for National Geographic News
The north Bering Sea, one of the world's richest feeding grounds for whales, walruses, and sea birds, is warming to the point where animals are being forced to adapt or suffer the consequences.
The Bering Sea sits between Siberia and Alaska above the Aleutian Islands (see map). Its northern half was typically covered in solid ice for seven months of the year.
But now there is less ice in general, and the seasonal melt is starting earlier in the spring, said Jacqueline Grebmeier, a marine ecology expert at the University of Tennessee in Knoxville.
Some animals, like gray whales, are moving farther north to follow the cold water. Meanwhile, pink salmon and pollock, fish typically found in the southeast Bering Sea, are moving into northern waters.
Other animals of the north Bering Sea may not be adapting enough to survive. Bearded seals and walruses, which feast on the sea's bottom-dwellers, are struggling with a reduced food source.
Also in trouble are diving Eider ducks, a threatened species under the U.S. Endangered Species Act.
"[The ducks'] population is going down, and their food supply is going down," Grebmeier said. Her team's results are published in today's issue of the online journal Science Express.
Meals on Ice
Warming of the Bering Sea is likely due to global climate change and to a weakening of the cold north winds that blow across the sea, affecting its temperature.
The sea is usually teeming with wildlife thanks to phytoplankton, the starting link in the region's food chain.
The tiny sea plants start to grow under the ice each spring until their population reaches a massive, nutrient-packed overgrowth by June.
As the overcrowded plants suffocate and die, their remains fall to the muddy bottom, creating a carbon-rich food layer for worms, shrimp, and clams.
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