Throughout Low-Ice Seasons, Some Polar Bears Are Turning to Glacier Ice

Throughout Low-Ice Seasons, Some Polar Bears Are Turning to Glacier Ice


Holes in sea ice present the right searching floor for polar bears trying to catch their major meals supply—seals. So when rising temperatures trigger sea ice to soften, polar bears’ existence is threatened, making them the poster species for a lot of local weather change studies and documentaries. Whereas each inhabitants of polar bears is threatened by the lack of this sea ice, some have developed diversifications to outlive low-ice seasons. In southeast Greenland, researchers have found a novel subpopulation of polar bears which have discovered a strategy to stay in an space with low sea ice by searching on glacial mélange—a floating combination of icebergs which have calved from glaciers, sea ice, and snow that varieties on the base of glaciers and survives the nice and cozy season.

The invention was revealed in June within the journal Science by a global group of Arctic scientists. The inhabitants is remoted and genetically distinct from different teams of polar bears and survives in fjords which might be freed from sea ice greater than two-thirds of the yr.

A typical picture of a polar bear on a sheet of melting sea ice within the Arctic. Most polar bears depend on sea ice for searching, and local weather change is threatening this very important habitat. Photograph: Gary Bembridge/Flickr

The Arctic Ocean is a mixture of liquid and frozen seawater on the North Pole. This space and the adjoining seas round it present a important, shrinking habitat for polar bears. Polar bears use sea ice to cross lengthy distances and hunt for ringed seals, their most popular prey, or different seals and marine mammals. Sometimes, polar bears wait by holes within the sea ice for his or her prey to floor for air to allow them to snatch them out of the water.

Whereas the ocean ice within the Arctic Ocean used to regain the mass it misplaced in summer season in the course of the chilly, darkish winter months, it has been steadily declining for many years. It has misplaced a median of 27,000 sq. miles of ice per yr since 1979. That is dangerous information for species that depend on sea ice, like polar bears, that at the moment are being compelled to spend extra time on land and quick for longer intervals of time. With sea ice breaking apart and retreating earlier in the summertime, many polar bears don’t have any or minimal entry to meals in the course of the hotter months, which impacts each their bodily and reproductive well being.

In keeping with the brand new research, an remoted polar bear inhabitants on the southeast Greenland coast dietary supplements the low-ice season by counting on glacier ice for searching when the ocean ice is gone. Not like sea ice, glaciers kind on land, whereas sea ice varieties and melts within the ocean. Glacier mélange is a floating combination of icebergs calved from glaciers, snow, and freshwater ice that varieties on the base of glaciers that terminate in lakes and rivers in fjords—slender valleys carved by historical ice motion. Since glaciers don’t absolutely soften in the summertime, they supply a searching floor for this subpopulation when sea ice is unavailable.

A fjord in Greenland with proglacial mélange. A subpopulation of polar bears in southeast Greenland hunt on glacier ice fairly than sea ice, as found in a current research. Photograph: NASA’s Marshall House Flight Middle/Flickr

Lead writer Kristin Laidre, an affiliate professor within the College of Aquatic and Fishery Sciences on the College of Washington, was conducting a decade-long survey of Greenland’s east coast polar bears along with her group after they realized they is likely to be two subpopulations fairly than one. “We have been assessing what we thought was a single subpopulation on Greenland’s 1800-mile-long east coast once we made this wholly sudden discovering,” Laidre stated in an interview with GlacierHub. The last decade-long survey tracked the motion, genetics, and demographics of polar bears alongside Greenland’s east coast. In addition they surveyed Indigenous subsistence hunters from east Greenland and integrated their conventional ecological data into the research.

By means of genetic and behavioral knowledge, Laidre and her group realized they’d discovered a brand new subpopulation of polar bears on the southeast coast of Greenland—the “most genetically remoted polar bears on this planet,” in keeping with Laidre. In different phrases, whereas these bears are nonetheless the identical species as different polar bears, they’re genetically and demographically completely different from different subpopulations. Genetic range is vital for species as a result of it permits them to adapt to altering environments. Whereas extra analysis must be achieved on the inhabitants, a mixture of genetic range and behavioral adaptation has allowed these bears to hunt on glacier ice throughout seasons of low sea ice to complement their diets.

Laidre emphasised that this analysis doesn’t imply that the bears should not threatened by the lack of sea ice. “Glacier ice might assist small numbers of polar bears survive for longer intervals below local weather warming, however it’s not accessible for the overwhelming majority of polar bears,” she defined. In the long term, she notes the significance of learning this inhabitants and different polar bears to grasp the place Arctic polar bears would possibly be capable of survive and the way genetic range may also help different species threatened by local weather change.


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