In the southeastern corner of Greenland, scientists have discovered an unexpected population of polar bears. This population has developed different habits to survive in its amazing – as far as polar bears are concerned – habitat, and the genome of bears is very different from many of their relatives. In addition to the novelty of these animals, they can also help inform scientists about how more traditional bears will live in the warming Arctic. new research.
This group of bears is distinguished by several things. Most of the year they survive by hunting from the ice that falls into the ocean after the Greenland Glacier breaks off; ice floats in the fjords, which these bears call home. This is unlike most other polar bear populations, which need sea ice to hunt. According to the World Wildlife Fund, between 22,000 and 31,000 polar bears remained in the world.
The research team used seven years of data collected in the region, along with 30 years of historical data. To obtain new data, the team contacted local hunters and used tissue samples taken from hunter kills to sequence bear genomes. They also used field research, satellite data – which also allowed them to study the geographical and sea ice conditions in the region – and collars to get an idea of the movement of bears.
“There’s a really big collection of data here,” said Ars Twila Moon, co-author and deputy lead scientist at the National Snow and Ice Data Center. “It took a lot of time in the field. This is a very remote area that requires difficult, time-consuming and difficult conditions for field work. “
The south-east of Greenland is rather poorly studied. This is due to the rugged, mountainous terrain and relentless weather that includes heavy snowfall. These difficulties also probably explain why bears are isolated. The region is surrounded by mountains, the Greenland Ice Sheet and the Danish Strait.
Most polar bears use sea ice to hunt, but this is a limited option for southeastern Greenland. Only sea ice is observed in the region from February to May. However, movement data suggest that bears are different from their relatives. They probably walk on glacial ice that flows into fjords, and travel to the mountains to reach other fjords in search of food, often seals.
“We found that sea ice rarely existed for more than four months a year – in some fjords in a few years, even much less,” Moon said.
According to the collected and sequenced sample, bears are genetically very different from others of the same species. There are another 19 observed populations of polar bears, and their genomes are relatively similar to each other; this isolated subpopulation stands out. According to the study, this is the most genetically isolated population of polar bears on Earth, and they may have been in this area of Greenland for hundreds of years.
As climate change continues to reduce sea ice levels, bears in other regions can adapt to life as populations in southeastern Greenland. However, Moon suggested not to admire such an opportunity. “Perhaps there is a tendency to feel that it gives [feeling of] “Polar bears are saved,” she said. “Unfortunately, there are a lot of them [few] places that thus provide a large amount of glacial ice … For many Arctic polar bears, such ice is not available. “
This means that many populations of polar bears will not be able to adapt to life on glacial ice, as has the population of south-eastern Greenland. The numbers of these Greenland bears are also quite small – only a few hundred individuals – perhaps due to the difficulties of the terrain when bears are trying to find a mate. Thus, regions such as south-east Greenland may not be able to contain large groups of bears. Another issue: The Greenland Ice Shield, which provides the glacial ice that bears use to hunt, also melts. This is true for other glaciers around the Arctic, Moon said.
However, bears in southeastern Greenland are in their harsh habitat. As Greenland’s ice sheet is losing ice, it is not retreating in equal numbers all along the coast. In southeastern Greenland, a lot of snow falls in the winter, which helps feed the glaciers. Researchers also note that the region could act as a small-scale climate storage, a place where the species can survive for a while when the sea ice will decrease. The article also notes that several similar habitats exist in other parts of the Arctic, such as Svalbard – Norwegian territory – and other parts of Greenland.
“We do not expect this coastal ice to recede from its current location as quickly as areas of the ice sheet, such as the west or southwest coast,” Moon said. “It’s a nuance of the environment.”
Science, 2022. DOI: 10.1126 / science.abk2793 (About DOI)