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Faunal evidence for a late quaternary trans-Antarctic seaway

A tiny marine filter-feeder that anchors itself to the sea bed offers new clues about the stability of the West Antarctic Ice Sheet. As part of a study for the Census of Antarctic Marine Life (CAML), BAS scientists analysed sea-bed colonies of bryozoans from coastal and deep-sea regions around the continent and from further afield. Striking similarities were found 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 (WAIS).

This new finding means that these animals could have spread across both seas only by means of a trans-Antarctic seaway, through what is now a 2km-thick layer of ice. It also suggests that this seaway opened up during a recent interglacial, perhaps as recently as 125,000 years ago, when sea level was about 5m higher than today.

While some geological evidence suggests that the 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 have been obliterated during ice ages by advancing glaciers that bulldozed their fossil remains off the continental shelf.

This new biological evidence contributes to glaciological investigations focused on the future stability of the WAIS, which may have a major impact on the rate of sea-level rise in the coming centuries. Scientists estimate that a complete collapse of the WAIS would raise global sea level by around 3.3m to 5m.

Find link to the full paper in the NERC Open Research Archive


David K. A. Barnes and Claus-Dieter Hillenbrand


Global Change Biology (2010) 16, 3297–3303, doi: 10.1111/j.1365-2486.2010.02198.x