A unique polar bear population has been discovered in Greenland

This population, numbering about several hundred individuals, is looking for seals in the freshwater ice released by the area’s glaciers that flow into the Danish Strait.

Prof. Kristin Laidre of the Polar Science Center at the University of Washington and her colleagues were pleased with this discovery because, unlike other populations, this one lives in a region with virtually no sea ice, creating an environment that similar to which will prevail, according to climate models, in the High Arctic by the end of the 21st century.

The – very pessimistic – predictions about the future survival of the species are based on large -scale climate displays and do not take into account the role smaller habitats may represent. climate shelters.

You should know that biologists link the future of polar bears to the presence of sea ice on which they rely on hunting.

The identity of this population gives hope, according to Prof. Laidre, whose other population of polar bears will adapt to the rapid disappearance of sea ice caused by warming temperatures, is particularly marked in the Arctic.

endangered animals

The authors of this work were published in the journal Science (New window) (in English) has been studying this population since 2011 with the aim of assessing its status in the context of climate change.

That said, scientists have been documenting the movements, genetics and demographics of these polar bears over 36 years – data that has enriched the work carried out over a decade.

An isolated population

The researchers first established, using satellite telemetry, that a particular group living south of the 64th parallel north does not interact with bears living north of the same parallel. They also noticed that some bears in this group migrate between fjords present in the territory, while others may remain in one fjord for many years.

The degree of geographical isolation of bears in southeastern Greenland distinguishes them from other subpopulations.explain the authors.

Regional adaptation

At first glance, the current sea ice conditions in this region do not seem to be conducive to the survival of the polar bear population.

During the winter and spring, bears in southeastern Greenland use fast ice (masses of sea ice frozen on the coast) for movement and hunting. However, the number of days per year when this rapid ice is present, varies from 0 to 153. On average, this ice pack, which forms in February and disappears at the end of May, is present. 89 days a year.

The region therefore has no sea ice for more than 250 days a year, which greatly exceeds the seasonal fasting threshold for polar bears, which varies from 100 to 180 days.

Our data show that bears in southeastern Greenland instead use glacial mixing (freshwater ice in front of glaciers) as a hunting platform during the sea-ice-free season, whereas in most parts of arctic, polar bears must move above the ground or follow. the receding sea ice in the north towards the polar basinnotice the researchers in their study.

The information collected also shows that some bears that migrate outside the fjords present in the territory are often caught in ice carried by the currents of the East Greenland coast, which drift an average of 189 km in 2 weeks. Now, all these ursids swim towards the shore, then walk on land towards their origin for a month or two, showing the great loyalty of the animals in this region.

So, according to researchers, this group of bears seems to be adapted their movements to the specific physical geography of the region.

genetically different

The study also shows that this population is genetically very different from others.

Analysis of 40 bear genomes, 372 individual microsatellite sequences and 16 blood transcriptomes establishes this without hesitation.

By analyzing and comparing data collected from 3,064 bears from all populations outside the Arctic Basin, the scientists determined that the newly identified population was the most isolated.

According to researchers, the uniqueness of this group has evolved over several hundred years of separation. The oldest reference to polar bears in South Greenland dates back to the 1300s, and the first written record in the West documenting the presence of bears in the fjords of southeastern Greenland dates from the 1830s.

These data support DNA tests, suggesting that the southeastern Greenland bears sampled in the study share a common ancestor that appeared about 200 years ago and is therefore genetically isolated from at that time.

Bears in southeastern Greenland have few chances of dispersal. Their habitat is characterized by steep coastal topography with fjords separated by mountains over 2000 m and narrow glaciers. To the west, dispersal is limited by the Greenland ice sheet. To the east is the open waters of the Danish Strait, said the research team.

A population that must be protected

Kristin Laidre and her colleagues say polar bears in southeastern Greenland meet the criteria for recognition as the 20th subpopulation ofUrsus maritimus.

In a perspective text published along with their article, evolutionary biologist Elizabeth Peacock, an expert on polar bear conservation at Emory University in the United States, argued for group conservation to preserve genetic diversity, and the evolutionary potential of species.

” The population of Southeast Greenland is a small, genetically distinct group of bears with a unique ecology. “

The conservation of this polar bear population represents an important test of the modern influence of the half-century-old international treaty on the conservation of polar bears.he added.

The Polar Bear Conservation Agreement began in 1976 and binds five countries (United States, Russia, Norway, Denmark and Canada). One of its purposes is to take immediate action to implement other conservation and management measures population.