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MEPS 142:75-86 (1996)  -  doi:10.3354/meps142075

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

Pesant S, Legendre L, Gosselin M, Smith REH, Kattner G, Ramseier RO

Environmental control and potential fate of phytoplankton production were investigated in the Northeast Water Polynya (77° to 81°N), from 23 May to 31 July 1993. Sampling covered a mosaic of conditions ranging from open to fully ice-covered waters. Three regimes of phytoplankton production are identified, on the basis of the contribution of phytoplankton size fractions (>5 µm and <5 µm) to total pigment biomass and production: (1) One regime corresponded to heavily ice-covered (>50%) 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. (3) In the other regime, the surface layer was strongly influenced by melt water, the pycnocline was relatively deep (>10 m), the biomass was dominated by large phytoplankton, production was shared by small and large phytoplankton, and maximum chl a was associated with the pycnocline. The dominant taxa in the 3 production regimes were flagellates, pennate diatoms and centric diatoms, respectively. The different primary production regimes reflect different export characteristics and could correspond to different pelagic food webs.

Phytoplankton production regimes · Size fractions · Exportation · Food webs · Northeast Water Polynya

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