USA
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State of the Lakes Ecosystem Conference
Aquatic Community Health
of The Great Lakes
October 1994
Environment Canada
nvironmental Protection Agency
EPA 905-D-94-001a
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State of the Great Lakes Ecosystem Conference
AQUATIC COMMUNITY HEALTH
OF THE GREAT LAKES
Joatph F. Koonct
Dtpartmtnt of Biology
Cast Wtittrn Rtwrvt Unlvtrilty
Cltvaland, Ohio
July, 1994
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Table of Contents
Acknowledgments ii
EXECUTIVE SUMMARY 1
1.0 INTRODUCTION 3
1.1 Concepts of Ecosystem Health 3
1.2 Great Lakes Aquatic Ecosystem Objectives 5
1.3 Indicators 6
1.3.1 Fish and Wildlife Health Indicators 6
1.3.2 Community Health Indicators 7
2.0 STATUS AND TRENDS FOR FISH AND WILDLIFE HEALTH 11
3.0 STATUS AND TRENDS FOR COMMUNITY HEALTH . 15
3.1 Case Study: Lake Erie .. ....'. 17
3.2 Oligotrophic Waters 18
4.0 MANAGEMENT IMPLICATIONS 21
4.1 Evaluation of Stresses 21
4.2 Management Challenge 22
5.0 LITERATURE CITED 25
Figures 29
NOTICE TO READER
These Working Papers are intended to provide a concise overview of the status
of conditions in the Great Lakes. The information they present has been
selected as representative of the much greater volume of data. They
therefore do not present all research or monitoring information available.
The Papers were prepared with input from many individuals representing
diverse sectors of society.
The Papers will provide the basis for discussions at SOLEC. Readers are
encouraged to provide specific information and references for use in
preparing the final post-conference versions of the Papers. Together with
the information provided by SOLEC discussants, the Papers will be
incorporated into the SOLEC Proceedings, which will provide key information
required by managers to make better environmental decisions.
11
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Acknowledgments
Many individuals have contributed to this paper. I have drawn heavily from the work of the
Lake Ontario Pelagic Health Indicators Committee. Members of this committee and others who
contributed material for the paper are:
John Eaton
Uwe Borgmann
J. H. Leach
W. J. Christie
R. M. Dermott
E. L. Mills
C. J. Edwards
R. A. Ryder
Michael L. Jones
William. W. Taylor
S. R. Ken-
Terry Marshall
Glen A. Fox
Chip Weseloh
Joseph H. Elrod
Ora Johnannson
David Best
C. P. Schneider
U.S. Environmental Protection Agency
Great Lakes Laboratory for Fisheries and Aquatic Sciences
Ontario Ministry of Natural Resources
Ontario Ministry of Natural Resources (retired)
Department of Fisheries and Oceans
Cornell University
U.S. Department of Agriculture
Ontario Ministry of Natural Resources
Ontario Ministry of Natural Resources
Michigan State University
Bedford Institute of Oceanography
Ontario Ministry of Natural Resources
Canadian Wildlife Service
Canadian Wildlife Service
U.S. Fish and Wildlife Service
Great Lakes Laboratory for Fisheries and Aquatic Sciences
U.S. Fish and Wildlife Service
NY Department of Environmental Conservation
The financial support of the USEPA, U.S. Fish and Wildlife Service, and the Great Lakes Fishery
Commission for a leave-of-absence appointment as Ecosystem Partnership Coordinator for the
Great Lakes Fishery Commission made this work possible. Thanks are also due to C. K. Minns,
J. R. M Kelso, and J. W. Owens for particularly strong and helpful criticisms of the manuscript.
Aquatic Community Health • SOLEC working paper
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EXECUTIVE SUMMARY
By setting a goal of restoring the chemical, physical, and biological integrity of the Great Lakes,
Canada and the United States have implicitly invoked an historical benchmark for assessing
recovery. Relative to this standard, the Great Lakes ecosystems are extremely unhealthy. The
catastrophic loss of biological diversity and subsequent establishment of non-indigenous
populations is the most striking indication of degradation of the Great Lakes.
At least 18 historically important fish species have become depleted or have been extirpated from
one or more of the lakes. Amplifying this loss of species diversity is the loss of genetic diversity
of surviving species. Prior to 1950, Canadian waters of Lake Superior supported about 200
distinctive stocks of lake trout, including some 20 river spawning stocks. Many of these stocks
are now extirpated, including all of the river spawners. The loss of genetic diversity of lake trout
from the other lakes is even more alarming, with complete extirpation of lake trout from lakes
Michigan, Erie, and Ontario and only one or two remnant stocks in Lake Huron.
Accompanying this loss of diversity was a series of invasions and introductions of exotic species.
Since the 1880s, some 139 non-indigenous species have become established in the Great Lakes.
Non-indigenous fish species that have established substantial populations include sea lamprey,
alewife, smelt, gizzard shad, white perch, carp, brown trout, rainbow trout, Chinook salmon, coho
salmon, and pink salmon. Other major invasions include the spread of purple loosestrife into
Great Lakes wetlands, and the population explosions of zebra and quagga mussels in Lake St
Clair and Lake Erie. Together, the non-indigenous species have had a dramatic and cumulative
effect on the structure of the aquatic communities of the Great Lakes, and their persistence poses
substantial problems for the restoration and maintenance of native species associations.
Changes in the biological diversity of the Great Lakes are caused by a host of chemical, physical,
and biological stresses. Major stresses include:
- large-scale degradation of tributary and nearshore habitat for fish and wildlife;
- imbalances in aquatic communities due to population explosions of invading species
such as sea lamprey, alewife, white perch, and zebra and quagga mussels;
- reproductive failure of lake trout;
- alterations of fish communities and loss of biodiversity associated with over-fishing and
fish stocking practices; and
- impacts of persistent toxic chemicals on fish and wildlife.
Biological stresses have caused a greater decline in health of the Great Lakes than physical and
chemical stresses. Historically, over-fishing and introduction of exotic species have had
devastating effects. Loss and degradation of aquatic habitat, however, are also important sources
of stress. In many cases, the effects of habitat loss are obscured by restructuring of aquatic
communities and through compensations by managers. In Lakes Ontario and Michigan and to
a lesser extent in Lakes Huron and Superior, stocking of salmonid predators compensates for the
effects of degraded habitat Without these stocking programs, there is insufficient reproduction
of non-indigenous salmonids and lake trout to sustain existing populations. In Lake Erie and
Aquatic Community Health - SOLEC working paper \
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other lakes with reproducing predators, fish communities have lost tributary spawning stocks, and
the species composition of the fish community reflects less dependence upon nearshore and
tributary habitat for spawning and nursery areas.
Persistent, toxic contaminants are also affecting fish and wildlife populations in the Great Lakes.
Observed effects include alteration of biochemical function, pathological abnormalities, tumors,
and developmental abnormalities. Contaminants are suspected of playing a role in recruitment
failures of lake trout, but the effects of exposure to contaminants are less clear for fish than for
wildlife. Eleven species of wildlife in the Great Lakes show evidence of contaminant impacts.
Three species (bald eagles, cormorants, and herring gulls) provide the best evidence both of the
severity of historical impacts and of recent improvements due to reductions in loadings.
However, the reproductive success of breeding eagle pairs eating Great Lakes fish remains lower
than those nesting inland, and occasional, local incidence of deformities indicate continuing
contaminant problems in some areas. Despite these encouraging trends, exposures to persistent,
toxic chemicals remain high enough to continue producing effects on fish and fish-eating wildlife.
Although the health of the Great Lakes remains degraded by historical standards, many indicators
show signs of improvement The extent of changes in the Great Lakes, however, poses a serious
challenge to obtaining consensus on specific objectives for the restoration of chemical, physical,
and biological integrity. Scientifically, it is possible to identify alternative configurations of
aquatic communities that are consistent with fundamental ecological principles and the goals of
the Great Lakes Water Quality Agreement With the possible exception of Lake Superior, the
degradation of historical community structure caused by various biological, physical, and
chemical stresses coupled with the establishment of large numbers of non-indigenous species
means that a return to pre-settlement conditions may not be possible. The question of how
closely restored aquatic communities should resemble historical conditions is more an issue of
social preference than a technical or scientific issue. Ultimately, the people living around the
Great Lakes must decide what their objectives are for ecosystem restoration and maintenance.
Only with such specific objectives will it be possible to decide on the current health of the Great
Lakes and to establish priorities for dealing with stresses responsible for impairment of that
health.
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1.0 Introduction
This paper summarizes current understanding of the health of the aquatic communities of the
Great Lakes. The range of communities includes aquatic species and terrestrial species (fish-
eating birds, mammals, and reptiles) that rely on aquatic food webs of the lakes or on habitat
with associated wetlands and other near-shore environments. The need for this summary comes
from the adoption of an ecosystem approach to management of the Great Lakes. More holistic
than a pollutant-by-pollutant approach to improvement of water quality associated with earlier
laws and agreements, the Great Lakes Water Quality Agreement of 1978 committed Canada and
the U.S. to a long-term goal of "...restoring and maintaining the chemical, physical, and
biological integrity of the waters of the Great Lakes basin ecosystem." Relying on an analogy
to human health, the restoration of integrity has become synonymous with returning the
ecosystems of the Great Lakes to a healthy state. Implicit in this goal is the recognition that
abuses due to the past 200 years of human activity in the Great Lakes basin have reduced the
health of the Great Lakes. The challenge is to balance ecosystem restoration and maintenance
with human development The necessity of this balance is the fundamental premise of
"ecologically sustainable economic development" advocated by the Brundtland Commission
(World Commission on Economic Development, 1987).
Evaluation of the health of the aquatic community of the Great Lakes is complicated.
Impairments to health of individual fish and wildlife are possible to detect through a variety of
indicators (e.g. tumor incidence, incidence of developmental anomalies, and incidence of disease
and parasitism), but the specific causes of health impairments and their population-level effects
are often ambiguous. For example, levels of mixed function oxidase enzymes are influenced by
exposure to a wide range of anthropogenic and natural substances, and such indicators of
exposure may or may not indicate an illness condition.
Assessing the health of populations and communities is even more complicated for at least three
reasons. First, because different causal factors may produce similar effects on populations,
identification of factors responsible for particular population impairments (elevated mortality or
morbidity rates or decreased reproductive rates) is difficult Second, populations and
communities are adaptive. Healthy communities share common functional integrity: ability to
self-regulate in the presence of internal or external stresses and ability to evolve toward
increasing complexity and integration. Thus, many different, "healthy" states may be functionally
equivalent Third, the Great Lakes are unique and very disturbed ecosystems. Many of the
original communities no longer exist, and introduced species have established viable if not
dominant populations. Without undisturbed communities to serve as reference benchmarks, the
determination of the wellness of an ecosystem requires a value judgment
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1.1 Concepts of Ecosystem Health
The concept of ecosystem health is often more symbolic than functional. As with human
health, maintenance and restoration of ecosystem health admits both curative and preventative
approaches. The curative approach finds what is wrong and fixes it while the preventative
approach attempts to minimize the risk of illness. Considering human health, the dichotomy of
the two approaches yields the current dilemma with technological approaches to medicine-
elimination of illness does not necessarily produce wellness. For humans, wellness is a harmony
of mind and body, and extensions of the health analogy to ecosystems falters because we lack
a definition of wellness (cf. Minns, in press). In the context of ecosystem management, we can
address the causality problem by associating stresses (e.g. pollution loading, habitat destruction,
and overexploitation) with impairments of beneficial uses. Without a wellness concept, however,
what constitutes an overall assessment of ecosystem health is a value judgement
To add objectivity to the concept of ecosystem health requires consideration of the adaptive
potential of ecological communities. Holling (1992) argues that a small set of processes structure
ecosystems. Within constraints of habitat characteristics and climate variability, ecological
communities display cycles that are characteristic of various ecosystem types. The structure of
climax communities of terrestrial ecosystems, as with their analogs in the aquatic communities
of the Great Lakes (cf. Loftus and Regier 1972), exists in balance with patterns of disturbance.
The result is a predictable set of patterns of ecosystem dynamics in which community
composition changes through a series of recognizable states before returning to a climax state (i.e.
persistent state). Climax states and succession transients are thus common elements to all natural
ecosystems, and a concept of ecosystem health must include reference to the feedback
mechanisms that govern natural cycles and persistence of climax states. As Rapport (1990)
states, ecosystem health depends upon the integrity of the homeostatic mechanisms, and "integrity
refers to the capability of the system to remain intact, to self-regulate in the face of internal or
external stresses, and to evolve toward increasing complexity and integration."
Natural, undisturbed ecosystems would seem to be good benchmarks for integrity or wellness.
Ryder and Kerr (1990) argue that ecological communities evolve toward co-adapted or
"harmonic" assemblages of species and that the status of the native species associations in
ecosystems is an indication of their integrity. However, chronological colonization and invasion
patterns are accidental, and multiple native species associations could evolve given slightly
different compositions of colonizing species.
This issue becomes especially important when ecosystem restoration is the main challenge as in
the Great Lakes. The original ecological communities no longer exist, and many exotic species
have established viable and at times dominant populations. Justification of preference for specific
community composition may be aided by historical analysis (e.g. Ryder 1990), yet alternate
composition, with similar ecological function, is certainly possible. At some level, the decision
about which ecological community to pursue in restoration becomes a social preference.
Scientific notions may contribute to the decision, but ultimately people must decide what their
objectives are for ecosystem restoration and maintenance. Hence, what constitutes "ecosystem
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wellness" is, in part, a value judgment
The notion of ecosystem health is also hierarchical. The integrity of an ecosystem is a complex
function of the health of its constituent populations, the biological diversity of its ecological
communities, and the balance between ecological energetics and nutrient cycling as constrained
by physical habitat At some levels in such a hierarchy, illness is much easier to detect
Evaluation of the health of fish and wildlife populations, for example, admits a direct extension
of notions of human health in which density, growth, incidence of disease, morbidity, and
mortality statistics are accepted measures of healthiness. The health of an individual organism,
in turn, is judged relative to normal biochemical and physiological functions. Indications of
impaired health derive from biochemical, cellular, physiological, or behavioral
characteristics, which can be observed and, to some degree, be associated with known causes.
Impaired health of an individual may manifest itself in its population through effects on
reproduction or mortality, and the proportion of unhealthy individuals in a population may
influence the entire ecological community by altering the balance of competition and predator-
prey relations that provide its dynamic structure.
1.2 Great Lakes Aquatic Ecosystem Objectives
The ecosystem approach, which was advocated with the 1978 Great Lakes Water Quality
Agreement, requires ecosystem objectives. With the adoption of the 1987 Protocols, specific
objectives were set forth in the Supplement to Annex 1:
Lake Ecosystem Objectives. Consistent with the purpose of this Agreement to maintain
the chemical, physical and biological integrity of the [waters] of the Great Lakes Basin
Ecosystem, the Parties, in consultation with State and Provincial Governments, agree to
develop the following ecosystem objectives for the boundary waters of the Great Lakes
System, or portions thereof, and for Lake Michigan:
(a) Lake Superior
The Lake should be maintained as a balanced and stable oligotrophic ecosystem
with lake trout as the top aquatic predator of a cold-water community and the
Pontoporeia hovi as a key organism in the food chain; and
(b) Other Great Lakes
Ecosystem Objectives shall be developed as the state of knowledge permits for the
rest of the boundary waters of the Great Lakes System, or portions thereof, and
for Lake Michigan.
The first effort of the Parties to draft ecosystem objectives for the other Great Lakes grew out
of the activities of the Ecosystem Objectives Working Group (EOWG) for Lake Ontario (Bertram
and Reynoldson 1992). Five ecosystem objectives have emerged from this effort:
The waters of Lake Ontario shall support diverse healthy, reproducing and self-sustaining
communities in dynamic equilibrium, with an emphasis on native species.
Aquatic Community Health - SOLEC working paper 5
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The perpetuation of a healthy, diverse and self-sustaining wildlife community that utilizes
the lake for habitat and/or food shall be ensured by attaining and sustaining the -waters,
coastal wetlands and upland habitats of the Lake Ontario basin in sufficient quality and
quantity.
The waters, plants and animals of Lake Ontario shall be free from contaminants and
organisms resulting from human activities at levels that affect human health or aesthetic
factors such as tainting, odor and turbidity.
Lake Ontario offshore and nearshore zones and surrounding tributary, wetland and
upland habitats shall be sufficient quality and quantity to support ecosystem objectives
for health, productivity and distribution of plants and animals in and adjacent to Lake
Ontario.
Human activities and decisions shall embrace environmental ethics and a commitment to
responsible stewardship.
These objectives have been incorporated into the draft Lakewide Management Plan for Lake
Michigan. The Lake Superior Binational Program, which was created by the parties for a
demonstration of the zero discharge objective for toxic contaminants, has also used the
framework of these objectives to propose extensions of the ecosystem objectives adopted for
Lake Superior in the 1987 Protocols.
1.3 Indicators
1.3.1 Fish and Wildlife Health Indicators
Indicators of individual fish and wildlife health have developed from concern with disease and
abnormalities in physiology and behavior. Living organisms respond to environmental stresses
through a variety of physiological and behavioral mechanisms. Beitinger and McCauley (1990)
review the notion of a general adaptation syndrome at a physiological level that includes a
primary response in the endocrine system and a secondary response involving blood and tissue
alterations. Impaired health occurs when these adaptations are not sufficient to permit normal
function. Assessments of fish and wildlife health in the Great Lakes have employed a range of
specific indicators of these physiological responses to stress. A partial list would include:
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Indicator
Induction or Mixed Function
Oxidase Enzymes (MFO), e.g.
P450 1A1.
Inhibition of Amino Levulinic
Acid Dehydratase (ALA-D)
Hepatic Porphryia
Hepatic Vitamin A (Retinol)
Thyroid Related Abnormalities
Tumor Incidence
Fin Ray Asymmetry
Congenital Malformations
Disease Incidence
Parasite Incidence
Associated Stress
Induction indicates exposure to hydrophobia planar
chemicals such as PAHs, PCDD, and PCBs
Inhibition indicates exposure to inorganic lead compounds
Elevated levels of highly carboxylated porphyrins (HCPs) is
indicative of exposure to organochlorines (PCBs, HCB, and
TCDD)
Reduction in levels indicates unsatisfactory nutritional status
and/or effects of exposure to chemicals such as TCDD
Changes indicate altered metabolic status due to changes in
habitat and/or exposure to gortergins
Indicates toxic exposure to PAHs or other carcinogens, but
also may be due to viral and bacterial agents.
Indicates poor environmental quality
Increased incidence indicates excessive exposure to
developmental toxins and/or maternal health status
Increased incidence of Bacterial Kidney Disease (BKD) and
other bacterial and viral diseases in fish indicate nutritional
or chemical stress
Increased incidence indicates pollution or stress condition
These indicators represent responses of fish and wildlife to various stresses in the environment,
but their diagnostic specificity varies as effects move from biochemical to population levels.
Some biochemical indicators, such as induction of MFOs, are non-specific and indicate only
exposure to some types of organochlorines, which may come from anthropogenic or natural
sources. These exposures may or may not result in illness. Translation of the exposure
indicators to health assessment is not always straightforward (cf. Munkittrick 1993).
Nevertheless, these indicators together give indications of the quality of the environment with
respect to factors causing stress on biochemical and physiological processes.
1.3.2 Community Health Indicators
Like individual health indicators, the purpose of developing community health indicators is to
detect and diagnose pathology. Indicators of the health of an ecological community, however,
are imbedded in a hierarchical set of ecological interactions and in a poorly coordinated hierarchy
of ecosystem management jurisdictions and initiatives (cf. Evans, Warren, and Cairns, 1990).
Without an integrating framework, indicators of community health tend to focus on those parts
of an ecosystem most valued by their proponents. As Koonce (1990) has argued, this lack of an
Aquatic Community Health - SOLEC working paper
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integrating framework creates obstacles for the use of indicators to characterize trends for the
entire Great Lakes basin or to guide management actions to correct the pathologies. A pathology
from one perspective, after all, may be a beneficial condition to another. Gilbertson (1993), for
example, argues that the requirement for supplemental stocking of salmonids to work around the
failure of lake trout reproduction in Lake Ontario is symptomatic of a pathology, but many
recreational fishers prefer to catch non-native Chinook salmon and view emphasis on lake trout
rehabilitation as undesirable if in doing so the Chinook fishery declines. Ideally, community
health indicators should follow from the objectives for ecosystem management, but as discussed
below, ecosystem objectives are often not specific enough to provide a basis either for deriving
quantitative end points consistent with the objective, or for guiding the selection of an appropriate
set of indicators with which to monitor trends in ecosystem health and to specify corrective
action.
Attempts to develop sets of indicators have arisen in parallel with government mandates for
ecosystem management Within the International Joint Commission (DC), the Science Advisory
Board created an Aquatic Ecosystem Objectives Committee (AEOC) to develop ecosystem
objectives and indicators for the Great Lakes. These efforts led to proposed indicators based on
indicator species for oligotrophic portions of the Great Lakes (Ryder and Edwards 1985) and for
mesotrophic areas (Edwards and Ryder 1990). Following the 1987 revisions to the Great Lakes
Water Quality Agreement, Canada and the U.S. established a Binational Objectives Development
Committee, which subsequently formed the Ecosystem Objective Work Group (EOWG) to
continue development of ecosystem objectives and indicators. Various national initiatives have
also complemented the binational efforts. Noteworthy is the Environmental Monitoring and
Assessment Program (EMAP) of the Environmental Protection Agency. The primary goal of the
Great Lakes EMAP strategy under development (Hedtke et al, 1992) is to estimate current status
and trends of indicators for the ecological condition of each of the Great Lakes. As a result of
these various initiatives, formulation of indicators of aquatic community health of the Great Lakes
is only just beginning, and the indicators summarized here are thus far less robust than those for
fish and wildlife health.
Community health indicators fall into three categories: indicator or integrator species, ecosystem
function indicators, and composite indices of ecosystem integrity.
An example of the first category is the use of lake trout (Salvelinus namaycusK) and Pontoporeia
for oligotrophic ecosystems (Ryder and Edwards 1985) and walleye (Stizostedion vitreum) and
burrowing mayfly (Hexagenia limbatd) for mesotrophic waters (Edwards and Ryder 1990).
These species satisfy fundamental criteria for using species as surrogates of community health
(Edwards and Ryder 1990): a strong integrator of the biological food web at one or more trophic
levels; abundant and widely distributed within the system; and perceived to have value for human
use to make sampling easier.
An example of indicators of ecosystem function is the proposed use of biomass size spectra
(Sheldon et al. 1972) as measures of ecosystem health (Kerr and Dickie 1984). Table 1 lists this
and other candidate indicators of ecosystem function that have been evaluated by the Lake
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Ontario Pelagic Community Health Indicator Committee.
Finally, there are a wide variety of examples of composite indices (Karr 1981; Steedman 1988;
Rankin 1989; Yoder 1991; and Minns et al. in press). As Rapport (1990) notes, these indices
are based on a number of variables, but usually cover biotic diversity, indicator species,
community composition, productivity, and health of organisms. The Dichotomous Key, designed
to assess the health of the oligotrophic aquatic ecosystems (Marshall et al. 1987), is in fact an
example of an aggregate index using lake trout as a surrogate for the biological integrity of
oligotrophic portions of the Great Lakes.
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Table 1. Indicators proposed by the Lake Ontario Pelagic Community Health Indicator
Committee for ecosystem structure and functional energy flow (after Christie 1993).
Indicator
Biomass
or
production
size
spectrum
Yield of
piscJvores
Ratio of
Piscivore
to prey
biomass
Fraction of
yield as
native fish.
Zooplankto
n size
distribution
Total P
levels <=
10 mg/I
Msn
species
diversity.
Historical Data
None - some
current data in
Sprules group
Long-term
commercial
statistics. Some
recent creel census
data.
Comparable to
above; more data
available for the
predator species
than for the prey,
especially
nearshore.
Lake trout, rainbow
trout data back to
the 1950s, Chinook
salmon more
recent
Some data
available from
1972. Continuous
attheCCIW
Bioindex stations.
Monthly
surveillance (1976-
1981); biannual
survey (1982-
present)
standard guinet,
trawl, trapnet, seine
collections. Gillnet
data continuous
since 1957 and
1958 in Bay of
Quinte and
Kingston Basin.
Trawl data
continuous since
1972 in all areas.
Broken series for
the others.
Methodology tor Collection
Traditional net sampling,
various techniques for each
organism targeted .little
calibration.
Requisite reports from
commercial fishermen, spot
surveys of anglers and charter
boats.
Traditional fishery tools;
gillnets, trawls, trapnets,
seines.
Fin dips used in past, nasal
insert tags currently used in all
larger fish released Otolith,
scale, and fin ray
abnormalities used for fish
smaller at release, and for F2
and later recoveries.
Standard techniques used.
Recently extended by new
computerized count-measure
procedures.
Discreet depth samples at 1
meter
convennonai net sampling.
Programs need broadening to
include shoreline and small
species, integration to allow
comparison within and
between series.
Status of Assessment
Currently developing new
sampling methodologies
Inadequate bridging
between old and new
data series. Need better
institutional assessment
data and more
comprehensive creel, and
charter data.
Inadequate assessment
of small nearshore
species especially. No
bridging between inshore,
offshore programs.
Biased estimates of
relative biomass.
Currently developing new
sampling methodologies
based on sonar.
Methods of differentiating
genetic origins of
naturally produced fish
still developmental.
Currently applied in part-
spectrum applications.
All collections extant for
series comparisons.
Inshore data not
consistently collected.
Adequate methods
currently being used.
Consistent comparisons
with nearshore conditions
desirable.
Analysis needs u> tocus
on evenness component
of diversity. Statistical
analysis of variance in
each zone should
measure improving
health, and the reverse.
Interpretive status
Has utility in displaying
the entire structure of the
ecosystem.
Presently used to
measure fisherman
satisfaction. Convergence
on predicted yield
estimate can measure
ecosystem health.
Should measure
approach to steady state
conditions, and deviations
therefrom. Rigorous
attention to sampling
routine should allow
early-warning use of
variance, and trend data.
Data presently analyzed
in the form needed.
Not expressly used in
present lake reporting,
and especially useful
when compared with
nearshore data, and
placed in the context of
other indicators.
Analysis ongoing and
reliable. Good when
used hi conjunction with
other indicators; provides
information on the
baseline productivity of
the lake, and linkage to
future biological problems
related to return to
excess P loads.
(Conservative property, is
robust when developed
from comparable
collection techniques.
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2.0 Status and Trends for Fish and
Wildlife Health
Toxic contamination of the Great Lakes is a widely-perceived threat to fish and wildlife health.
A recent compilation by the Government of Canada of scientific literature on the effects of
persistent toxic chemicals (Anon. 1991b) concluded that persistent chemicals have had a
significant impact on fish and wildlife species in the Great Lakes basin. Observed effects include
alteration of biochemical function, pathological abnormalities, tumors, and developmental and
reproductive abnormalities. A possible consequence of these effects is a decrease in fitness of
populations. Contaminant body burdens in fish and wildlife also have led to alerting the public
through consumption advisories of a potential human health threat On the whole, however, the
effects of toxic contamination on wildlife are much clearer than for fish populations.
Fish populations in the Great Lakes do show evidence of exposure to toxic contaminants.
Induction of some mixed function oxidases (MFOs) (i.e. those which result in elevation of
ethoxyresorufun o-deethylase or aryl hydrocarbon hydroxylase activity) signals AHH receptor
activation, which may result in unfavorable biological responses. Surveys of MFO activity in
lake trout clearly indicate elevated levels in southern Lake Michigan and western Lake Ontario
(see Figure 1). Because mixed function oxidase enzymes are induced by a variety of toxic
chemicals, elevated MFO activity cannot be associated with specific toxic chemicals, nor is it
possible to attribute specific health effects to these elevated enzyme activities. Nevertheless, the
patterns of lake trout MFO activity coincide with geographic variation in contaminant loading.
White sucker (Catostomus commersoni) also showed similar patterns of higher MFO activity in
Lake Michigan and Lake Ontario, but also showed patterns of higher activity in the nearshore
than in fish sampled in off-shore environments (see Figure 2). Impairment of lake trout
reproduction in Lake Michigan seems to reflect this chemical contamination (Mac 1988), and,
by similarity of circumstances, chemical contaminants may be contributing to reproductive failure
of lake trout in Lake Ontario. Further clarification of the effects of chemical contaminants on
population health of fish may rest on resolution of methodological issues (Gilbertson et al 1990,
Gilbertson 1992).
Circumstantial evidence is also strong for chemically induced carcinogenesis in Great Lakes fish.
Summary of observations (Anon. 199 Ib) indicates that proof of causation of incidence patterns
of tumors is lacking. Nevertheless, the overwhelming evidence leads to the conclusion (Anon
1991b):
There is strong circumstantial evidence that environmental carcinogens are responsible
for the occurrence of liver tumours in brown bullheads from the Black, the Buffalo and
the Fox Rivers, and possibly in bullheads from several other Areas of Concern. There
is no "proof that chemical carcinogens are responsible for liver tumours in walleye and
saugerfrom the Keweenaw Peninsula, or in white suckers from western Lake Ontario.
However, the limited geographic distribution of the effects and the association with
contaminated environments indicates a chemical etiology.
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Not all fish diseases, however, have a chemically dominant etiology. Recent observation of
outbreaks of bacterial kidney disease (BKD) among Chinook salmon (Oncorhynchus tshawytscha)
in Lake Michigan, and the dramatic increase in their mortality in the late 1980s (see Figure 3),
have not been linked to contaminants. The Great Lakes Fish Disease Control Committee
concluded that "...the chinook mortality problem should be considered the result of an ecosystem
imbalance rather than the "fault" of any one pathogen" Although Renibacterium salmoninarum
is the causative agent of BKD, they believe that the disease is stress-mediated and not a simple
epizootic. However, they advise implementing hatchery practices to reduce the prevalence of
Renibacterium salmoninarum. To that end, the committee has proposed a set of guidelines for
the control of disease agents imported into the Great Lakes basin (Hnath 1993, Horner and
Eshenroder 1993). Other "diseases'1 have been observed to wax and wane in various fish
populations. Smelt populations in Lake Erie, for example, experienced an epizootic of
parasitism by the microsporidian, Glugea hertwigi, in the 1960s (Nepszy et al. 1978).
Relative to fish, effects of toxic contaminants on wildlife species are more extensively
documented. By 1991, various studies had identified contaminant-associated effects on 11
species of wildlife in the Great Lakes (Anon. 199 Ib). Affected species include shoreline mink
(Mustela visori), otter (Lutra canadensis), double-crested cormorant (Phalocrocorax auritus),
black-crowned night-heron (Nycticorax nycticorax), bald eagle (Haliaeetus leucocephalus),
herring gull (Larus argentatus), ring-billed gull (Larus delawarensis), Caspian tern (Sterna
caspid), common tern (Sterna hirundo), Forster's tern (Sterna forsteri), and snapping turtle
(Chelydra serpentina). Of these, 9 species showed historical evidence of reproductive
impairment due to contaminants (see Table 1, Anon. 19915, p. 563). Temporal and spatial trends
in samples of cormorants, bald eagles, and herring gulls provide important evidence for the
magnitude of the effects of contaminants on wildlife health and recent improvements.
Cormorants began to nest in the Great Lakes earlier in this century. Estimates of abundance in
the 1940s and 1950s indicated about 1000 pairs, but these numbers declined substantially through
the 1970s (Scharf and Shugart 1981, Price and Weseloh 1986, and Weseloh et al in press).
Productivity studies clearly implicated reproductive failure evident in the early 1970s (Figure 4),
resulting from DDE-induced egg shell thinning, as the cause of these declines. Since 1979
cormorant populations have increased substantially throughout the Great Lakes (Weseloh et al.
in press), but prevalence of bill defects and other developmental anomalies throughout the 1980s
suggest that sufficient amounts of PCBs and other toxic contaminants occurred in fish to
influence the embryo development of these and other colonial, fish-eating bird species,
particularly in Green Bay (Fox et al. 1991, Gilbertson et al. 1991).
Bald eagles have shown drastic declines throughout their North American range. Wiemeyer et
al. (1984) suggested that toxic contaminants have contributed to these declines with DDT causing
eggshell thinning and reproductive impairment Restrictions on the manufacture and use of DDT,
PCB, and other organic compounds seemed to reverse these trends, and within the conterminous
U.S. the Fish and Wildlife Service reported that bald eagles had recovered from a low of 400
pairs nationwide in 1964 to 2700 pairs in 1989 (Anon. 199 Ib). Great Lakes populations have
followed this recovery trend, but reproductive success of breeding pairs nesting on shorelines of
12
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the Great Lakes or on tributaries with adfluvial fish populations from the Great Lakes are lower
than those nesting inland (Best et al. in press). Between 1966 and 1992, seven bald eaglets were
found with abnormal bills, 16 per 10,000 banded (Bowerman et al. in press), and the U.S. Fish
and Wildlife Service reported that four eaglets with deformities were found on Great Lakes
shorelines in 1993 (Best personal communication, East Lansing Fact Sheet, July 8, 1993).
More than any other wildlife species, the herring gull has become an indicator of contaminant
trends in the Great Lakes (Mineau et al. 1984). As year-round residents, adult herring gulls
offer a monitoring opportunity to detect regional variability in contaminant stress that is not
complicated by migratory patterns characteristic of other fish-eating bird species (Weseloh et al.
1990). Since 1974, the Canadian Wildlife Service has maintained a long-term monitoring
program for toxic chemicals through a network of 13 sites throughout the Great Lakes. In
general, organochlorine residues in herring gull eggs have declined from higher levels in the early
Table 2. Temporal and geographic variations of productivity of Great Lakes Herring Gulls,
1972-1985 (after Table 10, Anon. 1991b, p. 601), expressed as 21 day-old chicks per pair.
Lake Ontario
Snake 1.
Scotch Bonnet 1.
Brother's 1.
Presq-iePk.
Black Ant 1.
Mugtfsl.
Lake Erie
Big Chicken 1.
PortCobome
Mkfctel.
Lake Huron
Chantry 1.
Double 1.
Lake superior
AgawaRk.
Granite 1.
1972 1973 1974 1975 1976 1977
0.21 1.01
0.12 0.06 0.15 1.10
0.10
0.06
0.08
1.52
0.45
0.48 0.65 0.79
1.48 1.12
1.32 1.55
1978
0.86
1.01
1.47
1.45
1.70
1.40
157
1.66
1.12
1979
1.60
156
1.63
2.17
2.17
0.88
1.70
1980
1.49
1.62
2.17
225
0.40
1.40
1981
1.73
2.13
1.40
1.60
2.10
2.16
2£3
0.37
0.46
1982 1983 1984 198
5
1.34
1.17
2.17 0.95 1.00
1.84
1.25 2.33
0.14 0.37 0.85 1.30
1.39 1.39
1970s (Anon. 1991b, p. 332). As is the case with cormorants, temporal and geographic variation
of productivity reflect these trends (Table 2). Reproductive success was low in the early 1970s
and has improved since.
Although the etiology of these changes has not been rigorously determined, egg exchange
experiments indicate both intrinsic and extrinsic factors were involved, and biochemical markers
provide substantial indication that biochemical abnormalities are strongly associated with diets
contaminated by polyhalogenated aromatic hydrocarbons (Fox et al 1988). Gilbertson et al.
(1991) have proposed mechanisms to account for these reproductive effects. According to Fox
(1993), "studies of impairments to health using such biomarkers as induction of mixed function
oxidases, alterations in heme biosynthesis, retinol homeostasis, thyroid function and DNA
integrity and various manifestations of reproductive and developmental toxicity in these birds
suggests that the severity varies with time and location and generally decreased between the
Aquatic Community Health - SOLEC working paper 13
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early 1970s and late 1980s. However, these studies confirm tine continued presence of sufficient
amounts of PCBs and related persistent halogenated aromatic hydrocarbons in forage fish to
cause physiological impairments in these birds over much of me Great Lakes basin." Fox (1993)
also argues "these injuries are most prevalent and severe in, but not confined to, hotspots such
as Saginaw Bay, Green Bay, Hamilton Harbour, and the Detroit River."
14
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3.0 Status and Trends for Community
Health
Objectives for restoration of the physical, chemical, and biological integrity of the ecosystems
of the Great Lakes have not defined explicit interim goals. Realizing that pre-Columbian states
of the Great Lakes ecosystems represented one definition of a "healthy" ecosystem, one interim
goal for restoration could be re-establishment, to the maximum possible extent, of natural
communities. Alternatively, an interim goal could be the restoration of a functional equivalent
of historical communities. Although this issue (i.e. development of indicators and end points for
ecosystem objectives) is under active consideration, the historical benchmark remains an
important reference point with which to judge the extent of degradation of Great Lakes
ecosystems and the prospects for various levels of restoration.
Any assessment of the status and trends of ecosystem health must begin with the catastrophic loss
of biological diversity and subsequent establishment of non-indigenous populations. Fish play
a major role in structuring aquatic ecosystems, as tress do in many terrestrial ecosystems (Steele
1985). Summaries of the changes in the fish species composition of the Great Lakes (Lawrie and
Rahrer 1973, Wells and McLain 1973, Berst and Spangler 1973, Hartman 1973, and Christie
1973) reveal substantial alteration of the fish communities. Table 3 lists the species that have
either disappeared from the lakes or have been severely depleted, but these losses belie a much
more fundamental loss of genetic diversity among surviving indigenous species. Goodier (1981),
for example, showed evidence that Canadian waters of Lake Superior supported about 200
spawning stocks, including 20 river spawning stocks, of lake trout prior to 1950.
Accompanying these changes in diversity of Great Lakes fishes was a succession of invasions
and intentional introductions of non-indigenous fish species. Species that have established
substantial populations include: sea lamprey (Petromyzon marinus), alewife (Alosa
pseudoharengus), smelt (Osments mordax), gizzard shad (Dorosoma cepedianum), white perch
(Morone americand), carp (Cyprinus carpio),\*TOvm trout (Salmo trutta), Chinook
S2Amon(Oncorhynchus tshawytscha), coho salmon(0. kisutch), pink sa\mon(O.gorbuscha),
rainbow trout (O, mytiss). Since 1985, other species such as the ruffe (Gymnocephalus cernuus),
the rudd (Scardinius erythrophthalmus), fourspine stickleback (Apeltes quadroons), and two
species of goby (Neogobius melanostomus and Proterorhinus marmoratus) have also invaded the
Great Lakes (Mills el al. 1993). Including these introductions, Mills et al. (1993) have
documented 139 non-indigenous aquatic organisms (plants, invertebrates, and fish) that have
become established in Great Lakes ecosystems.
The pre-Columbian species assemblages of the Great Lakes represented an adaptive complex that
was an essential determinant of the wellness of Great Lakes ecosystems. The loss of so much
diversity diminished the health of the Great Lakes, but recent efforts to restore fish communities
raise the question of whether it is possible to establish a standard of functional equivalency to
Aquatic Community Health - SOLEC working paper 15
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Table 3. Summary of fish species lost or severely diminished by lake in the Great Lakes. An
asterisk (*) indicates stocking programs exist to attempt re-introduction. Status codes are 1
(Depleted), 2 (Extirpated), and 3 (Extinct).
Common
Lake sturgeon
Longjaw Cisco
Lake herring
Lake whitefish
Bloater
Deepwater
Kiyi
Blackfin Cisco
Shortnose Cisco
Shortjaw Cisco
Burbot
Fourhorn
Emerald shiner
Atlantic
Lake trout
Sauger
Blue pike
Soecies Name
Acipenser
Coregonus alpenae
C. artedii
C. clupeaformis
C. hoyi
C. johannae
C. kifd
C. nigripinnis
C. reighardi
C. zenithicus
Lota lota
Myoxocephalus
Notropis
Salmo solar
Salvelilnus
Stizostedion
S, vitreum glaucum
Suoerior
1
1
1
2
1
Huron
1
2
2
2
2
2
2*
Michigan
1
2
1
2
2
2
1
3
2
2*
Erie
1
2
2
1
1
2*
2
3
Ontario
1
2
2
2
1
1
3
2*
2*
3
these historical fish communities. By launching an aggressive, bi-national program to control sea
lamprey, which with overexploitation caused the extirpation of lake trout in Lake Michigan and
Lake Huron as well as a substantial reduction in the lake trout of Lake Superior, the Canadian
and U.S. governments prepared the way for an intensive stocking program to reintroduce lake
trout, and introduce non-indigenous salmonid predators, to all of the Great Lakes. These efforts
have certainly resulted in development of highly successful sports fisheries in the Great Lakes
that surpasses historical communities in the range of species available to anglers. The stability
of these fisheries, however, is not clear. Except for Lake Superior, the salmonid stocking
programs are not complemented by sufficient natural reproduction to sustain current populations.
The fisheries, in fact, are dependent upon the continuation of artificial propagation. Furthermore,
the prey species complex that support these predators is also dominated by unstable populations
of invading species like alewife and smelt The loss of the highly adaptive coregonid complex
and native lake trout stocks has thus left a void that introductions have so far failed to fill.
Indicators of ecosystem function have not been applied systematically to the Great Lakes, but
some studies hint at continuing problems. Biomass size spectrum studies of Lake Michigan
(Sprales et al. 1991) have shown promising results for the use of particle-size spectra in
analyzing food web structure. Through this analysis, Sprules et al. (1991) found that piscivore
biomass was lower than they expected. The imbalance in the food web appears to be limited
availability of prey fish production to the mix of stocked piscivore species. Zooplankton size
distribution, as a component of the biomass size spectrum, also indicates imbalance between
planktivory and piscivory. According to the Lake Ontario Pelagic Health Indicator Committee
16
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(Christie 1993), a mean zooplankton size of 0.8 to 1.2 ram shows a healthy balance in the fish
community. Over the period 1981 to 1986, the observed range of mean size of zooplankton was
0.28 to 0.67 mm (Johannsson and O'Gorman 1991), indicating excess planktivory. Emerging
evidence for 1993, however, suggests that Lake Ontario may be undergoing an abrupt shift in
zooplankton size with a collapse of the dominant prey fish population (E. L. Mills, Cornell
University, personal communication). The recent trends in Lake Michigan and Lake Ontario may
indicate mat declines in productivity of both lakes associated with reduced phosphorus loading
make these systems less able to sustain predator stocking levels that were successful earlier.
Recent modeling studies of Lake Michigan and Lake Ontario (Stewart and Ibarra 1991; and
Jones et al. 1993) indicate a strong possibility that excessive stocking of predators is de-
stabilizing the food webs in these ecosystems.
3.1 Case Study: Lake Erie
The recent history of Lake Erie further illustrates how tenuous is the continuing effort to restore
the health of the Great Lakes. As reviewed by Hartman (1973), the ecosystem integrity of Lake
Erie reached its lowest point in the decade of the 1960s. The combined effects of eutrophication,
over-exploitation of fishery resources, extensive habitat modification, and pollution with toxic
substances had severely degraded the entire ecosystem of Lake Erie. Once-thriving commercial
fisheries had all but disappeared and the populations of the last remaining native predator, the
walleye, had fallen to a record-low level. Beginning in the 1970s, new fishery management
strategies and pollution abatement programs contributed to a dramatic reversal. Lake Erie
walleye fisheries rebounded to world-class status (Hatch et al 1987), and point-source
phosphorus loading has declined to target levels in the 1972 Great Lake Water Quality
Agreement (Dolan 1993). These reductions were accompanied by a dramatic decrease in the
abundance of nuisance and eutrophic species of phytoplankton (Makarewicz 1993a) and an
associated decline in zooplankton biomass (Makarewicz 1993b). Surveys of the benthic
macroinvertebrate communities further illustrate the improvement in the most degraded sediment
areas of Western Lake Erie. Compared with surveys conducted in 1969 and 1979, Farara and
Burt (1993) found that there was a marked decline in the abundance of pollution tolerant
oligochaetes and that overall the macroinvertebrate community of Western Lake Erie has shifted
to more pollution intolerant and facultative taxa.
The invasion of zebra mussels into Lake Erie has affected this recovery trend. Leach (1993)
reported that associated with zebra mussel increases was a 77% increase in water transparency
between 1988 and 1991, a 60% decrease in chlorophyll a, and a 65% decline in number of
zooplankters. Although Leach (1993) has observed an increase in the amphipod Gammarus in
nearshore benthic communities dominated by zebra mussels, Dermott (1993) has observed an
inverse relation to abundance ofDiporeia and the Quagga mussel, which appears to be a second
Dreissena species. These abrupt changes in water quality and associated plankton and benthic
communities make predictions about future status of the Lake Erie ecosystem highly uncertain.
Despite the recovery of walleye, however, the causes of current trends of change in the structure
and function of the Lake Erie ecosystem are dominated by effects of non-indigenous species.
Aquatic Community Health - SOLEC working paper 17
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The extent of the changes in community structure of the Western and Central basins is so great
that the historical species composition is unlikely to serve as an achievable benchmark with
which to assess ecosystem health.
3.2 Oligotrophic Waters
The offshore, oligotrophic portions of the Great Lakes also seem to show variable recovery. The
lake trout surrogate indicator (Edwards and Ryder 1985) is the only indicator of aquatic
community health that has been systematically applied to the oligotrophic areas of the Great
Lakes. As documented in Edwards et al (1990), this indicator is a composite index, which is
derived from a wide range of conditions necessary to sustain healthy lake trout stocks. The
rationale for the use of lake trout as a surrogate for ecosystem health is based on the notion that
lake trout niche characteristics and historical dominance in the Great Lakes provide the best basis
to detect changes in overall ecosystem health. The index is based on scores from a Dichotomous
Key of questions about lake trout or their habitat (Marshall et al. 1987). A score of 100 indicates
pristine conditions. For the period 1982-85, Edwards et al. (1990) indicate that Lake Superior
had the highest score (i.e. was the least degraded) followed by Lake Huron, Lake Ontario, Lake
Michigan, and Lake Erie (Figure 5). The Dichotomous Key further allows dissection of the
indicator score into components associated with various stress categories. In all cases except
Lake Erie, contaminants are an important cause of lower indicator values (Figure 6).
Marshall et al. (1992) reported on historical and expected future trends in the lake trout indicator
for the period 1950 to 1995. The overall value of the indicator showed a decline through the
mid-1960s with a projected recovery by 1995 approaching 1950 levels (Figure 7). Ryder (1990)
argues that this recovery pattern indicates that recovery to near pristine conditions is a reasonable
goal. Dissection of the score into stress categories, however, indicates that contaminant problems
are not improving as rapidly as other stresses (Figure 8). In an independent effort, Powers (1989)
applied the Dichotomous Key to explore trends in the ecosystem health of Lake Superior and
Lake Ontario. Her conclusions were similar to the findings of Marshall et al. (1992) for Lake
Superior, but she found that Lake Ontario's trends indicated substantial and continuing imbalance.
Powers (1989) explored the possible effects of various fishery management schemes on the future
health of the Lake Ontario. In 1973, the indicator showed a degraded state, and ecosystem health
appeared to decline through 1983 in spite of a rather substantial recovery of recreational fishing
(Figure 9). Future projections showed a recovery to the 1973 level as rehabilitation of lake trout
approached the goals set in the Lake Trout Rehabilitation Plan for Lake Ontario (Schneider et
al., 1985). Other aspects of the Lake Ontario system health profile (Figure 9), however, are more
troubling. In spite of achieving some of the interim goals for lake trout rehabilitation by 1988,
the system health of Lake Ontario resists exceeding the degraded condition in 1973. Over the
period 1973 to 1988, the lake trout population and other salmonid populations have increased
markedly due to intensive stocking efforts. The indicator implies that this rehabilitation effort
did not increase system health. Closer analysis of the stress categories (Figure 10) reveals that
toxic contamination contributes significantly to the decrease in system health. Lake trout
18
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restoration provided an indication of just how degraded the Lake Ontario ecosystem really was.
Further recovery of system health in Lake Ontario seems to be hindered by fundamental shifts
in the fish community (Environmental Biotic stresses), future levels of exploitation (Exploitation
stress), and continuing toxic contamination. Whether the indicator is sensitive enough to
improvements in these stresses is not clear, but it certainly does not show any indication of
improvement of system health despite a massive investment of resources in the rehabilitation of
Lake Ontario.
Composite indices other than the Dichotomous Key of Marshall et al (1987) have also been
applied to portions of the Great Lakes. The Ohio Environmental Protection Agency, for example,
has attempted to characterize the state of the estuarine fish communities in Ohio waters of Lake
Erie (Thoma, unpublished report, OEPA). Using an Index of Biotic Integrity (IBI), the Ohio
EPA found that only one of fourteen estuaries sampled met minimal integrity and health criteria
(Figure 11). Factors responsible for the degraded state of the estuarine communities include
extensive habitat modification, point source discharges, and diffuse, non-point sources effects
preclude most sampled sites from attaining minimal goals. However, the most serious
degradation is the modification of wetlands in the estuaries (Thoma, unpublished report).
Aquatic Community Health - SOLEC working paper in
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20
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4.0 Management Implications
The Great Lakes today do not meet current ecosystem objectives. Li recent years, various
indicators show improving conditions in all lakes. All of the lakes have some extremely
degraded areas associated with local pollution sources. Apart from its areas of concern, Lake
Superior is clearly in the best state of recovery, and even considering continuing concern about
levels of toxic contaminants in fish and wildlife, ultimate achievement of the objectives seems
a reasonable goal. The governments of Canada and the U.S., in fact, have selected Lake Superior
for a demonstration program for zero discharge of toxic contaminants as part of their
responsibilities under the Great Lakes Water Quality Agreement. All of the other Great Lakes,
however, have some significant problems that will impede future recovery. These include: large-
scale degradation of tributary and nearshore habitat for fish and wildlife; inadequate reproduction
of many native predatory fish; imbalance of aquatic communities associated with population
explosions of invading species like sea lamprey, white perch, and zebra mussels; expectations of
production from fish communities through stocking and exploitation levels that are not consistent
with the productive capacity of the ecosystems; and contaminant levels in fish and wildlife that
are sufficient to continue producing effects on health of humans, fish, and fish-eating wildlife.
4.1 Evaluation of Stresses
Chemical pollution of the Great Lakes has decreased. Phosphorus loading targets have been
attained for Lake Erie and Lake Ontario, and there is continuing improvement in the regulation
of non-point sources of nutrient and sediment loading throughout the Great Lakes basin.
Although trends are also encouraging, declining levels of toxic contaminants in fish and wildlife
have leveled off (cf. companion paper on the state of toxic contaminants in the Great Lakes).
Concern with this continuing contamination led the National Wildlife Federation and the
Canadian Institute for Environmental Law and Policy to call for more active efforts of
governments to adopt a uniform system of consumption advisories for fish and to move more
aggressively to promote a program for zero discharge of toxic contaminants (Anon. 199 Ic).
The 1987 Protocols to the GLWQA created an initiative for Lakewide Management Plans
(LaMPs) to address the need for a more coordinated approach to management of critical
pollutants. Management plans for toxic chemicals have been the first focus of these efforts in
Lake Ontario and Lake Michigan. These efforts promise continued downward trends in chemical
pollution, if progress is made on reduction of atmospheric input, on suppression of the
resuspension of contaminated sediments, and on control of input from non-point sources. Future
progress in restoration of the ecosystems of the Great Lakes will then depend upon reducing
physical and biological stresses.
The physical integrity of the ecosystems in the Great Lakes basin has been degraded by a wide
range of historical human activities. The assessment of Ohio's estuarine fish communities
(Thoma, unpublished report) is typical of other areas in the Great Lakes. Thoraa lists several
Aquatic Community Health - SOLEC working paper 21
-------
types of habitat modifications that contribute to degradation: wetland filling, marina
construction, shipping channel construction and maintenance, and bank alterations with either rip
rap or vertical bulkheads. Throughout the Great Lakes, natural shorelines, wetlands, and
tributaries have disappeared or have been altered. Impoundments and siltation have eliminated
spawning habitat for adfluvial fish species, and nearshore fish communities and nursery areas for
off shore fish species have been seriously impaired. The magnitude of these effects has been
well documented for some Areas of Concern (e.g. Ohio EPA, 1992). However, the overall
effects of these habitat modifications on the health of open-water fish communities are not readily
documented. In Lakes Ontario and Michigan and to lesser extents in Huron and Superior,
stocking of top predators obscures the effects of degraded habitat In Lake Erie, Lake St. Clair,
and mesotrophic portions of the other Great Lakes (e.g. Green Bay, Bay of Quinte, and Saginaw
Bay) the fish communities may have already compensated for these effects by restructuring and
elimination of tributary dependent stocks. A major challenge to aquatic resource managers will
be the inventory and classification of this habitat (cf. Busch and Sly 1992) to support planning
for preservation and remediation of critical habitat
Although physical and chemical stresses have contributed to the decline in the integrity of Great
Lakes' ecosystems, stresses associated with biological factors have, in fact, caused much more
severe degradation, particularly in lake ecosystems. The primary stresses are over-exploitation
of biological resources and introduction of exotic organisms. Sustainable exploitation of
renewable, natural resources is a challenge to managers. Ludwig et al. (1993) argue that
technical and social factors combine in such a way that the challenge may never be fully met
Certainly, the history of the Great Lakes offers dramatic examples of the effects of over-fishing
and mismanagement Christie (1972) documents the major role of over-fishing in destabilizing
the fish community of Lake Ontario, and similar findings are available for Lake Erie (Nepszy
1977), Lake Michigan (Wells and McLain 1973), Lake Huron (Berst and Spangler 1973), and
Lake Superior (Lawrie and Rahrer 1973). The interaction of exploitation and the deliberate and
accidental introduction of non-indigenous species has proven to be extremely disruptive. The
invasion of sea lamprey into the upper Great Lakes resulted in the demise of lake trout in Lake
Michigan and Lake Huron and the loss of a number of lake trout stocks in Lake Superior before
an international program for the control of sea lamprey was begun in the 19SO's (Smith and
Tibbies 1980). The extent of the disruption of the food web by sea lamprey and more recently
by zebra mussels and the spiny water flea have led to recommendations for more stringent
controls on introductions (DC and GLFC 1990). Mills et al. (1993) document 139 non-
indigenous species that have become established since the 1880s. Although few of these species
have had the disruptive impact of purple loosestrife, sea lamprey or zebra mussels, they have a
cumulative effect on the structure of aquatic communities of the Great Lakes, and their
persistence raises substantial problems for the rehabilitation and maintenance of native species
associations.
4.2 Management Challenge
Various indicators clearly show that the present state of the health of aquatic communities of the
22
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Great Lakes does not satisfy the ecosystem objectives adopted by Canada and the United States.
Although some of these indicators show signs of improvement, managers will find an emerging
problem in obtaining agreement on quantitative specification of endpoints for the indicators that
will specify attainment of ecosystem objectives. The goal of the GLWQA is to restore and
maintain the integrity of the ecosystems of the Great Lakes. Until now, there has been an
assumption that specification of ecosystem integrity is largely a scientific or technical issue. The
extent of historical disruption of aquatic communities and the establishment of large numbers of
non-indigenous species, however, may preclude the use of native associations (i.e. pre-settlement
ecosystems) as benchmarks for ecosystem integrity.
At best, scientific analysis will allow specification of alternative configurations of the structure
of aquatic communities in the Great Lakes that are consistent with fundamental ecological
principles. The ultimate selection of a restored state is thus a matter of social preference.
Because social preference for state of the Great Lakes ecosystems embodies an implicit set of
uses, the specification of quantitative end points for the indicators is embroiled in the
determination of acceptable ways of using the resources of the Great Lakes. Ecosystem
objectives do not address the issue of how to balance the various uses of these resources, and
managers may find future progress toward attaining the goals of the GLWQA impeded by the
lack of consensus on the desired state of aquatic ecosystems.
The role of State-of-the-Lakes reporting is to define the condition of the ecosystems of the Great
Lakes relative to the desired state and to identify and prioritize management initiatives necessary
to improve and/or to maintain it As such, the State of the Lakes Report is a vital part of a
strategic management process. However, management of the Great Lakes is deficient as a
strategic planning process. As Naisbitt (1980) stated, strategic planning requires a strategic vision
with explicit milestones. As discussed above, the goals and specific objectives in the GLWQA
do not serve as a strategic vision nor does it provide milestones. The challenge of ecosystem
management in the Great Lakes, therefore, is as much a challenge to institutional structure as to
individual management agencies.
Aquatic Community Health - SOLEC working paper 23
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24
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5.0 Literature Cited
Anonymous. 1991 a. Toxic Chemicals in the Great Lakes and Associated Effect*. Volume I: Contaminant Level*
and Trend*. Environment Canada, Department of Fisheries and Occam, and Health and Welfare Canada.
488 p.
Anonymous. 1991 b. Toxic Chemicals in jbe Great Lakes and Associated Effects. Volume II: Effects.
Environment Canada, Department of Fisheries and Oceans, and Health and Welfare Canada, pp 495-755.
Anonymous. 1991 c. A prescription for healthy Great Lakes, Report of the Program for Zero Discharge. National
Wildlife Federation and the Canadian Institute for Environmental Law and Policy. 65 p.
Beitinger, T. L. and R. W. McCauley. 1990. Whole-animal physiological processes for jfae assessment o| stress in
fishes. J. Great Lakes Res. 16:542-575.
Berst, A. H. and G. R. SpangJer. 1973. Lake Huron-The ecology of the fish community and man's effects on it,
Great Lakes Pish. Comm., Tech. Rep. 21. 41 pp.
Bertram, P. E. and T. B. Reynoldson. 1992. Developing ecosystem objectives for the Great Lakes: policy, progress
and public participation. J. Aquat. Ecosys. Health 1:89-95.
Best, D. A., W. W. Bowerman, T. J. Kubiak, S. R. Winterstein, S. Postupalsky, M. C. SbieldcasUe, and J. P. Giesy.
(in press). Reproductive impairment of bald eagles along the Great Lakes shorelines of Michigan and Ohio
IV World Conf. Birds of Prey and Owls.
Bowerman, W. W., T. J. Kubialc, J. B. Holt, D. L. Evans, R. G. Eckstein, C. R. Sindelar, D. A. Best, and K. D.
Kozie. In press. Observed abnormalities in mandibles of nestling bald eagles (Haliaeetus leucocephalus).
Bull. Environ. Contain. Toxicol.
Buscb, W, N. and P. G. Sly 1992. The Development of an Aquatic Habitat Classification System for Lakes. CRC
Press, Ann Arbor. 225 p.
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Figure 1. Mixed function oxidase (aryl hydrocarbon hydroxylase) activity in lake trout (Salvelinus namaycush) from the Great Lakes, 1982 -1988.
(From P Hodson. National Water Research Institute Canada. Burlington, Ontario. Personal Communication.)
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I
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Figure 2. Mixed function oxidase (aryl hydrocarbon hydroxylase) activity in white suckers (Catostomus commersoni) from the Great Lakes, 1982
(From P. Hodson, National Water Research Institute Canada, Burlington, Ontario. Personal communication.)
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