Antarctica’s melting ice sheets have given scientists a new insight to the weird and wonderful life in the seas around the continent that have been sealed off for 12,000 years. This unique and thriving underwater world is being transformed by climate change.

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 (3,860 sq mile) sea floor for animal life.

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.

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.”

This pattern may not be repeated in future, however. Michael Stoddart, the leader of the CAML 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.”

More scientific research into the affects of climate change on polar regions is getting under way this week. The International Polar Year (IPY) will see thousands of scientists, from more than 60 nations, working together on 220 projects in the largest polar research programme for 50 years.