Thursday, January 14, 2010

Scientists go to extremes for Arctic research

If you want to know how polar bears are doing, it's not enough to spy on them with satellite telemetry and other technology. You have to go where they live.

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You have to tap into the stories these bears carry in and on their bodies, and drop in on the tiniest of organisms beneath the places they walk, the ones that feed the shrimp-like creatures that feed the fish that feed the seals that feed the bears.

That's what scientists did for five weeks this fall aboard the U.S. Coast Guard Cutter Polar Sea as they addressed the question: How are polar bears coping with sea-ice loss due to climate change?

To get some answers, they traveled to a part of the world few get to see, and far fewer get to see from beneath the sea ice. Or would want to.

"It's definitely not for everyone," said Katrin Iken, associate professor of marine biology at the University of Alaska Fairbanks, who led the team of ice researchers from UAF.

The ice divers, layered in polypropylene, fleece and dry suits, went to work through holes cut in the ice to gather samples from biological communities associated with sea ice. Tethered to a team member above, they went as deep as 40 feet to explore the bottoms of ice ridges -- the underwater version of the pressure ridges up top -- for a look at what lives down there.

In the big picture, it's all about understanding what melting ice means to the larger food web in the Arctic.

To Iken, the underside of sea ice is a beautiful and fascinating place.

Shawn Harper, team member and underwater photographer, calls it "captivating" and "otherworldly."

Among those working up top was George Durner, an Anchorage research zoologist with the USGS Alaska Science Center. He's been capturing and collecting data on polar bears since the early 1990s, helping keep tabs on the southern Beaufort Sea population, currently estimated at 1,500. Durner and his colleagues do the majority of their sampling in the spring based out of Barrow, Prudhoe Bay and Kaktovik, flying 50-100 miles offshore.

"You can only fly a helicopter so far before you have to go back and get more fuel," he explained.

The Polar Sea expedition offered a chance to go places he's never been able to access before, including this summer's ice pack, the edge of which was more than 200 miles off the coast of Alaska.


Access to this remote sea-ice habitat will help researchers understand how bears that spend their summers in profoundly different ways fare by comparison in the face of climate change.

In the past two decades, due to extensive sea ice retreat, bears have split up, either spending their summers on the deep-water pack ice far offshore, or spending it on land. Based on radio telemetry, researchers estimate that at least 80 percent stay with the pack ice. And what they are hearing from seal researchers is that there aren't a lot of seals out that far.

One problem: This year, the extent of the summer sea ice was the third-lowest on record.

Researchers had their sights on 11 previously collared bears for recapture and comparative sampling. But because the ice was too thin to do their work safely, for themselves and for the bears, they were able to capture and sample only four.

"The irony of it all is the very processes whose effect we are attempting to study was basically keeping us from doing our research," Durner said. "But we did get some very good data from these animals, and we learned a lot."

He and other project scientists, including collaborators from the University of Wyoming and the U.S. Fish & Wildlife Service, are still analyzing that data, so it will be awhile before they can say what it all means.

That, he said, is going to take a lot of serious thinking.

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