Authors: Post, A.L., O’Brien, P.E., Beaman, R.J., Riddle, M.J., De Santis, L.
Publication: GeoHab 2010, 3-6 May 2010, Welington, New Zealand.
Dense coral-sponge communities on the upper continental slope at 570-950 m off George V Land, East Antarctica have been identified as ‘vulnerable marine ecosystems’ (VMEs) by CCAMLR and are now closed to bottom fishing. The challenge now is to understand their likely distribution on other parts of the Antarctic margin. We propose some hypotheses to explain their distribution on the George V margin.
Icebergs scour to about 500 m in this region and the lack of such disturbance is a likely factor allowing the growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons. The canyons in which they occur receive descending plumes of Antarctic Bottom Water formed on the George V shelf and these water masses could entrain abundant food for the benthos. The canyons harbouring rich benthos are also those that cut the shelf break. Such canyons are known sites of high productivity in other areas because of a number of oceanographic factors, including strong current flow and increased mixing with shelf waters, and the abrupt, complex topography.
These proposed mechanisms provide a framework for the identification of other areas where there is likely to be a risk of encountering such VMEs.