Opwarming oceanen bedreigt krill

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krill20102015SYDNEY, Australia — Every day for a week, So Kawaguchi peered intently into the jars of cold water holding harvested krill eggs. None were hatching. In his laboratory in Hobart, Tasmania, on the edge of the Southern Ocean, he could see that the carbon dioxide he had pumped into the icy seawater had killed the eggs.

“We thought the krill might be more robust,” said Dr. Kawaguchi, a biologist who works for the Australian government’s Antarctic Division. “We were not expecting such a clear result.”

Those key moments in his laboratory more than seven years ago were pivotal in the career of Dr. Kawaguchi, who has been studying krill for 25 years. His recent research has led to dire predictions about how global carbon emissions will significantly reduce the hatch rates of Antarctic krill over the next 100 years.

Krill, typically about the size of a pinkie and similar in appearance to shrimp, are one of the most abundant animal species on earth, and a cornerstone of the Antarctic ecosystem. They form schools that can be miles long and miles deep, with thousands of crustaceans packed into each cubic foot.

Commercial trawlers revisit known breeding grounds, where they can vacuum up thousands of tons of krill over a fishing season. Most of the catch is used to feed farmed fish. But extraction of krill oil for human consumption is more profitable, Steve Nicol, an adjunct professor at the University of Tasmania, said.

In the Southern Ocean, most marine life is a direct predator of krill or just one step removed. Diminishing krill stocks can mean less food for squid, whales, seals, fish, penguins and sea birds.

“Higher levels of carbon dioxide in the water mean greater levels of ocean acidification,” said Dr. Kawaguchi, whose laboratory holds the only research tanks in the world used to breed and study krill. “This interrupts the physiology of krill. It stops the eggs hatching, or the larvae developing.”

Conservationists want tracts of Antarctic waters protected until scientists better understand the links between different species of marine life there.

“We are concerned with the concentrated fishing around the Antarctic Peninsula, which is also the fastest warming place on the planet,” said Andrea Kavanagh, the Washington-based director of the Pew Charitable Trusts’ global penguin conservation campaign.

In Hobart, Dr. Kawaguchi pumped carbon dioxide into his jars, acidifying the water to mimic conditions that might occur over the next three centuries.

“If we continue with business as usual, and we don’t act on reducing carbon emissions, in that case, there could be a 20 to 70 percent reduction in Antarctic krill by 2100,” Dr. Kawaguchi said. “By 2300, the Southern Ocean might not be suitable for krill reproduction.”

Source: The New York Times

krill20102015SYDNEY, Australia — Every day for a week, So Kawaguchi peered intently into the jars of cold water holding harvested krill eggs. None were hatching. In his laboratory in Hobart, Tasmania, on the edge of the Southern Ocean, he could see that the carbon dioxide he had pumped into the icy seawater had killed the eggs.

“We thought the krill might be more robust,” said Dr. Kawaguchi, a biologist who works for the Australian government’s Antarctic Division. “We were not expecting such a clear result.”

Those key moments in his laboratory more than seven years ago were pivotal in the career of Dr. Kawaguchi, who has been studying krill for 25 years. His recent research has led to dire predictions about how global carbon emissions will significantly reduce the hatch rates of Antarctic krill over the next 100 years.

Krill, typically about the size of a pinkie and similar in appearance to shrimp, are one of the most abundant animal species on earth, and a cornerstone of the Antarctic ecosystem. They form schools that can be miles long and miles deep, with thousands of crustaceans packed into each cubic foot.

Commercial trawlers revisit known breeding grounds, where they can vacuum up thousands of tons of krill over a fishing season. Most of the catch is used to feed farmed fish. But extraction of krill oil for human consumption is more profitable, Steve Nicol, an adjunct professor at the University of Tasmania, said.

In the Southern Ocean, most marine life is a direct predator of krill or just one step removed. Diminishing krill stocks can mean less food for squid, whales, seals, fish, penguins and sea birds.

“Higher levels of carbon dioxide in the water mean greater levels of ocean acidification,” said Dr. Kawaguchi, whose laboratory holds the only research tanks in the world used to breed and study krill. “This interrupts the physiology of krill. It stops the eggs hatching, or the larvae developing.”

Conservationists want tracts of Antarctic waters protected until scientists better understand the links between different species of marine life there.

“We are concerned with the concentrated fishing around the Antarctic Peninsula, which is also the fastest warming place on the planet,” said Andrea Kavanagh, the Washington-based director of the Pew Charitable Trusts’ global penguin conservation campaign.

In Hobart, Dr. Kawaguchi pumped carbon dioxide into his jars, acidifying the water to mimic conditions that might occur over the next three centuries.

“If we continue with business as usual, and we don’t act on reducing carbon emissions, in that case, there could be a 20 to 70 percent reduction in Antarctic krill by 2100,” Dr. Kawaguchi said. “By 2300, the Southern Ocean might not be suitable for krill reproduction.”

Bron: The New York Times