As the Arctic heats up at a rate almost four times the global average, polar bears are among the losers and viruses, bacteria, and parasites are among the winners, researchers say. According to a study published in the journal PLOS One, polar bears are at much greater risk of being exposed to at least five different pathogens than they were a few decades ago. Researchers compared blood and fecal samples taken from a relatively healthy population of bears in the Chukchi Sea between 1987 and 1994 to samples taken between 2008 and 2017. They found evidence that exposure to pathogens including the parasite that causes toxoplasmosis had risen sharply.
"With warming, it just allows pathogens to persist in environments they couldn't persist in before," study co-author Karyn Rode, a wildlife biologist at the US Geological Survey's Alaska Science Center, tells Science News. Melting sea ice is forcing the bears to spend more time on land, where there is a greater risk of exposure to some parasites that have expanded their ranges amid rising temperatures. But researchers believe much of the exposure came from the bears' prey, including seals and whales. "The polar bears are a good indicator for what's happening in the ecosystem," Rode tells the Washington Post. "We know that pathogens' transmission pathways are changing, including in the Arctic."
Smithsonian reports that one of the most surprising changes was a sharp rise in exposure to Neospora caninum, which usually affects cows. The exposure was linked to "consumption of bowhead whales, which are primarily available to Chukchi Sea polar bears on land as beached or hunter-harvested carcasses," researchers wrote. Rode says the pathogens probably aren't enough to kill bears on their own, but they could further weaken bears already struggling to find food as sea ice vanishes. "Bears in general are pretty robust to disease," Rode tells the BBC, but the study "just highlights" how things in the Arctic are changing. (More polar bears stories.)
,
uBlock 
,
and
Ghostery 
)
