Warmer Arctic lures life that rarely bears the cold
Clams and whales find opportunity in climate calamity
ABOARD THE USCGC HEALY — On a ship near the top of the planet, a 120-pound steel claw dumps out mud freshly scooped from the bottom of the sea. Jackie Grebmeier gets to work with a pair of tweezers, picking shrimplike critters called amphipods out of the muck.
Grebmeier has been digging up animals in the waters between Alaska and Russia for more than 30 years. And she has noticed a trend: A retreat has begun here at the edge of the Arctic. With temperatures rising, creatures such as amphipods have been inching northward.
Meanwhile, clams and fish and whales from balmier climes have begun to move in.
“We’re starting to see changes that we’ve never seen in the decades we’ve been studying this area,” says Grebmeier, a biological oceanographer at the University of Maryland Center for Environmental Science in Solomons.
As scientists debate whether ice-free Arctic waters might someday support more total life, they are beginning to puzzle out which species will be losers and which will be winners.
Life off Alaskan shores, from plankton to polar bears, is tied to sea ice that covers these waters in winter. Spring melting triggers an explosion of microscopic plants that fall to the seafloor, to be eaten by bottom-dwellers.
But lately the ice in the north Bering Sea, the gateway to the Arctic from the Pacific Ocean, has been diminishing. One spot Grebmeier has been returning to for a long time had fewer days of ice in each of the last three years than at any time since measurements began in the 1970s.
This vanishing act can be felt by the humblest creatures near the bottom of the food chain, including amphipods and small clams, which have been migrating northward.
With their food on the move, clam-eating sea ducks have been falling in numbers. Gray whales usually at home in the Bering Sea have been spending more time in waters farther north —specifically, the Chukchi Sea, above Alaska.
Fin whales also have been showing up in the Chukchi. So have humpbacks and minke whales. None of these are traditional Arctic species, Grebmeier says.
“Boom times” is how Sue Moore describes the situation for these whales. She’s a biological oceanographer with the Fisheries Office at the National Oceanic and Atmospheric Administration.
Scientists at sea in August with Grebmeier, on the largest ship in the Coast Guard’s fleet, have seen other signs of change. Grebmeier’s companions studied such things as bacteria in the water that could be influencing cloud formation and dormant algae that might come to life if temperatures continue to rise, and walruses and poison shellfish.
While sifting through bottom-dwellers from the Chukchi, which the Healy visited after the Bering Sea, Laura Gemery, an ecologist with the United States Geological Survey, discovered some shells the size of grains of sand. They belong to crustaceans that aren’t usually found so far north.
Her finding echoes a surprising observation made years ago in the Chukchi. Russian scientists came across what she calls “a n incredibly l a rg e amount” of big Pacific clams, Pododesmus macrochisma, that typically live in warmer places south of Alaska and near Japan and California.
Temperature measurements made by the Healy suggest that historical barriers to entry are weakening in the Arctic.
Consider a cold spot in the north Bering Sea. Lee Cooper has spent years studying this pool, where temperatures are typically zero degrees Celsius.
This summer, it had a surprise in store. “It warmed up over zero degrees this year — for the first time ever, we believe,” says Cooper, a biogeochemist at UMCES. At these temperatures, says Cooper, “fish have no reason not to migrate north.”