| IOF SEMINAR – March 15, 2024 |
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The Canary in the Coal Mine is Black and White: Chemical Contaminants of Concern and Hydrocarbons in Endangered Southern Resident Killer Whales from BC, Canada
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| Killer whales (Orcinus orca) from British Columbia (BC, Canada) are among of the most contaminated cetacean species in the world. They are ecologically, culturally and economically-important species in Canada’s west coast and powerful spiritual beings for coastal First Nations communities. Yet, endangered southern resident killer whales (SRKWs), with a small population of ~73 or 74 individuals, are affected by cumulative environmental stressors and human-made threats, including lack of both quality and quantity of its main diet item (Chinook salmon, Oncorhynchus tshawytscha), physical disturbances by underwater noise (acoustic pollution), marine pollution and climate change. Concentrations and potential health implications of contaminants of emerging concern (CECs), new persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in SRKWs have been scarcely documented. In this seminar, I will share the findings of the first concerted ecotoxicological assessment of CECs: alkylphenols (APs), triclosan, methyl triclosa; and, new POPs such as hexabromocyclododecane [HBCCD], and per- and polyfluoroalkyl substances (PFASs), known as “forever chemicals” (PFOS, PFOA, PFHxS), as we ll as PAHs in skeletal muscle and liver samples of SRWK and investigate in utero transfer of these contaminants. Samples were collected from stranded, necropsied individuals from 2006-2018 in BC, Canada, in collaboration with Fisheries and Ocean Canada (DFO) and the Animal Health Centre, BC Ministry of Agriculture, Food and Fisheries. The most prevalent compounds were 4-nonylphenol (4NP), a predominant AP (median 40.84 ng/g ww), and interestingly, 7:3-fluorotelomer carboxylic acid (7:3 FTCA) was the primary PFAS (median 66.35 ng/g ww) observed for first time in killer whales from BC, followed by PFOS and PFOSA. For PAHs, C3-phenanthrenes/anthracenes (mean: 632 ng/g lw), C4-dibenzothiophenes (mean 334 ng/g lw), and C4-phenanthrenes/ anthracenes (mean: 248 ng/g lw) presented the highest concentrations across all tissue samples. PAH diagnostic ratios indicated a dominant petrogenic-sourced contamination for SRKWs (i.e., more contaminated with hydrocarbon coming from oil/petroleum sources) in comparison to Bigg’s (transient) killer whale, which showed a dominant signal of pyrogenic hydrocarbon sources (e.g., coming from vegetation and coal biomass burning and wildfires). A mother-fetus skeletal muscle pair revealed evidence of CECs, POPs, and PAH maternal transfer. Maternal transfer ratios indicated 4NP as the most transferred contaminant from mother to fetus (95%), while low molecular weight PAHs (C3-fluorenes, dibenzothiophene, and naphthalene) also exhibited higher maternal transfer rates. Our contaminant data serve to inform regulation and mitigate pollutant sources and contamination by emerging chemicals (e.g., “forever chemicals” or PFASs) in SRKWs’ critical habitat and prevent oil spills by improving hydrocarbon emission regulations and transitioning away from fossil fuel consumption with the aim to conserve this iconic species. |
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