Antarctic Sea Creatures Hypersensitive to Warming

Jan. 26, 2009— -- ROTHERA BASE, Antarctica, Jan 26 (Reuters) - Thriving only in near-freezing waters, creatures such as Antarctic sea spiders, limpets or sea urchins may be among the most vulnerable on the planet to global warming, as the Southern Ocean heats up.

Isolated for millions of years by the chill currents, exotic animals on the seabed around Antarctica -- including giant marine woodlice and sea lemons, a sort of bright yellow slug -- are among the least studied in the world.

Now scientists on the Antarctic Peninsula are finding worrying signs that they can only tolerate a very narrow temperature band -- and the waters have already warmed by about 1 Celsius (1.6 Fahrenheit) in the past 50 years.

"Because this is one of the most rapidly warming areas on the planet and because the animals are so temperature sensitive...this marine ecosystem is at higher risk than almost anywhere else on the planet," said Simon Morley, a marine biologist at the British Antarctic Survey at Rothera.

"A temperature rise of only 2-3 degrees (Celsius) above current temperatures could cause these animals to lose vital functions," he said.

In warmer waters, laboratory studies show that clams and limpets lose the ability to right themselves if they land upside down. Such a skill is vital in Antarctica's shallows, where icebergs regularly scrape across rocks on the seabed.

"Will they be here in 100 years' time?" Morley said, standing by blue tanks of sea cucumbers, worms and others. "I think that we will see changes in the ecosystems, more in some species and less in other species.

"It does look as if these mechanisms are truly applicable worldwide," he said.

Studies of clams in Singapore also show that they find it hard to burrow if temperatures rise, he said. Coral reefs can also suffer damage if temperatures rise even slightly.

The U.N. Climate Panel has a best estimate that air temperatures may rise by between 1.8 and 4.0 Celsius this century, due to a build-up of greenhouse gases.

Rothera's waters range from about minus 2 Celsius in winter, kept from freezing by saltiness, to 1 Celsius in summer.