Warming of Bering Sea causing animals to migrate north

Bering Sea, which is home to a number of sea animals including whales, walruses, sea birds and fishes, is rapidly warming, threatening the ecosystem that thrives in its icy waters, a study, by University of Tennessee researchers, has said.

For a minimum of seven months a year, north Bering Sea, located between Siberia and Alaska, sees a solid ice cover. However, in the past decade, the temperatures on the floor of the sea have been showing rapid escalation, with the surface temperatures in 2004 hitting a high of 50 degrees Fahrenheit. Earlier, the temperature would hover around 32 degrees Fahrenheit.

According to Jacqueline Grebmeier, the lead author of the study, besides experiencing lesser ice, the region is also battling earlier annual melting of ice, with the melting in 1997 coming three weeks prior to its normal date.

This is posing problems for many animal species that source their food from bottom-feeders, like phytoplankton, which require extremely cold climates to survive. These bottom-feeders are slowly facing dwindling populations, causing animals from different parts to encroach upon other territories, leading to scarcity of food and subsequent loss of habitat.

While some like gray whales are coping by shifting base to the north in search of colder waters, others like bearded seals, walruses and Eider ducks are perishing, facing competition from fishes like pink salmons invading their territory to feed on pollock, a bottom-feeding species proliferating in northern Bering Sea due to increased temperatures.

“(Eider ducks') population is going down, and their food supply is going down. We're seeing that a change in the physical conditions is driving a change in the ecosystems. What we are seeing is a change in the boundary between the sub-Arctic and the Arctic ecosystem. The potential is real for an ecosystem shift that will be felt farther north,” Grebmeier said.

According to Lee Cooper, a co-author of the study, the massive disruptions in Bering Sea due to small climatic changes can be explained by the fact that the sea is a shallow one with a depth of less than 200 feet.

“(The study) demonstrates the biological effect in an area so shallow that it doesn't take much to fundamentally change the system. It's a little sobering,” Cooper said. The researchers say that the likelihood of these changes being irreversible are high, and reversal to cold temperatures might not undo them. Bering Sea, which spans an area of over 700,000 square miles, is separated from the North Pacific Ocean by the Alaska Peninsula and Aleutian Islands.

Expressing concerns at the findings, oceanography scientists stressed the importance of halting global warming in its tracks and warned about the consequences for ecology should such changes continue. They point to the complaints of subsistence hunting tribes, like Yupik of St Lawrence Islands, who have reported thinning of ice.

“In the southeast, fish population and bottom-dweller changes are happening in the context of a complete loss of sea ice. But in the northern Bering Sea, ecological changes are occurring in the context of shifts in the quality of the sea ice. The ice there is broken and thin compared with ice floes that were more the norm,” said James Overland of National Oceanic and Atmospheric Association's Pacific Marine Environmental Laboratory.

Scripps Institution of Oceanography's John Hildebrand felt that immediate action was required to prevent such ecological changes that can have devastating repercussions for mankind somewhere down the line.

“We need to make every effort possible to give them a chance to survive. I can't predict at all how climate change would play into the lives of right whales. It definitely will play into their lives but how, we don't know,” he said. The findings of the study have been reported in he journal Science.

Written by : Archibald Freeman