An isolated population of polar bears has been discovered in Greenland and appears to have adapted to global warming, surviving despite a lack of sea ice for most of the year.
Most of those animals rely on sea ice to hunt seals, but Arctic sea ice is rapidly declining. According to one study, the isolated population found in the southeast of the island is genetically distinct, giving hope that it will acclimatize to the melting ice.
The researchers, whose study was published in Nature, They located polar bears in fjords, surrounded by mountains, an ice cap to the west, and an ocean to the east. Because the region is so far south in the country, the sea ice cover lasts only about a hundred days a year.
The team of scientists believe that the isolated subpopulation has adapted to hunting on ice that has broken off from glaciers.
Through genetic analysis, they found that these polar bears had been isolated from other groups along the eastern coast of Greenland for at least 200 years.
Kristin Laidre, senior fellow at the Center for Polar Sciences, Applied Physics Laboratory at the University of Washington, and her colleagues, as well as the Greenland Natural Resources Institute, conducted an advanced habitat analysis, combining an archive of 36 years with movement, genetic and demographic data, including traditional ecological knowledge and natural history observation.
Laidre, who has worked on problems of animal ecology applied to the Arctic, observed a behavior of polar bears in this group that had not been reported, that is, the use of ice cool in marine terminal glacial fronts, also known as melange glacier, as a platform to hunt seals throughout the year.
Tracking data he and his colleagues used also showed that the bears did not move very far and even returned to their usual environment when swept up by platforms in the swift current off the east coast of the island. The animals jumped from one to another, swam back to shore, and returned to their environment.
“This small, distinct group could shed light on how polar bears might persist in an ice-free Arctic,” adds Laidre, lead author of the study.
“It’s the most genetically isolated population of polar bears on the planet,” said Beth Shapiro, a co-author of the research and a professor and geneticist at the University of California, Santa Cruz. “We know that this population has lived separately from others for many years and that the group size has remained small throughout this time.”
Laidre cautioned: “We need to be careful when extrapolating our findings, because the glacier ice that makes it possible for southeastern Greenland bears to survive is not available in most of the Arctic.”
While other bear populations must move overland or migrate with receding sea ice to less productive polar areas during the ice-free season, this adaptation allows the bears of southeastern Greenland to succeed in an otherwise inhospitable place.
According to the researchers, the results have implications for polar bear conservation, as they suggest that terminal sea glaciers, although of limited availability, may serve as previously unrecognized climate refugia.
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