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HomeScienceSome polar bears in Greenland survive on surprisingly little sea ice

Some polar bears in Greenland survive on surprisingly little sea ice

“Pihoqahiak” means “ever-wandering one,” and is an Inuit title for the polar bear, a creature recognized to roam huge expanses of sea ice, generally plodding 1000’s of kilometers a yr looking for seals.

However alongside the fjord-cut shoreline of southeast Greenland, the place the ocean freezes over for only a few months of the yr, some remoted polar bears are surviving as homebodies.

In contrast to most polar bears, these bears don’t comply with the ocean ice throughout its annual recession or transfer onto land to hunt. As an alternative, the artful ursids stalk seals on close by glacial mélange — a floating mishmash of icebergs, sea ice fragments and snow that persists year-round close to the entrance of glaciers within the fjords, researchers report within the June 17 Science.

“They’re residents in fjords which are sea ice–free for greater than eight months of the yr,” says Kristin Laidre, a biologist on the College of Washington in Seattle. “Usually, a polar bear wouldn’t have the ability to survive with out sea ice for that lengthy.”

For polar bears (Ursus maritimus), sea ice isn’t simply frozen seawater; it’s the platform they often use to hunt their most popular prey — seals. However as human-caused local weather change raises Earth’s world temperature, that ice is disappearing. The variety of polar bears that reside on sea ice within the Beaufort Sea within the Arctic Ocean and Canada’s Hudson Bay is already declining. Researchers estimate that most different subpopulations of the bears will collapse by 2100 until greenhouse fuel emissions are curbed. The Worldwide Union for Conservation of Nature classifies the species as “susceptible.”

The fjords of southeast Greenland and comparable, restricted areas may grow to be a final, momentary refuge for a small variety of bears, although solely curbing local weather change can save the ice-dependent species, Laidre and her colleagues say. Glacial mélange isn’t widespread within the Arctic, and what exists may disappear if temperatures rise an excessive amount of.

Laidre and her colleagues estimate that a number of hundred bears could dwell within the fjords of southeast Greenland, although additional work is required to acquire a extra exact depend.

The southeast Greenland group got here to the researchers’ consideration whereas they had been learning polar bears alongside east Greenland’s coast to supply recommendation to the Indigenous peoples who hunt the bears for subsistence. An evaluation of 83 receiver-tagged polar bears from 1993 to 2021 revealed that, for probably the most half, bears dwelling south of about 64° N latitude don’t work together with bears to the north, and vice versa.

Southeast Greenland bears could also be principally remoted by Greenland’s ice sheet to the west and a fast present to the east, which may sweep seafaring bears south and stifle northward motion, the researchers say.

In northeast Greenland, the median distance traveled by tagged bears was 40 kilometers each 4 days. However within the southeast area, the median distance traveled was simply 10 kilometers each 4 days, with bears generally touring between neighboring fjords and generally remaining in the identical fjord all yr.

“For a polar bear, that’s nothing,” says Steven Amstrup, a zoologist and chief scientist of the conservation group Polar Bears Worldwide, based mostly in Bozeman, Mont., who was not concerned within the research. “Apparently they’re discovering sufficient assets there that they don’t must make these enormous, huge actions.”

Southeast Greenland bears hunted on sea ice when it was current throughout a couple of months in winter and spring, the researchers discovered. For the remainder of the yr, the ursids used the glacial mélange that packed the fjords as looking grounds.

“They use it identical to sea ice,” Laidre says. “They’re in a position to stroll [and hunt] on the mélange … they usually can swim round between the items of ice and ambush seals.”

A polar bear mother and two cubs move across glacial mélange
A polar bear mom and two cubs transfer throughout glacial mélange in southeast Greenland in September 2016.NASA OMG

It’s not totally stunning that polar bears have settled on the fronts — or toes — of glaciers within the fjords, Amstrup says. “Oftentimes, the toes of those glaciers are very productive areas,” he says, as a result of glacial meltwater can flush vitamins from deeper within the ocean up towards the water’s floor. “You would possibly count on that they’d have seal populations [that] may assist bears.”

The researchers additionally analyzed uncommon genetic variations within the southeast Greenland bears. That work revealed that the sampled animals shared a typical ancestor about 200 years in the past and have basically stored to themselves since. “They’re probably the most genetically remoted polar bears on this planet,” Laidre says. Conserving the distinctive bears will probably be vital for safeguarding the species’ genetic range, which is already low, she says.

However for all their peculiarity, even southeast Greenland polar bears will perish with out human local weather motion, Laidre and Amstrup agree (SN: 12/15/10). “Lack of Arctic sea ice continues to be the first menace to all polar bears,” Laidre says. “This research doesn’t change that.”



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