The oceans off the Antarctic peninsula are some of the most mysterious on the planet. A thick cover of ice has concealed what life they contain for the past few millennia. But with the rise in global temperatures, speeded by the gaping hole in the ozone layer above Antarctica, some of these ice sheets have collapsed, giving an opportunity for science to discover a thriving underwater world in the grip of transformation due to climate change.
The Census of Marine Antarctic Life (CMAL) project has found new species, together with more common ones that were able to survive in the Antarctic because the temperature of the sea is rising. Minke whales, for example, have been discovered in large numbers. CMAL scientists have 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, because of the higher temperatures linked to human-induced climate change.
Julian Gutt, a marine ecologist at Germany’s Alfred Wegener Institute for Polar and Marine Research, who led the CMAL 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,” he said.
The break-up of the Larsen ice shelves opened up a pristine area of sea floor the size of Jamaica — a habitat that has been sealed off from above for several thousand years. Researchers spent 10 weeks scouring the 10 000 square kilometre sea floor for animal life.
By probing as far as 850m under water, using a remote camera, they collected about 1 000 specimens, including 15 shrimp-like species, known as amphipods, thought to be new to science.
The star attraction is a 10cm-long crustacean from the amphipod family Shackletonia. Gutt said the new biodiversity information would be fundamental in understanding the functioning of the ecosystem. ‘The results of our efforts will advance our ability to predict the future of our biosphere in a changing environment.”
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 about 2 000m 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.
‘We counted a surprisingly high number of Minke whales,” said Gutt. ‘This means the ecosystem in the open water adapts very fast to the new conditions, because the algae grow. Krill feeds on the algae and whales feed on the krill.”
This pattern, however, may not be repeated in future. Michael Stoddart, the leader of the CMAL project, said one consequence of the rising global temperatures was a fall in plankton such as algae that grow underneath sea ice, which would have knock-on effects to animals higher up the food chain, all the way up to whales. ‘Algae is a source of abundant, high-quality winter food and is central to the health of the whole ecosystem,” he said.
Gauthier Chapelle, a biologist at the Brussels-based International Polar Foundation, said: ‘This is virgin geography. 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.” —