1994 State of the Lakes Ecosystem
Conference
Background Paper
Aquatic Community Health
of the Great Lakes
August 1995
Environment Canada
United States Environmental Protection Agency
EPA 905-R-95-012
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State of the Great Lakes Ecosystem Conference
Background Paper
AQUATIC COMMUNITY HEALTH
OF THE GREAT LAKES
Joseph F. Koonce
Department of Biology
Case Western Reserve University
Cleveland, Ohio
August, 1995
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Table of Contents
Acknowledgments iv
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
13.2 Community Health Indicators.... 7
2.0 STATUS AND TRENDS FOR 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
List of Figures 29
Figures ., 30
Aquatic Community Health - SOLEC Background Paper iii
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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 U.S. Environmental Protection Agency
Uwe Borgmann Great Lakes Laboratory for Fisheries and Aquatic Sciences
J. H. Leach Ontario Ministry of Natural Resources
W. J. Christie Ontario Ministry of Natural Resources (retired)
R, M. Dermott Department of Fisheries and Oceans
E. L. Mills Cornell University
C. J. Edwards U.S. Department of Agriculture
R. A. Ryder Ontario Ministry of Natural Resources
Michael L. Jones Ontario Ministry of Natural Resources
William, W. Taylor Michigan State University
S. R. Kerr Bedford Institute of Oceanography
Terry Marshall Ontario Ministry of Natural Resources
Glen A. Fox Canadian Wildlife Service
ChipWeseloh Canadian Wildlife Service
Joseph H. Elrod U.S. Fish and Wildlife Service
Ora Johnannson Great Lakes Laboratory for Fisheries and Aquatic Sciences
David Best U.S. Fish and Wildlife Service
C. P. Schneider 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 teave-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.
IV
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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 witi be
incorporated into the SOLEC Proceedings, which will provide key information required by
managers to make better environmental decisions.
Aquatic Community Health - SOLEC Background 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
Aquatic Community Health - SOLEC Background Paper 1
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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 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. Rolling (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
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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 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
hoyi 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.
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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.
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 of Mixed Function
Oxidase Enzymes (MFO), e.g.
P4501A1.
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 earboxylated 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 goitergins
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.
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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 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 wo± 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 a/.,
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.
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An example of the first category is the use of lake trout (Salvelinus namaycush) and Pontoporeia for
oligotrophic ecosystems (Ryder and Edwards 1985) and walleye (Stizostedion vitreum) and burrowing
mayfly (Hexagenia limbata) 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 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 Late Ontario Pekgic Community Health Indicator
Committee for ecosystem structure and functional energy flow (after Christie 1993).
Indicator
Biomass or
production
size
spectrum
Yield of
piscivores
Ratio of
Rsdvore to
prey
biomass
Fraction of
yield as
native fish.
Zooplankton
size
distribution.
Total P
levels <= 10
mgfl
Fish
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 at the
Caw Bioindex
stations.
Monthly surveillance
(1976-1981);
biannual survey
(1982-present)
Standard glllnet,
trawl, trapnet, seine
collections. Glllnet
data continuous
since 1957 and 1956
in Bay of Quinte and
Kingston Basin.
Trawl data
continuous since
1972 in all areas.
Broken series for the
others.
Methodology for 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.
Rn clips used In past, nasal
insert tags currently used In all
larger fish released. Ototith,
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
Conventional 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 to focus 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
In 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.
10
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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) (Le. 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 Rgure 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
etal. 1990, Gilbertson 1992).
Circumstantial evidence is also strong for chemically induced carcinogenesis in Great Lakes fish.
Summary of observations (Anon. 1991b) indicates that proof of causation of incidence patterns of
tumors is lacking. Nevertheless, the overwhelming evidence bads 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, Homer and Eshenroder 1993). Other "diseases" 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. 1991b). 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 caspia), common tern (Sterna hirundo),
Forster's tern (Sterna forsteri), and snapping turtle (Chelydra serpentind). Of these, 9 species showed
historical evidence of reproductive impairment due to contaminants (see Table 1, Anon. 1991b, 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 baM eagles had recovered from a low of 400 pairs
12
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nationwide in 1964 to 2700 pairs in 1989 (Anon. 1991b), Great Lakes populations have foEowed this
recovery trend, but reproductive success of breeding pairs nesting on shorelines of 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 baM 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
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 !.
Presq'ile Pk.
Black Ant 1.
Muoo's 1.
Lake Erie
Big Chicken t.
Port Colbome
Middle 1.
Lake Huron
Chantry I.
Double 1.
Lake Superior
Agawa Rk.
Granite 1.
1972 1973 1974
0,21
0,12 0.06
0.10
0.06
0.08
0.45
0.48
1975 1976 1977 1978
1.01 0.86
0.15 1.10 1.01
1.52 1.47
0.65 0.79 1.45
1.70
1.48 1.12 1,40
1.57
1.32 1.55 1.66
1.12
1979
1.60
1,56
1.63
2.17
2.17
0.88
1.70
1980
1.49
1.62
2.17
2.25
0.40
1.40
1981
1.73
2.13
1.40
1.60
2.10
2.16
2.23
0.37
0.46
1982 1983
1.34
2.17
1.84
1,25
0,14 0.37
1,39
1984
1,17
0.95
2.33
0.85
1.39
1985
1.00
1.30
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 1970s (Anon. 199 Ib, 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
Aquatic Community Health - SOLEC Background Paper 13
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varies with time and location and generally decreased between the early 1970s and late 1980s.
However, these studies confirm the continued presence of sufficient amounts of PCBs and related
persistent halogenated aromatic hydrocarbons in forage fish to came physiological impairments in
these birds over much of the 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 (Le. 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 pky 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 Spangfer 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.
Aquatic Community Health - SOLEC Background 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 Name
T .akfi stiiromn
Lonciaw cisco
Lake herons
Lake whitefish
Bloater
Deeowater cisco
KiM
Blackfin ciseo
Shortnose cisco
Shortiaw Cisco
Burbot
Fourhorn scutate
Emerald shiner
Atlantic salmon
Lake trout
Sauger
Blue oike
Snecies Name
Arinrnspr fiuvesrenx
Coresonus alpenae
C, artedii
C. clupeaformis
C. hovi
C, iohannae
C. MM
C. nisripinnis
C. reishardi
C. zenithicus
Lota lota
Mvoxocephalus
Notropis atherinoides
Salmo solar
Salvelilnus namavcush
Stizostedion canadense
S. vitreum elaucum
Sunerior
1
1
1
2
1
Huron
1
2
2
2
2
2
2*
Michigan
1
2
1
2
2
2
1
3
2
2*
Rrie
1
2
2
1
1
2*
2
•3
Ontario
1
2
2
2
1
1
3
2*
2*
3
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
(Osmerus mordax), gizzard shad (Dorosoma cepedianum), white perch (Morone americand), carp
(Cyprinus carpio),brown trout (Salmo trutta), Chinook sakmn(Oncorhynehus tshawytscha), coho
salmon(O. idsutch), pink Bahaot^O.gorbuscha), rainbow trout (O, myldss). Since 1985, other species
such as the ruffe (Gymnocephalus cernuus), the rudd (Scardinius erythrophthalmus), fourspine
stickleback (Apeltes quadracus), and two species of goby (Neogobius melanostomus and
Proterorhinus marmoratus) have also invaded the Great Lakes (Mills et 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 these historical
fish communities. By launching an aggressive, bi-national program to control sea lamprey, which with
overexploitation caused the extirpation of lake trout m 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
16
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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 fifl.
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 (Sprules 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 (Christie 1993), a mean zooplankton size of 0.8 to 1.2
mm 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 that declines in productivity of both lakes assockted 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
Aquatic Community Health - SOLEC Background Paper 17
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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 ampMpod Gammarus in nearshore benthic communities
dominated by zebra mussels, Dermott (1993) has observed an inverse relation to abundance of
Diporeia 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. 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 (ie. was the least degraded) followed by
Lake Huron, Like 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
18
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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. From the perspective of fish management agencies and the recreational fishing industry, these
changes represent successful restoration of an extremely degraded fish community. The indicator,
however, implies that this rehabilitation effort did not increase system health. Closer analysis of the
stress categories (Figure 10) reveals that toxic contamination has contributed significantly to the
decrease in system health. 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. Although some of these stress continue to
improve, an indicator based on historical benchmarks for lake trout, in contrast to one based on the
degraded state in 1960s, 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 Background Paper 19
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4.0 Management Implications
The Great Lakes today do not meet current ecosystem objectives. In 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. 1991c).
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.
Aquatic Community Health - SOLEC Background Paper 21
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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. Thoma lists several 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 (Wels and McLain 1973),
Lake Huron (Berst and Spangter 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 1950'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 (IJC 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.
22
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4.2 Management Challenge
Various indicators clearly show that the present state of the health of aquatic communities of the 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 (Le. 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.
One 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 Background Paper 23
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5.0 Literature Cited
Anonymous. 1991 a. Toxic Chemicals in the Great Lakes and Associated Effects. Volume I: Contaminant
Levels and Trends. Environment Canada, Department of Fisheries and Oceans, and Health and Welfare
Canada. 488 p.
Anonymous. 1991 b. Toxic Chemicals in the 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 the assessment of stress in
fishes. J. Great Lakes Res. 16:542-575.
Berst, A. H. and G. R. Spangler. 1973. Lake Huron-The ecology of the fish community and man's effects on it.
Great Lakes Fish. 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. Shieldcastle, 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. Kubiak, 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.
Busch, W. N. and P. G. Sly 1992. The Development of an Aquatic Habitat Classification System far Lakes. CRC
Press, Ann Arbor. 225 p.
Christie. W. J. 1972. Lake Ontario: effects of exploitation, introductions, and eutrophication on the salmonid
community. J. Fish. Res. Bd. Canada 29: 913-929.
Christie, W. J. 1973. A review of the changes in the fish species composition of Lake Ontario. Great Lakes Fish.
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Aquatic Community Health ~ SOLEC Background Paper 25
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28
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List of Figures
Figure 1. Patterns in observations of mixed function oxidase (MFO) activity in lake trout of the Great Lakes basin
(after Anon. 1991b, Fig. 2, p 521).
Figure 2. Patterns in observations of mixed function oxidase (MFO) activity in white sucker of the Great Lakes
basin (after Anon. 1991b, Fig. 3, p 522).
Figure 3. Harvest and BKD incidence trends for Chinook salmon in Lake Michigan. Data provided by Kelly
Smith, Michigan Department of Natural Resources.
Figure 4. Trends in productivity of double-crestested cormorants in Lake Ontario (after Table 6, Anon. 1991b, p.
589).
Figure 5. Scores for each Great Lake for the interval 1982-1985 from the Dichotomous Key. The vertical line in
each bar is the percent uncertainty associated with the score. Data are from Edwards et al. (1990, p. 601).
Figure 6. Contribution by stress category to Dichotomous Key scores for each Great Lake for the interval 1982-
1985. Vertical lines in each box represent percent uncertainty. Data are from Edwards et al. (1990, p. 602),
Codes for stress categories are C (contaminants), EP (exploitation and production), BE (biotic environmental), and
AE (abiotic environmental).
Figure 7. Comparison of annual harvest of all salmonines in Lake Superior with the score from the Dichotomous
Key. Data are from Marshall et al. (1992, p. 65).
Figure 8. Contribution by stress category to Dichotomous Key scores for trends in Lake Superior Data are from
Marshall et al. (1992, p. 64).
Figure 9. Estimated ecosystem health index for Lake Ontario in the period 1973 to 2002. Ecosystem health index
values were derived from the ecosystem health index of Ryder and Edwards (1985) by a recursive procedure
(Powers, 1989). Estimates of lake trout abundance are derived from the model documented in Jones et al. (1993).
Figure 10. Contribution of various stress categories to the degradation of ecosystem health in Lake Ontario, after
Powers (1989).
Figure 11. Minimum, maximum, and mean Index of Biotic Integrity (EBI) for 14 estuaries. For comparison the
Warm Water Habitat aquatic life use criterion value of 32 is plotted as a solid line. Figure is from Thoma
(unpublished report, Ohio EPA).
Aquatic Community Health - SOLEC Background Paper 29
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• OpenUke
• Harbours, Rivera, tap
Figure 1. Patterns in observations of mixed function oxidase (MFO) activity in lake trout of
the Great Lakes basin
30
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68.3
• Open Lake
• Harbours,
Figure 2. Patterns in observations of mixed function oxidase (MFO) activity in white sucker
of the Great Lakes basin
Aquatic Community Health - SOLEC Background Paper
31
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Harvest
(Thousands)
1000
1985 1986 1987 1988 1989 1990
(Harvest-*—BKD
Figure 3. Harvest and BKD incidence trends for
Chinook salmon in Lake Michigan
Young/Pair
s>a
0
Figure 4. Trends in productivity of double-crestested cormorants in Lake Ontario
32
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Score
100
80-
60-
40-
20--
Superior Mchigan Huron Erie Ontario
Figure 5, Scores for each Great Lake for the interval 1982-1985 from the Dichotomous Key
5 I £
Figure 6. Contribution by stress category to Dichotomous Key scores for each Great Lake
for the interval 1982-1985
Aquatic Community Health - SOLEC Background Paper
33
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Score (%)
80
Harvest
(kg/ha)
0.25
0.00
1960
1970
1980
1990
• DK Score-
•Sakrnnid Harvest
Figure 7. Comparison of annual harvest of all salmonines in Lake Superior with the score
from the Dichotomous Key, Data
34
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100 -]
80 -
£ 60 •
2
O AT\
o *HJ *
W
20-
*l
Exploitation &
Production
-
I +-"*
I .X*""'"'
\ JL"^\
M -i-""'l
i ^+— 1-" t '
1 . 1 . . . . . 1
""""""""1™™"""""™*"™ T 1 -J—.™.." J-™— ,,.^,-___^__™~-|— » — j
19SO 1960 1970 1980 1990
100 -
80-
£ 60-
£
o W
20-
1
"1 |_i-^+-^+
' X"^ _J._i-J'/l '
! 1
* f
Biotic
Environmental
I § iii i i i < * !
i t==TTTTTTT"f i ' t •"— f 1 i~™™"*-"~"} i j
1950 1960 1970 1980 1990
100 i
80 -
£ 60-
£
8 40 •
20-
0.
+_+_l._+_h_h_+_l._f_+
Abiotic
Environmental
1950 1960 1970 1980 1990
100 i
80-
£ 60-
g
8 40 •
20-
0.
"
"'
-
X,
\
/+^i_,^+
r '
Contaminant
1950 1960 1970 1980 1990
Figure 8. Contribution by stress category to Dichotomous Key scores for trends in Lake
Superior
Aquatic Community Health - SOLEC Background Paper
35
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Figure 9.
BHI Score
60
Number
600000
1970 1975 1980 1985 1990 1995 2000 2005
•EHI-
•LTAbund
Estimated ecosystem health index for Lake Ontario in the period 1973 to 2002
Stress
40
1979
1985
1991
1997
2003
I Exploit D Env Bbtic • Env Abiotic H Contam
Figure 10. Contribution of various stress categories to the degradation of ecosystem health in
Lake Ontario
36
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IB! Values
35-
30-
25-
10-
5-
0.
— _
i
-----
;ji
~ Western Lake E
!
1 *
' \
> 2
^ 1 WWH€rtorion~
I^lf iltjl
, . . .
; —
Max
— — —
Eastern
- —
Lake Erie
'~ft^3
Min
it||l| |lf fill
5 W > O ^ O
Figure 11 Minimum, maximum, and mean Index of Biotic Integrity (IBI) for 14 estuaries.
(For comparison the Warm Water Habitat aquatic life use criterion value of 32 is
plotted as a solid line)
Aquatic Community Health - SOLEC Background Paper
37
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