Study of Sea-bed Colonies of Bryozoans Suggest Evidence for Trans-Antarctic Seaway
31.08.2010 - Water & Oceans, Ice & Snow, Flora & Fauna, Antarctic
Within the framework of a study for the Census of Antarctic Marine Life (CAML), scientists from British Antarctic Survey (BAS) had a look at sea-bed colonies of bryozoans. Analyzing these colonies, which stretch from coastal to deep-sea regions around Antarctica, the team found similarities in different species of bryozoans separated by about 2,400 kilometers of the West Antarctic Ice Sheet. In their findings, published in the journal Global Change Biology, the team suggests that the species could have spread across the Ross and Weddell Seas only by means of a trans-Antarctic seaway, which has since turned into thick ice over time.
According to the team, this Antarctic seaway could have opened up during a recent interglacial period at a time when the global sea level reached about 5 meters above its current level. Because the larvae of these animals sink to the seabed and anchor themselves to it in their adult stage over a short period, the species are quite unlikely to have been moved around by ocean currents. Yet the striking resemblance between the two different species from the Weddell and Ross Seas suggests that colonization of both by the species is necessarily linked to a past trans-Antarctic seaway.
However, outside the field of biology, the evidence the team found might prove crucial in the studies on the stability of the West Antarctic Ice Sheet (WAIS). These studies are, in turn, crucial in determining the rate of sea level rise in the coming centuries. While a complete future collapse of the WAIS could raise the sea level worldwide by up to 5 m, the lead author of the paper, Dr David Barnes of the British Antarctic Survey, said that the research “[…] provides compelling evidence that a seaway stretching across West Antarctica could have opened up only if the ice sheet had collapsed in the past.”
