further threats to Antarctic biodiversity:
Crabs are poised to return to the Antarctic shallows, threatening creatures such as giant sea spiders and floppy ribbon worms, says a UK-US team.
Some have evolved without predators for tens of millions of years.
Bony fish and sharks would move in if waters warm further, threatening species with extinction, they say.
In the last 50 years, sea surface temperatures around Antarctica have risen by 1 to 2C, which is more than twice the global average.