MESOPLANKTON IN THE EASTERN PART OF THE KARA SEA AND OB AND YENISEI RIVERS ESTUARIES

The material was collected in the second part of September, 1993. Average mesoplankton biomass in the marine ice-neritic community was 17.3 g/m2. Calanus finmarchicus s.l. made up about a half of that. The surface desalted waters ingabited with a saltish-water species complex and the lower sea waters with the impoverished marine species complex were clearly distinguished in the rivers estuaries. In the Yenisei estuary the mesoplankton biomass was low and varied from 0.3 to 2.9 g/m2. Zooplankton of the Gulf of Ob was, on the contrary, in abundance. The plankton biomass in the near-bottom layer reached 20.6 g/m3, or 65.2 g/m2 in the zone of hydrochemical and salinity front. As a whole, the Kara Sea in an oligotrophic water body: in September primary production is lower that in the poorest ocean regions (Sargasso Sea). The bulk of detritus sinks to the bottom and is not used by zooplankton cummunities.