Распределение зоопланктона в поверхностном слое Шекснинского водохранилища
Zooplankton distribution in the superficial layer of the Sheksna Reservoir

Summary/Abstract: The results of the studies of zooplankton collected in the superficial layer in different parts of the Sheksna Reservoir at the beginning of the August 2007 are presented. A total of 71 species have been recorded among which crustaceans prevail in the number of species, abundance and biomass. Zooplankton is distributed unevenly in the surface layer; the maximum density and biomass are recorded in the north-eastern part of the Lake Beloye – 164 000 ind/m3 and 1.06 g/m3, in the Sizma extension – 124 000 ind/m3 and 1.60 g/m3 and in the near-dam reach - 185 000 ind/m3 and 1.36 g/m3, respectively. The minimum values are recorded near the mouths of rivers Kovzha Belozerskaya (17 000 ind/m3 and 0.10 g/m3) and Kema (10 000 ind/m3 and 0.06 g/m3). Because of high concentration of fine-dispersed mineral suspended matter the water transparency decreases significantly. The water is polluted with the oil products and the rotifers of the genus Brachionus – indicators of polluted water – are dominated in the plankton. Zooplankton in the surface layer where blue-green algae are in mass differs from deeper horizons in lower abundance and biomass.

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