Arctic Sea Ice Loss Linked To Spread Of Deadly Marine Mammal Virus

An adult male ribbon seal loafing on the ice. NOAA Fisheries, Polar Ecosystems Program

The melting of Arctic sea ice could have repercussions that extend into the realm of infectious agents, opening up new pathways for the spread of deadly viruses in marine mammals. A 15-year study, published in Scientific Reports, highlights the fragility of a changing environment for the planet’s Arctic species.

"Phocine distemper virus was first recognized as an important pathogen in harbour seals in 1988 when it caused an outbreak and mass mortality among European harbour seals in the North Atlantic Ocean," said study author Tracey Goldstein, associate director of the One Health Institute at the UC Davis School of Veterinary Medicine, to IFLScience.

"The virus causes respiratory infections and neurologic disease (ie. seizures) in most species but we do not know what effects it has in Alaskan pinnipeds and northern sea otters."

Phocine distemper virus (PDV) is a pathogen responsible for the death of thousands of European harbour seals in the North Atlantic in 2002 and sea otters in Alaska in 2004. At the time, the questions of how, when, and why the virus transmission occurred were never fully resolved. Now, a recent study links sea ice loss with the ability of animals to seek new routes in the ice, therefore creating greater opportunity to come into contact with infected animals. 

"In general, morbilliviruses are transmitted through respiratory droplets or by contact such as through fluids when animals are in close proximity and come into contact with each other," said Goldstein. 

To gain greater clarity on the spread of PDV, the team live-captured and sampled various seal species and northern sea otters for phocine distemper virus from 2001-2016. They also collected samples from dead or stranded animals. Satellite telemetry data and sea ice analysis were then used to link animal movement with open water routes and thus viral exposure.

"Peaks of PDV exposure and infection followed reductions in Arctic sea ice extent, potentially linking climate change to the introduction of PDV into the North Pacific Ocean," added Goldstein. "Climate change-driven reductions in sea ice extent in the Arctic Ocean are projected to increase. The health impacts of this new normal in the Arctic are unknown, but association of open water routes through Arctic sea ice suggest that opportunities for PDV and other pathogens to cross between North Atlantic and North Pacific species may become more common." 

Climate change and natural variability are reshaping Arctic environments, with a variety of complex influences at play. Last month's daily sea ice extent was the second lowest in the satellite record, just shy of 2016's October levels, according to the National Snow and Ice Data Center. Since October 15, sea ice extent in the Chukchi Sea was at an all time low for this time of year.

 

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