Do Arctic local sources of pollution influence the exposure of ringed seals (Pusa hispida) analyzed in contaminant monitoring programs?

Abstract

The monitoring of contaminants in Arctic wildlife is mainly designed for long-range transported chemicals and supports international initiatives to mitigate global threats from chemical pollution. As human activities increase in the Arctic, the question of potential impacts of local pollution on wildlife exposure has emerged. In this study, we examined the current monitoring practices and the state of knowledge of pollutants in Arctic ringed seals (Pusa hispida) from Canada, Greenland, Norway, Russia, and Alaska. We complemented this synthesis with a case study of ringed seal exposure from different locations in Canada (2008–2022) to test the potential influence of local pollution sources. Multivariate constrained ordination was applied to examine the effects of ringed seals biological metrics (age, sex, length, and stable isotopes as dietary proxies), settlement size, and potential local contaminant sources (infrastructures, industries) on contaminant concentrations [polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), trace elements] in seals. Results indicated that biological data, location, local source variables and sampling year explained 8.4% (PBDEs), 31.8% (OCPs), 41.0% (trace elements), 45.1% (PFAS), and 65.8% (PCBs) of the contaminant variation in seals through time. Variation partitioning showed that, out of these percentages, local source variables uniquely explained less than 4% of variation for PBDEs, OCPs, trace elements and PFAS compared to 17.5% for PCBs. Results suggest an effect of local contaminant sources that is tightly linked to study site characteristics as well as seal biology. Local sources should be identified and assessed at sampling sites close to communities to ensure efficient contaminant monitoring and effectiveness of mitigation measures.