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The ongoing loss of sea-ice cover is wreaking havoc on ecosystems across the Arctic, and may spell the end of more species than previously thought.

Arctic sea-ice cover has shrunk this year to the second lowest summer level ever recorded, following an unprecedented winter low. “There will be winners and losers,” says of Tern Again Consulting in Homer, Alaska. “Species that rely directly on sea ice, like ivory gulls, will run into difficult times.”

But less obvious species may also be in trouble. Renner and his colleagues examined data on sea ice and zooplankton, fish and seabirds in the south-east Bering Sea between 1975 and 2014. They found that most seabird and large zooplankton species were less abundant – by 90 per cent on average for birds – when sea ice melted early in spring, suggesting that these species will decline in a warmer climate.

“Such changes will result in a very different Bering Sea ecosystem, which currently supports one of the largest remaining palatable fisheries in the world,” says Renner.

It’s not just sea life that’s at risk. “To Arctic animals, the disappearance of ice could represent a new and serious impediment, particularly to moving among islands,” says at Université Savoie Mont Blanc in France.

His team studied the possible future effects of sea-ice loss on the Peary caribou, a culturally important animal for indigenous people, who use it for food and clothing.

These animals are also a critical part of the ecosystem in the Canadian Arctic Archipelago, which has more than 36,000 islands. The caribou travel over the ice between these islands to find food and shelter, to mate and to raise their young.

“Sea ice allows caribou populations to interact and allows for genetic exchange, which influences the productivity and diversity of these populations,” says of Trent University in Ontario, Canada, who also took part in the study.

Less connected

“Our results show that this connectivity among islands has declined since the 1980s,” says Jenkins. And this is set to get much worse by the end of this century. The loss of ice could disrupt caribou movement and gene flow. Over time, the animals may go extinct, says the study.

A lack of ice may also hamper the dispersal of plants, dooming them to extinction. “With the current rapid warming, plants need to move to colder places to track their climatic niche,” says  at the Arctic University of Norway in Tromsø. Her team used past data on sea ice and plants’ first arrival in the Arctic to show that plants are more likely to colonise new areas when sea ice is prevalent.

“By and large, the anticipated changes are off the charts,” says Renner. But the complexity of the ecosystem and lack of historical precedent means it is difficult to make accurate predictions about future changes, he adds.

“For species that rely on sea ice, there may be increasingly negative and irreversible consequences, with far-reaching effects on the structure and functioning of entire ecosystems,” says Yannic.

Journal reference: Biology Letters, DOI: ; ;

Read more: Polar wildlife under threat as ice melts and makes seas brighter