Temporal Trends of Legacy and Current-Use Halogenated Flame Retardants in Lake Ontario in Relation to Atmospheric Loadings, Sources, and Environmental Fate.

Since the phase-out of polybrominated diphenyl ethers (PBDEs), large amounts of alternative halogenated flame retardants (AHFRs) have been introduced to the market. Due to their persistence and toxicity, halogenated flame retardants (HFRs) have become a concern for the ecosystem and human health. However, there remains limited assessment of the atmospheric loadings, sources, and environmental fate of HFRs in Lake Ontario, which receives urban-related inputs and cumulative chemical inputs from the upstream Great Lakes from Canada and the United States. We combined long-term measurements with a modified multimedia model based on site-specific environmental parameters from Lake Ontario to understand the trends and fate of HFRs. All HFRs were detected in the air, precipitation, lake trout, and herring gull egg samples throughout the sampling periods. General decreasing trends were found for PBDEs, while the temporal trends for AHFRs were not clear. Physical-chemical properties and emissions significantly influence the levels, profiles, and trends. Using the probabilistic modeling, HFR concentrations in lake water and sediment were predicted to be close to the measurement, suggesting a good performance for the modified model. The loadings from tributaries and wastewater effluent were the primary input pathways. Transformations in the water and sedimentation were estimated to be the dominant output pathway for the three HFRs.

In vitro assessment of the genotoxicity and immunotoxicity of treated and untreated municipal effluents and receiving waters in freshwater organisms.

Municipal wastewater effluent is one of the largest sources of pollution entering surface waters in the Laurentian Great Lakes. Exposure to wastewater effluent has been associated with impaired immune systems and induction of genotoxicity to aquatic animals. Due to habitat degradation and environmental pollution linked to industrial development and population growth, several regions of the Great Lakes have been designated Areas of Concern (AOCs). In this study, we assessed the effect of extracts of sewage influent, (treated) effluent and receiving surface waters from the Hamilton Harbour AOC and the Toronto and Region AOC (Ontario, Canada) on the phagocytic immune response of rainbow trout (Oncorhynchus mykiss) kidney leukocytes and the genotoxicity (DNA strand breaks) of these extracts on freshwater mussel (Eurynia dilatata) hemocytes. We identified and quantified numerous chemicals present in the various samples extracted for exposure. In freshwater mussels, extracts from Hamilton Harbour AOC induced DNA damage with the most frequency (12 out of 28 samples) regardless of sample type, reflecting past and present industrial activities. In contrast, extracts from Toronto and Region AOC induced DNA damage infrequently (2 out of 32 (summer) and 5 out of 32 (fall) samples, respectively) and from different WWTPs at different times. None of the extracts induced any significant effect on phagocytosis of rainbow trout kidney leukocytes. The present study indicates that despite overall improvements to effluent quality, treatment of influent by WWTPs may not result in a corresponding improvement of the genotoxicity of effluents. In vitro bioassays are useful and cost-effective rapid-screening tools for preliminary assessments of contamination of aquatic ecosystems.

Environmental exposure to non-steroidal anti-inflammatory drugs and potential contribution to eggshell thinning in birds.

Abnormally thin eggshells can reduce avian reproductive success, and have caused rapid population declines. The best known examples of this phenomenon are the widespread population crashes in birds, mostly raptors, fish eating birds, and scavengers, caused by the pesticide DDT and its isomers in the 1960s. A variety of other chemicals have been reported to cause eggshell thinning. Non-steroidal anti-inflammatory drugs (NSAIDs), which are extensively and increasingly used in human and veterinary medicine, may be one particularly concerning group of chemicals that demonstrate an ability to impair eggshell development, based both on laboratory studies and on their known mechanism of action. In this review, we outline environmental and wildlife exposure to NSAIDs, describe the process of eggshell formation, and discuss pathways affected by NSAIDs. We list pharmaceuticals, including NSAIDs, and other compounds demonstrated to reduce eggshell thickness, and highlight their main mechanisms of action. Dosing studies empirically demonstrated that NSAIDs reduce eggshell thickness through cyclooxygenase inhibition, which suppresses prostaglandin synthesis and reduces the calcium available for the mineralization of eggshell. Using the US EPA's CompTox Chemicals Dashboard, we show that NSAIDs are predicted to strongly inhibit cyclooxygenases. NSAIDs have been observed both in the putative diet of scavenging birds, and we report examples of NSAIDs detected in eggs or tissues of wild and captive Old World vultures. We suggest that NSAIDs in the environment represent a hazard that could impair reproduction in wild birds.

Phenology of the transcriptome coincides with the physiology of double-crested cormorant embryonic development.

The rigorous timing of the dynamic transcriptome within the embryo has to be well orchestrated for normal development. Identifying the phenology of the transcriptome along with the physiology of embryonic development in birds may suggest periods of increased sensitivity to contaminant exposure depending on the contaminant's mechanism of action. Double-crested cormorants (Nannopterum auritum, formerly Phalacrocorax auritus) are commonly used in ecotoxicological studies, but relatively little is known about their functional transcriptome profile in early development. In this study, we tracked the phenology of the transcriptome during N. auritum embryogenesis. Fresh eggs were collected from a reference site and artificially incubated from collection until four days prior to hatching. Embryos were periodically sampled throughout incubation for a total of seven time points. A custom microarray was designed for cormorants (over 14,000 probes) and used for transcriptome analysis in whole body (days 5, 8) and liver tissue (days 12, 14, 16, 20, 24). Three main developmental periods (early, mid, and late incubation) were identified with differentially expressed genes, gene sets, and pathways within and between each developmental transition. Overall, the timing of differentially expressed genes and enriched pathways corresponded to previously documented changes in morphology, neurology, or physiology during avian embryonic development. Targeted investigation of a subset of genes involved in endogenous and xenobiotic metabolism (e.g., cytochrome P450 cyp1a, cyp1b1, superoxide dismutase 1 sod1) were expressed in a pattern similar to reported endogenous compound levels. These data can provide insights on normal embryonic development in an ecologically relevant species without any environmental contaminant exposure.

Clothianidin alters leukocyte profiles and elevates measures of oxidative stress in tadpoles of the amphibian, Rana pipiens.

Neonicotinoid pesticide use is widespread and highly debated, as evidenced by recent attention received from the public, academics and pesticide regulatory agencies. However, relatively little is known about the physiological effects of neonicotinoid insecticides on aquatic vertebrates. Amphibians (larval stages in particular) are excellent vertebrate bioindicators in aquatic systems due to their risk of exposure and sensitivity to environmental stressors. Previous work with wood frog (Rana sylvatica) tadpoles exposed to formulated products containing thiamethoxam or clothianidin in outdoor mesocosms found significant shifts in leukocyte profiles, suggesting the tadpoles were physiologically stressed. The main objective of the present study was to characterize this stress response further using complementary measures of stress after exposure to clothianidin on northern leopard frogs (Rana pipiens) during their aquatic larval stages. Laboratory static-renewal exposures were conducted over eight weeks with the technical product clothianidin at 0, 0.23, 1, 10 and 100 µg/L, and diquat dibromide at 532 µg/L was used as a positive control. We assessed tadpole leukocyte profiles and measures of oxidative stress as these sub-lethal alterations could affect amphibian fitness. We found changes in several types of leukocytes at 1 and 10 µg/L, suggesting that these tadpoles exhibited signs of mild physiological stress. Clothianidin also induced an oxidative stress response at 0.23, 1 and 100 µg/L. However, we found no differences in survival, growth, development time or hepatosomatic index in frogs exposed to clothianidin. Our study indicates that tadpoles chronically exposed to clothianidin have increased stress responses, but in the absence of concentration-response relationships and effects on whole-organism endpoints, the implications on the overall health and fitness of these changes are unclear.

Bioaccumulation and physiological responses of the turtle Chelydra serpentina exposed to polychlorinated biphenyls during early life stages.

Despite the North American production ban of polychlorinated biphenyls (PCBs), PCBs are ubiquitous in the environment and in wildlife tissues. Chelydra serpentina serpentina (common snapping turtle) have been used as environmental indicators of PCB pollution upwards of 40 years given their high site fidelity and high trophic position. Despite their long use as indicators of PCB contamination, the effects of PCBs in reptiles remain largely unknown. In this study, we performed two experiments to assess i) bioaccumulation and ii) toxicity of PCBs to 1-month-old C. s. serpentina, to aid in interpretation of PCB burdens. Food pellets were spiked at an environmentally relevant concentration (0.45 µg/g) of the PCB mixture Aroclor 1254 to model hepatic bioaccumulation and depuration, through feeding, for 31 days and clean food for 50 days, respectively. No significant differences in PCB concentrations were observed in liver tissue over the course of the experiment, suggesting that juvenile turtles can likely metabolize low environmentally occurring concentrations of PCBs. Additionally, a dose-response experiment, performed to determine hepatic toxicity and bioaccumulation in juvenile C. s. serpentina, showed a 1.8-fold increase in hepatic expression of cyp1a when fed A1254-spiked pellets (12.7 µg/g; range 0-12.7 µg/g). This gene induction correlates with the significant increase of group 3 PCB congeners measured in the turtle liver, which are known to be metabolized by CYP1A. This study indicates that C. s. serpentina may be a good environmental indicator for PCBs, while more research is needed to assess the effects of body burdens in wild C. s. serpentina.

N-phenyl-1-naphthylamine (PNA) Accumulates in Snapping Turtle (Chelydra serpentina) Liver Activating the Detoxification Pathway.

Substituted phenylamine antioxidants (SPAs) are used in Canadian industrial processes. SPAs, specifically N-phenyl-1-naphthylamine (PNA), have received very little attention despite their current use in Canada and their expected aquatic and environmental releases. There is a research gap regarding the effects of PNA in wildlife; therefore, Chelydra serpentina (common snapping turtle) was studied due to its importance as an environmental indicator species. A chronic experiment was performed using PNA spiked food (0 to 3446 ng/g) to determine its toxicity to juvenile C. serpentina. A significant increase in cyp1a mRNA level was observed in the liver of turtles exposed to 3446 ng/g PNA, suggesting that phase I detoxification is activated in the exposed animals. Additionally, a significant decrease in cyp2b transcript level was observed at the two lowest PNA doses, likely indicating another metabolic alteration for PNA. This study helped determine the molecular effects associated with a PNA exposure in reptiles.

Toxicity of the pharmaceuticals finasteride and melengestrol acetate to benthic invertebrates.

The toxicity of endocrinologically active pharmaceuticals finasteride (FIN) and melengestrol acetate (MGA) was assessed in freshwater mussels, including acute (48 h) aqueous tests with glochidia from Lampsilis siliquoidea, sub-chronic (14 days) sediment tests with gravid female Lampsilis fasciola, and chronic (28 days) sediment tests with juvenile L. siliquoidea, and in chronic (42 days) sediment tests with the amphipod Hyalella azteca and the mayfly Hexagenia spp. Finasteride was not toxic in acute aqueous tests with L. siliquoidea glochidia (up to 23 mg/L), whereas significant toxicity to survival and burial ability was detected in chronic sediment tests with juvenile L. siliquoidea (chronic value (ChV, the geometric mean of LOEC and NOEC) = 58 mg/kg (1 mg/L)). Amphipods (survival, growth, reproduction, and sex ratio) and mayflies (growth) were similarly sensitive (ChV = 58 mg/kg (1 mg/L)). Melengestrol acetate was acutely toxic to L. siliquoidea glochidia at 4 mg/L in aqueous tests; in sediment tests, mayflies were the most sensitive species, with significant growth effects observed at 37 mg/kg (0.25 mg/L) (ChV = 21 mg/kg (0.1 mg/L)). Exposure to sublethal concentrations of FIN and MGA had no effect on the (luring and filtering) behaviour of gravid L. fasciola, or the viability of their brooding glochidia. Based on the limited number of measured environmental concentrations of both chemicals, and their projected concentrations, no direct effects are expected by these compounds individually on the invertebrates tested. However, organisms are exposed to contaminant mixtures in the aquatic environment, and thus, the effects of FIN and MGA as components of these mixtures require further investigation.

Rapid increase in contaminant burdens following loss of body condition in canvasbacks (Aythya valisineria) overwintering on the Lake St. Clair region of the Great Lakes.

Overwintering canvasbacks were collected in the Lake St. Clair region of the Great Lakes in the winter of 2008/09 and livers were analyzed for organochlorines, mercury (Hg), and selenium (Se). We found dramatic increases in hepatic concentrations of Hg, Se, sum PCBs, p,p'-DDE, and other organochlorines in canvasbacks in which concentrations in February were greater than concentrations in November when overwintering ducks arrived in the study area. Increases in contaminant burdens were generally greatest between December and January which also coincided with the period when ducks from Lake St. Clair (LSC) moved following freeze-up of the Lake to forage on the St. Clair River (SCR), an area of known historic contamination, and upstream of LSC. Body condition estimated using body metrics and measured using lipid reserves (after controlling for body size) increased in LSC ducks but subsequently decreased in SCR ducks. This rapid loss of body condition through loss of lipid reserves was one factor likely driving the dramatic increase in contaminant burdens and particularly for organochlorines which were inversely related to body condition in SCR ducks. Increased exposure due to foraging in closer proximity to contaminant sources and changes in diet associated with the movement of ducks may have also contributed to temporal trends. Concentrations overall were below those associated with toxicity with the exception of Se for which 30% of ducks exceeded the Se threshold that is considered elevated and one duck exceeded the threshold associated with possible toxicity. Fitness consequences of reduced lipid reserves include reduced survival, delayed migration, reduced breeding propensity, and transfer of contaminant burdens to eggs. Food availability, ice cover, and movements of canvasbacks are additional factors influencing contaminant accumulation and lipid reserves in waterfowl utilizing this important wintering location.

Acute and chronic toxicity of neonicotinoid and butenolide insecticides to the freshwater amphipod, Hyalella azteca.

Neonicotinoids are the most widely used insecticides in the world. They are preferentially toxic to insects while displaying a low toxicity toward vertebrates, and this selective toxicity has resulted in the rapid and ubiquitous use of these compounds. However, neonicotinoids have been detected in agricultural surface waters and are known to cause adverse effects in non-target aquatic organisms. A wide range of toxicity has been reported for aquatic crustaceans, but most of the studies focus on the acute effects of imidacloprid, and few data are available regarding chronic effects of other neonicotinoids or neonicotinoid replacements (e.g., butenolides). The objective of this study was to assess the acute and chronic toxicity of six neonicotinoids (imidacloprid, thiamethoxam, acetamiprid, clothianidin, thiacloprid, and dinotefuran) and one butenolide (flupyradifurone) to the freshwater amphipod Hyalella azteca. Chronic (28-d), water-only, static-renewal tests were conducted. Survival was assessed weekly, and growth was measured at the end of the exposure. Effects of neonicotinoids varied depending on the compound. Acute (7-d) LC50s were 4.0, 4.7, 60, 68, 230, and 290 µg/L for clothianidin, acetamiprid, dinotefuran, thiacloprid, imidacloprid, and thiamethoxam, respectively. Chronic (28-d) survival and growth were reduced at similar concentrations to acute (7-d) survival for thiamethoxam, acetamiprid, clothianidin, and dinotefuran. However, chronic survival and growth of amphipods exposed to imidacloprid and thiacloprid were reduced at lower concentrations than acute survival, with respective 28-d LC50s of 90 and 44 µg/L, and EC50s of 4 and 3 µg/L. Flupyradifurone was intermediate in toxicity compared to the neonicotinoids: 7-d LC50, 28-d LC50, and 28-d EC50 were 26, 20, and 16 µg/L, respectively. The concentrations of imidacloprid and clothianidin reported for North American surface waters fall within the effect ranges observed in this study, indicating the potential for these compounds to cause adverse effects to indigenous populations of H. azteca.

Substituted diphenylamine antioxidants and benzotriazole UV stabilizers in blood plasma of fish, turtles, birds and dolphins from North America.

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are additives used in industrial and commercial applications to prevent degradation by oxidation and are contaminants of emerging environmental concern. Little is known about the fate of these contaminants in wildlife, particularly in reptiles, birds and marine mammals. Nine SDPAs and six BZT-UVs were measured in blood plasma of seven fish species, snapping turtles (Chelydra serpentina), double-crested cormorants (Phalacrocorax auritus), and bottlenose dolphins (Tursiops truncatus) from various locations in North America. Plasma SDPAs were more frequently (90-100%) detected and with higher concentrations (median: 25-270 pg g-1, wet weight (ww)) in organisms from urban areas than rural locations (median:  double-crested cormorants > bottlenose dolphins. Of the three quantifiable BZT-UVs, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328) showed higher detection frequency in most species of fish, bird and turtle (range of 0-67%), indicating the widespread distribution of UV328 in the aquatic environment of lower Great Lakes region.

Legacy of legacies: Chlorinated naphthalenes in Lake Trout, Walleye, Herring Gull eggs and sediments from the Laurentian Great Lakes indicate possible resuspension during contaminated sediment remediation.

Polychlorinated naphthalenes (PCNs) are legacy contaminants, produced primarily as flame retardants and dielectrics until phased-out in Europe and North America in the 1970s. Spatial and temporal trends (1979-2013) of PCN concentrations were studied in whole fish and herring gull eggs throughout the Great Lakes and St. Lawrence River, whereas sediments were analyzed for 2011-2013 only. For both fish and gull eggs, concentrations of PCNs were highest in western Lake Erie (7660 & 3020pg/gww respectively), and declined downstream to St. Lawrence River (range: 34-2370pg/gww). For sediments, concentrations were highest in suspended sediments from the Detroit River (264,000pg/g), and were lower in surficial sediments downstream to the St. Lawrence River (range=440-19,300pg/g). PCNs declined at all sites from ~1980 to 1995, but in Lake Erie concentrations of PCNs increased in gulls fish from 1995 until 2005. The resurgence in PCNs in biota corresponded to the timing of remedial dredging of sediment highly contaminated with PCNs in the Detroit River, whose effects appear to manifest themselves downstream to Lake Ontario. Congener profiles of PCNs differed between Lake Erie and Lake Ontario until post-dredging, where PCN profiles of fish in both lakes became increasingly more similar. PCNs in gull eggs were mostly hepta-PCNs, whereas fish had higher concentrations of lower chlorinated PCNs. Patterns of PCNs in gulls and fish appear to be influenced by differences in not only routes of exposure and differential metabolic ability, but also resuspension of PCN contaminated sediments.

Lethal and sublethal toxicity of neonicotinoid and butenolide insecticides to the mayfly, Hexagenia spp.

Neonicotinoid insecticides are environmentally persistent and highly water-soluble, and thus are prone to leaching into surface waters where they may negatively affect non-target aquatic insects. Most of the research to date has focused on imidacloprid, and few data are available regarding the effects of other neonicotinoids or their proposed replacements (butenolide insecticides). The objective of this study was to assess the toxicity of six neonicotinoids (imidacloprid, thiamethoxam, acetamiprid, clothianidin, thiacloprid, and dinotefuran) and one butenolide (flupyradifurone) to Hexagenia spp. (mayfly larvae). Acute (96-h), water-only tests were conducted, and survival and behaviour (number of surviving mayflies inhabiting artificial burrows) were assessed. Acute sublethal tests were also conducted with imidacloprid, acetamiprid, and thiacloprid, and in addition to survival and behaviour, mobility (ability to burrow into sediment) and recovery (survival and growth following 21 d in clean sediment) were measured. Sublethal effects occurred at much lower concentrations than survival: 96-h LC50s ranged from 780 µg/L (acetamiprid) to >10,000 µg/L (dinotefuran), whereas 96-h EC50s ranged from 4.0 µg/L (acetamiprid) to 630 µg/L (thiamethoxam). Flupyradifurone was intermediate in toxicity, with a 96-h LC50 of 2000 µg/L and a 96-h EC50 of 81 µg/L. Behaviour and mobility were impaired significantly and to a similar degree in sublethal exposures to 10 µg/L imidacloprid, acetamiprid, and thiacloprid, and survival and growth following the recovery period were significantly lower in mayflies exposed to 10 µg/L acetamiprid and thiacloprid, respectively. A suite of effects on mayfly swimming behaviour/ability and respiration were also observed, but not quantified, following exposures to imidacloprid, acetamiprid, and thiacloprid at 1 µg/L and higher. Imidacloprid concentrations measured in North American surface waters have been found to meet or exceed those causing toxicity to Hexagenia, indicating that environmental concentrations may adversely affect Hexagenia and similarly sensitive non-target aquatic species.

Comparative toxicity of azo dyes to two infaunal organisms (Hexagenia spp. and Tubifex tubifex) in spiked-sediment exposures.

Azo dyes are synthetic compounds used as industrial colorants, and some are predicted to be inherently toxic, bioaccumulative, and/or persistent based upon their chemical composition. This study addresses data gaps in current research which include the need to evaluate the toxicity of hydrophobic azo dyes to benthic invertebrates. The toxicity of a solvent dye, Sudan Red G (SRG), and two disperse dyes, Disperse Yellow 7 (DY7) and Disperse Orange 13 (DO13), to Hexagenia spp. and Tubifex tubifex was assessed in spiked-sediment exposures. The dye compounds appeared to degrade readily in the equilibrium and exposure periods, suggesting a limited persistence of the parent compounds in the environment under test conditions. Although azo dye degradation products could not be reliably quantified, one was detected in DY7 sediment samples that elicited toxic effects to Hexagenia and Tubifex, providing evidence that DY7 degrades. Hexagenia survival and growth endpoints responded with similar sensitivity to the dyes, but DY7 was the most toxic, with a 21-day IC25 (concentration associated with 25% inhibition) for growth of 9.6 µg/g. Comparatively, Tubifex reproduction was the most sensitive endpoint for all dyes with 28-day IC25s for young production ranging from 1.3 to 11.8 µg/g. At sublethal concentrations, toxic effects to Tubifex differed between dyes: the solvent dye exerted an effect primarily on gametogenesis (cocoon production), while disperse dyes, most notably DY7, caused effects on embryogenesis (development of worm inside the cocoon). This study indicates that there could be potential hazard to oligochaetes based on the observed effect concentrations, but given the lack of environmental measurements, the risk of these compounds is unknown. Further research is required to determine if degradation products were formed in all dye samples and whether toxicity was caused by the parent molecules, which have limited persistence under test conditions, or by their degradation products. To avoid underestimating toxicity, this study stresses the need to use an infaunal deposit feeder such as the oligochaete Tubifex in sediment toxicity assessments where highly hydrophobic compounds are present.

Substituted Diphenylamine Antioxidants and Benzotriazole UV Stabilizers in Aquatic Organisms in the Great Lakes of North America: Terrestrial Exposure and Biodilution.

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are industrial additives of emerging environmental concern. However, the bioaccumulation, biomagnification, and spatial distribution of these contaminants in the Great Lakes of North America are unknown. The present study addresses these knowledge gaps by reporting SDPAs and BZT-UVs in herring gull (Larus argentatus) eggs, lake trout (Salvelinus namaycush), and their food web in the Great Lakes for the first time. Herring gull eggs showed much higher detection frequency and concentrations of target SDPAs and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328) than that of the whole body fish homogenate. For herring gull eggs, the samples from upper Great Lakes contained significantly greater levels of SDPAs than those eggs from lower lakes, possibly due to the differences in terrestrial food in diet. Interestingly, the predominant SDPAs in herring gull eggs were dinonyl- (C9C9) and monononyl-diphenylamine (C9) which were previously shown to be less bioaccumulative than other SDPAs in fish. In contrast, dioctyl-diphenylamine (C8C8) was the major SDPA in lake trout, and biodilution of C8C8 was observed in a Lake Superior lake trout food web. Such variations in herring gull eggs and fish indicate the differences in accumulation and elimination pathways of SDPAs and BZT-UVs and require further elucidation of these mechanisms.

Volatile Methylsiloxanes and Organophosphate Esters in the Eggs of European Starlings (Sturnus vulgaris) and Congeneric Gull Species from Locations across Canada.

Volatile methylsiloxanes (VMSs) and organophosphate esters (OPEs) are two suites of chemicals that are of environmental concern as organic contaminants, but little is known about the exposure of wildlife to these contaminants, particularly in birds, in terrestrial and aquatic ecosystems. The present study investigates the spatial distributions of nine cyclic and linear VMSs and 17 OPEs in the eggs of European starlings (Sturnus vulgaris) and three congeneric gull species (i.e., herring gull (Larus argentatus), glaucous-winged gull (L. glaucescens), and California gull (L. californicus)) from nesting sites across Canada. ∑VMS concentrations for all bird eggs were dominated by decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and octamethylcyclotetrasiloxane (D4). With European starlings, birds breeding adjacent to landfill sites had eggs containing significantly greater ∑VMS concentrations (median: 178 ng g-1 wet weight (ww)) compared with those from the urban industrial (20 ng g-1 ww) and rural sites (1.3 ng g-1 ww), indicating that the landfills are important sources of VMSs to Canadian terrestrial environments. In gull eggs, the median ∑VMS concentrations were up to 254 ng g-1 ww and suggested greater detection frequencies and levels of VMSs in aquatic- versus terrestrial-feeding birds in Canada. In contrast, the detection frequency of OPEs in all European starling and gull eggs was lower than 16%. This suggested that low dietary exposure or rapid metabolism of accumulated OPEs occurs in aquatic feeding birds and may warrant further investigation for the elucidation of the reasons for these differences.

Municipal wastewater treatment plant effluent-induced effects on freshwater mussel populations and the role of mussel refugia in recolonizing an extirpated reach.

Global human population and urbanization continually increase the volume of wastewater entering aquatic environments. Despite efforts to treat these effluents, they contribute a diverse suite of substances that enter watersheds at concentrations that have the potential to elicit adverse effects on aquatic organisms. The relationship between wastewater treatment plant (WWTP) effluent exposure and biological responses within aquatic ecosystems remains poorly understood, especially at the population level. To examine the effect of WWTP effluents on sentinel invertebrates, freshwater mussels were assessed in the Grand River, Ontario, in populations associated with the outfall of a major WWTP. This watershed, within the Laurentian Great Lakes basin, has a diverse community of twenty-five species of mussels, including nine Species at Risk, and is representative of many habitats that receive WWTP effluents regionally as well as globally. Surveys were conducted to assess the presence and species richness of freshwater mussels. In total, 55 sites downstream of the WWTP were examined using timed visual searches with one or 2 h of effort spent searching 100 m segments. Although seven species of mussels were found in moderate abundance (mean of 8 mussels per hour of searching across 2 sites) upstream of the WWTP outfall, no live mussels were observed for 7.0 km downstream of the WWTP. Long-term water quality monitoring data indicate that ammonia and nitrite concentrations along with large seasonal declines in diel dissolved oxygen were associated with the extirpation of mussels downstream of the WWTP. The first live mussels found downstream were below the confluence with a major tributary indicating that in addition to an improvement in water quality to a state that enables mussels (and/or their fish hosts) to survive, a nearby mussel refuge may have facilitated the recolonization of the depauperate WWTP-impacted zone.

Mercury levels in herring gulls and fish: 42 years of spatio-temporal trends in the Great Lakes.

Total mercury levels in aquatic birds and fish communities have been monitored across the Canadian Great Lakes by Environment and Climate Change Canada (ECCC) for the past 42 years (1974-2015). These data (22 sites) were used to examine spatio-temporal variability of mercury levels in herring gull (Larus argentatus) eggs, lake trout (Salvelinus namaycush), walleye (Sander vitreus), and rainbow smelt (Osmerus mordax). Trends were quantified with dynamic linear models, which provided time-variant rates of change of mercury concentrations. Lipid content (in both fish and eggs) and length in fish were used as covariates in all models. For the first three decades, mercury levels in gull eggs and fish declined at all stations. In the 2000s, trends for herring gull eggs reversed at two sites in Lake Erie and two sites in Lake Ontario. Similar trend reversals in the 2000s were observed for lake trout in Lake Superior and at a single station in Lake Ontario. Mercury levels in lake trout continued to slowly decline at all of the remaining stations, except for Lake Huron, where the levels remained stable. A post-hoc Bayesian regression analysis suggests strong trophic interactions between herring gulls and rainbow smelt in Lake Superior and Lake Ontario, but also pinpoints the likelihood of a trophic decoupling in Lake Huron and Lake Erie. Continued monitoring of mercury levels in herring gulls and fish is required to consolidate these trophic shifts and further evaluate their broader implications.

The effects of pharmaceuticals on a unionid mussel (Lampsilis siliquoidea): An examination of acute and chronic endpoints of toxicity across life stages.

The toxicity and bioconcentration of 3 pharmaceuticals (amitriptyline, iopamidol, and sertraline) were examined using multiple life stages (larval, juvenile, and adult) of the unionid mussel Lampsilis siliquoidea. The endpoints examined varied with life stage but included survival, behavior (algal clearance rate, filtering frequency), and oxidative stress. Iopamidol was not toxic at concentrations up to 101 mg/L. Sertraline was the most toxic chemical (50% lethal concentrations [LC50] and effect concentrations [EC50] = 0.02-0.04 mg/L), but exposure did not induce oxidative stress. Glochidia and juveniles were more sensitive than adult mussels. Algal clearance rate in juvenile mussels was the most sensitive endpoint assessed, similar to or lower than the LC50 values for glochidia. However, the compounds examined were not toxic at concentrations detected in the environment. The relative bioconcentration factors were sertraline > amitriptyline > iopamidol. These results suggest that glochidia toxicity could be a screening tool for rapidly assessing the toxicity of chemicals of concern to freshwater mussels. Environ Toxicol Chem 2017;36:1572-1583. © 2016 SETAC.