Increasing temperatures and salinity result in decreased ecosystem diversity, UBC study finds.

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Sora, K. J., Wabnitz, C. C. C., Steiner, N. S., Sumaila, U. R., Hoover, C., Niemi, A., Loseto, L. L., Li, M.-L., Giang, A., Gillies, E., & Cheung, W. W. L. (2024). Historical climate drivers and species’ ecological niche in the Beaufort Sea food web. In C. Byron (Ed.), ICES Journal of Marine Science. Oxford University Press (OUP).

Ecosystems can be impacted and changed by a lot of different things, including human activities, stormwater runoff, contaminants, invasive species, and climate change.

Climate change especially can disturb sensitive ecosystems and can cause increases in water temperature, sea ice loss, ocean deoxygenation, and changes in seawater salinity. In the Arctic, the impacts of climate change are more severe compared to the global average. This poses big problems for not only animals like the beluga whale and Arctic cod, but also the Indigenous people who have been closely dependent on Arctic biodiversity for food and culture for millennia.

Using ecosystem modeling, UBC researchers explored the effects of climate change in the Canadian Arctic, including the area on the Beaufort Sea shelf — the Tarium Niryutait Marine Protected Area.

The study, published in the ICES Journal of Marine Science, found that higher water salinity and temperatures decreased ecosystem diversity and changed the trophic levels, biomass, and consumption rates of some marine mammals and fish groups, including: beluga whales, Arctic cod, and polar cod.

“In higher temperatures, fish have higher metabolic demands which can cause stress responses in the animals.” said lead author Kristen Sora, a PhD student at the UBC Institute for the Oceans and Fisheries. “This may have detrimental consequences for the fish, marine mammals and other animals in the Arctic.”

Canadian Arctic waters

The Beaufort Sea Shelf and Slope (BSS) is a part of the Arctic Ocean, right off the Yukon and Northwest Territory’s northern coast. It’s a rich marine environment and home to migratory birds, bowhead whales and many marine mammals, including belugas and polar bears.

The Tarium Niryutait Marine Protected Area (TN MPA) was designated in August 2010 and was Canada’s first Arctic marine protected area. It was created to help protect beluga whales and their ecosystems while also respecting Inuvialuit cultural and spiritual connections to the land and ocean, and ensuring that these traditions and practices continue.

“The Arctic Ocean is under a lot of pressure right now and with climate change, it’s only going to get worse,” said principal investigator, Dr. William Cheung, professor and director of the Institute for the Oceans and Fisheries. “This will severely challenge the unique marine biodiversity in the area, as well as the Indigenous and other communities that depend on it for food, livelihood, and culture.”

The UBC study examined the BSS and TN MPA over 50 years to identify changes and trends in food webs and key species under climate change to compare the individual and cumulative effects of different climate change related factors.

“This study helps us understand changes in the Arctic ecosystems under climate change, and will help governments, local communities and Indigenous communities to develop adaptation strategies for conservation, food security and sovereignty,” said Cheung.

Indigenous Peoples in the Arctic

The Inuvialuit, Gwich’in and other Indigenous peoples lived along the Mackenzie river for thousands of years, and there are over 40 Indigenous groups that live along the Arctic. Indigenous Peoples in the Arctic have lived on the land for a millennia but due to colonization and climate change, are being rapidly pushed out of their lands, cultural and spiritual practices and ways of life.

“Climate change has disproportionate impacts on vulnerable communities, including Indigenous Peoples ,” said Cheung. “We hope that the findings from this study could help support Indigenous and local communities to develop effective climate adaptation strategies for food security, wellbeing and conservation.”

Impacts on marine mammals and fish

Climate change creates widespread stress on aquatic health across the Arctic Ocean and changes ice and flow patterns in rivers, reduces snow-cover and water levels in deltas, and impacts water quality in northern parts.

This has potentially devastating impacts for the fish and marine mammals in the area, including the thousands of beluga whales belonging to the Eastern Beaufort Sea population who return to the shallow and warm Mackenzie River Estuary, including the TN MPA.

In the summer and fall, migratory fish move out of the Mackenzie River and follow currents along the shore to feeding and rearing areas in the TN MPA.

What next?

We still don’t understand a lot about Arctic ecosystems, and the impacts of temperature and salinity are not well defined in the Arctic, which makes conservation science uncertain. These UBC researchers are now looking to the Tarium Niryutait and the Anguniaqvia niqiqyuam Marine Protected Areas in the Beaufort Sea and Amundsen Gulf to understand more about this diverse and vulnerable region.

“Climate change is a huge threat and we need to understand as much as we can about its impacts on the environment,” said Sora. “Our next steps are going to be trying to learn more about different species’ risks and vulnerabilities to climate change.”

Historical climate drivers and species’ ecological niche in the Beaufort Sea food web was published in the ICES Journal of Marine Science.