D.V. Weseloh

Reproductive Outcomes in Colonial Fish-Eating Birds: A Biomarker for Developmental Toxicants in Great Lakes Food Chains: I. Historical and Ecotoxicological Perspectives

Colonial fish-eating birds have been used as convenient model populations in which to study the impact of chronic exposure to complex mixtures of persistent lipophilic environmental contaminants within the Great Lakes ecosystem. To date, published reports of contaminant-induced adverse reproductive outcomes exist for six species. We briefly review the studies of the herring gull (Larus argentatus), Forsters tern (Sterna forsteri), and the double-crested cormorant (Phalacrocorax auritus) to illustrate the use of reproductive outcomes in fish-eating birds as a biomarkerfor developmental toxicants in Great Lakes food chains. We discuss the management implications of using various species for such purposes. We recommend that cormorants be used more extensively in biomonitoring programs to measure exposure and effects of polyhalogenated aromatic hydrocarbons and other contaminants in aquatic food chains in the Great Lakes.

Reproductive Outcomes in Colonial Fish-Eating Birds: A Biomarker for Developmental Toxicants in Great Lakes Food Chains: II. Spatial Variation in the Occurrence and Prevalence of Bill Defects in Young Double-Crested Cormorants in the Great Lakes, 1979–1987

Abstract Congenital malformations are relatively uncommon in most wild bird populations. Here we document the occurrence of bill malformations in double-crested cormorant ( Phalacrocorax auritus ) chicks from colonies in Green Bay and elsewhere in the Great Lakes and in reference areas off the Great Lakes, in the years 1979 through 1987. In the Great Lakes, 31,168 cormorant chicks were examined during 147 visits to 42 colonies. Seventy of these chicks had crossed or deflected bills or bills in which the mandibles differed in length. Only two of the 20,962 chicks examined during 82 visits to 35 colonies in reference areas located in the prairies and northwestern Ontario had bill defects. The probability of observing a malformed chick on a visit to a colony in Green Bay was 10 to 32 times greater than on a visit to a colony in the reference areas. Bill defects were observed at only two (6%) of the colonies in the reference areas. This proportion was exceeded in six of eight geographic regions within the Great Lakes and was highest (73%) in Green Bay colonies. The prevalence of malformed chicks in Green Bay (52.1 per 10,000)was markedly greater than in all other regions during this period. These bill defects are an example of developmental asymmetry and are an indicator of developmental stability within local populations. Other investigations in Lake Michigan suggest that chemicals such as polyhalogenated aromatic hydrocarbons (e.g., PCBs) that induce aryl hydrocarbon hydroxylase are responsible for the defects observed defects.

Spatial and Temporal Trends in Organochlorine Contamination and Bill Deformities in Double-Crested Cormorants (Phalacrocorax Auritus) from the Canadian Great Lakes

The levels of organochlorine contaminants (OCs) in the eggs of double-crested cormorants (Phalacrocorax auritus) from the Canadian Great Lakes, Lake Nipigon and Lake-of-the-Woods were monitored between 1970 and 1995. PCBs and p,p′-DDE were present at the highest concentrations. Significant declines in OC concentrations on the Great Lakes were observed over this period for Lake Ontario, Lake Superior, Georgian Bay and North Channel but not Lake Erie where levels remained relatively stable. In the early 1970s, the greatest OC levels were generally observed in cormorant eggs from nesting sites in Georgian Bay and North Channel of Lake Huron. Between 1984 and 1995 mirex and PCB levels were consistently highest in samples from Lakes Ontario and Erie, respectively. Similar levels of PCDDs and PCDFs were observed from all regions of the Canadian Great Lakes in 1989. In general, OC levels in cormorant eggs between 1984-95 were ranked as follows: Lake Erie>Lake Ontario ≥ Lake Superior>Lake Huron. In 1995, eggshell thickness in Canadian Great Lakes cormorants, ranged from 0.423 to 0.440 mm and was on average only 2.3% thinner than pre-DDT era values. Between 1988 and 1996, 31 cormorant chicks with bill defects were observed at 16 different colonies (21% of all colonies surveyed) in Lakes Ontario and Superior, Georgian Bay and North Channel, and the main body of Lake Huron. No bill deformities were observed at reference sites in northwestern Ontario (Lake Nipigon and Lake-of-the-Woods). For the period 1988-96, the prevalence of bill defects in cormorant chicks (0.0 to 2.8/10,000 chicks) did not differ significantly (P > 0.05) among most regions in the Canadian Great Lakes. Georgian Bay was the only region to show a significant decrease in the prevalence of bill defects between the periods 1979-87 and 1988-95.

Organochlorine Contaminants in Herring Gull Eggs from the Detroit and Niagara Rivers and Saginaw Bay (1978–1982): Contaminant Discriminants

Abstract The levels of organochlorine residues found in eggs of herring gulls are reported for the Detroit River, the Niagara River, and Saginaw Bay from 1978 to 1982. Levels were determined for DDT, DDE, PCBs, mirex, hexachlorobenzene, dieldrin, mercury, and seventeen other organochlorine compounds at various intervals during the study. The levels of PCBs and HCB in eggs from Fighting Island from the Detroit River are among the greatest of any found in more than 25 colonies surveyed since 1978. Organochlorine levels from these sites are compared with data from our Annual Monitor Colonies. Discriminant function analysis indicates that levels of OCs found in eggs of herring gulls from these locations are statistically unique. These results indicate the herring gull has value as an indicator of regional chemical contamination in the Great Lakes.

Environmental Contaminants in Eggs of the Common Snapping Turtle (Chelydra serpentina serpentina) from the Great Lakes-St. Lawrence River Basin of Ontario, Canada (1981, 1984)

Abstract Common snapping turtle eggs were collected at nesting sites from two locations in 1981 and eight locations in 1984 in Ontario, Canada, and analyzed for chlorinated hydrocarbons. Nine locations were within the Great Lakes-St. Lawrence River basin and one location, Algonquin Provincial Park, served as a control site outside the basin. Total PCBs ranged from 0.057 to 4.76 mg/kg (wet wt.) among the Great Lakes-St. Lawrence River samples. Mean total PCB concentration at Algonquin Park was 0.187 mg/kg. Eggs from Hamilton Harbour, Port Franks, Bay of Quinte/Murray Canal, and Lake St. Clair were the most contaminated among the ten sample locations. There was statistically significant variation in concentrations of all organochlorine compounds among sites. In some locations, there was high variation in contamination among clutches. A pool of eggs from Hamilton Harbour contained 67 ng/kg of 2378-tetrachlorodibenzo-p-dioxin and 14.0 ng/kg of23478-pentachlorodibenzofuran. Some dioxin congeners were present in turtle eggs at concentrations higher or equal to that in herring gull eggs from Hamilton Harbour. Comprehensive GC/MS analysis of the Hamilton Harbour eggs also revealed the presence of trace amounts of o,p-dicofol, octachlorostyrene, and toxaphene. Geographic variation in contaminant levels in snapping turtle eggs from wetlands is similar to that in spottail shiners and herring gull eggs collected in the pelagic zone of the Great Lakes. This may be due to the consumption of migrant fish by snapping turtles in nearshore wetlands.

Evaluation of the effects of toxic chemicals in Great Lakes cormorants: has causality been established?

-Toxic contaminants have influenced Double-crested Cormorant (Phalacrocorax auritus) reproduction on the Great Lakes for at least three decades. Four recent studies of contaminants in cormorants of the Great Lakes region are reviewed for their conformation with epidemiological criteria used to infer cause and effect linkages (CELs). Growth of the population was interrupted by DDT which led to egg-shell thinning and reduced reproduction which hid other developmental problems that were most likely caused by planar PCB, dioxin and furan contaminants. Three studies investigated embryo viability and deformities in the post-DDT era. A study of the effects of planar contaminants measured by the H4IIE bioassay technique on egg viability wasjudged to be strong demonstration of contaminant effects on the cormorant population. Two studies of bill defects and the co-occurrence of embryonic abnormalities with specific toxic PCB and dioxin congeners as cormorant teratogens were found to have weaknesses, but were consistent with the paradigm that planar chlorinated hydrocarbons (PHHs), especially the non-ortho-substituted PCB congeners, are now the most important toxic chemical problem for cormorants in the Great Lakes. The rapid uptake of PHHs and great interspecific variations of sensitivity to effects of these chemical between Larids and cormorants have been observed. These biochemical differences and high cormorant fecundity help account for the rapid recovery of cormorants on the Great Lakes. PHHs have relatively trivial impacts on cormorant populations, but do cause significant damage to individuals in a dose-dependant manner. Congener-specific and bioassay techniques support the development of a new toxic chemical paradigm with large implications to policy, management and water quality criteria used to make regulatory decisions. Cormorants may have actually benefited from exposure to toxic contaminants in their competition with large gulls (Larus spp.) on the Great Lakes in the post-DDT era.

Metals and Essential Elements in Herring Gulls from the Great Lakes, 1983

Abstract Adult and prefledged herring gulls were collected from one location each in Lakes Ontario, Erie, Huron, and Superior. Composite samples of liver, kidney, and feather were analyzed for 24 elements and composite samples of bone for 22 elements. After consideration of quality assurance results, concentrations of 16 elements (Al, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, P, Pb, Sr, Ti, Zn) in liver, kidney, and feather were accepted for presentation while 6 elements were accepted from bone (Ca, Cd, Hg, P, Pb, Zn). Only lead, cadmium, and mercury values were of toxicological interest. Data on other trace elements are presented as baseline values among locations for each tissue and age class. Concentrations of Cd, Pb, and Hg were higher in adults than in prefledged young. Metal levels varied among different tissues with Cd highest in kidney (2.16 μg/g; Hamilton Harbour, Lake Ontario), Pb highest in bone (30.0 μg/g; Double Island, Lake Huron), and Hg highest in feather (6.11 μg/g; Middle Island, Lake Erie). Lead levels in both age classes were generally higher in tissues from the two upper lakes colonies than in samples from the lower lakes. Cadmium and mercury levels did not vary greatly among locations. Levels found are below those associated with metal toxicoses in laboratory studies with other avian species.

Geographical Distribution of Contaminants and Productivity Measures of Herring Gulls in the Great Lakes: Lake Huron 1980

Abstract The concentrations of DDE, PCBs (1:1 mix of Aroclor 1254:1260), mirex, HCB, QCB, and tetrachlorobenzenes in eggs of herring gulls are presented for nine colonies in Lake Huron in 1980, as part of intensive investigations of herring gull numbers, biology, and contaminant burdens in that year. Additional data are given for seven other organochlorine contaminants at two colonies. These data are analyzed in relation to eggshell thickness, clutch size and reproductive output, and population trends at sample colonies. Levels of all contaminants measured were markedly lower than during the 1970s, and eggshells were only 6% thinner on average than during the pre-DDT era. Levels of most organochlorine (OC) residues were highest in eggs from Saginaw Bay, which remains one of the most heavily contaminated sites on the Great Lakes. Discriminant function analyses provided reasonably good regional, but not colony-specific, separation of eggs based on suites of OCs. Reproductive output was relatively high, and we found little evidence of impaired reproduction attributable to OC contamination or burden in 1980. Lake-wide, herring gull numbers were increasing slightly, but decreasing at colonies on the main body of Lake Huron.

Levels of Polychlorinated Biphenyls, Including Coplanar Congeners, and 2,3,7,8-T4 CDD Toxic Equivalents in Double-crested Cormorant and Herring Gull Eggs From Lake Erie and Lake Ontario: A Comparison Between 1981 and 1992

Abstract Eggs of double-crested cormorants and herring gulls collected from Lakes Erie and Ontario during 1981 and 1992 were analyzed for PCB congener concentrations, including non-ortho congeners 77, 126, and 169. Total PCB in herring gulls, measured as Aroclor 1254/1260, was significantly lower in 1992, although differences in chemical concentrations in Lake Erie birds were not of the same magnitude as those observed in Lake Ontario. Changes in concentration of total PCB in cormorant populations were not significant in Lake Ontario, and only a small change was observed in Lake Erie cormorants. In 1981, cormorants and herring gull eggs were similarly contaminated in Lake Ontario and Lake Erie, but in 1992, Lake Erie eggs were significantly more contaminated than those from Lake Ontario. An examination of changes in concentrations of individual congeners suggested that in cormorants, the decrease in PCB concentrations was due primarily to the loss of low K ow congeners. All congeners, however, contributed to the decline of PCBs in herring gulls. Toxic equivalents (TEQs) estimates revealed that congener 126 dominated the TEQs in both species in Lake Ontario and Lake Erie, and were highest in herring gulls. Although estimates of total TEQs in herring gulls in both lakes were lower in 1992, there was little change in TEQs in double-crested cormorants. These results support the conclusion that chemical accumulation patterns are regulated to some degree by both ecological and limnological processes.

Assessing Seasonal Variation in Counts and Movements of Bonaparte’s Gulls Larus philadelphia on the Niagara River, Ontario

Abstract We assessed potential factors contributing to variation in counts of staging Bonaparte’s Gulls (Larus philadelphia) on the Niagara River in southern Ontario. Much of the Mississippi Flyway population of this species stages each autumn at this site, en route to the Gulf coast and Mexico. Between 1986-96, weekly or bi-weekly counts were made of gulls flying to their nocturnal roost at the mouth of the Niagara River entering Lake Ontario, to assess the seasonal and temporal patterns of movement. Counts began each year in early October, corresponding to the ‘second wave’ of gulls. Generally, this second wave of autumn movements began in early October to late November (median 1 November) and continued until late January or mid-February (median 5 February). Model selection based on a repeated measures analysis (Generalized Estimating Equations) demonstrated a quadratic relationship between counts and time of year and a linear relationship with daily count duration. Less evidence existed for the role of mean daily temperature in explaining variation (positive relationship) in counts; more data, or inclusion of different weather variables (e.g., wind, cloud cover), may demonstrate that it is more important than our models suggest. Maximum counts were from early November to late January (median 6 December). Peak daily totals per season varied between 6,300 (1993/94) and 40,000 (1990/91). Migration counts may be useful to help monitor populations of this species, provided that variables affecting seasonality in counts are accounted for and the turnover rate of individual gulls staging in the area is determined (e.g., through mark-recapture or radio-telemetry studies).