High Salinity Shelf Water signature in the new formed AABW near Cape Adare: implications for dark ocean ecosystems

In the Pacific sector, High Salinity Shelf Water (HSSW) is a key constituent of the Antarctic Bottom Water (AABW) that plays an important role in ventilating the global deep ocean. HSSW is formed by brine release during sea ice formation when katabatic wind produces important polynya phenomena mainly in southern Victoria Land near Terra Nova Bay (TNB). HSSW fill-up the whole Drygalsky basin as bottom water, dense enough to flow northward and trigger downslope processes to the abyssal depths near C. Adare region. During February 2006, within the XXI° PNRA expedition, CLIMA & PolarDOVE Projects, a benthic boundary layer mooring was deployed off the Cape Adare at 2300 meter depth. At the same time few transects of the shelf break were carried out in order to have a snapshot of the shelf-slope system behaviour. The mooring was recovered successfully in January 2008 given us the opportunity to have a two year long time series of the evolution of the bottom boundary layer during IPY period. The biological determinations showed a clear signal of high metabolic processes within the HSSW, at the same the 2 year long T-S-currents analysis of the benthic boundary layer allows us to make some hypothesis of dark ecosystem functioning.