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Pollutants in Arctic ringed seals

With National Indigenous Peoples Day having taken place on June 21, this month’s Science Behind the Scenes focuses on ringed seals, a subsistence food for many people in Inuit communities.

A team of Environment and Climate Change Canada scientists led by Magali Houde, as well as scientists from Fisheries and Oceans Canada examined long-term trends in persistent organic pollutants (POPs) in Arctic ringed seals. In some cases, the data dates back to the 1970s. They published their findings earlier this year in Science of The Total Environment in an article titled "Trends of persistent organic pollutants in ringed seals (Phoca hispida) from the Canadian Arctic". While conducting scientific research in the Canadian Arctic, scientists worked closely with northern communities for help in understanding ecology and the effect of climate-related changes on the ringed seals. Hunters in many northern communities as well as hunting and trapping associations helped with sample collection and coordination and provided ongoing support to researchers.

Decreasing POPS overall but results vary

The good news is, overall, there has been a decrease in the level of POPs found in ringed seals. Enhanced regulations have led to a decrease in many (but not all) POPs found in seals. Bans on the production and use of such chemicals as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) led to a long-term and significant reduction of these chemicals in ringed seals, with declines of up to 9.1 percent in the Hudson Bay region.

According to the article, results suggest that “North American and international regulatory bans and phase outs have led to the long-term reduction of POPs in Canadian Arctic ringed seals by reducing emissions from primary sources.” Concentrations of most POPs decreased at a high rate in the Hudson Bay, the southernmost region that was a part of this study. Researchers believe this may be due to the proximity to sources of contamination and the hydrology of the Bay, where contaminants may remain for less time than they do in regions with deeper water. The decline of major POPs in more northern regions such as the Beaufort Sea and Arctic Archipelago have not been as rapid. Researchers believe this may have to do with the larger amount of sea ice in northern areas. Sea ice also has an impact on contaminants since it acts as a “contaminant reservoir” making it easier for contaminants to reach wildlife in the Arctic.

In addition, some chemicals (e.g., hexachlorobenzene [HCB]) have increased in some locations. This increase may be due to HCB being identified as a byproduct in the production of substances such as pesticides.

What’s next?

In future studies, researchers hope to better understand the relation between climate change and the concentration of contaminants in ringed seals.

They will also continue to participate in an ongoing science outreach project conducted in northern schools. Since 2016, a team of researchers led by Dominique Henri (Environment and Climate Change Canada) has organized school workshops engaging northern students, Inuit elders, and scientists in sharing their knowledge about ringed seals. These workshops allow scientists to discuss their work and provide an opportunity for Inuit elders to share their knowledge of ringed seals with students and researchers. Collaboration and communication between northern residents and researchers working on contaminants in the Canadian Arctic are key to moving toward a deeper understanding of northern ecosystems, rooted in science and Indigenous knowledge.

This project was funded by the Northern Contaminants Program (Crown-Indigenous Relations and Northern Affairs Canada) and by Environment and Climate Change Canada.

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