Climate change will harm life on the deep ocean floor, study finds

A study of the most remote forms of life on Earth has found that their splendid isolation on the deep seabed will not protect them from environmental catastrophes on the surface.

Scientists used to believe that a global disaster that wiped out most of the life on Earth would not touch the unusual organisms that live around the mineral-rich vents on the sea floor. But research by a team of British scientists has found that even these deep-sea creatures which live in total darkness and survive on the chemical energy oozing from mineral vents on the seabed are not immune from the seasonal changes above.

"The marine ecosystem may be even more interconnected than we previously realised and in fact there may be nowhere for life to hide from global catastrophes," said Jon Copley of Southampton University.

"I used to think that life on the deep ocean-floor environment is pretty much quarantined from what happens in the sunlit world up here thanks to their chemical energy supply," Dr Copley will tell the British Association's Science Festival today.

A study of a species of tiny shrimp living around deep-sea vents has found that they produce microscopic larvae as part of their lifecycle and that when these larvae migrate they have to rely on food coming down from the sunlit waters above. So the animals living on the deep seabed have to time the hatching of their eggs to coincide with spring blooms of microscopic plant life growing at the surface – a link that has been overlooked.

Dr Copley and his colleagues studied deep-sea shrimps and mussels and found they have a reproductive cycle that is seasonal – just like surface creatures – even though they are totally isolated from the changes in the seasons. They have to do this to ensure their larvae survive.

"So if an asteroid slams into the Earth and blocks out the Sun, these environments won't be perfect air-raid shelters," he said. "Similarly if climate change were to alter the pattern of life on the surface waters, I would suggest that potentially such changes could be communicated even to these remote corners on the ocean floor.

"Finding seasonality down there shows life beneath the waves is more connected than we realised."