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.

Water and sediment as sources of phosphate in aquatic ecosystems: The Detroit River and its role in the Laurentian Great Lakes.

Eutrophication of freshwater ecosystems and harmful algal blooms (HABs) are an ongoing concern affecting water quality in the Great Lakes watershed of North America. Despite binational management efforts, Lake Erie has been at the center of dissolved reactive phosphate driven eutrophication research due to its repeated cycles of algae blooms. We investigated the Detroit River, the largest source of water entering Lake Erie, with the objectives to (1) characterize Detroit River phosphate levels within water and sediment, and (2) use multiple chemical and isotopic tracers to identify nutrient sources in the Detroit River. Riverine water and sediment samples were collected at 23 locations across 8 transects of the Detroit River. The bulk δ15N values from sediments were enriched compared the δ15N values of nitrate from water samples, consistent with biogeochemical cycling in the sediment. Principle component analysis of multiple chemical tracers from water samples found spatial variation consistent with multiple sources including synthetic and manure-derived fertilizers and wastewater effluent. The concentrations of phosphate dissolved in water were within regulatory guidelines; however, sediments had elevated concentrations of both water- and acid-extractable phosphate. Sediment-sequestered legacy phosphorus historically deposited in the Detroit River may be transported into Lake Erie and, if mobilized into the water column, be an unrecognized internal-load that contributes to algal bloom events. Globally, freshwater ecosystems are impacted by numerous non-point source phosphorus inputs contributing to eutrophication and the use of multiple tracer approaches will increase our ability to effectively manage aquatic ecosystems.

Effect of season and habitat on PCB bioaccumulation by caged bluegill sunfish deployed in a Great Lakes area of concern.

Bluegill sunfish were caged in the Detroit River, Ontario, Canada, for 64 days to determine bioaccumulation rates of PCBs. Deployments involved placing fish in cages suspended in the water (suspended cages) compared to cages partially buried in sediments. Deployments were performed in the summer and winter months. During summer, fish exhibited significant increases in body weight and lipid content (sediment associated cages only), whereas in winter, body weights did not change. Lipid normalized PCB concentrations and PCB mass in fish increased significantly with time in summer deployments, but not in winter. Fish continued to accumulate PCBs over the 64 days caging duration except for PCBs 33, 49, and 52 in sediment associated cages. There were no significant differences in the bioaccumulation of PCBs between cage types. This study confirms that biomonitoring studies using caged fish should ensure chemical toxicokinetics are consistent when comparing bioaccumulation results among sites and/or time points.

Temporal and spatial patterns of contaminants in Lake Erie watersnakes (Nerodia sipedon insularum) before and after the round goby (Apollonia melanostomus) invasion.

Temporal and spatial trends in contaminant concentrations were assessed in Lake Erie watersnakes, a threatened (USA)/endangered (Canada) species restricted to western Lake Erie. Temporal changes in plasma contaminant levels were determined in 1990 and 2003, and spatial patterns in 2003 at 12 sites, throughout the species' range. During this period, the watersnakes' diet changed from fish (75%) and amphibians (25%) that avoid zebra mussels, to round gobies (95%) that feed extensively on zebra mussels. Temporal trends indicate that watersnakes on Pelee and North Bass Islands showed a marginal increase in hexachlorobenzene levels, and a significant decline in dieldrin, oxychlordane, and heptachlor epoxide, likely reflecting declines in aerial deposition and clearing of local vineyards. The contaminants with the greatest burdens, sum PCBs and p,p'-DDE, remained stable in the snakes, consistent with trends in other local biota, suggesting that although the dietary switch to round gobies meant consumption of a more contaminated diet, their diet remained at the same trophic position. We suggest that the watersnakes' PCB and p,p'-DDE temporal patterns reflect the lack of change in sediment concentrations with minimal influence from their dietary switch. Similar to top avian predators, PCBs, p,p'-DDE, and technical chlordane, are most prevalent in watersnakes; this ranking remains unchanged. In 2003, the watersnakes demonstrated significant spatial differences in concentrations of p,p'-DDE, dieldrin, technical chlordane and its metabolites. Their 2003 concentrations of p,p'-DDE, and to a lesser extent PCBs, exceed the recommended interim no-observable effects levels on watersnake embryonic survival. Further investigations are required to determine if these higher levels of PCBs, p,p'-DDE, and technical chlordane, affect reproductive and physiological parameters of the Lake Erie watersnake. Until concentrations of sediment contaminants decline in western Lake Erie, these endangered/threatened watersnakes will continue to be exposed to higher concentrations of persistent organic pollutants.

Snapping turtles (Chelydra serpentina) as bioindicators in Canadian areas of concern in the Great Lakes Basin. 1. Polybrominated diphenyl ethers, polychlorinated biphenyls, and organochlorine pesticides in eggs.

We examined the concentrations and spatial patterns of congeners of PBDEs, PCBs, and organochlorine pesticides in snapping turtle (Chelydra serpentina) eggs from Areas of Concern (AOCs) on the Canadian shores of Lake Ontario, St. Lawrence River, and connecting channels. Eggs from Lyons Creek (Niagara River AOC) reflected a local PCB source over a range of 7.5 km (3.2-10.8) from the Welland Canal. PCB contamination in eggs declined with increasing distance from the Welland Canal, whereas the relative contribution of congeners associated with Aroclor 1248/1254 increased with sigma PCB concentrations. Compared to turtle eggs from other sites in Lake Erie and Lake Ontario, eggs from Lyons Creek and Snye Marsh had PCB congener patterns that reflected a strong contribution from Aroclor 1254. PCBs in the eggs were associated with industrial sources and reflected the composition of different Aroclor technical mixtures. Organochlorine pesticides in eggs tended to be highest at Hamilton Harbour and Bay of Quinte AOCs, and were dominated by DDE, sigma chlordane, and mirex. In contrast, PBDE congener patterns in turtle eggs resembled PentaBDE technical formulations regardless of absolute concentrations or location, and were largely associated with urban environments.

Contaminants in lesser and greater scaup staging on the lower Great Lakes.

The decrease and subsequent lack of recovery of the North American scaup population has increased concerns about contaminants acquired during migration. We collected 189 fall- and spring-migrant lesser (Aythya affinis) and greater scaup (A. marila) on the lower Great Lakes (LGL) to determine if organic contaminants and trace elements in scaup livers were increased and to evaluate sources of variation in selenium (Se) burdens. We found that all organic contaminants were below toxic levels. Of 18 trace elements, only Se was detected at increased (>10-ppm dry-mass) levels. Se in lesser scaup increased but remained constant in greater scaup throughout fall; levels were increased in 14% of lesser scaup and 46% of greater scaup. During spring, Se increased in lesser scaup but decreased slightly in greater scaup; levels were increased in 75% of lesser scaup and 93% of greater scaup. We suggest that Se may be problematic for some breeding female scaup after departing the LGL, but more research is needed to determine the extent to which it affects scaup demographics.

Influence of vegetation in mitigation of methyl parathion runoff.

A pesticide runoff event was simulated on two 10 m x 50 m constructed wetlands (one non-vegetated, one vegetated) to evaluate the fate of methyl parathion (MeP) (Penncap-M). Water, sediment, and plant samples were collected at five sites downstream of the inflow for 120 d. Semi-permeable membrane devices (SPMDs) were deployed at each wetland outflow to determine exiting pesticide load. MeP was detected in water at all locations of the non-vegetated wetland (50 m), 30 min post-exposure. MeP was detected 20 m from the vegetated wetland inflow 30 min post-exposure, while after 10d it was detected only at 10 m. MeP was measured only in SPMDs deployed in non-vegetated wetland cells, suggesting detectable levels were not present near the vegetated wetland outflow. Furthermore, mass balance calculations indicated vegetated wetlands were more effective in reducing aqueous loadings of MeP introduced into the wetland systems. This demonstrates the importance of vegetation as sorption sites for pesticides in constructed wetlands.

Evaluation of chloroform/methanol and dichloromethane/hexane extractable lipids as surrogate measures of sample partition capacity for organochlorines in fish tissues.

Organic contaminant concentration data are often lipid normalized to provide an indication of the chemical fugacity in the sample or to compare the relative equilibrium status of samples from the same environment. This study compared lipid normalized PCB and organochlorine concentration data for tissues of individual fish when lipids were measured using chloroform/methanol (CM) or dichloromethane/hexane (DH) extractions. The CM extraction produced higher lipid yields for dorsal muscle (8-fold difference) and carcass (1.7-fold difference) compared to DH extractions, while both methods yielded comparable lipid contents for liver and adipose tissue. Lipid normalized tissue/carcass PCB and organochlorine concentration ratios were variable across tissue types when lipid contents from the CM technique were used, whereas, tissue/carcass concentration ratios approached the expected value of unity for each tissue when DH-derived lipids were used. These data suggest that the tissue lipid content as derived using the DH extraction provided a better surrogate measure of sample partition capacity than tissue lipids determined using the CM technique.

The influence of diet properties and feeding rates on PCB toxicokinetics in the ring dove.

The influence of diet properties and feeding rate on the uptake and elimination of polychlorinated biphenyls (PCBs) was investigated in ring doves (Streptopelia rissoria). Elimination rates of PCBs were determined in birds dosed with an Aroclor mixture (1242:1248:1260, 1:1:1) and allowed to depurate on uncontaminated high-lipid or low-lipid/high-fiber diets for 105 days. Uptake rates for seven additional PCBs not found within the above Aroclor mixtures were studied in the same birds by feeding high- or low-lipid PCB-spiked diets for 15 days. The two diet treatments contributed to differences in feeding rates, fecal egestion rates, and total fat volume of the birds. Uptake rate constants of PCBs were higher for the low-lipid diet group, whereas PCB assimilation efficiencies were similar between the two groups. Whole-body elimination rates of Aroclor PCBs were most strongly influenced by the chlorine substitution pattern of the congeners, such that PCBs containing an open meta-para site on one of the phenyl rings were rapidly cleared from the animal. Whole-body elimination rates for persistent PCBs could only be determined for PCB 28; other congeners exhibited negligible elimination over the depuration period. For the latter compounds, fecal elimination rates were estimated using the excreta/carcass distribution coefficient and excreta production rates. For PCB 28, the fecal elimination rate was similar to the whole-body elimination rate, suggesting that fecal elimination of persistent PCBs dominates whole body elimination of these compounds. Diet treatment effects were less evident for PCB elimination rates compared to uptake rates. Steady-state biomagnification factors were estimated to range from 1.0 to 5.1 for rapidly cleared PCBs and from 27 to 97 for persistent congeners.

Quantitative biomonitoring of PAHs using the Barnes mussel (Elliptio complanata).

The elimination rate constants (k(2)) of nine polycyclic aromatic hydrocarbons (PAHs) were examined for the freshwater mussel Elliptio complanata. The concentrations of fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[ a]anthracene, chrysene, benzo[ b]fluoranthene, and indeno[1,2,3-c,d]pyrene revealed a significant inverse relationship with time and their k(2) values ranged from 0.10 to 0.22 day(-1). The k(2) values of these significantly cleared PAHs were similar to k(2) values observed for nonmetabolized organochlorines in mussels previously reported in the literature. The inverse relationship between k(2) and K(ow) provides evidence that the nine PAHs were being passively eliminated from the mussels and that they can be used to calibrate the mussel as a quantitative biomonitor. A general expression relating elimination rate constants and chemical K(ow) is derived for hydrophobic contaminants in E. complanata. The k(2) versus log K(ow) regression equation for mussels developed herein was similar to other studies documenting the elimination of PCBs and PAHs in a number of bivalve species.

Bioaccumulation and toxicokinetics of 42 polychlorinated biphenyl congeners in American kestrels (Falco sparverius).

The bioaccumulation and toxicokinetics of 42 polychlorinated biphenyls (PCBs) was determined in male American kestrels exposed to an Aroclor-contaminated diet for 120 d followed by a 348-d depuration period. The birds were housed under ambient outdoor temperatures to permit normal fluctuations in body weight during the study. Whole body PCB clearance, plasma/fat distribution coefficients, and plasma PCB clearance constants were determined for individual PCBs to calibrate a two-compartment rate constant model in order to describe PCB elimination in the birds. Plasma/fat partition coefficients (K(PF)) averaged 0.0060 +/- 0.0001 for all congeners of study, were not dependent on chemical hydrophobicity, and did not change in summer versus winter sacrificed animals. Plasma clearance constants (k'pc) for PCBs were observed to be dependent on both chlorine substitution patterns and congener hydrophobicity. Polychlorinated biphenyl congeners categorized as readily cleared congeners contained vicinal meta-para hydrogen substituents on at least one phenyl ring, while slowly cleared congeners were chlorine hindered at these positions. A general equation was derived to predict plasma clearance constants for all tri- to octachlorobiphenyls based on the presence of an open meta-para site on one of the phenyl rings and from the n-octanol-water partition coefficient of the chemical. The equation was validated by comparing predicted versus measured relative biomagnification factors of PCBs determined in birds at the end of the dosing period. The two-compartment model calibrated for PCB elimination in American kestrels may be used to describe PCB toxicokinetics in wild birds provided that seasonal fluctuations in the fat content of the modeled population is known.

Courtship behavior of captive American kestrels (Falco sparverius) exposed to polychlorinated biphenyls.

Polychlorinated biphenyls (PCBs) adversely affect reproduction in birds. Captive adult male and female American kestrels (Falco sparverius) were studied to investigate the potential behavioral and hormonal alterations during the courtship period resulting from clinical exposure to PCBs. American kestrels ingested 7 mg/kg/body weight/bird/day of a 1:1:1 mixture of Aroclors 1248, 1254, and 1260 through their diet of day-old cockerels. The dietary dosage of Aroclors resulted in environmentally relevant total PCB residues in the eggs, averaging 34.1 microg/g wet weight (geometric mean). There was no difference between treatment and control birds in the circulating levels of total androgens (p = 0.44) or in 17 beta-estradiol (p = 0.29), one week following pairing. Male kestrels exposed to dietary PCBs exhibited significantly more sexual behaviors (p = 0.034) and flight behaviors (p = 0.026) than the control males. Sexual behaviors of male kestrels included; nest-box inspections, solicitation of copulation, the offer of food to the female, and giving the female food. The flight behaviors of the male included; flying from one perch to another and aerial display. In addition, the frequency of male sexual behaviors were correlated (r = 0.605, p = 0.001) with total PCB residues in the eggs of their mates. A concurrent study found that these same PCB-exposed kestrels experienced a delay in clutch initiation as well as a greater number of completely infertile clutches.

Quantifying maternal and dietary sources of 2,2',4,4',5,5'-hexachlorobiphenyl deposited in eggs of the ring dove (Streptopelia risoria).

The influence of maternal versus dietary sources of polychlorinated biphenyls (PCBs) deposited to eggs of ring doves (Streptopelia risoria) was investigated. Mature birds that lay a clutch of two eggs every 12 to 15 d were fed a diet of pellets spiked with 2,2',4,4',5,5'-hexacholorobiphenyl (unlabelled isotope designated as [12C]PCB153) for 25 d. The birds were subsequently switched to a diet containing isotopically labeled [U-13C12]PCB153 at similar concentrations for an additional 63 d. The toxicokinetics of [12C]PCB153 and [13C]PCB153 were followed in egg and carcass samples with time. Isotopic ratios of PCB153 in yolk lipids were identical to those in carcass lipids after introduction of diet 2, and they did not resemble those of the food at the time of egg formation. The data indicate that the PCB composition of eggs directly reflects the composition of maternal tissues, not the diet, at the time of yolk formation. Egg yolk:carcass lipid concentration ratios for the two isotopes were significantly less than one, averaging 0.33+/-0.02 (mean +/- standard error). Lipid normalized egg:maternal tissue contaminant concentration ratios for persistent organochlorine chemicals in the literature were reviewed for other avian species. The results provide a preliminary data set that suggests egg:maternal tissue contaminant concentration ratios vary among species, particularly among species that invest different quantities of lipids to a clutch of eggs. The results support the hypothesis that dilution of contaminants in egg lipids relative to maternal lipids is related to the reproductive strategy employed by the species.

Changes in egg composition of American kestrels exposed to dietary polychlorinated biphenyls.

Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 microg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.