LAKE ERIE
LAKE WIDE
JVlAWACiEJVIENT
PLA1V
Lake Erie Lakewide Management Plan (LaMP)
Technical Report Series
Executive Summary
Animal Deformities or Reproduction Problems
Keith Grasman, Christine Bishop, William Bowerman
James Ludwig and Pamela Martin
April 2000
Lake Erie LaMP Technical Report No. 7

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Technical Report 7
Animal Deformities or Reproduction Problems
Prepared for the Lake Erie LaMP
Preliminary Beneficial Use Impairment Assessment
Keith A. Grasman, Lead Author
Co-Authors: Christine A. Bishop, William W. Bowerman, James P. Ludwig,
Pamela A. Martin
April 2000
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NOTE TO THE READER:
This technical report was prepared as one component of Stage 1, or "Problem Definition," for the
Lake Erie LaMP. This report provides detailed technical and background information that
provides the basis for the impairment conclusions recorded in the LaMP 2000.
This document has been extensively reviewed by the government agencies that are partnering to
produce the LaMP, outside experts, and the Lake Erie LaMP Public Forum, a group of citizen
volunteers. This review was designed to answer two questions:
•	Is the document technically sound and defensible?
•	Do the reviewers agree with the document conclusions regarding impairment?
In its present form, this report has been revised to address the comments received during that
review process, and there is majority agreement with the impairment conclusions presented.
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List of Abbreviations
AOC
Area of Concern
DDE
1,1 -dichloro-2,2-bis(/>chlorophenyl)ethylene
DDT
1,1,1 -trichloro-2,2-bis(p-chlorophenyl)ethane
IJC
International Joint Commission
LaMP
Lakewide Management Plan
LC50
lethal concentration for 50% of the population
96h LC50
lethal concentration required to kill 50 percent of the test

population within 96 hours
LOEC
lowest observed effect concentration
NOEC
no observed effect concentration
PAH
polycyclic aromatic hydrocarbons
PCB
polychlorinated biphenyl
TFM
3 -trifluoromethyl-4-nitrophenol
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7.1 Introduction
Industrial activity, agriculture, and development have led to many changes in the Lake Erie
ecosystem. During the 1960s and 70s, pollution was associated with reproductive failures and
population declines in many species of fish-eating wildlife. Since the 1970s, many problem
pollutants have been restricted or banned, but additional chemicals have been introduced into
Lake Erie. Furthermore, significant changes in the aquatic community, such as the introduction
of the zebra mussel (Dreissena polymorpha) and other exotic species, have changed how energy,
and potentially pollutants, move through the food web. As part of the Lake Erie Lakewide
Management Plan, it is important to:
•	assess the current reproductive status of Lake Erie wildlife to determine whether impairments
continue,
•	assess the causes of these impairments whenever possible, and
•	identify important data gaps concerning reproduction and deformities in Lake Erie wildlife.
For each species addressed in this assessment, the primary questions to be answered are "is the
reproductive health of this species impaired, and what is the extent of the impairment?"
Whenever possible, current reproductive status is compared to species-specific criteria for
reproductive success.
Reproductive impairments cannot be understood clearly without considering the factors that
cause them. Determining the cause(s) of the impairments, whenever possible, is a secondary
purpose of this assessment. However, most of the data describing impairments has been
collected in toxicological studies directed at determining the causes of the problems, especially
pollutants. Ideally, large monitoring studies of reproduction or population status would be used
to determine impairment first. Subsequently, additional investigations would then look for the
factors causing the impairment. However, in some cases, much (but not all) of the evidence for
impairment comes from a risk assessment (e.g., comparing egg or diet residues to a reference
dose), which by its definition includes a potential causal factor.
If such a risk assessment suggests impairment, then that is one part of the weight of evidence for
impairment. It does not rule out other factors (non-chemical or other chemicals) that might
contribute to the impairment. This assessment also addresses the level of confidence that can be
ascribed to the status and potential cause(s) of the impairment. This includes evaluation of the
quality of the data and identification of data gaps and research needs.
7.2 Assessment Criteria and Approach
According to the International Joint Commission (IJC), an animal reproductive or deformity
impairment occurs when "wildlife survey data confirm the presence of deformities (e.g., cross-
bill syndrome) or other reproductive problems (e.g., eggshell thinning) in sentinel wildlife
species (IJC 1989)." Sentinel wildlife species are indicators of environmental conditions,
especially pollutants. Fish-eating wildlife and other species that spend a significant part of their
life in or near the water often make good sentinel species.
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Using the IJC listing criteria, the LaMP needed to determine the types of survey data that would
confirm impairments for Lake Erie. Great Lakes Areas of Concern (AOCs) have used two
benchmarks to define wildlife deformity and reproductive impairments:
•	when the incidence rates of cross-bill syndrome, reproductive failure, etc. are significantly
(95% probability level) higher than incidence rates at control sites, or
•	when bald eagle (Haliaeetus leucocephalus) reproduction is less than one eaglet per active
nest.
While these impairment benchmarks are appropriate for the Lake Erie LaMP, they are not
comprehensive enough. Data and evaluation criteria are available for sentinel species other than
the bald eagle. Species-specific criteria may be based on biological or chemical assessments.
These species-specific criteria are based on benchmark concentrations that must not be exceeded
in order to maintain normal reproduction or a healthy or stable population, or on reproductive
values measured at reference sites not impacted by pollutants. Typical measures of reproductive
success include rates of embryonic survival or fledging success (i.e., in birds, survival to flying).
For example, the above-mentioned productivity standard of 1.0 young per occupied nest has
been used as the recovery goal for healthy populations within the Northern States Bald Eagle
Recovery Plan (Grier et al. 1983). Other biological criteria are discussed in the sections on each
species.
Lowest Observable Effects Concentrations (LOECs; concentrations at which reproductive effects
are statistically different from reference sites) or No Observed Effect Concentrations (NOECs;
highest observed concentrations at which reproduction is not statistically different from reference
sites), measured in field and laboratory studies, can be used to derive chemical criteria that must
not be exceeded in order maintain normal reproduction or a healthy population. For example,
reproductive NOEC criteria for bald eagle eggs are 4.0 mg/kg for total PCBs, 3.5 mg/kg for p,p'-
DDE, and 1 mg/kg for dieldrin (all expressed as fresh, wet-weight; Wiemeyer et al. 1984;
Wiemeyer et al. 1993; Giesy et al. 1995). If chemical concentrations above these criteria are
known to be present in fish and wildlife tissues in the Lake Erie ecosystem, we can conclude that
impairment is likely, even if a particular population has not been monitored for reproductive
effects and deformities. Such a finding is a good tool to focus future reproduction and
population studies. A risk assessment based on field-derived exposure levels and species-
specific effect levels avoids the uncertainties of interspecies extrapolations and estimated
exposure (by modeling).
There are also important effects not mentioned in the IJC listing criteria, but which can
nevertheless be used to indicate whether impairment is occurring or is likely to occur. As the
fields of biochemistry, molecular biology, and physiology have advanced during the last 25
years, biologists have gained additional tools for investigating the effects of pollutants on
wildlife. Often these physiological variables are called biomarkers—biochemical, cellular, or
physiological changes that indicate exposure to and toxic effects of pollutants (e.g., immune
function, histology, vitamin A stores, porphyria, liver enzyme activity, reproductive hormones).
Measurement of impairments within the body helps to explain deformities and reproductive
problems seen on the organismal level. The application of these state-of-the-art techniques is
similar to laboratory tests performed by a physician to elucidate the causes and severity of
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particular diseases. Environmental toxicologists have successfully used biochemical and cellular
biomarkers to investigate contaminant-associated impairments in fish and wildlife species,
including many Great Lakes studies. Measurement of these characteristics in sentinel species
can provide important supplemental information to more traditional assessments of reproductive
performance and deformities.
Therefore, the LaMP has adopted a weight of the evidence approach to this particular assessment
where information related to all of the above-mentioned criteria are considered, where available,
to draw impairment conclusions for a particular species.
7.3 Scope of the Assessment
It should be noted that contaminant studies tend to look at effects on a particular organism in a
particular location versus population-wide effects. Per the IJC listing criteria, this assessment
is not required or intended to determine whether basin-wide or sub-population effects are
occurring due to the identified deformities or reproductive problems. The purpose of this
assessment is to identify whether reproduction or deformity problems are occurring due to
chemical contaminants. Population-level impairments are covered in the degradation of wildlife
populations assessment.
Reproductive effects do not immediately or always translate into population effects. For
example, if a population is near its carrying capacity (point at which species is in equilibrium
with its environment), then there may not be enough resources (food, nesting habitat, etc.) for all
young to survive to reproductive age. Hence, up to a point, a decrease in production of young
due to a contaminant may not affect adult population size because many young would have died
anyway. However, if the population is below its carrying capacity, a decrease in production of
young may prevent the population from reaching carrying capacity. In this situation, the
impairments summarized in Table 7.1 can become more significant when all stressors to a
particular species group are summed (contaminants, habitat loss, exotics, etc.).
The geographic boundary of the area where impairments are identified includes the open waters
of Lake Erie, the nearshore areas, embayments, river mouths, and the lake effect zone of
tributaries. The Lake Saint Clair watershed is not included in the scope of the Lake Erie LaMP
beneficial use impairment assessment. However, the source and/or cause of impairment may fall
outside the above-mentioned geographic boundary.
Deformity and (or) reproductive impairments have been assessed for:
•	aquatic birds, including bald eagles, colonial waterbirds, and tree swallows,
•	fish-eating mammals, including mink (Mustela vison) and river otter (Lutra canadensis), and
•	amphibians and reptiles, including snapping turtles (Chelydra serpentina serpentina) and
eastern spiny softshell turtles (Apalone spiniferus), frogs and toads in general, and
mudpuppies (Necturus maculosus).
Findings for each group are presented in Table 7.1 and following text in section 7.4.
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7.4 Impairment Conclusions
Table 7.1 Summary of Animal Deformity or Reproduction Impairment Conclusions
Species/
Species Group
Reproduction
Deformities
Physiology
Notes
Impaired?
Likely Cause
Impaired?
Likely
Cause
Impaired?
Likely
Cause
Type of Impairment
Bald Eagle
Yes; observed;
exposure above
effect levels
PCBs,
dieldrin, DDE
Yes; observed
PCBs
No data


* Extent of impairment is probably
obscured by hacking/fostering and
immigration from less contaminated
inland territories
Colonial
Waterbirds
Yes; observed in
herring gull;
exposure above
effect levels in
herring gull,
cormorant, and
common tern eggs
PCBs,
possibly other
chemicals
Yes; observed;
exposure above
effect levels
PCBs
Yes;
observed;
exposure
above effect
levels
PCBs, other
organochlorines
(OCs)
Immune system,
reproductive organs,
thyroids, liver
enzymes, vitamin A
and porphyrins*
*	Most data from W. basin and herring
gulls
*	Tree nesting cormorants hard to
study, but contaminant concentrations
are among highest in Great Lakes and
are likely associated with embryonic
mortality and deformities
*	Cause of recent reproductive failures
of herring gulls on W. Sister Is. may
include PCBs, microcystin, and (or)
other factors
*	Although Caspian terns have
attempted to colonize LE as recently as
1996, they are still too rare in the basin
for field study.
Tree Swallow
No

No data

No


* Significant OC exposure; resistance
to effects may make swallow a poor
indicator species for other insect-eating
songbirds
Mirik
Likely; PCB levels
in food above effect
levels
PCBs
No data

No data;
likely, based
on PCB levels
in food



Otter
Insufficient data,
but likely based on
predicted high
exposure
PCBs
No data

No data


* Too rare in Erie basin for study, as
they were re-introduced in 1986.
Snapping
Turtle
Not observed, but
exposure at some
Ohio sites above
effect levels
PCBs, other
OCs
Not observed,
but exposure at
some Ohio
sites above
effect levels
PCBs,
other
OCs
Likely
organochlorines
Endocrine
/reproductive

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Table 7.1 Summary of Animal Deformity or Reproduction Impairment Conclusions (continued)
Species/
Species Group
Reproduction

Deformities
Physiology
Notes
Impaired?
Likely Cause
Impaired?
Likely
Cause
Impaired?
Likely
Cause
Type of Impairment
Frogs/Toads
Likely
High DDE
and nitrates
No data

No data


* Nitrate concentrations in Lake Erie
watershed often exceed lethal and
sublethal concentrations for
amphibians in laboratory experiments
(see section 7.4.1.6)
Mudpuppies
Considered likely
by the authors;
determined to be
inconclusive by the
LaMP (see sections
7.4.1.6 and 7.5)

Yes; observed
PAHs
and OCs
No data


* Data from the Grand River in Ohio
and elsewhere in the Great Lakes
indicate acute mortality following
TFM application for sea lamprey
control (see section 7.4.1.6)
*porphyrins - the liver synthesizes heme, which is important for hemoglobin and some enzymes. PCBs and other organochlorines block this process and cause the accumulation of intermediate
products called highly carboxylated porphyrins.
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7.4.1 Reproductive Impairments
7.4.1.1	Bald Eagle
Bald eagles nesting within 8 km of Lake Erie have impaired reproduction. Although bald eagle
productivity, the number of fledglings (survival to age of flying) per nest, has increased since
1980, the Ohio Lake Erie eagles remain below the recovery goal of 1.0 young fledged/occupied
nest. Increases in the reproductive success of the Lake Erie basin bald eagle sub-population may
have been influenced by several factors that potentially confound linkages between exposure to
contaminants in Lake Erie and biological effects. A large number of uncontaminated nestlings
were introduced to the sub-population through hacking and fostering projects along the Ontario
and Ohio shorelines during the mid-1980s. There appears to have been a great increase in
nesting success within the time period associated with the sexual maturation of these introduced
birds. The recovery of the bald eagle throughout North America, including inland areas near the
Great Lakes, has created a pool of young eagles dispersing to find available and unclaimed
breeding territories. The high turnover of adults along the Ohio and Michigan shorelines of Lake
Erie suggests the possibility of colonization of these territories by eagles raised elsewhere.
Reproductive success tends to increase following replacement of an older adult in a shoreline
territory.
Because human interventions and natural immigration have potentially led to the introduction of
adult eagles that were not exposed developmentally (i.e., in ovo) to Lake Erie contaminants, a
risk assessment based on comparison of contaminant concentrations in eagle eggs to known
adverse effect concentrations is particularly insightful. Eagle eggs from the Ohio and Ontario
shorelines of Lake Erie consistently exceed PCB and dieldrin criteria, and often exceed the p,p'-
DDE criterion for adverse effects. These Lake Erie data, when interpreted in the context of
studies showing effects of organochlorines on eagle reproduction elsewhere in North America,
strongly suggest that current concentrations of organochlorines in Lake Erie are causing
reproductive impairment of bald eagle reproduction.
7.4.1.2	Colonial Waterbirds
DDE-induced eggshell thinning does not appear to be important at current levels of
contamination for any of the species examined.
There are significant reproductive and physiological impairments in herring gulls from western
Lake Erie. The cause of the reproductive impairment requires further investigation. Potential
causes include contaminants, cyanobacterial toxin (microcystins), and infectious diseases. Many
but not necessarily all of the physiological impacts, including immunosuppression and altered
thyroid function and vitamin A status, are associated with PCB exposure. Current PCB
concentrations in Lake Erie herring gull eggs, especially in the western basin (20 ug/g), are
sufficient to cause some embryonic mortality (LOEC 5.0 ug/g).
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While the tree nesting habits of Lake Erie cormorants make reproductive assessments difficult,
measurement of PCB concentrations in Lake Erie cormorant eggs suggests the strong probability
of reduced hatching success and increased rates of deformities.
Recent data for common terns in the western basin indicates reproductive impairment caused
primarily by predation. However, organochlorine concentrations in eggs are high enough to
contribute to reproductive impairment.
Overall, PCB concentrations in Lake Erie, primarily in sediments but also the water column, are
high enough to present a significant risk of reproductive and physiological effects in fish-eating
colonial waterbirds, especially in the western basin.
7.4.1.3	Tree Swallows
There does not appear to be reproductive impairment in Lake Erie tree swallows. Tree swallows
are good indicators of exposure to contaminants via aquatic insects, but they tend to be resistant
to the reproductive impacts (measured in terms of embryonic survival and fledging success) of
organochlorine exposure. Other species of insectivorous passerine birds in Lake Erie may be
more sensitive to the reproductive effects of contaminants.
7.4.1.4	Mink and River Otter
Trapping data provide our only estimates of mink population abundance. However, factors such
as trapping effort and correlation with muskrat abundance confound the analysis of trapping data
as an indicator of reproductive success. Some assessments of numbers of trapped mink suggest
lower mink populations along Lake Erie, but other assessments show little difference from inland
areas.
Although strong population data do not exist, laboratory studies clearly show that mink are
highly sensitive to the lethal, reproductive, and immunosupressive effects of PCBs. The few
existing data on Lake Erie mink tissue residues indicate that wild mink are exposed to potentially
harmful concentrations of PCBs. Analysis of important prey species for mink suggests high
concentrations of PCBs above dietary concentrations known to adversely affect mink in the
laboratory, strongly indicating potential reproductive impairments.
Otters were extirpated from the Lake Erie watershed by 1900, and there is no data to support or
refute an association between PCBs and reproduction and population impairments in Lake Erie,
although data from other locations indicates a cause-effect relationship. Exposure to PCBs is
often greater for otters than mink, and otters may be equally sensitive to the effects of PCBs.
Recovery of otter populations are still impaired in the Lake Erie basin, as evidenced by the need
for introduction programs in the Lake Erie region, and the relatively rare observations of otter
families in the Lake Erie watershed despite reintroduction programs.
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7.4.1.5 Reptiles
The few available studies on turtles have shown that contaminant concentrations in snapping
turtle eggs from Big Creek Marsh and Rondeau Provincial Park, Lake Erie (Canada) are not
associated with elevated rates of embryotoxicity or deformities. Concentrations of PCBs
detected in eggs from two sites in Ohio are similar to those from Hamilton Harbour where
reproductive anomalies have been correlated with PCB exposure in snapping turtle eggs.
Feminization effects noted in a correlational study between organochlorine concentrations in
plasma and effects in adult male snapping turtles from Long Point (Canada) indicate subtle
endocrine disrupting effects may be occurring.
Contaminant concentrations in Lake Erie water snakes from Pelee Island are high enough to
justify a study of health and reproductive effects.
Contaminant concentrations in the eastern spiny softshell turtle and the corresponding low rates
of hatching in eggs in the Lake Erie basin suggest further investigation of contaminant effects is
warranted. This species is considered threatened by the Province of Ontario.
7.4.1.6 Amphibians
Contaminant concentrations, including organochlorine and polycyclic aromatic hydrocarbons,
have been measured in amphibians at various locations in the Canadian Lake Erie basin. Studies
of biological effects are sparse. The presence of p,p'-DDE in some amphibians from Point Pelee
suggests that further study is required to determine the sensitivity to p,p'-DDE of amphibian
species native to Lake Erie. Deformity rates of mudpuppies at Long Point and in the Detroit
River are elevated well above the background rates reported for inland areas of the Great Lakes
and St. Lawrence River basin. However, a contaminant-associated etiology has not been
confirmed at this time.
Emerging Issues
Nitrates and 3-trifluoromethyl-4-nitrophenol (TFM) are two chemicals that do not
bioaccumulate. Nevertheless, they are pollutants that have been shown to cause biological
impacts to amphibians. Because less research and monitoring data is generally available for
amphibian populations as a group, the mechanisms for the observed biological effects of these
chemicals are not as clearly defined as those for other organisms. A short summary of what is
known is provided below.
A review by Rouse et al. (1999) evaluated the risk of direct and indirect effects of nitrate on
amphibian populations. This review used a simple comparison of known environmental nitrate
concentrations in North American waters to nitrate concentrations known to cause toxicity in a
laboratory setting to amphibian larvae and other species that play an important role in amphibian
ecology. Lethal and sublethal effects in amphibians are detected in laboratory tests at nitrate
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concentrations between 2.5 and 385 mg/L Amphibian food sources such as insects and predators
such as fish are also affected by elevated levels of ammonia and nitrate in surface waters.
Of 8000 water samples from rivers in the watersheds of Lake Erie and St. Clair in the Canadian
Great Lakes and in U.S. states in the Lake Erie watershed, 19.8% had nitrate levels above 3
mg/L. This concentration was known to cause physical and behavioral abnormalities in some
amphibian species in the laboratory. A total of 3.1% samples contained nitrate levels that would
be high enough to kill tadpoles of native amphibian species in laboratory. This may have
important implications for the survival of amphibian populations and the health of food webs in
general. However, these predictions are based on laboratory-based studies and need to be tested
in the wild.
The sensitivity of mudpuppies, frog tadpoles and adult frogs to TFM use in the Great Lakes has
been noted (Gilderhus and Johnson, 1980). TFM is intended to control larval sea lamprey and
has been used historically in 19 (8 in U.S./l 1 in Canada) of the 842 tributaries to Lake Erie for
sea lamprey (Petromyzon marinus) control. Since 1995, TFM has been applied in Conneaut
Creek and the Grand River in Ohio and Big Creek and Big Otter Creek in Ontario. Only four
Lake Erie tributaries (Big Creek Ontario, and 3 U.S. tributaries) are currently scheduled for
future regular treatments every 4 to 6 years.
When TFM is used, amphibians have regularly been found dead in creeks immediately after
treatment in Lake Erie watersheds and elsewhere in the Great Lakes (Gilderhus and Johnson,
1980; Matson, 1990). Laboratory tests have confirmed that species native to the Great Lakes
basin such as gray tree frog, leopard frog, and bullfrog are sensitive to field applied rates of TFM
(Chandler and Marking, 1975). In the Grand River, Ohio, Matson (1990) found that in the year
following TFM application (1997), mudpuppy population size decreased by a minimum of 29%
in the segment treated. In 1999, the Grand River was treated with TFM and dead mudpuppies
were found downstream of the application zone within twenty-fours hours.
Because TFM is not bioaccumulative and is only applied periodically in closely controlled and
monitored conditions, the associated mudpuppy mortality is often perceived to be insignificant.
However, mudpuppies do not become sexually mature until 4 to 6 years of age. Given the past
and projected future schedule for TFM applications, there is the potential for the TFM
applications to match periods when large numbers of mudpuppy are reaching an age when they
can reproduce. In addition, TFM is generally applied in the spring when stream flows are higher.
Therefore, TFM has the potential to kill a portion of the existing females before they lay their
eggs in May and June. For these reasons, future study is needed to determine the significance of
the mortality and the life stages most affected (see section 7.5).
7.4.2 Deformity Impairments
The weight of evidence from field and laboratory studies shows a causal association between
dioxin-like chemicals and developmental deformities such as crossed bills. In the Great Lakes,
the largest proportion of dioxin-like activity is attributable to PCBs. Deformities, which are an
impairment per the IJC listing criteria, have been observed in Lake Erie eagles, and are suspected
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in herring gulls (based on anecdotal observations) and in cormorants (based on comparing PCB
concentrations in Lake Erie eggs to concentrations at other Great Lakes sites where elevated
deformities have been documented). The rate of deformities in Lake Erie eagles is greatly above
the background rate for birds and is similar to the rate in cormorants in Green Bay, which
isamong the highest reported rates. The observation of two deformed herring gulls in western
Lake Erie, which has high PCB contamination, provides further evidence for an impairment.
The tree-nesting habits of Lake Erie cormorants precludes the examination of large numbers of
chicks, but PCB concentrations in these eggs are similar to or greater than the concentrations in
Green Bay cormorant eggs, so a high deformity rate is predicted for Lake Erie cormorants.
7.5 Potential Research Issues and Priority Information Gaps
Programs and funding for monitoring contaminant concentrations and assessing their biological
effects have declined in recent years. Maintenance of these programs is essential for assessing
recovery from impairment, detecting the emergence of new problems, and filling the information
gaps described in this section.
•	Most of the major contaminants considered in this report are organochlorines, because
research shows that they have caused past and current reproductive impairments and
population-level effects. More environmental data are available for this class of chemicals
than others. However, other newer industrial chemicals and pesticides are released into the
Lake Erie ecosystem in large quantities. Few biomonitoring studies have examined the
concentrations and biological effects of these chemicals in Lake Erie wildlife. Recent
advances in laboratory and field toxicology have shown that some of these chemicals (e.g.,
nonylphenol, bisphenol A, atrazine, aldicarb) are able to disrupt the function of the
endocrine, immune, and nervous systems, often following low level exposure during
development.
•	Due to improvements in the health of national populations of bald eagles in both the U.S. and
Canada, the level of effort to monitor or band Lake Erie bald eagles has decreased in recent
years. However, contaminant impacts are still affecting the recovery of the Lake Erie sub-
population. Therefore, it is important to continue studies of reproductive success,
deformities, and contaminant concentrations in blood and eggs. It is also important to
consider continuing banding/color marking studies to allow tracking of individual eagles
from the territories where they are raised to the territories where they breed. Until about 2
years ago, this was done across the entire lake. Today this type of more intensive monitoring
is more spotty and declining due to reduced funding. Studies of recruitment patterns will be
essential for answering questions about the high turnover rate of adult eagles breeding on the
Lake Erie shoreline, the survival and reproductive success of eagles exposed
developmentally to contaminants from Lake Erie, and the rate of immigration from inland
areas to the Lake Erie shoreline.
•	The cause of the reproductive impairment in herring gulls on West Sister Island requires
further investigation. Toxicologically significant concentrations of microcystin toxin have
been found in the livers of one herring gull from West Sister Island and a number of Caspian
tern chicks from Saginaw Bay, which bears some similarity to western Lake Erie in terms of
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primary productivity and PCB concentrations. The accumulation of microcystin toxin in
colonial waterbirds is an emerging issue that deserves further study. Other potential causes
of the reproductive failure include PCB-induced wasting syndrome, infectious disease, or
some interaction among these factors.
•	A formal deformity survey in herring gulls should be initiated to better estimate the rate of
deformities. A deformity survey should be conducted in cormorants if significant numbers
(i.e., hundreds) nest on the ground in the future.
•	Birds, such as tree swallows, that eat emergent aquatic insects can accumulate high
concentrations of organochlorines and other contaminants. Although studies of Lake Erie
tree swallows from the eastern and central basins have shown only a few biochemical effects
and no reproductive effects, biologically significant impacts are possible in more sensitive
species, especially in the western basin where organochlorine concentrations are higher.
Such studies should be initiated.
•	Little is known about the potential exposure of wild diving ducks to contaminants through
consumption of zebra mussels. A significant proportion (52%) of diving ducks (scaup,
goldeneye, bufflehead, scoter, and oldsquaw) had zebra mussels in their gizzards at the time
of collection (Hamilton and Ankney 1994). The potential for physiological effects following
consumption of contaminated zebra mussels has not been studied.
•	Better information is needed for mink and otter in the following areas: population surveys,
tissue residues, and contaminant concentrations in food. The Canadian Wildlife Service has
initiated a mink carcass collection to take place from 1999-2001 within the Canadian Lake
Erie watershed. Trapper-caught carcasses from Lake Erie marshes and inland tributaries will
be analyzed for contaminants, and examined histopathologically and morphologically.
Measurements of reproductive organs will be made to determine possible contaminant effects
on reproductive development. Collections of mink carcasses and potential food items from
two Lake Erie Marshes were made in 1998, and will be analyzed for carbon and nitrogen
stable isotope ratios, a technique that provides information on the diet of marsh-living mink.
Ongoing monitoring of mink populations in shoreline marshes using track censuses is
planned.
•	Few studies exist that examine both the levels and associated effects of contaminants on
reptiles living in the Lake Erie watershed. The few studies that exist for Lake Erie have
primarily examined contaminant concentrations in tissues and eggs. Contaminant
concentrations in Lake Erie water snakes from Pelee Island are high enough to justify a study
of health and reproductive effects. The Canadian Wildlife Service, World Wildlife Fund and
Upper Thames River Conservation Authority recently initiated such a study.
•	Contaminant concentrations in the threatened eastern spiny softshell and the corresponding
low rates of egg hatching in the Lake Erie basin suggest that further investigation of
contaminant effects is warranted. The Canadian Wildlife Service, World Wildlife Fund and
Upper Thames River Conservation Authority recently initiated such a study.
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•	Further investigation of contaminant levels and effects in the common snapping turtle is
warranted in coastal wetlands of Lake Erie, especially the western basin and marshes in the
U.S. Hatching success and deformity rates should be examined. The University of Guelph
and the Canadian Wildlife Service are studying other endpoints, such as differential effects
on males versus females and behavioral effects in snapping turtles from Lake Ontario and the
St. Lawrence River. These endpoints could be examined in Lake Erie populations in the
future.
•	Data are needed about the sensitivity of amphibian eggs, larvae, and adults to DDT
concentrations presently occurring in water and the food web of coastal wetlands, especially
in Point Pelee National Park.
•	There are conflicting opinions about the significance of non-target species sensitivity,
particularly mudpuppy, to TFM (when used for sea lamprey eradication), and its implications
for potential impairment. Therefore, the impact of TFM on amphibian populations needs to
be assessed by monitoring populations of mudpuppies and other amphibians pre- and post-
application. From a reproductive standpoint, it is particularly important to determine if TFM
has greater impacts on certain age classes and/or egg-bearing females.
•	Based on laboratory studies, nitrate concentrations in agricultural watersheds of Lake Erie
are high enough (3.1 % of water samples) to exceed the LC50 or sublethally affect (19.8% of
water samples) amphibian tadpoles of various species. The results of these laboratory studies
need to be verified in wild populations.
7.5 References
Chandler, J.H. and L.L. Marking. 1975. Toxicity of the lampricide 3-trifluoromethyl-4-
nitrophenol (TFM) to selected aquatic invertebrates and frog larvae. Invest. Fish Control 62:1-7.
Giesy, J.P., Bowerman, W.W., M.A. Mora, P.D. Jones, D.A. Verbrugge, R.A. Othout, J.L.
Newsted, C. Vandervoort, C.L. Summer, R.J. Aulerich, S.J. Bursian, J.P. Ludwig, M. Ludwig,
G.A. Dawson, T.J. Kubiak, D.A. Best, and D.E. Tillitt. 1995. Contaminants in fishes from Great
Lakes-influenced sections and above dams of three Michigan rivers: III. Implications for health
of birds of prey. Arch. Environ. Contamn. Toxicol. 29:309-321.
Gilderhus, P. A. and B.G.H Johnson. 1980. Effects of sea lamprey (Petromyzon marinus)
control in the Great Lakes on aquatic plants, invertebrates, and amphibians. Can. J. Fish. Aquat.
Sci. 37:1895-1905.
Grier, J.W., J.B. Elder, F.J. Gramlich, N.F. Green, J.B. Kussman, J.E. Mathisen, and J.P.
Mattsson. 1983. Northern States Bald Eagle Recovery Plan. USDI-Fish and Wildlife Service,
Washington, DC, 105 pp.
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Hamilton, D.J., and C.D. Ankney. 1994. Consumption of zebra mussels Dreisennapolymorpha
by diving ducks in Lakes Erie and St. Clair. Wildfowl 45:159-166.
IJC. 1989. Proposed Listing/Delisting Criteria for Great Lakes Areas of Concern. Focus on
International Joint Commission Activities. Volume 14, Issue 1, insert.
Matson, T.O. 1990. Estimation of numbers for a riverine Necturus population before and after
TFM lampricide exposure. Kirtlandia 45:33-38
Rouse, J.D., C. A. Bishop, and J. Struger. 1999. Nitrogen Pollution: An assessment of the
impact on amphibians. Env. Health Persp. 107:1-6.
Wiemeyer, S.N., T.J. Lamont, C.M. Bunck, C.R. Sindelar, F.J. Gramlich, J.D. Fraser, and M.A.
Byrd. 1984. Organochlorine pesticide, polychlorobiphenyl, and mercury residues in bald eagle
eggs— 1969-1979—and their relationships to shell thinning and reproduction. Arch. Environ.
Contam. Toxicol. 13:529-549.
Wiemeyer, S.N., C.M. Bunck, and C.J. Stafford, 1993. Environmental contaminants in bald
eagle eggs—1980-84—and further interpretations of relationships to productivity and shell
thickness. Archiv. Environ. Contam. Toxicol. 24:213-227.
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