELATED TO
COOLING WATER USE
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Section IX. RADIOECOLOGICAL CONSIDERATIONS RELATED TO COOLING
WATER USE
TABLE OF CONTENTS
General Discussion of Problem . 345
Conclusion . 346
Priority Effort 347
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Section IX. RADIOECOLOGICAL CONSIDERATIONS RELATED TO COOLING
WATER USE
General Discussion of Problem
Within the scope of the charge to the Lake Michigan Cooling
Water Studies Panel, radioecological considerations are limited
to the area of the cooling water discharge where temperature and
other effluents remain measurably higher than ambient levels.
The effect of radiation from both internal and external sources
on a wide variety of aquatic biota have been examined in consider-
able detail in the laboratory, and to a lesser extent in the field.
The objective of much of this work was to establish the lethal
radiation dose (LD50) for various aquatic organisms. The effects
of radiation on reproductive capacity, spawning behavior, and life-
span have also been investigated in laboratory and field experiments.
It is clear that radiation does effect some biological para-
meters in adverse manner although the one of outstanding concern
is reproduction. These effects increase as a function of increased
temperature. Radiation should be regarded as a biological stress
similar to temperature variations from the norm, chemical toxicants,
and disease states except that long-term and cumulative effects
must be considered. Under the "as low as practicable" concept for
routine releases from nuclear operations, it is doubtful if biota
resident immediately in the discharge will receive an additional
radiation dose equal to natural background (about 125 mrad/year).
Hence, radiation per se will be a minor contributing factor rather
than a primary causative factor in the biological effect of
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discharges from once-through cooling of nuclear power stations.
However, in order that observed biological effects (if there are
such) in the outfall region not be falsely attributed to radia-
tion, or conversely to another causative agent if radiation levels
are high, the following measures are recommended:
1. Radiation exposure levels to aquatic biota should be
calculated on the basis of radiological monitoring data
at specific nuclear plant sites.
2. Radionuclide analyses should be performed at least
seasonally on representative biota collected in the dis-
charge region and the internal dose from such analysis
i
should be calculated for these same biota. This recom-
mendation is probably fulfilled by most current radiologi-
cal monitoring programs.
3. Deploy clams or other suitable shellfish as biological
accumulators and indicators of maximal radionuclide up-
take and exposure; TLD dosimeters should be employed along
with these biological probes. Taken together, these
devices (Clams and TLD's) should provide a reasonable
estimate of the upper limit of radiation exposure ex-
perience by resident biota at any given site.
Conclusion
In summary, the subcommittee feels that biological effects due
to radiation under routine operation of nuclear power plants will
be minimal, and in all probability unmeasurable. For the sake of
completeness, however, it is felt that a quantitative fix on
radiation levels should be obtained at various plant sites to test
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the validity of this prediction.
Priority Effort
In light of limitations of the interest of the Panel to radio-
ecological aspects of the cooling water alone, and to the findings
of the author, that biological effects due to radiation during
routine operation of nuclear plants will be minimal, no research
priorities have been assigned.
The author has recommended the following effort in order to
insure that these limitations may be satisfied. Obviously no
priority value or categorization is necessary.
A priority effort should be made to establish whether data on
radioactivity from present monitoring programs is adequate to
reliably predict the dose to the biota entrained or otherwise in-
teracting with thermal discharge. Field measurements of radiation
exposure are a necessary part of this effort.
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APPENDIX
Comments of Members and Participants
of the Panel related to Report Number 1
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Appendix
Comments of Members and Participants
of the Panel related to Report Number 1
During the course of preparation of Report Number 1, a number of comment
periods were designated by the Panel. On June 6, 1975, the final draft
was forwarded to members and active participants of the Panel (those
individuals who had commented on the previous draft report) for a final
comment period. At the July 8, 1975 meeting, comments were distributed to
authors of various sections of the report. Following discussion, authors
agreed to incorporate comments where possible and prepare a written response
to those comments which they did not choose to incorporate.
The following comments and written replies are the product of this endeavor:
Comments related to Section III
Measurement of the Effects of Cooling
Water Use on Physical Parameters
Comment of Jacob Verduin, Southern Illinois University, Carbondale, Illinois:
There is a great deal of data available concerning the chemical changes associated
with once-through cooling. The data show that the chemical changes are small.
No attempt has been made to summarize, review, or reference such data in the
report.
Numerous studies have been made concerning the present, and projected level
of thermal loading in Lake Michigan. These contain estimates of the temperature
increment that can be associated with present and projected (year 2000) thermal
injections. Such studies have not been reviewed, or referenced in the report.
Pertinent information on lake currents near the shore has been ignored. Bellaire
made a study of currents in Lake Michigan (Publ. No. 10, Great Lakes Research
Division, University of Michigan, Ann Arbor, 1963) that can be used to assign
approximate values to alongshore currents. He portrays a net northward flow
parallel to the west shore of about 0.3 miles per hour. Such a current pattern
will move water from the Chicago area to the Milwaukee area in about 20 days.
Consequently, any data obtained in the Milwaukee area probably reflect a strong
influence of contributions from the Chicago area.
During 1973 six current meters were maintained near Zion, Illinois, by Hydrocon,
Inc. These records confirm the net northward flow described by Bellaire, and
show that periods of near-zero current flow usually last for only a few hours.
Current reversals occur at 2-3 day intervals, there is an average northward
flow of 4.6 miles per day, an average southward flow of 2.2 miles per day,
yielding a net northward flow of about 2.4 miles per day.
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Such currents have a profound influence on the dispersal of thermal (and other)
injections, and they have a distinct bearing on proposed monitoring programs.
For example: A "Reference" station located 8 miles north of a point of injection
will be occupied by water that has moved up from the injection point within the
previous few days. All direct evidence of a thermal injection will have been
obliterated, but the biota sampled will not be "Reference" biota but will
contain individuals that have recently passed through a thermal plume area.
There are many other pertinent data that should be referenced and evaluted if
the report were to comply with the initial charge (page 2) to review background
information relating to thermal discharges....
A written reply to these comments was not received.
Comments related to Section IV
Measurement of the Effects of
Cooling Water Use on Chemical Parameters
Comment of J.J. Ney, Wisconsin Electrict Power Company, Milwaukee, Wisconsin:
Operational Monitoring (pp. 114-115) presents an unjustifiably intense intake-
discharge monitoring program. Studies at Lake Michigan power plants have
demonstrated that concentration of nutrient and general water quality parameters
are not perceptibly affected by condenser passage. However, concentrations do
change on a seasonal basis. The parameters included in weekly measurement
(p. 115) need be measured only seasonally.
A written reply to this comment was not received.
Comments related to Section V
Measurement of the effects of
Cooling Water Use on Primary Producer
and Consumer Communities
Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
The field study guides described in this section are based to a large extend on
two assumptions. It is assumed that residence time of plankton is sufficiently
long that plume populations can be defined and thermal effects (through plume
vs. reference area comparisons) isolated. A second, related assumption is that
thermal input induces first-order perturbation such that change in lake populations
can be traced to heat as the causative agent. Evidence to data from numerous
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studies tends to negate these assumptions. Plume entrainment time is generally
limited to a few hours. Nutrient input from agricultural runoff and point
sources is the primary agent of historical change in Lake Michigan planktonic
communities.
While the 16 mile-transect sampling program in the various biological provinces
as detailed for both phytoplankton and zooplankton assemblages should enable
documentation of changes over time, it does not in itself permit determination
of the sources of change. The site-specific program utilizing as many as 64
sampling stations at all depths is incapable of defining heat-induced changes
to the transient populations.
A more constructive approach, partially outlined in this section, involves the
development of predictive models of the reaction of the plankton communities
to thermal addition. Input would include-quantification of plumes, entrainment
time and characterization (seasonal composition and abundance) of nearshore
planktons assemblages. Short-term and repeated exposure bioassays and in-situ
productivity experiments should be employed to determine thermal tolerance and
response. Ultimately, models could be tested by field observation and simulation
techniques. Like other studies described in this section, some of the necessary
methodology remains to be developed. However, the total effort should be
considerably less intensive and more fruitful since general models could be
adapted to site-specific situations.
It is of interest that this approach is being used to define water quality
standards for nekton, which are capable of establishing resident discharge-area
populations. The fact that planktonic populations are incapable of such residency
further recommends developnent of the modeling approach to assess thermal effects.
Written reply of E.F. Stoermer, University of Michigan, Ann Arbor, Michigan:
The possibility of greater reliance on modeling was discussed at considerable
length by this subcommittee. Two major points became obvious from these
discussions: (1) There is a great deal of uncertainty if state of the art
simulation models can deal with the time transients possible in the near-shore
zone of Lake Michigan; and (2) Data requirements for viable model would certainly
be no less stringent than those proposed. It is probably desirable to work
toward developing realistic ecological models of the scale Dr. Mey envisions,
but it should be recognized that this would require considerable effort and
resources beyond those presently employed by contractors engaged in site studies
on Lake Michigan.
Comment of R.P. Herbst, The University of Wisconsin, Waukesha, Wisconsin:
General Comments:
These items have not been adequately addressed in the Microbiology Section.
1. The study area and areas of concentration should be indicated along
with a rationale for those limits.
a. Extensive and statistically sound use should be made of reference
locations and times.
2. Collection of data on each environmental parameter should be justified.
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Specific Comments:
Page 137 - Sub-paragraphs numbered 2 and 3 of. Measurements which should be
made.„„,, Rationale is not provided nor study design! Again justification is
needed as to why ten stations are required when a minimum of two will be
sufficient. Why are depth samples measured when the plume floats? Depth
sampling will provide information on light penetration but why is this necessary?
What is the justification for estimating nitrogen fixation? I cannot identify
any rationale as to why this information would serve to be useful or how it
would be applied to thermal discharges with the possible exception of baseline
academic information. I think some rationale should be presented as to its use
and validity for some environmental parameter affected by thermal discharges.
Is it to be a metabolic indicator of the blue-green algal populations„ or the
amount of nitrate added to Lake Michigan from this source compared to sewage,
industrials agricultural, and natural inflows such as rivers and rainfalls etc.?
Page 138 - First and second paragraphs on the page beginnings "In addition....
There is very little justification for doing any of this work as well as more
speculative statements without support. For instance why should there be an array
of stations to "16 statute miles from shore" if the thermal discharge never
reaches this far and "significant changes" in the algal populations occur over
very short distances?!" It is further stated that these stations could serve as a
possible monitor of whole lake effects. I see no way that this could be possible
especially when it was stated earlier that the open lake's populations are
completely different! Therefore9 how could whole lake effects be determined from
this sampling pattern? This is better attempted from the experimental procedures
mentioned in the following paragraphs although there are severe limitations. In
additions the Statistical Analysis Section also presents the procedures for
detecting variability as well as differences between locations and neither implies
nor suggests a sampling scheme as indicated here. If the authors provide a
statistical design for this "16 mile transect" perhaps its purposes etc. can be
ascertained. If again this is a "gut feeling" or a "nice bit of information" it
should be so stated. If it can be justified that this will indeed provide some
"monitor of possible whole lake effects" it should be so indicated.
In summation of my comments, I think it would be especially important for this
section to have an economic assessment. It would be very noteworthy if extended
to detail the information considered essential for thermal discharges and that
which is of academic interest. This would enable a more precise evaluation of
suggested studies and techniques for not only the writers but potential users.
A great deal of the material in the Microbiology Sections while necessarily being
the opinions of the authors and not the consensus of the Panel, would not answer
with anymore validity9 statistical designs of a more basic nature to assess effects
of thermal discharges. Further, when costs for redundant data are examined, the
financial consequences to taxpayers via grants, etc. as well as potential users
are extremely high and might better be channeled into special studies of a nature
which would delineate cause, effect and possible redesign.
Finally, I would like to compliment both Dr. Stoermer and Dr. Neese for a fine
effort. Having actively participated in the many Panel discussions regarding the
report and their section it becomes only too apparent that it is easy to criticize
but that not enough recognition is given to the good parts. All aspects of this
section cannot be completely satisfactory to everyone nor will they necessarily
answer with any finality many of the questions asked. I think both men have
attempted to provide the necessary background, etc. for this section. With only
a few exceptions they have done an excellent job.
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A written reply to these comments was not received.
Comment of Roy F. Heberger. U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
In the current draft, most of my technical comments were adopted. I remain
firmly opposed to use of the trophic level references. They are confusing and
often misleading. The footnote on page 146 is, in my opinion, inadequate with
regard to this problem. The only purpose the footnote served was that of
avoiding necessary changes in the text.
A written reply to this comment was not received.
Comment of Jacob Verduin, Southern Illinois University, Carbondale, Illinois:
The recommendations concerning investigation of phytoplankton are unrealistic.
The intensity of sampling number of depth intervals, number of stations, and
biochemical analyses recommended (chlorophyll, organic nitrogen, organic carbon,
nutrient uptake rates, nitrogen fixation rates, etc.) are not justified by any
explanation of the goal such analyses are designed to achieve. It seems, rather,
that most of the phytoplankton researches that have appeared in the literature
during the past twenty years are here recommended for a monitoring program at
an unprecedented level of sampling intensity in the hope that such a program may
reveal some evidence of thermal impacts on the communities.
The program does not hold real promise of such a result. The postulated effects
of thermal injection are:
a. injury by superoptimal temperature
b. stimulation of metabolism by increased temperature within the range
of tolerance
c. shift in major component species from desirable to nuisance forms
However, none of these effects are specific for thermal injuections.
Injury to aquatic organisms has been a demonstrated effect of chlorination, and
it is well known that chlorination of sewage effluents is required by Health
Department regulations. Moreover, the currents along the west shore of
Lake Michigan are of such magnitude and direction that waters from the Chicago
area are distributed along the shore all the way to Milwaukee. If one were to
establish a detectable injury to phytoplankton between Waukegan and Milwaukee, how
would one distinguish between damage from chlorinated sewage effluents and damage
from postulated thermal injury?
Stimulation of phytoplankton metabolism is a well-known effect of nutrient enrich-
ment. Sewage outfalls, storm runoff from lawns and fields, provide such injections.
If one were to establish a detectable increase in phytoplankton metabolism between
Waukegan and Milwaukee, how would one distinguish between the stimulus derived
from nutrient enrichment and that derived from the postulated thermal stimulus?
The trickling filters of sewage treatment plants are heavily populated with blue-
green algae, which constantly break away from the filter and enter the lake as a
potential innoculum of nuisance algae. If one were to detect an increase in
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nuisance algae between Waukegan and Milwaukee how would one distinguish between
the importance of this source and the postulated influence of thermal impacts?
There is no evidence in the report that the serious problem of separating such
effects is recognized. There certainly are no recommendations which will serve
to isolate these effects so that a clear conclusion can be reached as to which
source is responsible for a particular kind of community perturbation. The
presence of sewage outfalls and the plant nutrient injections from the watershed
must have an order of magnitude larger impact on lake ecology than the thermal
injections of power plants on the lake.
Finally, there is an abundant literature concerning the response of aquatic (and
other) organisms to temperature change. This literature makes it possible to
evaluate the metabolic changes that are likely to occur in a thermal plume.
Analyses of this kind have been made and are available, both in the scientific
literatures, and in testimony presented at operating permit hearings. They reveal
that phytoplankton and zooplankton passing through a plume in Lake Michigan are
likely to experience a 15 percent increase in their metabolic rate for a period
of about two hours, after which they will return to ambient temperatures and
normal metabolic rates. There is no evidence that such an experience has any
prolonged or deleterious effects. Moreover, photosynthetic and respiratory rates
have been measured within thermal plume areas under normal plant operation. These
studies confirm the correctness of the predictions based on temperature coefficients
gleaned from the literature. The failure to reference any of this literature, and
to summarize and evaluate the predictions concerning metabolic rates in thermal
plumes which have been derived from it, represents noncompliance with the first
paragraph of the charge to the panel, as quoted on page 2 of this report.
Written reply of E.F. Stoermer, University of Michigan, Ann Arbor, Michigan:
It would appear to me that the substance of Dr. Verduin's extended comment is
that anthropogenic effects on the Lake Michigan ecosystem are multiple, complex,
and synergistic. It would appear to me that this is precisely why a reasonably
comprehensive data collection program is needed to partition thermal effects. It
is, unfortunately, a fact of life that Lake Michigan is a highly perturbed system.
At this time it is entirely futile and unproductive to speculate what might be if
other environmental insults did not exist. What is needed are studies which will
evaluate the impact of thermal loadings on the real world Lake Michigan system
as it exists. I agree with Dr. Verduin that it may eventually be necessary to
extend studies to include synergisms, which presently appear improbable, such as
the imput from trickling filters, but I do not think it possible to anticipate all
possible effects in the present document.
Comments related to Section VII
Measurement of the Effects of
Cooling Water Use on the Fishery
1. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
As per your July 1, 1975S request to Mr. Howe, we have rewritten my
June 25, 1975, letter concerned with the Fisheries Section of the Panel
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Report in order to meet your needs for the final report. Commonwealth
Edison requests that this section of the Report be deleted unless
Mr. Edsall and Mr. Yokum reply to our January 16, 1975, comments as per the
Minutes of the October 1, 1974, meeting.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We responded verbally to the comments in your letter of January 16, 1975,
(as directed by the Panel on October 1, 1974) at a meeting held in the
Region V EPA office (Mr. Howe represented your company at that meeting).
We were advised by Mr. Bremer on July 1, 1975, that you subsequently
requested a written reply to your letter of January 16, 1975, and we
provided that reply on July 2, 1975.
2. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Unless they have already done so, they should also reply to comments of
Dr. Verduin, Dr. Ney and Mr. Patriarche. The authors rebuttal to these
comments should subsequently be appended to the report along with the
comments.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We responded verbally to Mr. Patriarche who seemed satisfied with our
reply and prepared a written response to Dr. Ney; we have not been advised
that Dr. Verduin requested a written response and so did not prepare one.
3. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Because we believe based on past experience that no substantial changes
will be made in the Fisheries Section, we also request that the Qualifying
Statement (page iii)be identified. This modification should emphasize that
the various Sections reflect primarily the opinion of the authors and are not
a result of Panel consensus and do not constitute Panel approval.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We believe the comment regarding our unwillingness to make substantial
changes in the Fisheries Section is untrue. We invite the reader to
examine the 10/1/73, 2/22/74, 5/23/74, 10/29/74 drafts of Fisheries Section
and to compare these earlier versions with the most recent one, which is being
readied for publication. For example, as the result of discussions with
Mr. Howe (and others), we:
1. updated and increased (nearly doubled the length of) the Literature
Cited Section of the Fisheries portion of the Report;
2. altered the text of the Report relating to the tagging program to
make it clear that mark and recapture studies are not recommended
for use in the estimation of population size;
3. changed the performance criterion that asked the field sampling
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program be adequate to detect differences of 5% (at a = 0.05)
to one adequate to detect true differences of only 20% (at a = 0.05);
4. added the Qualifying Statement on pages 256-257;
5. revised, reordered, and "nested" our research priorities;
6. expanded and revised the Introduction;
7. added Figures VII-1 and 2 to provide a basis for bridging the
gap between the intake and discharge effects sections of this
report;
8. we did not attempt to present a complete review of the literature
regarding cooling water use effects but rather selected for
presentation only what we believe were important overview papers
or papers that would lead the reader to the most current, relevant
literature or to important ongoing studies.
See also our response to comment 4.
4. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
We have prepared a modified Qualifying Statement which is attached for
Panel consideration. (Statement not attached - cf. written reply to
this comment).
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
The Report now carries a Qualifying Statement that was approved by a majority
of the Panel on July 8, 1975.
5. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Our last general consideration relates to impingement and station entrainment
of various fish life history stages. A different committee addressed these
considerations, and all reference in the Panel Report to fish impingement and
entrainment should be deleted as referenced to the Intake Committee Report.
We further note that neither consideration was a charge of the Panel in the
November 9, 1972, U.S. EPA Statement which established the Intake Committee
and Panel.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We believe that the Panel was charged by the Region V Administrator to deal
with the subject of cooling water use, which includes consideration of the
entrapment/entrainment issue.
As authors of the Fisheries Section we exercised our prerogative of modifying
the content of that section. The opportunity to comment on that section in
your letter of July 3, 1975, was afforded you.
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6. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
We strongly recommend that this Panel meet all of the original directives
before assuming additional responsibilities. For example, the charge to the
Panel was "to review background information dealing with past, present and
future studies relating to thermal discharges in Lake Michigan". This has not
been done, and in fact this charge should have been addressed before any
recommendation related to additional studies was made. The recommendation
for additional studies was the last and not first charge of the Panel which
is the logical order by which the charges should be addressed.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We believe the record shows that the Panel reviewed the ongoing research
programs at the Cook, Zion and Point Beach plants.
7. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
The Fisheries Section consists entirely of additional studies without review of
past, present and planned future studies to support their proposal or list
of priorities.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We cannot comment on the companies "planned future studies" because we have
not been privileged to see these plans (but see also our response to
comment 6).
8. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
The Fisheries Section should also delete references to impingement since the
previous report we reviewed did not discuss impingement.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
We have discussed impingement only to the extent we believed necessary to
provide an adequate perspective for viewing discharge effects.
9. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
We strongly disagree with the statement on page 245 which indicates that
current information on rhe abundance and dynamics of fish stocks is inadequate
to assess impingement losses as they relate to respective populations. There
is an abundance of literature or unpublished information related to stocking
rates, commercial catch and standing crop of several species. Losses at
screens are currently being computed and these losses can easily be compared
to these population statistics to determine if there is a concern.
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We point out on page 293 of the Report that limited information does exist
on the abundance and dynamics of the fish populations of Lake Michigan
(and indeed reference our unpublished report dealing in part with alewife
abundance in Lake Michigan). However, we believe, as stated in the Report,
that the available information is not yet adequate to assess the significance
of the impingement losses at Lake Michigan power plants, and (as also stated
in the Report) that the present basis for concern over the adverse effects
of existing power plants on the fishery productivity of the lake is partly
conjectural.
We assume that if an adequate demonstration of the significance (or non-signif-
icance) of these impingement losses could be made on the basis of the available
data that such a demonstration would probably have been made.
10. Comment of J.H. Hughes, Commonwealth Edison, Chicago. Illinois:
On page 293, the authors reference a report which contains a standing crop
estimate of alewives. This is undoubtedly the species which constitutes most
of the biomass removed at traveling screens. Yet from reading page 245, one
is led to believe there is no information available.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We certainly did not intend to imply that no information is available and
would be agreeable to inserting a parenthetical statement on page 245
directing the reader to page 285 of the report.
11. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois;
We have no additional general comments about the Fisheries Section and would
like now to specifically address the before and after studies described on
pages 258-276. The following is basically a reiteration of our comments in
my January 16, 1975, letter which the authors have not addressed.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
See our response to comment 1.
12. Comment of J.H. Hughes, Commonwealth Edison. Chicago. Illinois:
The tremendous effort which the study plan recommends will not meet the
stated objectives of determining size of fish stocks at the specific sites.
The authors indicate mark and recapture methods will be used in making these
estimates. All models, using such a technique, assume no immigration or
emigration in the area for which the population estimate is to be made. The
authors should review the assumptions in those references they used to support
their techniques on page 265.
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Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
We are aware of the assumptions inherent in the use of mark and recapture
data to estimate population size. The Before and After Section of the
Report does not recommend that mark and recapture studies be used for this
purpose (see page 273 of the Report), but rather that they be used to
provide an assessment of which populations or stocks are resident or not
resident in the site area.
13. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
There is more than adequate information to document that considerable movement
takes place within a given study area and plume area. The authors should
review some of the work conducted by Spigarelli (1972) at Point Beach.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We refer the reader in particular to the following papers which describe
onshore-offshore movements of fishes and movements of fishes within and
between effluent plumes in Lake Michigan: Wells, L. 1968. Seasonal depth
distribution of fish in southeastern Lake Michigan. U.S. Fish and Wildlife
Service, Fish. Bull. 67(1): 1-15, and to papers by Spigarelli, Spigarelli
et al., Romberg et al., and Thommes et al. that appear in the Argonne
National Laboratory Annual Report for 1973 (full citations of these latter
papers are giver, in the Fisheries Section of the Report).
14. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Results of studies by Cochran (1974) at Waukegan Station demonstrated that
the plume does not interrupt seasonal onshore-offshore movements, and in
general, plume abundance is not much different than abundance in reference
areas.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We suggest the reader study carefully Cochran (1974) and also those papers
cited in the response to comment 14.
15. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Not only would the program not determine population size, which is the stated
objective, but it could result in a greater kill of sport salmonids than
impingement.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
Given a 6-year Before and After sampling program (as outlined in the Report),
an annual bottom gill net catch of 686 salmonids (data for 1973-1974; Table 1
of your letter), a four-fold increase in sampling effort (comment 19), and
100% mortality of fish caught in these nets (comment 20), we assume you
would calculate a maximum kill in bottom gill nets, of (6 x 686 x 4 =) 16,486
salmonids at the sampling site; using the data from Table 1 for the 6 months
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in 1974 we assume you would calculate a maximum kill of (6 x 474 x 2 x 4 =)
22,752 salmonids as a result of the sampling plan. Using a three-fold
increase in sampling effort (comment 20) we assume you would calculate a
kill of (6 x 686 x 3 =) 12,348 salmonids at the sampling site on the basis
of your 1973-1974 data (your Table 1) and a kill of (6 x 474 x 2 x 3 =)
8,532 salmonids on the basis of your 1974 data (your Table 1).
Given an impingement kill of 145 salmonids per year (1973-1974 data from
Table 1 of your letter) for the estimated 40-year life of the Zion Plant
(316a demonstration for the Zion Plant) we calculate a maximum kill of
(145 x 40 =) 5,800 salmonids by impingement; using the 1974 data we calculate
an impingement kill of (138 x 2 x 40 =) 11,040 salmonids due to impingement.
The validity of the above estimates for the field sampling program must be
viewed in respect to the responses we made below to comments 19-25 and 28-29.
Likewise the estimates of the impingement loss cannot be verified by us with-
out information on the seasonal pattern of entrainment during one calendar
year of full plant operation.
We agree that the loss of salmonids and other valuable fishes killed by
impingement and by the field sampling program is regrettable, but we cannot
offer any alternative to measuring the effects of cooling water use that does
not require the sampling of stocks and the killing of fish.
As stated in paragraph 3 of page 256 and paragraph 2 of page 257 of the Report,
we clearly recognize that sampling plans and levels of sampling effort other
than those proposed in these guidelines may be adequate for answering tEe
questions posed in these guidelines. A clear demonstration of which of these
questions can or cannot be answered with existing data or with data from ongoing
studies would be of great interest to the Panel and to us.
16. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
This is the only effect of power plant operation, outside of speculations about
chlorine, for this group which has been documented.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We refer the reader to pages 35-46 and 71-74 in Edsall and Yocum (1972)
and to the papers of the Argonne National Laboratory cited in response to
comment 13.
We believe that no adequate studies have been done at Great Lakes power plants
of the effects of plant shutdown during that period of the year when
salmonids in the plume would be susceptible to cold shock kill, despite the
fact that shutdowns occur at this time of the year and that salmonids are
present in the plumes at this time of the year; adequate data are also lacking
for the effects of gas bubble disease despite the fact that conditions exist
in effluent plumes during the colder portion of the year that could cause
mortality (see Otto, 1973; full citation is given in the Fisheries Section of
the Report.)
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17. Comment of J.H. Hughes. Commonwealth Edison, Chicago. Illinois:
Most State Conservation Departments would probably be reluctant to allow
such a program.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We believe that the State Conservation Departments will make the appropriate
decision in this regard.
18. Comment of J.H. Hughes, Commonwealth Edison, Chicago. Illinois:
We made a comparison of salmonid impingement at Zion with numbers collected
in the monitoring program. Our sampling effort is about 3-4 times less than
that recommended in the Report, and the results of this comparison can be
found in the following table:
Comparison of salmonids collected at
Study
Interval
July 1973
to
June 1974
Total
July 1974
to
Dec. 1974
Total
travelling screens
lake monitoring by gi
Species
with numbers collected in
11 nets, trawls
Sampling
and seines
Method
Gill Net Trawl Seine
Lake Trout
Rainbow Trout
Brown Trout
Coho Salmon
Chinook Salmon
Lake Trout
Rainbow Trout
Brown Trout
Coho Salmon
Chinook Salmon
237
11
41
339
58
686
152
24
55
116
127
474
12 0
3 3
18 12
2 0
4 330
39 345
1 0
0 1
1 0
0 0
1 16
3 17
Impingement
1
5
4
133
2
145
13
60
21
44
0
138
362
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
We cannot respond to this comment without being advised of the manner in
which this estimate was obtained (see also our response to comment 24).
19. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Assuming 100% kill of only gill net collected fish, the number of sal mom'ds
killed in Zion's present monitoring program was four times higher than the
number impinged in the first year of operation, at what admittedly was
reduced operating levels.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We have no basis for not accepting this statement.
20. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
The monitoring program for the last six months of 1974 killed about 2 1/2
times more salmonids than were impinged.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We believe the correct value, based on the data in Table 1 and the
assumption of 100% mortality is 3.4 rather than 2.5.
21. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
Assuming a proportional increase in the number of salmonids killed in
'onitoring if the proposed study plan were initiated, approximately 1350
salmonids would have been lost or about 10 times the number impinged. This
projection was based on increasing the number of bottom gill nets from
16/month in our present monitoring program to 46/month in the Panel Report.
Writter raply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
See response to comment 16.
We believe the stated assumption of 100% mortality of salmonids captured
in gill nets (and the apparent implied assumption of zero mortality of fish
collected in trawls and seines?) is open to debate. Mortality would depend
on a number of factors including: the manner in which the nets and their
catch were handled; the season of the year (water temperature is important);
the size of the individual captured relative to the size of the net mesh in
which the individual was captured; the species captured (large coho salmon
die quickly in gill nets and chinook salmon less rapidly whereas lake trout
can survive gill net capture and release if proper precautions are taken).
Assuming a 100% kill of the 474 salmonids captured in gill nets (comment 20)
and a three-fold increase in sampling effort (comment 19) you would expect
a kill of 1,422 fish; likewise a four-fold increase in sampling
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effort would result in a kill of 1,894 salmonids—more than a ten-fold
increase. However, we believe these estimates of kill are open to debate
because the assumption of 100% mortality is not verified (see response to
comment 20) and because it has not been shown that estimates of a three- to
four-fold increase in sampling effort reflect sampling effort that would
occur at times and places where salmonids would be present (see comment 22).
22. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
These estimates did not include any salmonids which would be killed by the
oblique nets which would substantially increase the number killed.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
Generally oblique gill nets catch far fewer fish per linear foot of net
than do bottom gill nets, unless fish are distributed throughout the water
column or are much less abundant on the bottom than at higher levels in
the water column.
See also our response to comment 21.
23. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
It can also be expected that the number killed would increase for power
plants located in states where extensive salmonid stocking programs are
underway.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We agree that larger numbers of salmonids probably would be captured and
killed in areas of higher salmonid abundance.
24. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
We did not have time to stratify these projections by depth contour...
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan;
This is essential if your statements regarding the magnitude of the loss
of salmonids resulting from implementation of the sampling plan outlined
in the Fisheries Section of the Report are to be accepted at face value.
25. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
...but we did not use the general tactic employed by Mr. Edsall and
Mr. Yocum in their review of power plant studies. In this case we would
have selected the single gill net with the highest number of salmonids and
multiplied by 552 or the total number of sets for each year.
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
This comment appears to be related to a review we prepared for the Panel
of the PL 92-500, section 316a demonstration for the Zion Plant. We
believe it would not be proper to deal with it here but wish to point out
that it suggests that the view expressed in comment 6 is not entirely
justified.
26. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
The before and after studies are estimated to cost approximately $1 million
dollars/year or $6 million dollars for a new station with 3000-4000 cfs
intake flow.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We cannot respond to this comment without access to the cost factors on
which the estimate is based.
27. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
In light of the above review, the studies should be substantially reduced.
We recommend that sampling be done only within the 10 meter depth contour
as recommended by Mr. Patriarche. In addition, sampling for quantitative
purposes should also be designed to evaluate primarily the dominant species
as recommended by Dr. Verdiun.
(NOTE: Six lines of comment have been deleted here and are presented
below as comment 28.)
An attempt to detect these differences at each location over time and between
locations within time in Figure VII-3 for most species would be ecologically
irresponsible and should require an Environmental Impact Statement.
Thus, we urge that for quantitative purposes only two locations, one reference
and one experimental, be sampled with sufficient intensity to detect a 20%
change. This experimental design would permit an evaluation of preoperational-
operational abundances as well as attraction - avoidance to the thermal plume.
Furthermore, the sampling effort should be restricted only to dominant species.
These studies, including the bottom trawls, use relative abundance as an
index to population change and do not estimate population size.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We believe that the Questions to be Answered that are presented in the
Fisheries (and Entrapment/Entrainment) Section(s) of the Report require
answers if the effects of cooling water use on the fish and the fisheries
of Lake Michigan are to be adequately assessed. These Questions can be
answered with existing data if adequate data exist, or with new data yet
to be collected.
We enclose a copy of our response to Dr. Ney's letter of July 1, 1975, which
deals with the issues raised in your comment above. (Enclosure is not a
part of this appendix.)
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28. Comment of J.H. Hughes, Commonwealth Edison, Chicago, Illinois:
On page 257, the authors recommend a sampling effort which can detect a
20% change in population size with a = 0.05. This should only be done for
major species at a few locations since the number of replicates at each
location would also have to be substantially increased above the two
replicates the authors recommend if they wish to detect a 20% change.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We believe Mr. Howe informed us that a 20% change in population size with
a = 0.05 could be obtained with the data currently being collected for
your company which we believe involves duplicate (two replicates) sampling
(Cochran 1974).
**************************
1. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
It is unfortunately not possible to endorse this section or even to provide
brief constructive comments which render it more scientifically acceptable.
A number of fisheries biologists who have reviewed it have expressed strong
reservations about both the feasibility of the proposed program and its
ability to answer relevant questions concerning cooling water effects.
Alternative methodology has been suggested but largely ignored.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
Approximately 100 copies of the Lake Michigan Cooling Water Studies Panel
Report were distributed for comment and we have attempted to respond (as
directed by the Panel on 10/1/74) verbally or in writing to each person
who offered comments of substance on the fisheries section of the Report
and to make changes in the text of the Report that we believed would improve
the usefulness of that section of the Report as a guideline for assessing
the local and lakewide effects of cooling water use on the fish and the
fisheries of Lake Michigan.
Issues of substance in these written comments that did not result in modifi-
cation of the text of the final draft of the Report should be included in the
Appendix of the Report.
2. Comment of J.J. Ney, Wisconsin Electric Power Company. Milwaukee, Wisconsin:
The description of intake effects on Lake Michigan fishes (pp. 246-248 and
p. 250) is completely out of place in this section. The situation has been
thoroughly discussed in the Lake Michigan Cooling Water Intake Structure
Technical Committee Report (1973) and in Section VIII of this document.
Inclusion of a separate interpretation of the problem here serves only to
further confuse the issue.
366
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We believe that the charge to the LMCWSP by the Region V Administrator
included consideration of intake effects. We have discussed intake effects
in Section VII of the Report only to the extent necessary to provide an
adequate perspective for viewing discharge effects.
3. Comment of J.J. Ney. Wisconsin Electric Power Company, Milwaukee. Wisconsin:
The presentation of conjecture (e.g. "it is clear that all of the fish large
enough to be impinged on the travelling screens of existing power plants on
Lake Michigan are killed"...p. 250) as fact is especially deleterious to
objective analysis of entrapment effects.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
The reader is directed to paragraph 2 of page 250 of the Report from which
the above quote was excerpted. The remainder of the quote is, "...when they
are drawn into these plants because none of these plants are now equipped
with devices that would permit returning these entrapped or impinged fish
to the lake alive." We believe this is a true statement and as such can only
aid in the objective analysis of the effects of cooling water use.
4. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Most of the survival-threatening conditions noted on pp. 251-254 have not
been observed to occur as a result of Lake Michigan cooling water discharge.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
Various published studies (see pages 251-254 of the Report for references)
suggest that high velocity jet-type discharges may cause damage to fish.
Therefore, we believe that this potential problem area should be systematically
investigated at Great Lakes plants.
We believe that the potentially adverse effects of chlorine in waste heat
discharges have been adequately demonstrated (item 3 on page 251 of the Report).
We also believe that predation on fish fry incapacitated by heat shock and
mechanical damage has been observed in the discharge of the Nanticoke generating
plant on Lake Erie (item 5 on page 251 of the Report).
5. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Laboratory experiments and studies of other ecosystems serve only to define
areas of potential concern.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan;
We agree in part. We would add .that the behavioral responses of unconfined
fish at the cooling water use site must be studied to provide a completely
367
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satisfactory interpretation of laboratory or on-site bioassay studies.
6. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
This report was designed as a guide for study design. As with any guide,
flexibility in implementation of procedures is a requisite. While standardi-
zation of methodology is a commendable goal, it should not be realized at
the expense of rational design.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We agree in principle (see pages 256 and 257 of the Report); however, see also
our response to comment 18 as it relates to Lakewide Studies and the attendant
need for intersite standardization of sampling plans.
7. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Deviation from prescribed procedures (p. 257) do not require "clear justifi-
cation" (to whom?) since these procedures are often arbitrary in themselves
(See comments 8, 9, 10, and 11)
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We had hoped that the Report would be viewed as an attempt to provide a
comprehensive guide to aid in objectively determining the effects of cooling
water use on the fish and fisheries of Lake Michigan. We believe that the
accumulation of a scientifically acceptable body of fact regarding the effects
of this use of the waters of the lake is the best approach to resolving this
issue objectively. To this end we propose that the word "scientific" be
inserted between the words "clear" and "justification."
8. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Encompassing and saturation of the plume area with sampling stations is
exorbitantly expensive and unnecessary to determine cooling water effects.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We agree that the proposed sampling plan for Before and After studies will
be expensive, but have no way of determining its cost relative to the cost
of ongoing studies at Lake Michigan plants because information on the latter
costs are generally unavailable to us.
9. Comment of J.J. Ney, Wisconsin Electric Power Company. Milwaukee, Wisconsin:
Stations should be limited to 6-foot-interval depth contours within the
plume area and at similar depths in a representative reference area.
368
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Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We doubt that this proposed alternative plan would be an adequate substitute
for the plan offered in the Report. (See also our respone to comment 10).
10. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Adoption of the pattern in Figure VII-3 would impose a degree of rigidity
on the study design which can't be justified relative to the variable
configurations of plumes and lake morphometry for each unique facility.
Written reply of T.A.' Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
The sampling grid (Figure VII-3) was chosen after examining a large number
of other study plans. It incorporates what we believe are the most desirable
features of these other study plans as these features could be adapted to
the situation on Lake Michigan (for example, see: Carton, R.R. and
R.D. Hawkins. 1970. Guidelines: Biological surveys at proposed heat
discharge sites. U.S. Environmental Protection Agency. Water Pollution
Control Research Series. 16130—04/70. 99 pages).
Two of the major considerations we took into account in designing the grid
were lake morphometry/bathymetry(one determinant of the station locations
are the depth contours) and the variable nature of the effluent plumes (the
grid was designed to cover that portion of the lake in which the waste heat
from the plant could be expected to be detectable, plus a surrounding
reference or control area in which no temperature elevation could be expected
to occur).
The area of highest station density within the grid reflects what we believe
to be the area in which the plume will be most frequently located. Shoreline
extensions of stations (up to 7.5 m in both directions from the center line
were included to take into account the poorer mixing conditions that occur
when an offshore wind holds the effluent against the shoreline, thus creating
a more elongate plume. The lakeward extension of stations (those along the
center line on the 90-120 foot depth contours) was included primarily to
permit documentation of the offshore-onshore distribution and movements of
fish in the site area, as these would affect seasonal changes in vulnerability
of the various fish species and their life stages to the effects of the plant.
For example, if it could be demonstrated that the offshore waters of the lake
(rather than only the waters of the littoral zone) were an important nursery
area for most species of fish, our concern over locating plant intakes and
discharges in the littoral zone would be greatly reduced.
The "bilateral" symmetry of the grid (stations at depths of 60 feet and
shallower) was included as a design feature because it permits nested analysis
of the data.
11. Comment of J.J. Ney. Wisconsin Electric Power Company. Milwaukee, Wisconsin:
As a workable alternative, the following design should be considered:
369
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Sampling stations should be located at 6 foot-interval
depth contours within the plume. Owing to the variable
configuration of plumes, potential sampling stations
should be located on a grid, with actual stations dependent
on the plume configuration on each sampling day. One
station should be located in the immediate proximity of
the discharge. Fixed stations should be located on the
same depth contours in a representative, thermally-
unaffected reference area. To illustrate: if the area!
extent of a plume is limited to the 30 foot depth contour,
stations would be located along the 6', 12', 18', 24',
and 30' depth contours in the plume and in the reference
area. In this instance, a total of 10 stations would
be sampled.
Written reply of T.A. Edsall,. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan;
Because the stations are fixed,they can provide the time-series data needed for
a Before and After type analysis. We believe that the alternate sampling plan
outlined in the above comment would be more suitable for use in answering
questions posed on pages 276-280 (Intensive Plume Studies) of the Report
(see also our response to comment 10).
12. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
The Materials and Methods described beginning page 260 are unnecessarily
intensive to obtain answers to basic questions. The costs (biological and
economic) of this type of sampling program cannot be justified, especially
since direct evidence for significant adverse effects of thermal addition on
Lake Michigan fishes is negligible.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
To our knowledge it has not been adequately demonstrated that the effects of
power plant discharges on the fishes of Lake Michigan are negligible.
13. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Comparison with the results of previous sampling indicate that the gill net
sampling program along would kill in excess of 20,000 salmonids/site/year.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
The validity of this statement cannot be determined by us because the basis
for the estimate is not given.
14. Comment of J.J. Ney. Wisconsin Electric Power Company, Milwaukee. Wisconsin:
This is clearly intolerable to the various management groups; no one wants to
destroy the fishery in order to save it.
370
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Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
See our response to comment 18. Without answers to the Questions posed on
pages 293 and 294 of the Report, we are left with little on which to base
our assessment of the significance of the effect of cooling water use.
If use of the sampling plan results in an intolerable kill of salmonids and
other desirable fish, we believe the management groups with proprietary
interests in the fish and fisheries of the lake would order a reduction in
that kill.
15. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
The following modifications are suggested for consideration in development
of a realistic sampling plan:
Page 260 - la. Trawling should be conducted on transects along contours,
not at stations.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
This is covered in item c.2. on page 261 of the Report.
16. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 260 - lb(l). Use of the 16 ft. bottom trawl results in redundant sampling
in the 0-10 ft. zone. b(l) can be deleted in favor of using the 39 ft. trawl
at depths greater than 6 feet and the seine from 0-6 feet.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
The vessel required to tow a 39-foot trawl effectively would probably not
be able to operate safely in less than 10-12 feet of water; the 16-foot trawl
could be towed effectively and safely with smaller, shallow draft vessels at
water depths of less than 10 feet.
17. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 260. Bottom trawling is often not possible due to obstacles (rocks, trees,
etc.). Provision should be made for substitution of midwater trawl, so that
sampling will cover those depths contacted by the plume on the sampling day.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan;
If bottom trawling in shallow water is not possible, we would recommend the
use of a seine or trapnet. We believe midwater trawling technology has not
been developed to the point that we would recommend that it be used routinely
as a substitute for bottom trawling in shallow water.
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18. Comment of J.J. Ney, Wisconsin Electric Power Company. Milwaukee, Wisconsin;
Page 262- 1.3d. Age determination, if it is to characterize populations,
is an involved, laborious process which must be performed for each species.
Length-frequency analyses and condition factor determinations will provide
sufficient information concerning population structure and well-being to
reveal harmful effects. Aging, if conducted at all, should be confined to
species known to be resident. Applying this effort to transients in a
localized study is fruitless.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
Section VII of the Report deals with the assessment of both local and lake-
wide effects. The objectives of the lakewide studies are stated on page 292
of the Report and include a description of the age structure of the fish
populations of importance. The (local) studies we have outlined for
implementation at cooling water use sites are designed to provide data that
will contribute to the success of the lakewide study effort.
We would be agreeable to insertion of the following paragraph in the text
of the Report on page 262 between paragraph 2 and 3 of section 3d:
Scale samples should be taken monthly from at least 300 fish (age group I
and older) of each of the following species: smelt, alewife, yellow perch,
and each species of coregonine captured. If subsequent analyses of the age
composition o^ the annual catch shows agreement with estimates obtained by
resource agencies conducting similar research on the fish stocks of the
lake, this sampling effort can be reduced so that scales are collected
annually only during one of the fall sampling series.
19. Comment of J.J. Ney, Wisconsin Electric Power Company. Milwaukee, Wisconsin:
Page 264-265-(5)(a) through (5)(c) - Feeding habits, contamination, and
fecundity analyses should be limited to only those species known or suspected
of prolonged plume residence. Killing deepwater ciscoes, for example, to
perform these analyses is both superfluous and deleterious. (5) should
include a provision limiting sample preservation to those species suspected
. of plume residence.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We agree that items 5a-c should be performed on fish known or suspected
of prolonged plume residence. However, we do not wish to exclude the
possible need to study plume effects on those other fish species which may
avoid the plume or reside in the plume briefly. For example: if the
periodic presence of the plume in a given area alters the benthos community
in that area, the feeding opportunity of fish (that avoid the plume but
move into that area after the plume has departed) may be altered; also
the successful incubation of fish eggs spawned in a given area when the
plume is not impacting that area, may be reduced when the plume returns.
372
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20. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 265 e(l). Population estimates should only be made for resident
populations. As with aging, population estimation is a laborious and some-
what sophisticated process and should not be performed on transient species,
estimates for which would be useless.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
See paragraph 1 of the response to Comment 18.
21. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 266 2(a). Gill net sets should be located as follows: one oblique and
one bottom net at near field and at far field stations in the plume and at
comparable depths in the reference area. Sampling frequency should be
limited to four successive 12-hour sets.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
Reduction in the sampling effort below levels specified on pages 266 and
269 of the Report is desirable (see paragraph 2 on page 257 of the Report),
if it can be demonstrated (for the entire area impacted by the plume during
all seasons of the year) that the "Questions to be Answered" on page 258 of
the Report can be adequately answered with a reduced sampling effort.
We do not believe the alternate sampling program proposed in the above comment
would be an adequate substitute for the sampling plan presented for use in
the Before and After Section of the Report; we believe the alternate sampling
plan presented in the comment above may be better suited for studies of the
type outlined in the Intensive Plume Studies portion of the Report (pages 276-
287).
22. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 271 4a. Fry sampling should be conducted on transects along contours
from 6' to edge of plume and over same depths in reference area. Sample at
surface, middle depth and, where possible, bottom. 4c (2) should advise
night sampling to reduce larval avoidance.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
See response to comment 21.
23. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 272 5a. Pump sampling stations should be confined to 6' interval
depth contours in plume and reference area. 5b - Water should be passed
through 351 micron mesh to be compatible with entrainment sampling.
5c(2) Sampling should commence April 15, unless smelt are not considered.
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
See response to comment 21.
A number 30 mesh screen would retain the smallest fish egg that would be
encountered in Lake Michigan, therefore, there is no need to use a 351
micron mesh for pump sampling for fish eggs.
We agree that pump sampling should begin early enough in the spring to
assess deposition of eggs by smelt.
24. Comment of J.J. Ney, Wisconsin Electric Power Company. Milwaukee, Wisconsin:
Page 275 6(b) (2). Tagging should be performed coincidental to other
sampling, with viable fish tagged and returned. The separate effort outlined
here is unnecessary unless viable fish are not captured by trawl, seine and
gill net. Tagging should also be confined to these species suspected of
plume residence e.g., if brown trout members are seasonally higher in the
plume than in the reference area, tagging studies should be performed to
determine potential interference of the plume with migratory behavior.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We agree that "coincidental tagging" may provide enough fish to meet Before
and After study needs; but see also pages 276-287 of the Report.
25. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Intensive Plume Studies (page 276) and Laboratory Studies (page 289) afford
the best means of defining real problems of fish relative to cooling water
discharge. In the logical sequence of investigation, the seasonal plume
residence patterns of the various species should first be determined. Results
of thermal laboratory bioassay and behavioral studies can then be applied to
focus concern on those species for which adverse effects can be anticipated.
The field sampling program should then be refined to determine the magnitude
of such effects.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
In general we agree that the most obvious direct effects of cooling water
discharges on Lake Michigan fish will be most easily defined by means of
Intensive Plume Studies and Laboratory Studies. We are in general agreement
with the rest of the comment.
26. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee. Wisconsin:
The results of both Intensive Plume and Laboratory Studies should have
general application and need not be replicated at each site.
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
We believe that some of the studies conducted at each cooling water use
site may not have to be repeated at other sites.
27,, Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Intensive Plume Study No. 4 (p. 286) is only relevant if ATs experienced in
plume shifts or upwelling have a potential for deleterious effects. This
information has been, or can be, obtained in bioassay. The same holds for
chlorination. This study guide should note that efforts should be confined
to those species which show adverse effects at the AT or chlorination levels
observed at the site.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
We agree that information from the literature, or from the results of on-site
bioassay studies or studies conducted in the laboratory, together with infor-
mation on plant operating characteristics and local limnological conditions
can be used to provide a demonstration of the likelihood of damage to fish as
a result of the discharge of waste heat and toxic chemicals at a given site;
therefore, we also agree that these "non-field" studies can serve adequately
. as the basis for excluding species of fish from study of specific effects at
particular cooling water use sites.
28. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
There is little evidence that water quality in Lake Michigan varies so widely
as to necessitate site-specific chlorine toxicity tests (p. 287). Section III
of this report, while describing chemical parameters makes no mention (other
than influence of adjacent tributary streams) of intra-lake water quality
differences. Information obtained using water within the range of normal
Lake Michigan chemical composition should be of general application.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
We have seen no evidence to indicate that water quality in Lake Michigan at
the various cooling water use sites is so uniform as to preclude the need
for onsite or site-specific chlorine toxicity tests. Furthermore the design
and operating characteristics of plants on Lake Michigan vary widely and these
may be important in determining the probability of damage to fish occurring
as the result of chlorination.
29. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
(Pages 287-289). Although on-site bioassays can be of value in determining
actual effects of chlorination, cold shock etc. as they occur in the field,
it should be recognized that in-situ bioassays which require caging of fisK
apply artificial stress which can have an additive effect. Results of such
studies must be considered relative to their limitations. If the natural
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environment cannot be successfully simulated, on-site bioassays and
behavioral experiments may be worthless. Cage studies can be used to verify
results of laboratory experiments - an iterative procedure. However, results
at odds with lab findings are of value in inverse proportion to the artifi-
ciality of the situation.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
We realize the laboratory studies and on-site bioassays cannot be expected
to reproduce exactly the field conditions that result from cooling water use
at a particular site. We recognize that the behavioral responses of unconfined
fish at a cooling water use site must also be studied to provide a completely
satisfactory interpretation of non-field studies and therefore of the effects
of cooling water use.
The procedures that we recommend on pages 288 and 289 of the Report represent
the best methodological approaches available at the time we drafted our contri-
bution to the Report. As better methods become available they should be used.
30. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee. Wisconsin:
Materials and Methods 1, 3, and 5 (pp. 288-289) are completely artificial
situations and results can have, at best, limited relevance. They should
be discounted.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We disagree (see responses to comments 27 and 29).
31. Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
In addition, all cage studies must include control groups and both groups
should be tested for sub-lethal physiological stress. It should also be noted
that results of all of these experiments have general application.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
We agree that the use of control or reference groups is essential and that
measures of both acute and sub-acute effects may be necessary and that some of
the results of these studies may have application at more than one cooling
water use site.
Comments related to Section VIII
Measurement of the Effects of Cooling Water Use
on Entrapped and Entrained Organisms
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Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Pump Location - Pumps should be located behind the traveling screens if at
all possible to avoid the problem of pumping adult fish in the collecting
nets. We have experienced several pump cloggings when numerous adult fish
inhabit the intake bays.
reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
I agree completely.
Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Planktonic eggs - It has been impossible to establish numbers of planktonic
eggs being entrained due to the problem referred to in Pump Location (above) and
compounded by the occurrence of ripe females in the intake that expel their
eggs during the stress of impingement. These eggs would be sampled on either
side of the screens thus possibly resulting in a significant error in estimates
of planktonic eggs.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
I believe that the freshwater drum (Aplodinotus grunniens) is the only fish
species in the Great Lakes that has a truly planktonic egg.
The problem of distinguishing between eggs entrained from the lake and those
expelled by entrained fish may be a difficult one, however, sampling simultane-
ously at the intake crib and in the traveling screen well should provide a basis
for determining the relative importance of the two sources.
Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Net Mesh Size - The recommended 351 micron size is not a normal stock size at
Wildco, thus necessitating a special size. Why is 351 micron mesh so critical.
Why not their 363 micron size? Its been our experience that the small 333
micron size we are using collects so much zooplankton and suspended material
that samples take much longer to pick at times. We are alsp using 571 micron
mesh at the Monroe Plant, due to the heavy organic load, and still collect eggs
and all developmental stages of fish.
Written reply of T.A. Edsall , U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
Our experience has show us that 351-micron mesh is about the largest mesh size
that will capture the smallest fish eggs and larvae found in the Great Lakes.
We have conducted no mesh selectivity studies using 363-micron mesh but suspect '
that it would result in a slightly lowered catch of the earliest life stages
of some Great Lakes species. There can also be little doubt that 571-micron
mesh would permit the loss of a considerably higher percentage of the earliest
life stages of several species of Great Lakes fish than would either 351- or
363-micron mesh. '
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Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Pump Type - What type of pump can be used to insure an adequate sample size and
still not cause damage and mortality to the larval fish? This should be
included in this report, and also inclusion of the basic plan for the Great
Lakes Fishery Laboratory's automated pump system, if that is the recommended
type.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor.
Michigan:
The Report suggests (pages 333-334) that "damage and mortality" assessment be
made with samples collected in plankton nets suspended in the cooling system
flow rather than with the samples obtained by pumping.
Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Pump Numbers - What procedure should be utilized to establish exact pump
locations when the plant has more than one unit? This should be in this
section, especially when investigators are asked to "document horizontal and
vertical stratification" in the intake and now I assume in the discharge.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
I can only suggest that the investigator take the empirical approach in
answering this question. If the investigation cannot demonstrate that he has
satisfied the assumptions implicit in sampling, then his results surely will
be open to debate.
Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
Determination of Live and Dead Larva. Has any work been done on survival
rates of larval fish pumped and collected in nets and the effect on them?
How long can a larval fish survive retention in a net, a matter of minutes or
several hours. This will directly affect frequency of sample removal and
determination of mortality.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor,
Michigan:
I agree that information of this kind is needed to adequately evaluate the
effects of entrainment in some situations.
Comment of R.S. Benda, Aquinas College, Grand Rapids, Michigan:
I agree this is probably one of the most important parts of the overall
evaluation of the impact.of once-through cooling, but it seems that aspects
are going to be difficult if not impossible to determine (i.e. page 330,
number 9). Thank you for allowing me to comment on the section. I'm sure
its been a difficult task to accomplish.
378
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Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
I agree that it may be difficult to answer question 9 on page 330, but if the
answer to question 3 on page 329 is "yes", then it becomes necessary to
address question 9 if means other than closed cycle cooling are sought to
reduce entrainment damage.
Comment of J.R. Gammon, De Pauw University, Greencastle, Indiana:
I have expressed the view previously concerning the entrainment section of the
Report, but let me briefly reiterate my views. I believe that the research
program outlined in this section is a very complete and ambitious one. I
would very much like to see it implemented at one or more (up to four strategi-
cally located) stations to test its capability and search out its difficulties.
However, I feel that such a program at each and every power station would not
be reasonable in terms of use of time, effort, and money.
A written reply to this comment was not received.
Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 329, Number 3. The phrase "when added to the other losses resulting from
cooling water use" should be deleted. Evaluation of cooling water intake
structure impact should be made separately (per Public Law 92-500, Section 316 (b))
from other cooling water use effects. Remedial (best available) technology for
cooling water intakes to alleviate entrainment/entrapment impact can be applied
without substantial modifications to other facets of power plant operation.
Since evaluation of the impact and the application of potential corrective
measures for cooling water intakes are not dependent on other aspects of cooling
water use, the issue is self-contained. If cooling water use effects are
considered in toto, it will be extremely difficult to determine appropriate
corrective action. If the present wording is retained, it could be construed
that Questions 4 - 9 on pp. 329-330 should be addressed in situations where
entrainment/entrapment is negligible, but other cooling water use effects on
fish populations are significant. In this instance, considerable effort and
expense would be directed toward answering irrelevant questions.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service. Ann Arbor.
Michigan:
I have asked to have the words, "...in itself, or...", inserted immediately
ahead of the phrase you suggest be deleted. I believe that this addition will
help convey to the reader the idea that evaluation of the significance of the
effects of entrainment on "non-screenable" fish, fish larvae, and eggs should
first be made independently of the other possible adverse plant impacts on
these classes of organisms. However, it should also be apparent to the reader
that the incremental loss of fish, fish larvae, and eggs cannot be judged
insignificant until it is added to the incremental losses caused by all of the
other aspects of plant operation and until this "total" loss is evaluated in
respect to its impact on the local and lakewide fish population for the (one)
plant operating alone and for the plant operating in concert with other similar
plants on the same water body.
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Comment of J.J. Ney, Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Page 333,. Sampling Frequency and Duration. Sampling should be performed
continuously every fourth day of plant operation April 15 - October 31, during
one year. Sampling in additional years should be contingent on the results
of the first year's study and may not be required. The Lake Michigan Cooling
Water Intake Technical Committee's Report on the Best Available Technology
(1973) recommends one day per week sampling as a minimum. The several regulatory
agencies which are currently administering Lake Michigan entrainment survey
programs have suggested sampling of approximately this frequency.
Written reply of T.A. Edsall. U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
I have seen no data which shows that "...sampling every fourth day..." (etc.)
would be adequate to describe the kinds and numbers of fish eggs and larvae
(ichthyoplankton) that are entrained (continuously), and until such data
demonstrating the adequacy of that sampling frequency are made available for
public review, I believe it is appropriate for me to support the sampling
program outlined in the Report.
Comment of J.J. Ney,-Wisconsin Electric Power Company, Milwaukee, Wisconsin:
Sample Processing (p. 333) and Sampling Process (p. 335) should be identical;
instructions need not be repeated.
Written reply of T.A. Edsall, U.S. Fish and Wildlife Service, Ann Arbor,
Michigan:
I disagree. The Sampling Process outlined on page 335 is for studies
designed to permit assessment of in-plant mortality of non-screenable fish,
fish eggs and larvae and requires examination of the samples at the time they
are collected. The Sampling Process outlined on page 333 is intended only to
determine the kinds and numbers of non-screenable fish, fish eggs, and larvae
that pass through the plant; this can be done from preserved samples as indicated
on page 333.
General Comments
related to Report Number 1
Comment of F.R. Boucher. Wisconsin Electric Power Company. Milwaukee. Wisconsin:
I have reviewed and diseased with my staff the Lake Michigan Cooling Water
Studies Panel (LMCWSP) Report recently entitled "A Statement of Concerns and
Suggested Ecological Research" and offer the following general comments as a
member,;of the LMCWSP.
1) While the document may well represent a "best efforts" attempt
by a panel of diverse technical background and interest, the report
unfortunately retains much of the inconsistency of approach, format
and possible purpose which plagued its earlier drafts. Most sections
are reasonably well-organized, defining pertinent questions concerning
380
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cooling water effects and proposing logical measures to provide answers.
This is especially true of the Macrozoobenthos Section. Other sections,
notably those dealing with Primary Producer and Consumer Communities
and with Fisheries, appear significantly less rationally developed and
may negatively affect the utility of the entire report. In these
sections, study measures of immense magnitude are described, often with
no clear explanation of why they might be either necessary or even
capable of providing useful answers relative to cooling water effects.
Little or no concern is given to the feasibility of their implementation.
It is obvious that the clarity and logic of these sections must be
markedly improved if our report is to reflect the quality and intention
of the Panel and be the meaningful document which we all intend it to be.
2) As I understand the motion adopted by the Panel at our October 1, 1974,
meeting, comments on the program were to be solicited for incorporation
into the October 29th draft of the Report. Comments not incorporated
were to be rebutted by the section authors. It is apparent that comments
on several sections were neither incorporated nor rebutted. For example,
Dr. J.J. Ney and other fisheries biologists have charged (ref. J. Ney
letter to T. Edsall» December 26, 1974) that the Fishery sampling program
would bill an intolerable (to management groups) number of sport fish.
This allegation, if true, could jeopardize acceptance of the entire
report; yet no response to it has been made. To satisfy the explicit
intention of the Panel expressed by its action of October 1st, the Report
cannot be finalized until the solicited comments are considered in this
manner.
3) As you yourself have noted in your June 6th memorandum, sections of
the Report reflect the view of a particular author. The Report clearly
is not a product of the Panel on the whole. It was for this very reason
that comments of other acknowledged experts were requested so that a more
balanced overview might be presented. It is fundamental to the production
of the Report as an objective and useful document that expert commentary
not be ignored and that the procedure adopted by the Panel be followed
prior to its completion, printing and distribution.
Written reply of E.F. Stoermer, University of Michigan, Ann Arbor,
Michigan:
Studies of the type outlined under the section on Primary Producer and Consumer
Communities are routinely accomplished by any number of scientific institutions.
I see no reason why the feasibility or implementation of such a project should
present "immense" problems to any qualified investigator.
Reply of K.E. Bremer, U.S. Environmental Protection Agency, Chicago, Illinois:
A reply to comment 2 is furnished on page 356, reply to comment number 2.
Comment of J.Z. Reynolds, Consumers Power Company, Jackson, Michigan:
This is in response to your request for consideration and comment on the final
draft of the Lake Michigan Cooling Water Studies Panel Report Number 1. Inasmuch
as I have commented in detail on previous draft sections of the report, I will
limit my remarks here to general observations of how I feel about the final
version of the report.
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The improvements that have been made from earlier drafts are largely editorial
and do not reflect much responsiveness of a technical or objective nature to
the comments received. The various sections remain largely the product of the
invividual authors, and are not a concensus of the Panel or those who commented.
The Microbiology and Fisheries Sections suffer most in this respect, since they
received the most critical comment but, lacking a formalized review procedure,
this must be the case to some degree for all sections. Therefore, the Qualifying
Statement should more clearly emphasize that the different sections represent
the personal views of the authors and various references to "Panel" views scattered
throughout the report are generally those of the section authors.
The final title for the report adequately characterizes the content, but much of
the "suggested ecological research" has not been justified in terms of scientific
validity or cost effectiveness. Suggested data collection activities are not
related to study objectives or the Panel's role of determining what is ecologically
significant or important. Further, while the priorities for research in each
category reflect some ordering of concerns, there has been no attempt to relate
the priorities of one category to the relative needs in another. This is a severe
limitation on the usefulness of the report.
I regret that I am not being very constructive in my comments, as you requested,
but I feel compelled to note also that the findings related to the charge to the
Panel, of reviewing and assessing the adequacy of studies relating to thermal
discharges, are not reflected in the report. In many cases the Panel, in reviewing
specific study plans, determined them to be adequate, but comparison with the
"suggested ecological research" would indicate they are totally inadequate. Such
contradictions without explanation, in my opinion, severely threaten the credibility
of the Panel as a technical advisory group.
A written reply to this comment was not received.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-905/3-75-001
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
A Statement of Concerns and Suggested Ecological
Research: Report Number 1 of the Lake Michigan
Cooling Water Studies Panel
5. REPORT DATE
November, 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Lake Michigan Cooling Water Studies Panel
C.D. Meyers and K.E. Bremer, editors
8. PERFORMING ORGANIZATION REPORT NO.
Report Number 1
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Lake Michigan Cooling Water Studies Panel
U.S. Environmental Protection Agency
230 South Dearborn Street
Chicago, Illinois 60604
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Surveillance and Analysis Division, Region V
230 South Dearborn Street
Chicago, Illinois 60604
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents a statement of concerns and suggested research by the
Lake Michigan Cooling Water Studies Panel. The intent of the statement is to assist
the development of investigations of the effects of cooling water use on Lake Michi-
gan.
The introductory considerations of Lake Michigan are presented in the first
section. The second section presents recommendations toward objective quantification
of the effects of cooling water use through proper statistical planning, study design,
and data collection. The remaining seven sections relate information the authors
consider basic to an understanding of the effects of cooling use on physical and
chemical aspects, primary producer and consumer communities, macrozoobenthos, fishery,
entrapped and entrained organisms, and radioecology of Lake Michigan.
All sections of the report attempt to produce improvement in research design and
a trend toward standardization of results. In addition, questions are posed and
ranked resulting in numerical priorities with the intent to guide research in those
areas of knowledge which are barriers to an adequate understanding of the effects of
cooling water use.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
Cooling Water
Aquatic Biology
Biostatistics
Entrainment
Benthos
Plankton
Fisheries
Hydrology
Water Chemistry
Limnology
Ecology
Lake Michigan
Thermal Effects
Radioecology
6 F
13 B
18. DISTRIBUTION STATEMENT
Limited number of copies from U.S. EPA,
Chicago. At cost of publication from NTIS,
5285 Port Royal Rd., Springfield.Va. 22161.
19. SECURITY CLASS (ThisReport)
21. NO. OF PAGES
20. SECURITY CLASS {Thispage}
22. PRICE
EPA Form 2220-1 (9-73)
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