Arctic sea ice loss opens marine mammals to deadly virus

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Scientists have linked Arctic sea ice loss to a deadly virus that could threaten marine mammals in the North Pacific, according to a new study.

Researchers identified phocine distemper virus, or PDV, a pathogen responsible for killing thousands of European harbor seals in the North Atlantic in 2002, in northern sea otters in Alaska in 2004, raising questions about when and how the virus reached them.

The 15-year study, published in the journal Scientific Reports, highlights how the radical reshaping of historic sea ice may have opened pathways for contact between Arctic and sub-Arctic seals that was previously impossible. This allowed for the virus’ introduction into the Northern Pacific Ocean.

“The loss of sea ice is leading marine wildlife to seek and forage in new habitats and removing that physical barrier, allowing for new pathways for them to move,” says corresponding author Tracey Goldstein, associate director of the One Health Institute at the School of Veterinary Medicine at the University of California, Davis.

“As animals move and come in contact with other species, they carry opportunities to introduce and transmit new infectious disease, with potentially devastating impacts.”

Researchers sampled marine mammals for phocine distemper virus exposure and infection from 2001 to 2016. Sampled mammals included ice-associated seals, northern fur seals, Steller sea lions, and northern sea otters from Southeast Alaska to Russia along the Aleutian Islands and the Bering, Chukchi, and Beaufort seas.

They assessed Arctic ocean sea ice and open water routes from the North Atlantic to North Pacific oceans. Satellite telemetry data helped link animal movement and risk factor data to demonstrate that exposed animals have the potential to carry phocine distemper virus long distances.

The researchers identified widespread infection and exposure to the virus across the North Pacific Ocean beginning in 2003, with a second peak of exposure and infection in 2009. These peaks coincided with reductions in Arctic sea ice extent.

“As sea ice continues its melting trend, the opportunities for this virus and other pathogens to cross between North Atlantic and North Pacific marine mammals may become more common,” says first author Elizabeth VanWormer, a postdoctoral researcher at UC Davis during the study and currently an assistant professor at the University of Nebraska, Lincoln.

“This study highlights the need to understand PDV transmission and the potential for outbreaks in sensitive species within this rapidly changing environment.”

Additional coauthors are from the University of Saint Andrews, the US Fish and Wildlife Service, National Oceanic and Atmospheric Administration Fisheries, Alaska Fisheries Science Center Marine Mammal Center, the University of Glasgow, Alaska Department of Fish and Game, the University of Alaska-Fairbanks, Queens University Belfast, Pirbright Institute, and the Alaska Veterinary Pathology.

The Morris Animal Foundation, the NOAA Oceans and Human Health Graduate Traineeship Program, the Alaska Fisheries Science Center Marine Mammal Laboratory, and the US Fish and Wildlife Service funded the work.

Source: UC Davis