Antarctic Icebergs Scouring Seabed are New Threat to Marine Life
Shrinking sea ice is significantly increasing the rate at which the icebergs scour the seabed and the study predicts that the Antarctic Peninsula is going to get hit more frequently.
Iceberg near Adelaide Island, Antarctica (top) and cushion stars, in the shallows of South Cove, Antarctic (bottom)
Iceberg near Adelaide Island, Antarctica (top) and cushion stars, in South Cove, Antarctic (bottom)
About 80 per cent of Antarctic marine life is found on the sea floor and the icebergs are crushing animals and plants that living up to 500 metres below the surface.
While they do promote biodiversity by creating space for marine animals to live, too much scouring could change the distribution of key species and affect the type and number of creatures living in Antarctic waters, the researchers warned.
The number of icebergs scouring the seabed is expected to increase in the short-term as global warming continues to reduce the size and duration of winter sea ice, the study published in the journal Science said.
Lead author of the survey, 'Ice scour disturbance in Antarctic waters', is Dan Smale of the British Antarctic Survey. He said: "Conversely, on longer time scales (centuries) we envisage a drastic reduction of ice disturbance, as glaciers of the Antarctic Peninsula retreat past their grounding lines and the amount of freefloating sea ice (which scours the very shallows) decreases."
This was the first attempt to test the relationship between iceberg scours and the formation of winter sea ice.
Dr Smale's team laid markers in grid patterns at different depths along the seabed in the West Antarctic Peninsula.
While a host of factors - including depth, seabed topography, prevailing wind directions and proximity to icebergs - influenced the probability of impact, the strength of the link between scours and sea ice formation was surprising, Dr Smale said.
"During years with a long sea ice season of eight months or so, the disturbance rates were really low, whereas in poor sea ice years the seabed was pounded by ice for most of the year," he said.
"This is because icebergs are locked into position by winter sea ice, so they are not free to get pushed around by winds and tides until they crash into the seabed."
The study has been dedicated to one of the authors, Kirsty Brown, a marine biologist, who died in 2003 during the fieldwork in the Antarctic.
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