PCB-Related Alteration of Thyroid Hormones and Thyroid Hormone Receptor Gene Expression in Free-Ranging Harbor Seals (Phoca vitulina)

Persistent organic pollutants are environmental contaminants that, because of their lipophilic properties and long half-lives, bioaccumulate within aquatic food webs and often reach high concentrations in marine mammals, such as harbor seals (Phoca vitulina). Exposure to these contaminants has been associated with developmental abnormalities, immunotoxicity, and reproductive impairment in marine mammals and other high-trophic-level wildlife, mediated via a disruption of endocrine processes. The highly conserved thyroid hormones (THs) represent one vulnerable endocrine end point that is critical for metabolism, growth, and development in vertebrates. We characterized the relationship between contaminants and specific TH receptor (TR ) gene expression in skin/blubber biopsy samples, as well as serum THs, from free-ranging harbor seal pups (n = 39) in British Columbia, Canada, and Washington State, USA. We observed a contaminant-related increase in blubber TR-α gene expression [total polychlorinated biphenyls (∑PCBs); r = 0.679; p < 0.001] and a concomitant decrease in circulating total thyroxine concentrations (∑PCBs; r = −0.711; p < 0.001). Consistent with results observed in carefully controlled laboratory and captive feeding studies, our findings suggest that the TH system in harbor seals is highly sensitive to disruption by environmental contaminants. Such a disruption not only may lead to adverse effects on growth and development but also could have important ramifications for lipid metabolism and energetics in marine mammals

Seabed Substrate Classification Charts for Vancouver Harbour and Vicinity

As part of the World Class Tanker Safety initiative of the Government of Canada, the Department of Fisheries and Oceans (DFO) Pacific region science division has been tasked with predicting species distributions and habitat suitability along northern shipping routes. Bottom substrate charts are key tools in developing habitat charts. They are important to stakeholders within DFO, Parks Canada, and Environment Canada as they are used to identify areas of potentially high biodiversity, increased oil spill susceptibility, or heightened importance to an ecosystem. Science staff at the Pacific Biological Station (PBS), and Canadian Hydrographic Service (CHS) have been developing a seabed classification model that analyses Multi-beam Echo Sounder (MBES) backscatter derivatives and bathymetry derivatives. This Iso-Cluster model has been enhanced with sediment grab data and ROV observations to further refine the algorithm. Additionally, a new tool using Random Forests (RF) machine learning has been developed and applied that may provide an objective and automated approach for predicting seafloor bottom types. The CHS has previously collected backscatter data from MBES bathymetric surveys conducted in and around Vancouver harbour from 2000-2012. While this data has traditionally been secondary to navigational chart production, more recently, CHS has received increasing requests for seabed classification products. With recent developments to MBES hardware and software, combined with the newly developed processing models, CHS is poised to provide better support for a seabed substrate charting project with Port Metro Vancouver. CHS will process this existing data using the ISO-Cluster model and present unsupervised initial bottom substrate maps

Persistent Organic Pollutants (POPs) in killer whales () from the Crozet archipelago, southern Indian Ocean

International audiencePersistent Organic Pollutants (POPs), including polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and dibenzofurans (PCDFs), are ubiquitous environmental contaminants of which significant concentrations are reported in upper trophic level animals. In 1998, we collected blubber biopsy samples (n=11) from killer whales () inhabiting the coastal waters around Possession Island, Crozet Archipelago, southern Indian Ocean, for contaminant analyses. Despite inhabiting an isolated region far removed from industrial activities, these killer whales can presently be considered among the most PCB-contaminated cetaceans in the southern hemisphere, with concentrations ranging from 4.4 to 20.5 mg/kg lipid weight (lw). PCDD levels ranged from below the detection limit (5 ng/kg) to 77.1 ng/kg lw and PCDF levels from below the detection limit (7 ng/kg) to 36.1 ng/kg lw. Over 70% of our study animals had PCB concentrations which exceeded a 1.3 mg/kg PCB threshold established for endocrine disruption and immunotoxicity in free-ranging harbour seals, suggesting that organic contaminants cannot be ruled out as an additional threat to this declining population

Persistent organic pollutants (POPs) in killer whales (Orcinus orca) from the Crozet Archipelago, southern Indian Ocean.

a b s t r a c t Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs), are ubiquitous environmental contaminants of which significant concentrations are reported in upper trophic level animals. In 1998, we collected blubber biopsy samples (n = 11) from killer whales (Orcinus orca) inhabiting the coastal waters around Possession Island, Crozet Archipelago, southern Indian Ocean, for contaminant analyses. Despite inhabiting an isolated region far removed from industrial activities, these killer whales can presently be considered among the most PCB-contaminated cetaceans in the southern hemisphere, with concentrations ranging from 4.4 to 20.5 mg/kg lipid weight (lw). PCDD levels ranged from below the detection limit (5 ng/kg) to 77.1 ng/kg lw and PCDF levels from below the detection limit (7 ng/kg) to 36.1 ng/kg lw. Over 70% of our study animals had PCB concentrations which exceeded a 1.3 mg/kg PCB threshold established for endocrine disruption and immunotoxicity in free-ranging harbour seals, suggesting that organic contaminants cannot be ruled out as an additional threat to this declining population. Crow

Heightened Biological Uptake of Polybrominated Diphenyl Ethers Relative to Polychlorinated Biphenyls Near-Source Revealed by Sediment and Plankton Profiles along a Coastal Transect in British Columbia

Polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) concentrations and profiles in paired sediment–plankton samples were determined along a 500 km transect in coastal British Columbia, Canada. PCB and PBDE levels in sediment were both greater in the industrialized Strait of Georgia than in remote northern sites and exhibited parallel spatial trends. In plankton, recent-use PBDE levels were higher near-source, while levels of legacy PCBs were uniform across sites. Principal component analysis of 95 PCB congeners illustrated the influence of proximity to source (i.e., latitude) on congener patterns for both matrices (sediment, <i>r</i>² = 0.52, <i>p</i> = 0.012; plankton, <i>r</i>² = 0.59, <i>p</i> = 0.016). The PCB pattern in plankton grew lighter with latitude, but the opposite pattern in sediments suggested that temperature-related fractionation, sediment processes, and basin-wide oceanography had divergent effects on each matrix. Biota-sediment accumulation factors (BSAFs) were greater for PBDEs than PCBs, but spatial profiles were similar; PCBs and PBDEs were near equilibrium in remote atmospherically driven sites (BSAF = 1.7 and 1.3) but accumulated preferentially in sediments at source-driven sites (BSAF = 0.2 and 0.4). The influences of particle-binding and hydrophobicity on the aquatic fate of PCBs and PBDEs was evident by the strong influence of log K_OW on congener-specific BSAFs (PCBs, <i>r</i>² = 0.18 <i>p</i> < 0.001; PBDEs, <i>r</i>² = 0.61 <i>p</i> < 0.001). While biotic uptake of PCBs has become spatially uniform in coastal BC because of dilution over time, biomagnification of PBDEs remains higher in industrialized waters

PCB related effects thresholds as derived through gene transcript profiles in locally contaminated ringed seals (Pusa hispida)

Causal evidence linking toxic injury to polychlorinated biphenyl (PCB) exposure is typically confounded by the complexity of real-world contaminant mixtures to which aquatic wildlife are exposed. A local PCB hotspot on the Labrador coast provided a rare opportunity to evaluate the effects of PCBs on the health of a marine mammal as this chemical dominated their persistent organic pollutant (POP) burdens. The release of approximately 260 kg of PCBs by a military radar facility over a 30 year period (1970-2000) contaminated some local marine biota, including the ringed seal (Pusa hispida). The abundance profiles of eight health-related gene transcripts were evaluated in liver samples collected from 43 ringed seals in the affected area. The mRNA transcript levels of five gene targets, including aryl hydrocarbon receptor (Ahr), interleukin-1 β (Il1b), estrogen receptor α (Esr1), insulin like growth factor receptor 1 (Igf1), and glucocorticoid receptor α (Nr3c1) correlated with increasing levels of blubber PCBs. PCB threshold values calculated using best-fit hockey-stick regression models for these five genes averaged 1,680 ± 206 ng/g lw, with the lowest, most conservative, being 1,370 ng/g lw for Il1b. Approximately 14% of the seals in the region exceeded this threshold. The dominance of PCBs in the seals studied enabled an assessment of the effects of this chemical on gene transcripts involved in regulating the health of a highly mobile predator, something that is rarely possible in the world of complex mixtures

Persistent organic pollutants in chinook salmon (Oncorhynchus tshawytscha): implications for resident killer whales of British Columbia and adjacent waters. Environmental Toxicology and Chemistry

Abstract-We measured persistent organic pollutant (POP) concentrations in chinook salmon (Oncorhynchus tshawytscha) in order to characterize dietary exposure in the highly contaminated, salmon-eating northeastern Pacific resident killer whales. We estimate that 97 to 99% of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), and hexachlorocyclohexane (HCH) in returning adult chinook were acquired during their time at sea. Highest POP concentrations (including PCBs, PCDDs, PCDFs, and DDT) and lowest lipids were observed in the more southerly chinook sampled. While feeding by salmon as they enter some more POP-contaminated near-shore environments inevitably contribute to their contamination, relationships observed between POP patterns and both lipid content and ␦ 13 C also suggest a migration-related metabolism and loss of the less-chlorinated PCB congeners. This has implications for killer whales, with the more PCB-contaminated salmon stocks in the south partly explaining the 4.0 to 6.6 times higher estimated daily intake for ⌺PCBs in southern resident killer whales compared to northern residents. We hypothesize that the lower lipid content of southerly chinook stocks may cause southern resident killer whales to increase their salmon consumption by as much as 50%, which would further increase their exposure to POPs