wild places | wild happenings | wild news
make a difference for our wild places

home | links | search the site
  all articles latest | past | articles by topics | search wildnews
wild news on wildsingapore
  Yahoo News 26 Feb 07
Collapse of two iceshelves exposes Antarctica's seabed beauty

PlanetArk 26 Feb 07
Exotic Animals Seen Where Antarctic Ice Used to Be
Story by Deborah Zabarenko, Environment Correspondent

WASHINGTON - Spindly orange sea stars, fan-finned ice fish and herds of roving sea cucumbers are among the exotic creatures spied off the Antarctic coast in an area formerly covered by ice, scientists reported on Sunday.

This is the first time explorers have been able to catalog wildlife where two mammoth ice shelves used to extend for some 3,900 square miles (10,000 square km) over the Weddell Sea.

At least 5,000 years old, the ice shelves collapsed in two stages over the last dozen years. One crumbled 12 years ago and the other followed in 2002. Global warming is seen as the culprit behind the ice shelves' demise, said Gauthier Chapelle of the Polar Foundation in Brussels.

"These kind of collapses are expected to happen more," he said. "What we're observing here is probably going to happen elsewhere around Antarctica."

Melting ice shelves are not expected to directly contribute much to global sea level rise, but glaciologists believe these vast swaths of ice act like dams to slow down glaciers as they move over the Antarctic land mass toward the coast.

Without the ice shelves, glaciers may move over the water more quickly, and this would substantially add to rising seas. Since 1974, 5,213 square miles (13,500 square km) of ice shelves have disintegrated in the Antarctic Peninsula.

SEA SQUIRTS

But the collapse of the ice shelves gave the scientists a unique opportunity to see what had been hidden beneath them; before the collapse, researchers could only peer through holes drilled deep into the ice.

Chapelle and other scientists from 14 nations traveled to the area aboard the icebreaking vessel Polarstern in a 10-week voyage to investigate underwater wildlife along the Antarctic peninsula, the part of the southern continent that curves up toward South America.

Looking down 2,800 feet (850 metres) into the icy water -- a comparatively shallow depth -- they found fauna usually associated with seabeds about three times that deep, in places where the creatures must adapt to scarcity to survive.

There were blue ice fish, with dorsal fins like ribbed fans and blood that lacks red cells, an adaptation that makes the blood more fluid and easier to pump through the animal's body, conserving energy at low temperatures.

Long-limbed sea stars, some with more than the usual five appendages, mingled with the ice fish, and groups of sea cucumbers were observed moving together, all in one direction.

The explorers also found thick settlements of fast-growing animals called sea squirts, which look like gelatinous bags, which apparently started colonizing the area only after the ice shelves collapsed.

Among the hundreds of specimens collected, the scientists identified 15 possible new species of shrimp-like amphipods, and four possible new species of cnidarians, organisms related to coral, jellyfish and sea anemones, the scientists said in a statement.

These specimens will be analyzed to determine whether they in fact are newly discovered species.

Yahoo News 26 Feb 07
Collapse of two iceshelves exposes Antarctica's seabed beauty

PARIS (AFP) - The collapse of two ice shelves in Antarctica has exposed an exquisite seabed ecosystem, including species of crustaceans and marine anemones that had never been identified, researchers said on Sunday.

The insight into Antarctica's hidden marine world came from the breakup of the Larsen A and B ice shelves, 12 and five years ago respectively, that later formed huge icebergs. Their collapse laid bare a 10,000-square-kilometer (3,800-square-mile) portion of the sea bed -- an area almost the size of Jamaica -- that had been roofed by ice for millennia.

Part of the area was explored by an unmanned robot, lowered from a German research vessel, the Polarstern (North Star), in a 10-week international expedition that ended on January 30.

"The breakup of these ice shelves opened up huge, near pristine portions of the ocean floor, sealed off from above for at least 5,000 years, and possibly up to 12,000 years in the case of Larsen B," said Julian Gutt, the expedition's chief scientist.

"(...) Until now, scientists have glimpsed life under Antarctica's ice shelves only through drill holes. We were in the unique position to sample wherever we wanted in a marine ecosystem considered one of the least disturbed by humankind anywhere on the planet."

The team of 52 scientists from 14 countries collected around 1,000 species, some of which are believed to be new to science, and took what they describe as "brilliant" images of unfamiliar creatures.

The newcomers to the book of knowledge about Antarctica include 15 shrimp-like crustaceans called amphipods, including one beast that was nearly 10 centimetres (four inches) long, the researchers said in a press release.

Four presumed new species of cnidarians -- organisms related to coral, jellyfish and sea anemones -- were also found. One of them lives on the back of a snail, showing a symbiotic relationship in which the snail provides locomotion for the cnidarian, and the cnidarian provides protection for the snail.

At present, international databases have recorded 5,957 forms of marine life, but as many as 11,000 more remain to be discovered.

The researchers discovered the ice shelf had covered a highly varied sea floor, ranging from bedrock to pure mud, with flora and fauna that were correspondingly diversified.

In shallower waters to depths of about 220 metres (715 feet), they came across rich patches of deep sea lilies, sea cucumbers and urchins -- an intriguing find, as these species usually lurk in deep water of around 2,000 metres (6,500 feet).

Ice shelves in Antarctica are caused by glaciers that reach the coast and then creep out to sea, floating on the water but still attached to land. In 1992, the so-called Larsen A ice shelf disintegrated, and in 2002, the Larsen B followed suit, creating the most massive icebergs ever seen.

The loss of the shelves is giving Antarctica-watchers the chance to see how different species move in to colonise the freshly uncovered seabed, starting with opportunistic gelatinous creatures called sea squirts and glass sponges.

Mammals, too, have moved in.

"It was surprising how fast such a new habitat was used and colonised by Minke whales in considerable densities," said German specialist Meike Scheidat. "They indicate that the ecosystem in the water column changed considerably."

The newly-opened vista also provides a barometer for change, for parts of the Antarctic coast are being hit by global warming at a far greater rate than other parts of the world. Local temperatures at the Larsen shelves have risen by 2.5 C (4.5 F) since the 1940s.

"This is virgin geography," said Gauthier Chapelle, a biologist at the Brussels-based International Polar Foundation. "If we don't find out what this area is like now following the collapse of the ice shelf, and what species are there, we won't have any basis to know in 20 years' time what has changed and how global warming has altered the marine ecosystem."
links
Related articles on Global marine issues
about the site | email ria
  News articles are reproduced for non-profit educational purposes.
 

website©ria tan 2003 www.wildsingapore.com