Marine Animals Suggest Evidence for a Trans-Antarctic Seaway
ScienceDaily (Aug. 31, 2010) — A tiny marine filter-feeder, that anchors itself to the sea bed, offers new clues to scientists studying the stability of the West Antarctic Ice Sheet -- a region that is thought to be vulnerable to collapse.
As part of a study for the Census of Antarctic Marine Life (CAML), scientists from British Antarctic Survey (BAS) analysed sea-bed colonies of bryozoans from coastal and deep sea regions around the continent and from further afield. They found striking similarities in particular species of bryozoans living on the continental shelves of two seas -- the Ross and Weddell -- that are around 1,500 miles apart and separated by the West Antarctic Ice Sheet.
This new finding, published this month in the journal Global Change Biology, leads the science team to conclude that these animals could have spread across both seas only by means of a trans-Antarctic seaway through what is now a 2 km solid layer of ice. They suggest also that this seaway opened up during a recent interglacial (warm period between ice ages) perhaps as recently as 125,000 years ago when sea level was about 5 metres higher than today.
While some geological evidence suggests that the West Antarctic Ice Sheet (WAIS) collapsed at least once in the last million years, scientists are keen to determine the frequency of collapse and to understand the processes and connections between warm periods and deglaciation events. Elsewhere around Antarctica the marine animals that could help scientists estimate the date when West Antarctica was ice free, were obliterated during ice ages by advancing glaciers that bulldozed their fossil remains off the continental shelf.
Article continues: http://www.sciencedaily.com/releases/2010/08/100831073254.htm