Walruses feed almost exclusively on mollusks and other invertebrates that live on the sea floor. As the ice-edge retreats beyond the continental shelf waters of the Chukchi Sea, the water could be too deep for walruses to dive for food.
The world may soon see the end of Black Guillemot and the Pacific walrus as a result of sea ice loss in the Arctic, according to scientists meeting at the Arctic Science Conference in Fairbanks, Alaska, this week.
Global warming is the culprit, the scientists say.
Along with their research teams, Dr. Brendan Kelly of the School of Fisheries and Ocean Sciences at the University of Alaska, and Dr. George Divoky, an ornithologist at the Institute of Arctic Biology at the University of Alaska, joined the Greenpeace icebreaker 'Arctic Sunrise' last month on a survey of marine mammals and seabirds, focusing on the Pacific walrus and the Black Guillemot. The expedition followed the edge of the Arctic pack ice between Alaska and Russia's Chukotka region.
According to the scientists, the ice-edge was further north than usual with potentially dire consequences for the study animals. The Arctic ice pack is retreating because of rapid warming of the western Arctic region over the past 30-40 years.
The retreat during the 1998 summer season has been extreme, with the ice edge at least 150 nautical miles north of Point Barrow, Alaska. It is normally much closer "at most a few tens of miles from Barrow," the scientists say.
Dr. George Divoky has been studying Black Guillemot in the Arctic for more than 20 years. Because the birds nest on shore but rely wholly on food at the ice edge of the ice pack, the warmer temperatures and retreating sea ice have a direct effect on their ability to survive. Their numbers were quite healthy throughout the 1970s and 1980s, but have declined dramatically in the 1990s, according to his recent survey.
"Black Guillemot are like the proverbial canary in the coal mine. Birds that are dependent on or constrained by snow and ice habitats are an excellent indicator of climate change because the effects of warming on these habitats are direct and immediate, unlike species occupying more diverse habitats that will respond more slowly to climate change. The guillemots are trying to tell us that Arctic Alaska has changed greatly in the last 30 years and more changes are on the way."
Satellite observations indicate a 3 percent per decade decrease in ice cover since the late 1970s, with the rate of loss accelerating this decade, according to Greenpeace. As the burning of fossil fuels continues unabated and the planet continues to warm, the Arctic ice is predicted to continue to thin and retreat, according to the group. This could spell disaster for walrus and guillemot populations as well as other ice-dependent species in the Arctic, say the scientists.
Walruses go out on the ice to rest, molt and bear their young. Males can weigh close to two tons -- about the weight of a pickup truck -- while females can weigh nearly one ton. As the sea ice thins, it is less able to support the weight of a single walrus let along a group of walruses, resulting in a loss of critical habitat.
In addition, walruses feed almost exclusively on mollusks and other invertebrates that live on the sea floor. As the ice-edge retreats beyond the continental shelf waters of the Chukchi Sea, the water could be too deep for walruses to dive for food.
"Walrus rely on the ice for feeding, resting and nursing their young. With the ice edge so much further north than usual, it's over deeper water and it makes it much more difficult for the nursing mothers and their young to reach the clams and other organisms on the seabed which they rely on for food," said Kelly, who has been studying the Pacific walrus and other marine mammals in this region for more than 20 years.
"From what we've seen on this trip, the walrus cow to calf ratio is much lower than we would like to see, and if the trend continues, we will definitely see a decline in the population. That may very well be due to the retreat of the ice."
For the past several years, Greenpeace has been working with scientists specializing in impacts of climate change at the polar regions, where models predict the most dramatic early impacts of global warming.
"Facilitating the work of respected Arctic biologists with our ship and logistical capabilities is one way we can help tell the world about the dramatic impacts of global warming already apparent in the western Arctic," said Melanie Duchin, Greenpeace climate campaigner who accompanied the ice-edge expedition last month.
"We cannot afford to burn more than one quarter of the reserves of fossil fuels that have already been identified if we are to avoid dangerous climate change and the work of these scientists shows even more clearly why governments must take action now to stop climate change."
For more information, contact Dr. George Divoky, (907)474-7640. Copyright 1998, Environmental News Network, All Rights Reserved
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