Polar mission

Marylanders are on international team gathering climate change data

April 12, 2009|By Tim Wheeler | Tim Wheeler,tim.wheeler@baltsun.com

The Arctic is warming, and the sea ice is thinner than anyone has seen before. That could spell trouble for walruses, sea ducks and a host of other species - including humans - that depend on the North to sustain them.

An international team of researchers, including some from Maryland, spent much of March aboard a Coast Guard icebreaker in the Bering Sea, gathering evidence that might help explain what's happening there. Enduring fierce winds and temperatures that dipped to minus 10 degrees Fahrenheit at times, they sampled the ice off the coast of Alaska, scooped up clams and other creatures from the sea bottom and scouted by helicopter across the vast white landscape to find and tag walruses.

"In some ways, it's like a three-ring circus," said Lee Cooper, chief scientist for the cruise and a research professor at the University of Maryland's Chesapeake Biological Laboratory. With nearly three dozen researchers from the United States, Canada and abroad, the icebreaker Healy was a hive of activity virtually around the clock.

The three-week cruise was part of a six-year, $52 million study of the changing climate's impact on a region whose importance stretches far beyond its shores. Besides offering early signs of an ecological upheaval that could sweep across a warming planet, the Bering Sea supplies half of the seafood eaten in the United States.

"Changes here affect the entire country and seafood markets abroad," said Francis Wiese, senior scientist for the North Pacific Research Board in Anchorage, which is coordinating the study in partnership with the National Science Foundation. Those changes also threaten the way of life and possibly the existence of remote native communities such as Savoonga on St. Lawrence Island. The Yup'ik people there have traditionally subsisted by hunting walruses and other prey across the frozen sea.

About a decade ago, scientists noticed that the ice covering much of the Bering Sea in winter was melting earlier and faster than before. Weak or vanishing ice means the long-tusked Pacific walruses that congregate in the shallow waters off Alaska's coast have fewer places to haul out of the frigid water.

The mammals feed mainly on clams, worms and other tiny creatures on the bottom, using their sensitive whiskers to locate prey amid the sand and muck. The ice provides the animals a floating platform on which to rest between foraging dives. The females also bear their young there.

As the ice begins to melt in April, the walruses begin moving north, passing through the Bering Strait to the Chukchi Sea by summer. The Chukchi sea ice also is melting more in summer, and scientists have noticed "some very dramatic responses" there, said Chad Jay, a scientist with the U.S. Geological Survey's Alaska Science Center in Anchorage.

With no ice left in their traditional shallow-water feeding grounds, many walruses have migrated to land along the coast.

"But we might be seeing some more subtle changes in the Bering as well," Jay said.

There, the husband-wife team of Cooper and Jacqueline Grebmeier, also a research professor at Maryland's Chesapeake lab, think the melting ice might be affecting more than the walruses' loafing habits. Sampling conducted over the past 25 years by Grebmeier and others has shown declines in the population of bottom-dwelling creatures in the eastern Bering Sea, meaning a decrease in the food supply for walruses, Cooper said.

The researchers think the drop-off in clams and worms could also stem from the changing climate, by affecting the bottom-dwellers' food supply.

Algae, tiny plant-like organisms that are the base of the sea's food chain, grow on the underside of the ice. In spring, lengthening daylight and warming temperatures trigger massive "blooms" of algae in the water along the receding edge of the melting pack. The mollusks and crustaceans on the bottom feed on the fallout from that burst of life in the water.

"Because the ice is starting to disappear earlier," Cooper said, "there may not be as much food getting to the bottom anymore in such a big pulse."

The Maryland research team spent hours outside on the stern of the 420-foot icebreaker, dredging the bottom and then screening out the clams and other creatures in the muck so they could be identified and counted.

Meanwhile, other scientists disembarked from the ship to take ice cores for analysis. As they worked, armed Coast Guard crew members kept watch across the white plain for polar bears that might see the scientists as their next meal.

Jay and his team took off from the Healy in a helicopter to find walruses and tagged 17 of them - from a distance, given the animals' size. Using a crossbow, they fired transmitters with barbed heads into the animals' blubbery hides so scientists could track their movements by satellite.

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