Evidence from octopus hints at ice sheet collapse

May 10th, 2012 - 2:09 pm ICT by IANS  

Sydney, May 10 (IANS) Genetic evidence from an Antarctic octopus indicates that the West Antarctic ice sheet - one of the world’s major ice sheets - could collapse if temperatures keep climbing.

Researchers analysed the genes of the Turquet’s octopus, which lives in the Southern Ocean surrounding Antarctica, during the census of Antarctic marine life, from 2005 to 2010, and International Polar Year in 2007.

Australian geneticist Jan Strugnell from the La Trobe University, who led the study, said adult Turquet’s octopuses don’t travel very much. They only move to escape from predators.

However, the team found that the genes from octopuses from the Weddell and Ross Seas, 10,000 km apart and on opposite sides of Antarctica, are startlingly similar, the journal Molecular Ecology and British website ‘Planet Earth’ report.

“Those two seas are completely separate, so we expected the genetics of these octopuses to be quite different,” says Strugnell.

However, because they are so similar, researchers think this would only have happened if there had been a previous collapse of the West Antarctic ice sheet which separates those two bodies of water, according to a La Trobe statement.

The British website reports that this collapse may have happened possibly as recently as 200,000 years ago, which suggests that scientists’ concerns about the state of today’s ice sheet could well be justified.

Strugnell says when the climate was much warmer, sea levels would have been substantially higher, because less water would have been locked up as ice. In this situation, the Ross and Weddell Seas could have been connected.

“Ocean currents both facilitate and hinder the flow of genes,” she says. “But the Antarctic Circumpolar Current almost certainly wouldn’t have facilitated so much dispersal by octopuses that two populations would have almost identical genetics if the ice sheet had been in place.”

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