Thursday, June 8, 2023

Study: Greenland’s polar bear sheds light on species’ future in a warming world

June 26, 2022 20:43 Is

Washington [US], June 26 (ANI): A new population of polar bears documented off the southeast coast of Greenland use glacier ice to survive despite limited access to sea ice, according to a new study from the University of Washington. This small, genetically distinct group of polar bears could be key to the future of the species in a warming world.
“We wanted to survey this area because we didn’t know much about polar bears in southeast Greenland, but we didn’t expect to find a new sub-population living there,” said lead author Kristin Ladre, A Polar Scientific Physics Laboratory at the University of Applied University of Washington. “We knew there were some bears in the region from the historical record and indigenous knowledge. We didn’t know how special they were.”
The study, published in the June 17 issue of Science, combines seven years of new data collected along the southeast coast of Greenland with 30 years of historical data from the entire east coast of the island. The Far Southeast region was poorly studied due to its unpredictable weather, jagged mountains and heavy snowfall. Newly collected genetic, motion and population data reveal how these bears use glacier ice to survive with limited access to sea ice.
“The loss of sea ice due to climate change threatens polar bears. This new population gives us some insights about how the species may persist in the future,” said Ladrey, a UW associate professor of aquatic and fisheries science. “But we need to be careful about drawing our conclusions, because the glacier ice that makes it possible for Southeast Greenland bears to survive is not available in most of the Arctic.”
The genetic difference between this group of bears and its closest genetic neighbor is greater than the difference observed for any of the 19 previously known polar bear populations.
“They are the most genetically isolated population of polar bears anywhere on the planet,” said co-author Beth Shapiro, a professor and geneticist at the University of California, Santa Cruz, and investigator at the Howard Hughes Medical Institute. “We know that this population has been isolated from other polar bear populations for at least several hundred years, and their population size has remained small throughout this time.”
Researchers think one reason the populations are so isolated is that bears are surrounded on all sides: sharp mountain peaks and the vast Greenland ice sheet to the west, the open waters of the Denmark Strait to the east, and From the fast-flowing East Greenland Coastal Current that threatens the offshore.
Before beginning fieldwork, the team spent two years gathering information and seeking input from polar bear subsistence hunters in eastern Greenland. Hunters participated throughout the study, contributed their expertise, and provided crop samples for genetic analysis.
Satellite tracking of adult females suggests that, unlike most other polar bears, which travel far from sea ice to hunt, Southeast Greenland bears are homebodies. They walk on ice inside protected fjords or break mountains to reach neighboring fjords on the Greenland Ice Sheet. Half of the 27 tracked bears accidentally swam an average of 120 miles (190 km) south on small ice floes caught in the East Greenland Coastal Current, but then disembarked and headed north to their home fjord.

“In a sense, these bears provide a glimpse into how Greenland’s bears might fare under future climate scenarios,” Ladrey said. “Sea ice conditions in Southeast Greenland today are higher than those predicted for Northeast Greenland by the end of this century.”
Between February and the end of May, Southeast Greenland bears can only access sea ice for four months. Sea ice provides the platform that the Arctic’s approximately 26,000 polar bears use to hunt seals. But polar bears cannot fast for eight months. For two-thirds of the year, Southeast Greenland polar bears rely on a different strategy: They hunt seals from freshwater ice caps that break up the Greenland ice sheet.
“The sea-ending glaciers in Southeast Greenland are a fairly unique environment,” said co-author Twyla Moon, deputy principal scientist at the National Snow and Ice Data Center. “Glass of this type are present in other places in the Arctic, but the combination of fjord shapes, high production of glacier ice and the enormous reserves of ice available from the Greenland Ice Sheet currently provide a steady supply of glacier ice.” “
The fact that bears can survive here suggests that sea-ending glaciers, and especially those that regularly calcify sea ice, may become small-scale climate refugia – places where Few polar bears can survive as the sea ice on the ocean surface declines. Similar habitats exist on sea-ending glaciers on other parts of Greenland’s coast and on the island of Svalbard, a Norwegian region east of Greenland.
“Even with rapid changes on the ice sheet, this region of Greenland has the potential to continue to produce glacial ice, with a coast that may look similar to today,” Moon said. Moon said.
The authors estimate that there are about a few hundred bears in Southeast Greenland, similar to other smaller populations. Body measurements show that adult females are smaller than in most areas. They also have fewer cubs, which may reflect the challenge of finding mates in the complex landscape of fjords and mountains. However, Ladrey cautioned that long-term monitoring is needed to know the future viability of Southeast Greenland bears and to understand what happens to polar bear subpopulations as they are affected by the decline in sea ice in the rest of the Arctic. The parts are cut quickly.
“If you’re concerned about conserving the species, then yes, our findings are hopeful — I think they show us how some polar bears can survive under climate change,” Ladre said. “But I don’t think glacier habitat is going to support large numbers of polar bears. That’s just not enough. We still expect to see a big decline in polar bears in the Arctic under climate change.”
The Government of Greenland will decide on any security and management measures. The International Union for Conservation of Nature, which helps oversee protected species, is responsible for determining whether Southeast Greenland bears are internationally recognized as a distinct population, ranked 20th in the world.
“It is important to preserve the genetic diversity of polar bears under climate change,” Ladre said. “Officially recognizing these bears as a distinct population will be important for conservation and management.” (ANI)

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