The fate of production in the central Arctic Ocean – top–down regulation by zooplankton expatriates?

We estimated primary and bacterial production, mineral nutrients, suspended chlorophyll a (Chl), particulate organic carbon (POC) and nitrogen (PON), abundance of planktonic organisms, mesozooplankton fecal pellet production, and the vertical flux of organic particles of the central Arctic Ocean (Amundsen basin, 89-88° N) during a 3week quasi-Lagrangian ice drift experiment at the peak of the productive season (August 2001). A visual estimate of approximately 15% ice-free surface, plus numerous melt ponds on ice sheets, supported a planktonic particulate primary production of 50-150mgCm-2d-1 (mean 93mgCm-2d-1, n=7), mostly confined to the upper 10m of the nutrient replete water column. The surface mixed layer was separated from the rest of the water column by a strong halocline at 20m depth. Phototrophic biomass was low, generally 0.03-0.3mgChlm-3 in the upper 20m and