CARBON AND NITROGEN UPTAKE RATES OF PHYTOPLANKTON FROM IN SITU INCUBATIONS UNDER THE SEA ICE IN THE CANADA BASIN

Abstract

Although ongoing changes in climate and ice conditions are expected to alter the carbon and nitrogen uptake rates of phytoplankton as primary producers in the Arctic Ocean, recently a few measurements have been done in the Canada Basin. The expedition in 2005 allowed us to provide a valuable data for the uptake rates of phytoplankton under the sea ice from in situ incubation, compare them with the 2002 data under different environmental conditions in the same basin, and form a backbone for any future discussion of impacts of global warming on the primary productivity in the region. The patterns of nutrient concentrations were similar, whereas the surface water temperature patterns were quite different between in 2002 and 2005. Since stronger light intensity through the sea ice reached to the ice bottom in 2005, the carbon and nitrogen uptake rates of phytoplankton under the sea ice were higher in 2005 than in 2002. The mean f-ratio from this study in 2005 was 0.31 (±0.12) which is within the range in the Arctic Ocean.