Loss of Arctic sea ice poses threat of deadly virus

A lengthy University of California Davis study highlights how the decline of Arctic sea ice may have opened pathways to the Arctic for a deadly pathogen responsible for killing thousands of European harbor seals in the North Atlantic in 2002.

Phocine distemper virus, or PDV, was identified in northern sea otters in Alaska in 2004, raising questions about when and how the virus got to them. Now researchers have concluded that the loss of sea ice is leading marine wildlife to forage in new habitats and opening new pathways for contact between Arctic and sub-Arctic seals, introducing the virus into the Northern Pacific Ocean.

The 15-year study was published in early November in the journal Scientific Reports.

“As animals move and come in contact with other species, they carry opportunities to introduce and transmit new infectious diseases, with potentially devastating impacts,” said Tracey Goldstein, associate director of the One Health Institute at the UC Davis School of Veterinary Medicine, and corresponding author of the study.

The research team sampled marine mammals for phocine distemper virus exposure and infection from 2001 to 2016. Sampled mammals included ice 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. Satellite telemetry data helped researchers link animal movement and risk factor data to demonstrate that exposed animals have the potential to carry phocine distemper virus for long distances.

Researchers identified widespread infection and exposure to PDV across the North Pacific Ocean starting in 2003, with a second peak of exposure and infection in 2009. Both peaks coincided with reductions in Arctic sea ice extent.

Collaborating institutions in the study include University of Saint Andrews, U.S. Fish and Wildlife Service, NOAA Fisheries, Alaska Fisheries Science Center Marine Mammal Center, University of Glasgow, Alaska Department of Fish and Game, University of Alaska Fairbanks, Queens University Belfast, Pirbright Institute, and Alaska Veterinary Pathology. Funding was provided by the Morris Animal Foundation and NOAA Oceans and Human Health Graduate Traineeship Program, with additional support from the Alaska Fisheries Science Center Marine Mammal Laboratory and the U.S. Fish and Wildlife Service.