The Great Lakes Fisheries Specimen Bank: a Canadian perspective in environmental specimen banking

Basin-Specific Pollutant Bioaccumulation Patterns Define Lake Huron Forage Fish

The Lake Huron ecosystem is unique among the Laurentian Great Lakes (USA/Canada) in that its surface area encompasses 3 distinct basins. This ecosystem recently experienced significant ecological restructuring characterized by changes in primary production, species dominance and abundances, and top predator energy dynamics. However, much of the evidence for this restructuring has been largely derived from biomonitoring data obtained from long-term sampling of the lake's Main Basin. We examined polychlorinated biphenyl (PCB) concentrations and the stable isotopes of carbon (δ¹³ C) and nitrogen (δ¹⁵ N) in rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi), and round goby (Neogobius melanostomus) to determine spatial variability in these environmental markers as indicators of the ubiquity of trophic restructuring throughout Lake Huron. Stable isotopes indicated that North Channel fish occupied trophic positions between 0.5 and 1.0 lower relative to Main Basin and Georgian Bay conspecifics, respectively. Sum PCB concentrations for 41 congeners were highest for fish from the Main Basin (27.5 ± 3.0 ng g^-1 wet wt) and Georgian Bay (26.3 ± 3.4 ng g^-1 wet wt) relative to North Channel (13.6 ± 1.2 ng g^-1 wet wt) fish. Discriminant functions analysis demonstrated basin-specific PCB congener profiles with individual species also having distinct profiles dependent on their basin of collection. These bioaccumulation patterns among Lake Huron forage fish mirror those reported for lake trout in this lake and indicate that the degree of food-web ecological restructuring in Lake Huron is not equivalent across the basins. Specifically, basin-specific PCB congener profiles demonstrated that differences among Lake Huron secondary and top predator consumer species are likely dictated by cross-basin differences in zooplankton community ecology and trophodynamics that can regulate the efficiencies of prey energy transfer and PCB congener bioaccumulation patterns in aquatic food webs. Environ Toxicol Chem 2020;39:1712-1723. © 2020 SETAC.

Temporal variations in embryotoxicity of Lake Ontario American eel (Anguilla rostrata) extracts to developing Fundulus heteroclitus

The recruitment of American eel (Anguilla rostrata) juveniles to Lake Ontario (LO), Canada has declined significantly since the 1980s. To investigate the possible contribution of maternally-transferred persistent organic pollutants (POPs) to this decline, this study measured temporal variations in the toxicity of complex organic mixtures extracted from LO American eels captured in 1988, 1998 and 2008 to developing Fundulus heteroclitus exposed by intravitelline (IVi) injection. The 1988 and 1998 eel extracts were most toxic, causing a pattern of sublethal embryotoxic responses similar to those previously reported in F. heteroclitus embryos exposed to single dioxin-like compounds (DLCs): stunted growth, craniofacial deformities, EROD activity induction, and reduced predatory capacities. The potency of extracts declined over time; the only significant effect of the 2008 eel extracts was EROD induction. The chemically-derived TCDD-TEQs of eel extracts, calculated using measured concentrations of some DLCs and their relative potencies for F. heteroclitus, overestimated their potency to induce EROD activity possibly due to interactions among POPs. Other POPs measured in eel extracts (non-dioxin-like PCBs, PBDEs and organochlorinated pesticides) did not appear to be important agonistic contributors to the observed toxicity. The toxicity of the complex mixtures of POPs measured in LO eels may have been underestimated as a result of several factors, including the loss of POPs during extracts preparation and a focus only on short-term effects. Based on the model species examined, our results support the hypothesis that contamination of LO with DLCs may have represented a threat to the American eel population through ecologically-relevant effects such as altered larval prey capture ability. These results prioritize the need to assess early life stage (ELS) toxicity of DLCs in Anguilla species, to investigate long-term effects of complex eel extracts to ELS of fish, and to develop biomarkers for potential effects in eel ELS sampled in the field.

Qualitative analysis of halogenated organic contaminants in American eel by gas chromatography/time-of-flight mass spectrometry

Target compound analysis with scanning mass spectrometers such as quadrupole or magnetic sector instruments is used extensively in environmental chemistry because of the selectivity, sensitivity, and robustness. Yet, target compound analysis selectively ignores the majority of compounds present in a sample, especially in complex matrices like fish. In this study, time-of-flight mass spectrometry was used to screen for and identify halogenated compounds in American eels (Anguilla rostrata). Individual and then pooled eel samples were analysed using electron ionization and electron capture negative ionization (ECNI) modes. Eels were differentiated by principal component analysis of chemical profiles and were grouped corresponding to their capture location, all with a single instrument injection per sample. Bromine containing compounds were further investigated by taking advantage of the selectivity of ECNI by utilizing the Br(-) ion m/z 79 and 81. A total of 51 brominated compounds were detected and their identities were attempted by authentic standards, library searching, and/or chemical formula prediction based on accurate mass measurements. Several PBDEs were identified in the samples, and the majority of the non-PBDEs identified were bromophenols, bromoanisoles, and bromobenzenes. These classes of compounds are synthesized for use in flame retardant production either as intermediates or as final products. However, their occurrence in eels was most likely the result of metabolism or break-down products of high production volume flame retardants like polybrominated diphenyl ethers and bromophenoxy compounds.

Spatial trends of organochlorinated pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers in Atlantic Anguillid eels

The bioaccumulation of lipophilic contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) can result in a reduction in fitness and spawner quality in eels and may be a factor in Anguillid sp. population declines. Contaminant concentrations in eels have been studied extensively in Europe, but data for American eels are severely lacking. Concentrations of PCBs, OCPs, and PBDEs were determined in American eel from eastern Canada and New York, USA, along with European eel from Belgium. Principal component analysis revealed that eels captured in the St. Lawrence estuary were a mixture of upstream migrants from the St. Lawrence River watershed, and fish captured in local tributaries. Contaminant concentrations were dependent on origin, related to the local environment, and were lower than historic values. In Canada, concentrations of OCPs and PCBs in eel tissues were below the Canadian human consumption guidelines for contaminants in fish, indicating that the current risk to consumers is low. However, concentrations of PCBs, total DDT, and mirex in eels from L. Ontario and the upper St. Lawrence R. were above Great Lakes guidelines for the protection of piscivorous predators. Concentrations of penta-BDE homologs exceeded the Canadian guideline for environmental quality in over half of the eels in this study, but concentrations of the other homolog groups were below the guideline.

Freezing To Preserve Groundwater Samples and Improve Headspace Quantification Limits of Water-Soluble Organic Contaminants for Carbon Isotope Analysis

Few systematic investigations have addressed the use of freezing for applications in analytical chemistry. Here, we tested its potential to preserve groundwater samples and to improve headspace quantification limits for compound-specific isotope analysis. Analysis of compound concentrations, as well as stable carbon isotope ratios, confirmed that trichloroethene was preserved in frozen suspensions of nanoscale zerovalent iron. In contrast, storage at 7 degrees C was ineffective, and complete degradation of TCE occurred in 4 weeks. Hence, freezing may stop even abiotic chemical reactions that would not be prevented by cooling or traditional preservation agents. In the absence of iron, we found that headspace concentrations of 14 organic contaminants were considerably higher over frozen solutions than at 25 degrees C, likely reflecting a freezing-out effect governed by Raoult's law. The observed enhancement depended on the salinity of the samples and was strongest for water-soluble, volatile compounds (values in brackets indicate the minimum observed effect out of six replicates): tert-butyl alcohol (TBA, 35-fold), methyl tert-butyl ether (MTBE, 14-fold), 1,2-dichloroethane (10-fold), or benzene (7-fold). In contrast, little enhancement was observed for less water-soluble compounds, such as tetrachloroethene. Although standard deviations of the measurements were too high for the method to be used for quantitative analysis of total compound concentrations, since we found that freezing introduces no measurable carbon isotope effect for TBA, MTBE, 1,2-dichloroethane, and benzene, the method is an effective way of increasing the sensitivity of compound-specific isotope analysis, particularly of water-soluble organic contaminants.

Trends of chlorinated organic contaminants in great lakes trout and walleye from 1970 to 1998

Levels of chlorinated organic contaminants in predator fish have been monitored annually in each of the Great Lakes since the 1970s. This article updates earlier reports with data from 1991 to 1998 for lake trout (Salvelinus namaycush) and (Lake Erie only) walleye (Sander vitreus) to provide a record that now extends nearly 30 years. Whole fish were analyzed for a number of industrial contaminants and pesticides, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethane (DDT), dieldrin, toxaphene, and mirex, and contaminant trends were quantified using multicompartment models. As in the past, fish from Lakes Michigan, Ontario, and Huron have the highest levels of PCBs, DDT, and dieldrin; Superior has the highest levels of toxaphene; and Ontario has the highest levels of mirex. In the period after curtailment of chemical use, concentrations rapidly decreased, represented by relatively short half-lives from approximately 1 to 9 years. Although trends depend on both the contaminant and the lake, in many cases the rate of decline has been decreasing, and concentrations are gradually approaching an irreducible concentration. For dioxin-like PCBs, levels have not been decreasing during the most recent 5-year period (1994 to 1998). In some cases, the year-to-year variation in contaminant levels is large, mainly because of food-web dynamics. Although this variation sometimes obscures long-term trends, the general pattern of a rapid decrease followed by slowing or leveling-off of the downward trend seems consistent across the Great Lakes, and future improvements of the magnitude seen in the 1970s and early 1980s likely will take much longer.

Levels and temporal trends of toxaphene congeners in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada

Environmentally relevant toxaphene congeners were determined in blubber samples of stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Canada. The purpose of this study was to evaluate the levels and the temporal trends (1988-1999) of a suite of six chlorobornanes (P26, P40/41, P44, P50, and P62) in the SLE belugas. P26 and P50 mean concentrations were in the same range as those reported for animals living in the Arctic environment suggesting that the atmospheric transport represents the main input of toxaphene to the SLE. A general exponential decline of chlorobornane concentrations in belugas was observed, except for P26 and P50 in males. On average, concentrations decreased by a factor of two in 8.5 years during the 1988-1999 time period. This rate of decline is similar to the reduction of toxaphene emission from agricultural soils in the southern United States reported over the same time period. Some differences in decline rates were observed among the studied CHB congeners. For instance, P62 decreased more rapidly than P26 and P50 in both male and female belugas. Several hypotheses were advanced to explain these differences such as selective metabolism of specific chlorobornanes by SLE belugas or their prey. However, a most likely explanation is the selective degradation of the technical product in soils and atmosphere in the source region.

Quality assurance in analysis of cryogenically stored liver tissue specimens from the NIST National Biomonitoring Specimen Bank (NBSB)

Portions of liver tissue specimens originally stored in the National Biomonitoring Specimen Bank (NBSB) and analyzed between 1980 and 1987 were re-analyzed in 1997 using instrumental neutron activation analysis (INAA) for the determination of 17 trace elements. Duplicate portions of each specimen had been stored at two different temperatures. The first was stored in a liquid nitrogen vapor-cooled freezer at -150 degrees C, standard NBSB storage conditions, and the other in an electric freezer maintained at -80 degrees C. Two portions of seven livers from each storage temperature were re-analyzed for this work. Results showed no changes in trace element content as a function of storage temperature, within the uncertainty of the method used. Results from these analyses agreed with results of initial analyses for most analytes in most sub-samples. Of the exceptions, five were due, in part, to an incorrect basis mass for the initial sub-specimen of one tissue, five with variable Zn results were attributed to difficulties in peak fitting for this element during INAA data processing, and the remaining were isolated differences discussed in this paper. Results of this work indicate that specimen storage and processing protocols are adequate to prevent noticeable contamination of specimens with trace elements, with the exception of Cr. Variability in Cr content was observed for the liver tissues which may have been caused by Cr contamination of the samples by the Teflon mill. Analyses of portions of Standard Reference Material (SRM) 1566a Oyster Tissue (certified in 1989) and SRM 1577a Bovine Liver (certified in 1982) were also included in this study for the purpose of quality control and to assess the stability of these freeze-dried powders that were stored at room temperature. No changes were observed in these materials.