Antarctic marine life under threat


This video is called Antarctic Wildlife.

From British daily The Independent:

Antarctic marine life threatened by crab invasion

By Steve Connor, Science Editor in Boston

Saturday, 16 February 2008

An army of shell-crushing crabs is poised to invade parts of the Antarctic Ocean that were off limits to the crustaceans for millions of years because of the intensely cold water.

Scientists believe that, as global warming causes sea temperatures in the region to rise, the unique shallow-water habitat of the Antarctic Peninsula will be transformed by the mass arrival of killer crabs.

Crabs are one of the top predators of the seabed but their enforced absence from the cold waters of the Antarctic has created an unusual community of shelled creatures that could disappear once the crabs invade, scientists said yesterday.

“The crabs are on the doorstep,” said Sven Thatje of the National Oceanography Centre at Southampton University.

“Rapidly rising sea temperatures off the Antarctic Peninsula are creating conditions that favour the return of shell-crushing predators after an absence of tens of millions of years,” Dr Thatje told the American Association for the Advancement of Science.

Sea-surface temperatures off the western Antarctic Peninsula have risen by 1C over the past 50 years, more than double the global average.

“Crab populations have already become established in deeper, slightly warmer waters. It is only a matter of time before they expand to shallow Antarctic habitats and radically alter community structure,” he said.

Marine life on the Antarctic seabed is a rare combination of giant sea spiders, marine pillbugs and bottom-dwelling fish with antifreeze in their bloodstream to prevent them from freezing solid.

In the absence of crabs and other fast-moving predators, such as sharks and rays, the main seabed predators are slow-moving sea stars and giant, floppy ribbon worms. “Crabs cannot flush magnesium out of their blood, so when they are already moving slowly because of the cold, the magnesium makes them pass out and die,” Dr Thatje said.

Clams, snails and other animals with hard skeletons have evolved into rare forms that are part of an unusual food web.

“Antarctic marine communities look like primeval communities from hundreds of millions of years ago because modern predators such as crabs and fish are missing,” said Rich Aronson of the Dauphin Island Sea Laboratory in Alabama. An invasion of crabs could completely change the habitat, and “that would be a tragic loss for biodiversity in one of the last truly wild places on earth”.

See also here.

New discoveries on life in Antarctic waters: here. Video: here.

From the tiny phytoplankton living under the ice to the penguins at the top of the food chain, the ecosystem of the Antarctic Peninsula is changing fast, driven by warming waters and a loss of sea ice: here.

Antarctic Life Hung By A Thread During Ice Ages: here.

Hibernation-like behavior in Antarctic fish — on ice for winter: here.

1 thought on “Antarctic marine life under threat

  1. Giant Starfish, Lilly Fields Found in Antarctic Waters

    Ray Lilley, Associated Press

    March 21, 2008 — Scientists who conducted the most comprehensive survey to date of New Zealand’s Antarctic waters were surprised by the size of some specimens found, including jellyfish with 12-foot tentacles and 2-foot-wide starfish.

    A 2,000-mile journey through the Ross Sea that ended Thursday has also potentially turned up several new species, including as many as eight new mollusks.

    It’s “exciting when you come across a new species,” said Chris Jones, a fisheries scientist at the U.S. National Oceanic and Atmospheric Administration. “All the fish people go nuts about that — but you have to take it with a grain of salt.”

    The finds must still be reviewed by experts to determine if they are in fact new, said Stu Hanchet, a fisheries scientist at New Zealand’s National Institute of Water and Atmospheric Research.

    But beyond the discovery of new species, scientists said the survey, the most comprehensive to date in the Ross Sea, turned up other surprises.

    Hanchet singled out the discovery of “fields” of sea lilies that stretched for hundreds of yards across the ocean floor.

    “Some of these big meadows of sea lilies I don’t think anybody has seen before,” Hanchet said.

    Previously only small-scale scientific samplings have been staged in the Ross Sea.

    The survey was part of the International Polar Year program involving 23 countries in 11 voyages to survey marine life and habitats around Antarctica. The program hopes to set benchmarks for determining the effects of global warming on Antarctica, researchers said.

    Large sea spiders, jellyfish with 12-foot tentacles, huge sea snails and starfish the size of big food platters were found during a 50-day voyage, marine scientist Don Robertson said.

    Cold temperatures, a small number of predators, high levels of oxygen in the sea water and even longevity could explain the size of some specimens, said Robertson, a scientist with NIWA.

    Robertson added that of the 30,000 specimens collected, hundreds might turn out to be new species.

    Stefano Schiaparelli, a mollusk specialist at Italy’s National Antarctic Museum in Genoa, said he thought the find would yield at least eight new mollusks.

    “This is a new brick in the wall of Antarctic knowledge,” Schiaparelli said.

    See also here.

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