Size-differential regimes of phytoplankton production in the Northeast Water Polynya (77*-81*N)

Abstract

Environmental control and potential fate of phytoplankton production were investigated in the Northeast Water Polynya (77" to 81N), from 23 May to 31 July 1993. Sampling covered a mosaic of conditions ranging from open to fully ice-covered waters. Three reglrnes of phytoplankton production are identified, on the basis of the contribution of phytoplankton size fractions (>5 pm and <S pm) to total pigment biomass and production: (1) One regime corresponded to heavily ice-covered ( > 5 0 % ) areas and was characterized by biomass and production dominated by small phytoplankton. The 2 other production regimes were found in open waters and/or mixed ice conditions. (2) In one case, surface stratification was strong, nutrients were abundant, biomass and production were dominated by large phytoplankton, and maximum chlorophyll a [chl a) was located near the surface.