ANTARCTIC SEA ICE - A HABITAT FOR THE FORAMINIFER NEOGLOBOQUADRINA-PACHYDERMA

The pelagic foraminifer Neogloboquadrina pachyderma (Ehrenberg, 1861) occurs in new ice, congelation ice, and the underlying water column of the Weddell Sea. Neogloboquadrina pachyderma is incorporated into the ice in large numbers at the time of its formation. The average number of foraminifers per liter of ice was 87 and numbers ranged between 0 and 1,075. Sea ice contained 70 times more foraminifers per unit volume than the underlying water column and on an areal basis the sea ice cover has approximately the same number of specimens as 60 m of underlying water column. The foraminifera are usually incorporated into the ice when it is being formed dynamically and are thus subsequently associated mainly with granular ice. Many foraminifers are able to survive and grow in the ice where algal biomass in winter is high compared to the water column, perhaps indicating an overwintering strategy. Arctic sea ice, on the other hand, is practically devoid of foraminifers. These observations may have implications for paleoceanographers who use N. pachyderma as a tool to reconstruct past surface water conditions.