August 16, 2022

During low ice seasons, some polar bears turn to glacier ice

During low ice seasons, some polar bears turn to glacier ice

Sea ice cavities provide a perfect hunting ground for polar bears looking for their main food source, seals. So when rising temperatures melt sea ice, polar bears are threatened, making them a poster species for many climate change reports and documentaries. While every polar bear population is threatened by the loss of this sea ice, some have developed adaptations to survive during periods of low ice. In southeast Greenland, researchers have discovered A unique subpopulation of polar bears that have found a way to live in an area with little sea ice by hunting. Icy melange– A floating mixture of icebergs produced from natural glaciers, sea ice and snow that forms at the base of glaciers and survives the warm season.

The discovery was published in the journal in June Science by an international team of arctic scientists. This population is isolated and genetically distinct from other groups of polar bears, surviving in fjords that are free of sea ice for more than two-thirds of the year.

A typical image of a polar bear on a sheet of melting Arctic sea ice. Most polar bears rely on sea ice for hunting, and climate change threatens this vital habitat. Photo: Gary Bebridge/Flickr

The Arctic Ocean is a mixture of liquid and frozen seawater in the Arctic. This area and the surrounding seas provide vital and shrinking habitat for polar bears. Polar bears use sea ice to cross long distances and hunt ringed seals, their favorite prey, or other seals and marine mammals. Typically, polar bears wait next to holes in the sea ice for their prey to come up for air so they can pull them out of the water.

As sea ice in the Arctic Ocean regains the mass it lost in the summer during the cold, dark winter months, it has been steadily shrinking for decades. lost on average 27,000 square miles of ice per year since 1979. This is bad news for species that rely on sea ice, such as polar bears, who are now forced to spend more time on land and fast for longer. As sea ice breaks up and retreats in early summer, many polar bears have little or no access to food during the warmer months, affecting both their physical and reproductive health.

An isolated polar bear population off the southeast coast of Greenland completes the low-ice season by relying on glacier ice for hunting when the sea ice disappears, according to a new study. Unlike sea ice, glaciers form on land, while sea ice forms and melts in the oceans. The melange of the refrigerator is one floating mixture Icebergs formed by glaciers, snow, and freshwater ice at the base of glaciers that terminate in lakes and rivers in fjords—narrow valleys carved by ancient ice movement. Because glaciers do not melt completely in summer, they provide hunting ground for this subpopulation when sea ice is unavailable.

Glacial melange in a fjord

A fjord in Greenland with a leading composition. A subpopulation of polar bears in southeast Greenland hunts on glacier ice instead of sea ice, as a recent study has discovered. Photo: NASA Marshall Space Flight Center/Flickr

Lead author Christian Leader, an associate professor in the School of Aquatic and Fisheries Sciences at the University of Washington, was conducting a ten-year survey of polar bears off the east coast of Greenland with his team when they realized they might be looking at two subpopulations instead. “We were assessing what we thought was a single subpopulation off the 1,800-mile-long east coast of Greenland when we made this completely unexpected find,” one leader said in an interview with GlacierHub. The study followed a decade of polar bear movements, genetics and populations along the east coast of Greenland. They also examined indigenous hunter-gatherers from East Greenland and incorporated their traditional ecological knowledge into the study.

Through genetic and behavioral data, Lauder and his team realized they had found a new subpopulation of polar bears off the southeast coast of Greenland — “the most genetically isolated polar bears in the world,” according to Lauder. In other words, while those bears are still other species of polar bear, they are genetically and demographically different from the other subpopulations. Genetic diversity is important to species because it allows them to adapt to changing environments. While more research needs to be done on the population, a combination of genetic diversity and behavioral adaptations have allowed these bears to hunt on glacier ice to supplement their diet during seasons of low sea ice.

Lauder emphasized that the research does not mean that bears are not threatened by the loss of sea ice. “Glacier ice may help a small number of polar bears survive for longer periods under a warming climate, but it is unavailable to the vast majority of polar bears,” he explained. In the long term, he points to the importance of studying this population and other polar bears to understand how Arctic polar bears can survive and how genetic diversity can help. Other species The threat of climate change


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