Legacy contaminant trends in the Great Lakes uncovered by the wildlife environmental quality index

Since the 1970s, wildlife managers have prioritized the recovery of Great Lakes ecosystems from contamination by Persistent Organic Pollutants (POPs). Monitoring and quantifying the region's recovery is challenged by the diversity of legacy contaminants in the environment and the lack of benchmarks for their potential biological effects. We address this gap by introducing the Wildlife Environmental Quality Index (WEQI) based on prior water and sediment quality indices. The tool summarizes, in a single score, the exposure of wildlife to harmful levels of multiple contaminants - with harmful levels set by published guidelines for protecting piscivorous wildlife from biological impacts. We applied the new index to a combined Canadian and American dataset of Herring Gull (Larus argentatus) egg data to elucidate trends in wildlife for eight legacy industrial pollutants and insecticides in the Great Lakes. Environmental quality of the Great Lakes region (as indexed by WEQI) improved by 18% between 2002 and 2017. Improvement came from reductions in both the scope of contamination (the number of guideline-exceeding contaminants) and its amplitude (the average size of guideline exceedances) at bird colonies. But recovery was unequal among lakes, with Lake Erie showing no improvement at one extreme. Weakly- or non-recovering lakes (Erie, Ontario, Huron) were marked by inconsistent improvement in scope and amplitude, likely due to ongoing loading, sediment resuspension and other stressors reported elsewhere. Fast-recovering lakes (Superior and Michigan), meanwhile, improved in both scope and amplitude. Contrasting trends and contaminant profiles (e.g., exceedances of PCBs versus DDTs) highlight the importance of lake-specific management for equalizing recoveries. Lower environmental quality at American than Canadian colonies, particularly in Lake Huron, further suggest uneven success in - and opportunities for - the binational management of wildlife exposure to legacy contaminants.

Assessing African Vultures as Biomonitors and Umbrella Species

African vulture populations are rapidly declining, yet funding and other resources available for their conservation are limited. Improving our understanding of which African vulture species could best serve as an umbrella species for the entire suite of African vultures could help conservationists save time, money, and resources by focusing their efforts on a single vulture species. Furthermore, improving our understanding of the suitability of African vultures as biomonitors for detecting environmental toxins could help conservation authorities to detect changes in ecosystem health. We used a systematic approach based on criteria selected a priori to objectively evaluate the potential of each of the 10 resident African vulture species as (i) an umbrella species for all of the African vulture species, and (ii) an avian biomonitor. For each criterion, we scored the respective African vulture species and summed the scores to determine which species was best suited as an umbrella species and as an avian biomonitor. Our results showed that, overall, certain aspects of vulture ecology (large population sizes, large body sizes, long lifespans, and their ability to be monitored over numerous seasons) support their suitability as biomonitors, while other ecological traits, including their diets and the public's perceptions of vultures, could diminish their suitability. The White-backed Vulture (Gyps africanus) was the best fit of the 10 vulture species in our assessment as both an avian biomonitor and an umbrella species for all African vulture species. Meanwhile, significant knowledge gaps for other species inhibit their utility as biomonitors. Due to their large home-range sizes, African vultures may only be useful as biomonitors at a regional scale. However, there could be value in using the White-backed Vulture as an umbrella species, as an aid to conserve the entire suite of African vulture species.

Pharmaceuticals in water, fish and osprey nestlings in Delaware River and Bay

Exposure of wildlife to Active Pharmaceutical Ingredients (APIs) is likely to occur but studies of risk are limited. One exposure pathway that has received attention is trophic transfer of APIs in a water-fish-osprey food chain. Samples of water, fish plasma and osprey plasma were collected from Delaware River and Bay, and analyzed for 21 APIs. Only 2 of 21 analytes exceeded method detection limits in osprey plasma (acetaminophen and diclofenac) with plasma levels typically 2-3 orders of magnitude below human therapeutic concentrations (HTC). We built upon a screening level model used to predict osprey exposure to APIs in Chesapeake Bay and evaluated whether exposure levels could have been predicted in Delaware Bay had we just measured concentrations in water or fish. Use of surface water and BCFs did not predict API concentrations in fish well, likely due to fish movement patterns, and partitioning and bioaccumulation uncertainties associated with these ionizable chemicals. Input of highest measured API concentration in fish plasma combined with pharmacokinetic data accurately predicted that diclofenac and acetaminophen would be the APIs most likely detected in osprey plasma. For the majority of APIs modeled, levels were not predicted to exceed 1 ng/mL or method detection limits in osprey plasma. Based on the target analytes examined, there is little evidence that APIs represent a significant risk to ospreys nesting in Delaware Bay. If an API is present in fish orders of magnitude below HTC, sampling of fish-eating birds is unlikely to be necessary. However, several human pharmaceuticals accumulated in fish plasma within a recommended safety factor for HTC. It is now important to expand the scope of diet-based API exposure modeling to include alternative exposure pathways (e.g., uptake from landfills, dumps and wastewater treatment plants) and geographic locations (developing countries) where API contamination of the environment may represent greater risk.

Perfluorinated sulfonate and carboxylate compounds and precursors in herring gull eggs from across the Laurentian Great Lakes of North America: Temporal and recent spatial comparisons and exposure implications

Chemicals of emerging concern (CECs) in the basin of the Laurentian Great Lakes of North America include per- and poly-fluoroalkyl substances (PFASs) classified as perfluoroalkyl acids. We investigated several PFASs, and specifically 13 C4-C16 perfluorinated carboxylic acids (PFCAs), 4 (C4, C6, C8 and C10) perfluorinated sulfonates (PFSAs), perfluoro-4-ethylcyclohexane sulfonate (PFEtCHxS) and selected precursors (e.g. perfluorobutane sulfonamide and perfluorooctane sulfonamide) in herring gull (Larus argentatus) eggs collected in 2012-2013 from 19 Canadian and U.S. colony sites across the Great Lakes. C6, C8 and C10 PFSAs, PFEtCHxS, and C7-14 and C16 PFCAs were quantifiable at >97% of the 114 egg samples. PFEtCHxS concentrations ranged from n.d. to 3.1ng/g ww (highest in Lake Michigan eggs). Mean Σ4PFSA (92 to 97% perfluorooctane sulfonate (PFOS)) and Σ9PFCA concentration ranges were 44 to 740 and 4.8 to 118ng/g ww, respectively. Σ4PFSA showed a clear increasing concentration trend from the northwest to the southeast colonies. Also, Σ4PFCA to Σ9PFSA concentration ratios in gull eggs were greater in eggs from Lake Superior relative to colonies in the other lakes. PFOS concentrations in some egg samples were greater than some of the known lowest observed effect concentrations (LOECs) measured and reported in captive bird model studies. This study showed the increasing complexity of PFAS-CECs, and emphasized the importance of continuing monitoring of bioaccumulative PFAS in Great Lakes herring gulls.

Spatial and temporal comparisons of legacy and emerging flame retardants in herring gull eggs from colonies spanning the Laurentian Great Lakes of Canada and United States

In the Laurentian Great Lakes basin of North America, an increasing number of chemicals of emerging concern (CECs) are being investigated, including legacy and replacement flame retardants (FRs). In the present study, 14 polybrominated diphenyl ethers (PBDEs), 23 non-PBDEs halogenated FRs (NPHFRs) and 16 organophosphate ester FRs (OPE-FRs) were analyzed in 100 individual eggs collected in 2012 and 2013 and in 15 egg pools of herring gulls collected in 2012 from 20 colonies across the entire Laurentian Great Lakes basin. For CEC-FRs in eggs from all colonies, 14 PBDEs, 12 NPHFRs and 9 OPE-FRs were quantifiable in at least one of the 115 analyzed samples. The mean sum PBDE (Σ14PBDE) concentrations ranged from 244 to 657 ng/g wet weight (ww), and on average were 1-2 orders of magnitude greater than the Σ12NPHFR concentrations (13.8-35.6 ng/g ww), and 2-3 orders of magnitude greater than Σ9OPE-FR concentrations (0.31-2.14 ng/g ww). Mean Σ14PBDE and sum of syn- and anti-Dechlorane Plus isomer (Σ2DDC-CO) concentrations in eggs from colonies within Laurentian Great Lakes Areas of Concern (AOCs) were in most cases greater than in eggs from nearby colonies outside of AOCs. Comparing CEC-FR concentrations in eggs collected in 2012-2013 to those previously measured in eggs collected approximately 7 years earlier (2006 and 2008) showed that Σ7PBDE (BDE-28, -47, -100, -99, -154,-153 and -183) mean concentrations in eggs from 6 colonies were approximately 30% less than they were in eggs from the same colonies from the earlier time period, whereas 3 current-use FR (BDE-209, HBCDD and Σ2DDC-CO) concentrations were significantly greater (p<0.05) than previously measured. Between 2006 and 2013 there were significant changes in individual PBDE patterns for BDE-71, -138, -153, -203, -206 and -207. Among all of the examined CEC-FRs, concentrations of Σ4PBDE (BDE-47, -99, -100 and -153) and HBCDD in gull eggs from all colonies were greater than or comparable to their lowest observed effect concentrations (LOECs) based on in ovo egg injection studies. Overall, the current profiles of a broad suite of FRs in Laurentian Great Lakes herring gull eggs highlights the need to better understand e.g., exposure-effect implications and metabolism of FRs, i.e. OPE-FRs, and emphasizes the importance of continued monitoring of CEC-FRs whose concentrations appear to be increasing, including BDE-209, HBCDD and DDC-COs.

Using nestling plasma to assess long-term spatial and temporal concentrations of organochlorine compounds in bald eagles within Voyageurs National Park, Minnesota, USA

The bald eagle (Haliaeetus leucocephalus) population at Voyageurs National Park (VNP) provides an opportunity to assess long-term temporal and spatial trends of persistent environmental contaminants. Nestling bald eagle plasma samples collected from 1997 to 2010 were analyzed for polychlorinated biphenyls (PCBs) and organochlorine pesticides. Trends of total PCBs, total DDTs, 4,4'-DDE, and Dieldrin were analyzed since >50% of nestling plasma samples had detectable concentrations. Total PCBs, total DDTs, and 4,4'-DDE concentrations have all decreased over time (26.09%, 24.09%, and 40.92% respectively). Concentrations of Dieldrin have increased by 50.25%. In this study, 61.1% of all nestlings sampled had detectable concentrations of Dieldrin from all time periods and all areas of VNP. Since Dieldrin is a banned pesticide in North America, the source of this increase is unknown. However, increases and fluctuations in Dieldrin concentration suggest contaminant levels in VNP may be linked to a new source or environmental process.

Role of sediments in modifying the toxicity of two Roundup formulations to six species of larval anurans

The role of sediment in modifying the toxicity of the original formulation of Roundup® and Roundup WeatherMAX® was examined in aqueous laboratory tests. Six species of anurans (Bufo fowleri, Hyla chrysoscelis, Rana catesbeiana, Rana clamitans, Rana sphenocephala, and Rana pipiens) were exposed at Gosner stage 25 to concentrations of the 2 herbicide formulations in 96-h, static, nonrenewal experiments in the presence and absence of sediment. All species tested had lower median lethal concentration values in water-only exposures of both formulations compared with exposures with sediment. Sediment significantly altered the potency slopes in all tests with the exceptions of H. chrysoscelis and R. clamitans when exposed to the original formulation of Roundup and H. chrysoscelis and R. sphenocephala when exposed to Roundup WeatherMAX. Thresholds were significantly different in all tests, including those in which potency slopes did not differ. Based on water-sediment exposures of the original formulation of Roundup, all 6 species tested had a margin of safety when compared with the predicted environmental concentration of the highest label application rate. Of the 6 species, 5 had a margin of safety when exposed to Roundup WeatherMAX. During incidental exposures in the field, sediments and organic matter present in aquatic systems provide significant sources of environmental ligands. If used according to label instructions, both herbicides should pose minimal risk to anuran amphibians in actual field applications. Environ Toxicol Chem 2014;33:2616-2620. © 2014 SETAC.

Lead and cadmium in the blood of nine species of seabirds, Marion Island, South Africa

Levels of lead (Pb) and cadmium (Cd) were investigated as potential stressors in nine species of breeding seabirds on Marion Island, South Africa. The majority of blood Pb levels (95 %) were below background exposure levels. Species was a significant factor in ranked means analysis for mean blood Pb levels. Fewer individual blood Cd levels (<60 %) were within background exposure levels and species was not significant. Elevated levels of Cd have been documented in other seabird species without apparent outward effects, which suggests that seabirds may be adapted to high cadmium environments, particularly from their diets. Overall, the results suggest Pb and Cd are not primary causes for concern in these seabirds.

Triploid grass carp susceptibility and potential for disease transfer when used to control aquatic vegetation in reservoirs with avian vacuolar myelinopathy

Avian vacuolar myelinopathy (AVM) is an often-lethal neurologic disease that affects waterbirds and their avian predators (i.e., bald eagles Haliaeetus leucocephalus) in the southern United States. Feeding trials and field surveys provided evidence that AVM is caused by a toxin-producing, undescribed cyanobacterium (UCB), which grows as an epiphyte on the leaves of submerged aquatic vegetation (SAV). Reservoirs with documented AVM epornitics support dense growth of nonnative SAV. Waterbirds ingest the toxin when feeding on aquatic plants with the epiphytic UCB, and secondary intoxication occurs when raptors consume these birds. Vegetation management has been proposed as a means to reduce waterbird exposure to the putative toxin. We fed aquatic vegetation with and without the UCB to triploid Grass Carp Ctenopharyngodon idella in laboratory and field trials. Only Grass Carp that ingested aquatic vegetation with the UCB developed lesions in the central nervous system. The lesions (viewed using light microscopy) appeared similar to those in birds diagnosed with AVM. Grass Carp that received aquatic vegetation without the UCB were unaffected. Grass Carp tissues from each treatment were fed to domestic chickens Gallus domesticus (an appropriate laboratory model for AVM) in a laboratory trial; the chickens displayed no neurologic signs, and histology revealed a lack of the diagnostic lesions in brain tissues. Results from our trials suggest that (1) triploid Grass Carp are susceptible to the AVM toxin, although no fish mortalities were documented; and (2) the toxin was not accumulated in Grass Carp tissues, and the risk to piscivorous avifauna is likely low. However, a longer exposure time and analysis of sublethal effects may be prudent to further evaluate the efficacy and risk of using triploid Grass Carp to manage aquatic vegetation in a system with frequent AVM outbreaks.

Relative toxicity of the components of the original formulation of Roundup to five North American anurans

The responses of five North American frog species that were exposed in an aqueous system to the original formulation of Roundup were compared. Carefully designed and un-confounded laboratory toxicity tests are crucial for accurate assessment of potential risks from the original formulation of Roundup to North American amphibians in aquatic environments. The formulated mixture of this herbicide as well as its components, isopropylamine (IPA) salt of glyphosate and the surfactant MON 0818 (containing polyethoxylated tallowamine (POEA)) were separately tested in 96 h acute toxicity tests with Gosner stage 25 larval anurans. Rana pipiens, R. clamitans, R. catesbeiana, Bufo fowleri, and Hyla chrysoscelis were reared from egg masses and exposed to a series of 11 concentrations of the original formulation of Roundup herbicide, nine concentrations of MON 0818 and three concentrations of IPA salt of glyphosate in static (non-renewal) aqueous laboratory tests. LC50 values are expressed as glyphosate acid equivalents (ae) or as mg/L for MON 0818 concentrations for comparison between the formulation and components. R. pipiens was the most sensitive of five species with 96 h-LC50 values for formulation tests, for the five species, ranging from 1.80 to 4.22 mg ae/L, and MON 0818 exposures with 96 h-LC50 values ranging from 0.68 to 1.32 mg/L. No significant mortality was observed during exposures of 96 h for any of the five species exposed to glyphosate IPA salt at concentrations up to 100 times the predicted environmental concentration (PEC). These results agree with previous studies which have noted that the surfactant MON 0818 containing POEA contributes the majority of the toxicity to the herbicide formulations for fish, aquatic invertebrates, and amphibians. These study results suggest that anurans are among the most sensitive species, and emphasize the importance of testing the herbicide formulation in addition to its separate components to accurately characterize the toxicity and potential risk of the formulation.

Comparative toxicity of two glyphosate formulations (original formulation of Roundup® and Roundup WeatherMAX®) to six North American larval anurans

The toxicity of two glyphosate formulations (the original formulation of Roundup® and Roundup WeatherMAX®) to six species of North American larval anurans was evaluated by using 96-h static, nonrenewal aqueous exposures. The 96-h median lethal concentration values (LC50) ranged from 1.80 to 4.22 mg acid equivalent (ae)/L and 1.96 to 3.26 mg ae/L for the original formulation of Roundup and Roundup WeatherMAX, respectively. Judged by LC50 values, four species were more sensitive to Roundup WeatherMAX exposures, and two species were more sensitive to the original formulation. Two of six species, Bufo fowleri (p < 0.05, F = 14.89, degrees of freedom [df] = 1) and Rana clamitans (p < 0.05, F = 18.46, df = 1), had significantly different responses to the two formulations tested. Increased sensitivity to Roundup WeatherMAX likely was due to differences in the surfactants or relative amounts of the surfactants in the two formulations. Potency slopes for exposures of the original formulation ranged from 24.3 to 92.5% mortality/mg ae/L. Thresholds ranged from 1.31 to 3.68 mg ae/L, showing an approximately three times difference in the initiation of response among species tested. For exposures of Roundup WeatherMAX, slopes ranged from 49.3 to 84.2% mortality/mg ae/L. Thresholds ranged from 0.83 to 2.68 mg ae/L. Margins of safety derived from a simulated direct overspray were above 1, except for one species in exposures of Roundup WeatherMAX. Laboratory data based on aqueous exposures are conservative because of the lack of environmental ligands; however, these tests provide information regarding the relative toxicity between these two Roundup formulations.

Using nestling feathers to assess spatial and temporal concentrations of mercury in bald eagles at Voyageurs National Park, Minnesota, USA

Bald eagles (Haliaeetus leucocephalus) have been utilized as a biosentinel of aquatic ecosystem health in the Great Lakes Region since the early 1960s. Bald eagle populations have been monitored at Voyageurs National Park (VNP), Minnesota, since 1973. For the past 20 years, researchers have collected feathers from nestling bald eagles to assess their dietary exposure to mercury (Hg) on Rainy, Kabetogama, and Namakan lakes in VNP. Mercury is an environmental pollutant with both natural and anthropogenic sources, and negatively affects many species of wildlife. In a previous study, geometric mean concentrations of Hg in feathers of nestling bald eagles were greater at VNP (20 mg/kg Dry Weight (DW)) than in nestling feathers from other Great Lakes subpopulations (~7 mg/kg DW), for the period 1985-1989. Current geometric mean concentrations have declined by 77.4% since 1989 at VNP. While all samples from 1985 to 1989 had detectable concentrations of Hg, 10% of current samples had concentrations below the reportable detection limit (0.001 mg/kg DW, n = 180). The major lakes at VNP are impounded, and Hg concentrations also declined greatly after the lake level stabilization order by the International Joint Commission was implemented in 1999. Mercury concentrations in feathers of nestling bald eagles from 1989 to 2010 ranged from ND (<0.001) to 34.97 mg/kg DW. The highest single concentration in a nestling was from Namakan Lake in 2010. The five-year geometric means for Rainy, Kabetogama, and Namakan lakes for 2006-2010 were 6.08, 1.07, and 5.56 mg/kg DW (n = 28, n = 32, n = 27) respectively. Although Hg concentrations in feathers of nestlings greatly declined after the change in water level management in 1999 and are lower than 1989 concentrations, recent samples suggest a gradual increase. Continued monitoring of nestling feather concentrations will be essential to assess this increase, to determine the source of Hg, to determine if there are changes to methylation potential, and to evaluate and optimize water level management.

Flame retardants and organochlorine pollutants in bald eagle plasma from the Great Lakes region

We report measurements of polybrominated diphenyl ethers and of emerging flame retardants in the plasma of nestling bald eagles sampled from early May to late June of 2005. Concentrations of total PBDEs ranged from 0.35 ng g(-1) ww to 29.3 ng g(-1) ww (average=5.7+/-1.9 ng g(-1) ww). The most abundant congeners were BDE-47, BDE-99, and BDE-100. The fully brominated congener, BDE-209, was detected in approximately one third of the samples at an average concentration of 1.2+/-0.72 ng g(-1) ww. Several emerging flame retardants, such as pentabromoethylbenzene (PBEB), hexabromocyclododecanes (HBCDs), and Dechlorane Plus (DP), were detected in these samples. Polychlorinated biphenyls (PCBs) and organochlorine pesticides were also detected at levels close to those previously published. A statistically significant relationship was found between total PBDE concentrations and total PCB and p,p'-DDE concentrations, suggesting that these compounds share a common source, which is most likely the eagle's food.

Productivity, embryo and eggshell characteristics, and contaminants in bald eagles from the Great Lakes, USA, 1986 to 2000

Chlorinated hydrocarbon concentrations in eggs of fish-eating birds from contaminated environments such as the Great Lakes of North America tend to be highly intercorrelated, making it difficult to elucidate mechanisms causing reproductive impairment, and to ascribe cause to specific chemicals. An information- theoretic approach was used on data from 197 salvaged bald eagle (Haliaeetus leucocephalus) eggs (159 clutches) that failed to hatch in Michigan and Ohio, USA (1986-2000). Contaminant levels declined over time while eggshell thickness increased, and by 2000 was at pre-1946 levels. The number of occupied territories and productivity increased during 1981 to 2004. For both the entire dataset and a subset of nests along the Great Lakes shoreline, polychlorinated biphenyls (SigmaPCBs, fresh wet wt) were generally included in the most parsimonious models (lowest-Akaike's information criterion [AICs]) describing productivity, with significant declines in productivity observed above 26 microg/g SigmaPCBs (fresh wet wt). Of 73 eggs with a visible embryo, eight (11%) were abnormal, including three with skewed bills, but they were not associated with known teratogens, including SigmaPCBs. Eggs with visible embryos had greater concentrations of all measured contaminants than eggs without visible embryos; the most parsimonious models describing the presence of visible embryos incorporated dieldrin equivalents and dichlorodiphenyldichloroethylene (DDE). There were significant negative correlations between eggshell thickness and all contaminants, with SigmaPCBs included in the most parsimonious models. There were, however, no relationships between productivity and eggshell thickness or Ratcliffe's index. The SigmaPCBs and DDE were negatively associated with nest success of bald eagles in the Great Lakes watersheds, but the mechanism does not appear to be via shell quality effects, at least at current contaminant levels, while it is not clear what other mechanisms were involved.

An extract of Hydrilla verticillata and associated epiphytes induces avian vacuolar myelinopathy in laboratory mallards

Avian vacuolar myelinopathy (AVM) is a neurological disease affecting bald eagles (Haliaeetus leucocephalus), American coots (Fulica americana), waterfowl, and other birds in the southeastern United States. The cause of the disease is unknown, but is thought to be a naturally produced toxin. AVM is associated with aquatic macrophytes, most frequently hydrilla (Hydrilla verticillata), and researchers have linked the disease to an epiphytic cyanobacterial species associated with the macrophytes. The goal of this study was to develop an extraction protocol for separating the putative toxin from a hydrilla-cyanobacterial matrix. Hydrilla samples were collected from an AVM-affected reservoir (J. Strom Thurmond Lake, SC) and confirmed to contain the etiologic agent by mallard (Anas platyrhynchos) bioassay. These samples were then extracted using a solvent series of increasing polarity: hexanes, acetone, and methanol. Control hydrilla samples from a reference reservoir with no history of AVM (Lake Marion, SC) were extracted in parallel. Resulting extracts were administered to mallards by oral gavage. Our findings indicate that the methanol extracts of hydrilla collected from the AVM-affected site induced the disease in laboratory mallards. This study provides the first data documenting for an "extractable" AVM-inducing agent.

Effect of In Ovo exposure to an organochlorine mixture extracted from double crested cormorant eggs (Phalacrocorax auritus) and PCB 126 on immune function of juvenile chickens

Organochlorine (OC) contaminants including polychlorinated biphenyls (PCBs) and p, p'-dichlorodiphenyldichloroethylene (DDE) have been associated with immune modulation in wild fish-eating birds from the Great Lakes. The objective of this study was to evaluate the immune function of juvenile chickens after in ovo exposure to PCB 126 or an environmentally relevant OC mixture extracted from eggs of double crested cormorants (Phalacrocorax auritus) from Green Bay, Lake Michigan, USA. Fertile white leghorn chicken (Gallus domesticus) eggs were injected before incubation with 0.55-1.79 ng TCDD equivalents (TEQ)/egg PCB 126 and 1.2-4.9 ng TEQs/egg of cormorant egg extract into the air cell in two separate experiments. After hatching, the immune function was tested using in vivo phytohemagglutinin (PHA) skin response in 11-day-old chicks, antibody titers to immunization with sheep red blood cells (SRBC) in 28-day-old chicks, and, at necropsy, thymus and bursal mass and cellularity. PCB 126 decreased antibody titers at all doses and decreased the thymus and bursa index but not cellularity at 1.79 ng TEQ/egg. The cormorant egg extract caused no significant alterations in immune function even though it has been demonstrated as immunotoxic in chicken embryos. However, twofold to threefold increases in total anti-SRBC titers in 28-day-old chicks exposed to 1.2 or 2.4 ng TEQ/egg of cormorant extract were similar to elevations in anti-SRBC titer observed in Caspian tern (Sterna caspia) chicks from a highly OC-contaminated site in Saginaw Bay, Lake Huron. Posthatch exposure to OC through fish consumption in addition to in ovo OC exposure might be associated with the immune modulation reported in wild birds. Chicks in this study might have begun to compensate for embryonic immunotoxicity by the ages at which we studied them.

Investigation of the link between avian vacuolar myelinopathy and a novel species of cyanobacteria through laboratory feeding trials

Avian vacuolar myelinopathy (AVM) is a neurologic disease affecting Bald Eagles (Haliaeetus leucocephalus), American Coots (Fulica americana), and other birds in the southeastern United States. The cause of the disease has not yet been determined, although it is generally thought to be a natural toxin. Previous studies have linked AVM to aquatic vegetation, and the current working hypothesis is that a species of cyanobacteria growing epiphytically on that vegetation is producing a toxin that causes AVM. Surveys of epiphytic communities have identified a novel species of cyanobacteria in the order Stigonematales as the most likely suspect. The purpose of this study was to further examine the relationship between the suspect Stigonematales species and induction of AVM, by using animal feeding trials. Adult Mallards and domestic chickens were fed aquatic vegetation from two study sites containing the suspect cyanobacterial epiphyte, as well as a control site that did not contain the Stigonematales species. Two trials were conducted. The first trial used vegetation collected during mid-October 2003, and the second trial used vegetation collected during November and December 2003. Neither treatment nor control birds in the first trial developed AVM lesions. Ten of 12 treatment Mallards in the second trial were diagnosed with AVM, and control birds were not affected. This study provides further evidence that the novel Stigonematales species may be involved with AVM induction, or at the least it is a good predictor of AVM toxin presence in a system. The results also demonstrate the seasonal nature of AVM events.

Activity patterns of biotransformation enzymes in juvenile chickens after in ovo dosage of PCB126

Little is known about the correlations between biotransformation enzymes in juvenile birds after exposure to environmental toxicants like PCBs. In this study eggs of domestic chicken (Gallus domesticus) were dosed with PCB126 in concentrations of 0.175-0.325 ng/g egg weight. Liver subcellular fractions were analyzed for activities of Phase 1 and Phase 2 biotransformation enzymes 2 and 5 weeks post-hatch. Ethoxyresorufin O-deethylase (EROD) activity was increased in both the 2-week and 5-week samples. Glutathione-S-transferase (GST) activity was increased in the 2-week samples only, but the 5-week samples showed an overall much higher GST activity, probably as a result of a still developing enzyme expression in maturing chickens. The same pattern was seen in the phenol-type UDP-glucuronosyltransferase (UGT) activity of the control animals. The week two samples showed a positive dose-response relationship for the UGT activity, but after 5 weeks this was reversed, possibly caused by inhibition of hydroxylated PCB metabolites. Phenol-type sulfotransferase (SULT) activities were not significantly correlated with time or dose. There was a strong positive regression between the Ah-receptor mediated EROD and UGT activities. The EROD activities were also positively correlated to the GST activities. Most interesting was a negative correlation between the UGT and SULT activities: an inhibited UGT activity appeared to be compensated by an increased SULT activity.

Concentrations of p,p'-DDE in plasma of nestling Wood Storks from Georgia

We determined the concentrations of organochlorine pesticides and total PCBs in plasma of nestling Wood Storks (Mycteria americana) from two colonies in Georgia in 2000. Of 20 compounds analyzed for, only p,p'-DDE was quantified in reportable concentrations, ranging from <2.0-174.0 ng/g wet weight (ww). Concentrations of p,p'-DDE were significantly greater (P<0.0001) in plasma of nestlings from an inland colony, Chew Mill (x 16.9 ng/g,ww) than a coastal colony, Harris Neck (x 1.2 ng/g,ww). Concentrations from nestlings from Chew Mill were significantly different among sampling weeks (P=0.01), with week 8 being significantly greater than weeks 1, 2, and 5. While the Chew Mill colony had much greater concentrations of p,p'-DDE in plasma of nestlings than the Harris Neck colony, reproduction was greater there (1.8+/-1.0 SD fledged young per nesting attempt) than Harris Neck (1.4+/-1.0 SD fledged young per nesting attempt). While concentrations of p,p'-DDE determined in plasma of nestling Wood Storks are an indirect measure of adult exposure to environmental toxicants, concentrations reported would not be considered detrimental to reproduction in these colonies.

Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species

Invasions of exotic species have created environmental havoc through competition and displacement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and associated epiphytic cyanobacterial species as a link to avian vacuolar myelinopathy (AVM), an emerging avian disease affecting herbivorous waterbirds and their avian predators. AVM, first reported in 1994, has caused the death of at least 100 bald eagles (Haliaeetus leucocephalus) and thousands of American coots (Fulica americana) at 11 sites from Texas to North Carolina (Thomas et al., 1998; Rocke et al., 2002). Our working hypothesis is that the agent of this disease is an uncharacterized neurotoxin produced by a novel cyanobacterial epiphyte of the order Stigonematales. This undescribed species covers up to 95% of the surface area of leaves in reservoirs where bird deaths have occurred from the disease. In addition, this species is rare or not found on hydrilla collected at sites where AVM disease has not been diagnosed. Laboratory feeding trials and a sentinel bird study using naturally occurring blooms of cyanobacteria on hydrilla leaves and farm-raised mallard ducks (Anas platyrhynchos) induced the disease experimentally. Since 1994 AVM has been diagnosed in additional sites from Texas to North Carolina. Specific site characteristics that produce the disjunct distribution of AVM are unknown, but it is probable that the incidence of this disease will increase with the introduction of hydrilla and associated cyanobacterial species into additional ponds, lakes, and reservoirs.

Establishing a food-chain link between aquatic plant material and avian vacuolar myelinopathy in mallards (Anas platyrhynchos)

Avian vacuolar myelinopathy (AVM) is a neurologic disease primarily affecting bald eagles (Haliaeetus leucocephalus) and American coots (Fulica americana). The disease was first characterized in bald eagles in Arkansas in 1994 and then in American coots in 1996. To date, AVM has been confirmed in six additional avian species. Attempts to identify the etiology of AVM have been unsuccessful to date. The objective of this study was to evaluate dermal and oral routes of exposure of birds to hydrilla (Hydrilla verticillata) and associated materials to evaluate their ability to induce AVM. Mallards (Anas platyrhynchos) were used in all trials; bobwhite quail (Colinus virginianus) also were used in one fresh hydrilla material exposure trial. Five trials were conducted, including two fresh hydrilla material exposure trials, two cyanobacteria exposure trials, and a frozen hydrilla material exposure trial. The cyanobacteria exposure trials and frozen hydrilla material trial involved gavaging mallards with either Pseudanabaena catenata (live culture), Hapalosiphon fontinalis, or frozen hydrilla material with both cyanobacteria species present. With the exception of one fresh hydrilla exposure trial, results were negative or inconclusive. In the 2002 hydrilla material exposure trial, six of nine treated ducks had histologic lesions of AVM. This established the first cause-effect link between aquatic vegetation and AVM and provided evidence supporting an aquatic source for the causal agent.

Clinical pathology of nestling marabou storks in Uganda

Packed cell volumes (PCV) and plasma chemistry parameters were measured in 20 nestling marabou storks (Leptoptilos crumeniferus) in January 2003 that were a part of a colony located in the center of the city of Kampala, Uganda. There were no significant differences (P> or =0.05) in plasma chemistry values or PCV between sexes with the exception of globulin and total plasma protein values, which were higher in females. There were significant differences (P< or =0.05) in blood glucose, creatine kinase, and globulin levels between birds of different body weight. Total plasma protein, uric acid, phosphorous, and creatine kinase were generally higher relative to published data on other avian species, including nestling white storks (Ciconia ciconia).

Clinical pathology and morphometrics of African fish eagles in Uganda

Packed cell volumes (PCVs) and plasma chemistry parameters were measured in 15 adult and 18 nestling African fish eagles (Haliaeetus vocifer) sampled from June 2002 through January 2003 in Uganda. Morphologic measurements were obtained from 15 adult eagles. All eagles were examined for blood parasites and sexed by examination of DNA from red blood cells. Ten adults and eight nestlings were sampled from Lake Mburo and five adults and 10 nestlings were sampled from Lake Victoria near Entebbe, Uganda. Analysis of variance was conducted to assess the association between site, age, sex, and plasma chemistry parameters and the association between sex and morphologic characteristics. Plasma chemistry values for nestling and adult African fish eagles were similar to those reported for other captive and free-ranging eagle species. Packed cell volumes for nestling African fish eagles were markedly lower than values reported for nestlings of other eagle species, although the mean estimated age of nestlings sampled also was lower. A significant association (P < or =0.05) was found between PCV of nestling eagles and study site (lower at Lake Mburo) but no association was found between PCV and nestling body weight (P> or =0.05). An unidentified Plasmodium sp. was present in erythrocytes of three nestlings from Lake Mburo. No other blood parasites were seen. There was significant variation (P< or =0.05) in PCV, calcium, phosphorous, potassium, cholesterol concentrations, and creatine kinase activity between adults and nestlings; all were lower in adults. Aspartate transaminase activity was higher in adults. Like other Haliaeetus sp., body weight, bill depth, culmen length, footpad length, and hallux length as well as bill depth measurements were significantly (P < or = 0.05) greater for females than males. The objective of the study was to provide baseline biologic and physiologic information that may prove useful in the management and study of captive and wild populations of African fish eagles.

MERCURY AND PERSISTENT ORGANIC POLLUTANT CONCENTRATIONS IN AFRICAN FISH EAGLES, MARABOU STORKS, AND NILE TILAPIA IN UGANDA

The purpose of this research was to evaluate persistent organic pollutant (POP) and mercury concentrations in tissues of African fish eagles (Haliaeetus vocifer) and Nile tilapia (Oreochromis niloticus) from Lake Victoria near Entebbe and Lake Mburo, Uganda. Marabou stork (Leptoptilos crumeniferus) nestlings from urban Kampala (40 km from Entebbe) also were sampled for POPs and mercury. Total mercury was measured in the breast feathers of eight nestling and 10 adult African fish eagles from Lake Mburo, 10 nestling and five adult African fish eagles from Lake Victoria near Entebbe, and 20 nestling marabou storks from Kampala from June 2002 through January 2003. Mercury concentrations in all samples were below levels associated with adverse effects in similar species. Mercury concentrations were significantly higher in eagle adults and nestlings from Entebbe than in adults and nestlings from Lake Mburo (P< or =0.05). No significant differences (P> or =0.05) were found in mercury concentrations between sexes or between the entire fish eagle population sampled at Entebbe and marabou stork nestlings sampled at nearby Kampala. Plasma samples from the same birds were analyzed for 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, aldrin, hexachlorocyclohexane (alpha-HCH), dieldrin, endrin, heptachlor and their metabolites, as well as total polychlorinated biphenyls (PCBs). Nile tilapia whole-body cross sections collected from Lake Mburo (n=3) and Lake Victoria near Entebbe (n=8) also were analyzed for these POPs and mercury. No samples contained POPs or PCBs at the limits of detection except for 4,4'-1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene in five adult eagle plasma samples (0.0026+/-0.0015 ppm wet weight) and five Nile tilapia samples (0.002+/-0.001 ppm wet weight) from Entebbe.

Chlorinated hydrocarbon contaminants in blood of black and turkey vultures from Savannah River Site, South Carolina, USA

Blood of adult and juvenile black and turkey vultures in the Savannah River Site of South Carolina, USA was analyzed for the presence of 2,3,7,8-chlorine substituted polychlorinated dibenzo-p-dioxins (2,3,7,8-PCDDs), dibenzofurans (2,3,7,8-PCDFs), -dioxin-like and -di-ortho polychlorinated biphenyls. Concentration ranges of 2,3,7,8-PCDD/DFs in blood of black and turkey vultures were 14.2-34.6 and 8.7-56.2 pg/ml wet wt., respectively. Dioxin-like PCBs were in the ranges of 815-4627 and 753-3611 pg/ml wet wt. respectively, in black and turkey vultures. Considerable concentrations of two congeners of di-ortho PCBs were noticed in the ranges of 1415-10325 and 663-7500 pg/ml respectively, in black and turkey vultures. Comparatively, greater toxic equivalency (TEQ) were observed in blood of turkey vultures with the ranges of 3.2-20, whereas black vulture contained 1.8-8.4 pgTEQ/ml wet wt. basis. The species-specific accumulation profiles of PCDD/DFs and dioxin-like PCBs may reflect the different feeding habits, ecology, metabolic capacity and migratory movements of these two scavenging species.

Concentrations and profiles of polychlorinated biphenyls, -dibenzo-p-dioxins and -dibenzofurans in livers of mink from South Carolina and Louisiana, U.S.A

In South Carolina, U.S.A., mink have been reintroduced from two apparently healthy populations to areas where populations have existed in the past but have been extirpated. High mortality was observed during transport of mink from the source populations. In order to elucidate the potential effects of dioxin-like compounds on the survival and reproduction of mink, concentrations of total polychlorinated biphenyls (PCBs), p,p'-DDE, dioxin-like PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) were measured in livers of mink collected from the source populations in South Carolina and Louisiana. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) for the South Carolina and Louisiana mink were 21 and 14 pg g(-1), wet wt., respectively. PCB and TEQ concentrations were close to the threshold values that can, under laboratory conditions, elicit toxic effects in ranch mink. Therefore, any additional exposures of these populations to TEQs might adversely affect their populations.

Associations between regional differences in polychlorinated biphenyls and dichlorodiphenyldichloroethylene in blood of nestling bald eagles and reproductive productivity

The relationship between regional reproduction rates of bald eagles (Haliaeetus leucocephalus) and concentrations of p.p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and total polychlorinated biphenyls (PCBs) in blood plasma from nestling bald eagles was assessed. Blood was analyzed from 309 nestlings from 10 subpopulations of eagles across the Great Lakes region. Geometric mean concentrations of p,p'-DDE and total PCBs were inversely correlated to the productivity and success rates of nesting bald eagles within nine subpopulations. Nestlings eight weeks of age and older had significantly greater geometric mean concentrations of total PCBs and p,p'-DDE than nestlings less than eight weeks of age. The ability to use measurements of p,p'-DDE and total PCBs in nestling blood to determine the potential impact of these contaminants on adult nesting on a regional scale was demonstrated.

Perfluorooctane sulfonate in fish-eating water birds including bald eagles and albatrosses

Perfluorooctane sulfonate (PFOS) was measured in 161 samples of liver, kidney, blood, or egg yolk from 21 species of fish-eating water birds collected in the United States including albatrosses from Sand Island, Midway Atoll, in the central North Pacific Ocean. Concentrations of PFOS in the blood plasma of bald eagles collected fromthe midwestern United States ranged from 13 to 2,220 ng/mL (mean: 330 ng/mL), except one sample that did not contain quantifiable concentrations of PFOS. Concentrations of PFOS were greater in blood plasma than in whole blood. Among 82 livers from various species of birds from inland or coastal U.S. locations, Brandt's cormorant from San Diego, CA, contained the greatest concentration of PFOS (1,780 ng/g, wet wt). PFOS was also found in the sera of albatrosses from the central North Pacific Ocean at concentrations ranging from 3 to 34 ng/mL. Occurrence of PFOS in birds from remote marine locations suggests widespread distribution of PFOS and related fluorochemicals in the environment.

Hematology and serum chemistries of nestling bald eagles (Haliaeetus leucocephalus) in the lower peninsula of MI, USA

Hematology constituents and serum biochemistries were determined in blood collected from 55 nestling bald eagles (Haliaeetus leucocephalus) from nest sites within the lower peninsula of Michigan in 1992. Hematological values were comparable to published ranges for birds for all but eosinophils, which were greater than normal. Serum chemistry values were similar to those of other birds for all but six parameters, uric acid, cholesterol, alkaline phosphatase, total protein, globulin, and urea nitrogen, which were greater and glucose which was less. Samples of blood collected from wild bald eagles can be used for hematologic parameters and serum chemistry. It is important for other studies of endangered species to obtain baseline data from healthy, wild animals in their natural environment, and for comparison of animals living in environments of greater exposure to those living in areas of lesser exposure to xenobiotics. We caution that arrangements for rapid analysis be done in advance of sample collection.

Assessment of environmental endocrine disruptors in bald eagles of the Great Lakes

Environmental endocrine disruption in wildlife has primarily focused on estrogenic/androgenic end points and their antagonists. We describe here the work that has occurred within the Great Lakes of North America that has used the bald eagle (Haliaeetus leucocephalus) as a sentinel species of the effects of environmental toxicants, including endocrine disruption. Our data suggests that population level effects of hormone disrupting chemicals, not necessarily estrogen/androgen mimics and their antagonists, have been associated with reproductive and teratogenic effects observed in the bald eagle population within the Great Lakes Basin. Additional laboratory and field studies are necessary to further clarify the role of environmental endocrine disruptors on reproduction in avian populations. The use of sea eagles (Haliaeetus spp.) as biosentinels of pollution in other regions of the world is also discussed.

Leucocytozoonosis in nestling bald eagles in Michigan and Minnesota

Thirteen of 21 nestling bald eagles (Haliaeetus leucocephalus) examined for blood parasites in Michigan and Minnesota (USA) during June and July 1997 had patent infections of Leucocytozoon toddi. No other parasites were seen. The degree of parasitemia was light and varied from 1 to 2 on the Ashford Scale. Several of the infected nestlings appeared to have elevated levels of heterophils in their peripheral circulating blood. One of the infected nestlings also showed signs of severe anemia. We believe this is the first report of L. toddi in the bald eagle.

Contaminants of fishes from Great Lakes-influenced sections and above dams of three Michigan rivers: III. Implications for health of bald eagles

Recently, there have been discussions of the relative merits of passage of fishes around hydroelectric dams on three rivers (Au Sable, Manistee, and Muskegon) in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on bald eagles that could consume such fishes from above and below dams on the three primary rivers. The hazard assessments were verified by comparing the reproductive productivities of eagles nesting in areas where they ate primarily fish from either above or below dams on the three primary rivers, as well as on two additional rivers in Michigan, the Menominee and Thunder Bay. Concentrations of organochlorine insecticides (OCI), polychlorinated biphenyls (total PCBs), 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ), and total mercury (Hg) were measured in composite samples of fishes from above and below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Mean concentrations of OCI, total PCBs, and TCDD-EQ were all greater in fishes from below the dams than in those from above. The hazard assessment indicated that current concentrations of Hg and OCI other than DDT (DDT+DDE+DDD) in fish from neither above nor below dams would present a significant hazard to bald eagles (Haliaeetus leucocephalus). Both total PCBs and TCDD-EQ in fishes from below the dams currently present a significant hazard to bald eagles, since their mean hazard quotients (HQ) were all greater than one.

A review of factors affecting productivity of bald eagles in the Great Lakes region: implications for recovery

The bald eagle (Haliaeetus leucocephalus) population in North America declined greatly after World War II due primarily to the eggshell thinning effects of p,p'-DDE, a biodegradation product of DDT. After the banning of DDT in the United States and Canada during the early 1970s, the bald eagle population started to increase. However, this population recovery has not been uniform. Eagles nesting along the shorelines of the North American Great Lakes and rivers open to spawning runs of anadromous fishes from the Great Lakes still exhibit impaired reproduction. We have explored both ecological and toxicological factors that would limit reproduction of bald eagles in the Great Lakes region. Based on our studies, the most critical factors influencing eagle populations are concentrations of environmental toxicants. While there might be some continuing effects of DDE, total PCBs and most importantly 2,3,7,8-tetrachlordibenzo-p-dioxin equivalents (TCDD-EQ) in fishes from the Great Lakes and rivers open to spawning runs of anadromous fishes from the Great Lakes currently represent a significant hazard to bald eagles living along these shorelines or near these rivers and are most likely related to the impaired reproduction in bald eagles living there.

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. II: Implications for health of mink

Populations of mink (Mustela vison) have declined in many areas of the world. Such declines have been linked to exposures to synthetic, halogenated hydrocarbons. In the Great Lakes region, mink are fewer in areas along the shore of the Great Lakes and their tributaries where mink have access to fish from the Great Lakes. Recently, there has been discussion of the relative merits of passage of fishes around hydroelectric dams on rivers in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on mink, which could consume such fishes from above or below dams on the rivers. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlordibenzo-p-dioxin equivalents (TCDD-EQ), and total mercury were measured in composite samples of fishes from above or below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Concentrations of organochlorine insecticides, PCBs, and TCDD-EQ were all greater in fishes from below the dams than those from above. Concentrations of neither organochlorine insecticides nor mercury in fishes are currently a risk to mink above or below the dams. All of the species of fishes collected from downstream of the dams contained concentrations of PCBs and TCDD-EQ, which represent a hazard to mink. The hazard index for PCBs was less than one for the average of all species from the upstream reaches of the Manistee and Au Sable Rivers, but not the Muskegon. The hazard index (concentration in fish/NOAEC) was greater than 1 for all of the species collected from below the dams, in all three rivers. The greatest hazard index was observed for carp (Cyprinus carpio) downstream on the Muskegon River. Because the concentrations of PCBs used in the hazard assessment were corrected for relative toxic potencies, the hazard ratios based on PCBs should be similar to those based on TCDD-EQ. This was found to be true. Thus, either total PCBs or TCDD-EQ could be used as the critical toxicant in the hazard assessment. However, if uncorrected concentrations of PCBs, expressed as Aroclors, were used in the hazard assessment, the toxicity of the weathered mixture would have been underestimated by approximately five-fold, and, in that instance, TCDD-EQ would be the critical contaminant for the hazard assessment.(ABSTRACT TRUNCATED AT 400 WORDS)

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. I: Concentrations of organo chlorine insecticides, polychlorinated biphenyls, dioxin equivalents, and mercury

Fishes of the Great Lakes contain hazardous chemicals such as synthetic halogenated hydrocarbons and metals. These fish can move from the lakes into the Great Lakes tributaries of Michigan. In doing so, they transport concentrations of contaminants which may represent a risk to wildlife. Concentrations of mercury (Hg), total polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ), total DDT complex, aldrin, endrin, dieldrin, heptachlor, heptachlor epoxide, lindane, hexachlorobenzene, cis-chlordane, oxychlordane, endosulfan-I, methoxychlor, trans-chlordane, and trans-nonachlor were determined in composite samples of fishes from above and below Michigan hydroelectric dams, which separate the fishes which have access to the Great Lakes from fishes that do not. Mean concentrations of total PCBs, TCDD-EQ, DDT, and most of the other pesticides were greater in composite samples of six species of fishes from below than above the dams on the Au Sable, Manistee, and Muskegon Rivers. Concentrations of mercury, were the same or greater above the dams than below. However, this difference was statistically significant only on the Au Sable. Mercury concentrations ranged from less than 0.05 mg/kg to 0.73 mg Hg/kg, ww. Total concentrations of PCBs ranged from 0.02 to 1.7 mg/kg, ww. Concentrations of 2,3,7,8-tetrachlordibenzo-p-dioxin equivalents varied among fishes and locations. The concentrations of TCDD-EQ ranged from 2.4 to 71 micrograms/kg, ww, with concentrations in carp being the greatest. Concentrations of TCDD-EQ were greater than the concentrations which would be expected to occur, due solely to the presence of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and technical mixtures of PCBs.