The seas around the Antarctic Peninsula are among the most mysterious places on earth. The collapse of some of the ice sheets has given scientists a rare opportunity for access, and they revealed that they had found a thriving underwater world that is being transformed by climate change. As well as new species, the Census of Marine Antarctic Life (CMAL) project found more common ones that were able to survive in the Antarctic because the temperature of the sea is rising. Minke whales were discovered in large numbers. The scientists also spotted a rare beaked whale off the coast of Elephant Island — the famous refuge of Ernest Shackleton's 21-man crew after a doomed attempt to cross Antarctica in 1916. Parts of the sea here were uncovered for the first time in recorded history when the Larsen A and B ice shelves collapsed, 12 and five years ago respectively, due to the higher temperatures linked to human-induced climate change. Scientists said the new survey would help predict what would happen to biodiversity as the world warms up.
The Larsen shelf is a fringe of ice in the north-west of the Weddel Sea, extending along the east coast of the Antarctic peninsula. In 2002, scientists watched in shock as 3,250 sq km of 220-metre-thick ice — the Larsen B shelf — fell into the sea. It had been stable for at least 12,000 years.
Larsen A, a smaller ice sheet, had collapsed seven years earlier, but this was around 4,000 years old. Global warming was undoubtedly to blame.
Julian Gutt, a marine ecologist at Germany's Alfred Wegener Institute for Polar and Marine Research, who led the expedition, said the area under the Larsen ice shelf was the least known ecosystem on earth. "So far, we did not have access to such areas, with the few exceptions of drill holes or cracks where people could deploy some remote video cameras."
The break-up of the Larsen ice shelves opened up a pristine area of sea floor the size of Jamaica. Researchers spent 10 weeks scouring the 10,000 sq km sea floor for animal life.
By probing as far as 850 metres under water, using a remote camera, they collected around 1,000 specimens, including 15 shrimp-like species, known as amphipods, thought to be new to science.
Star attraction
The star attraction is a 10-cm-long crustacean from the amphipod family Shackletonia. Professor Gutt said the new biodiversity information would be fundamental in understanding the functioning of the ecosystem. The scientists also found four new species of cnidarians, creatures that are related to coral, jellyfish, and sea anemones. One anemone-like creature was found living on the back of a snail, providing protection in return for transport.
In the relatively shallow waters of the Larsen zone, abundant numbers of deep-sea creatures that normally live at depths of 2,000 metres or so were found. These included deep sea lilies, sea cucumbers, and sea urchins. The scientists found dense patches of sea squirts and said they were probably able to colonise the Larsen B area only after ice shelf broke in 2002. Stoddart, leader of the CAML project, said one consequence of the rising global temperatures was a fall in plankton such as algae that grow beneath sea ice, which would have knock-on effects to animals higher up the food chain, all the way up to whales.
Other finds in the CAML expedition included clusters of dead clamshells littering an area of the ocean floor near a suspected "cold seep."
The expedition team also investigated fish populations in the islands north and west of the Antarctic peninsula. The results of 85 hauls over 19 days show that the biomass of two Antarctic cod species has increased since a survey in 2003, while stocks of Blackfin and Mackerel Icefish have decreased.
(The Hindu, 27th February, 2007)
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