MODERN SITUATION OF ZOOPLANKTON IN THE KHOROSHEE LAKE

Abstract

The Khoroshee Lake is a basin of regular fishing where fish productivity is 30-36 kg/ha. The research on zooplankton of the Khoroshee Lake was carried out in 2003-2004 and 2012-2015. Zooplankton contains 28 fish species from 3 systematic groups: 11 rotifers, 10 Cladocera and 7 copepods. Fish species number varied from 4 to 16 where Cyclops strenuus Fisch dominated in the zooplankton of the lake. Subdominants in different years are different: Daphnia cucullata Sars and Diaphanosoma brachyurum (Lievin) in 2003-2004; and Daphnia longispina (O.F. Müller) and Diaptomus gracilis Sars in 2012-2015. The average number of zooplankton varied from 15.075 tо 67.036 thousands of fish pro m3, and biomass - from 0.550 to 2.263 g/m3. The copepods made the prominent part of the number: their number was 80% of total number in 2003 and biomass - 51.9; in 2004- 78.2 and 51.3% correspondently. The number of copepods varied from 70.1 to 74.3 % in 2013-2015 and biomass - from 54.2 to 67.3 %. Copepods domination in zooplankton is explained by grazing of copepod zooplankton by the fish. The Khoroshee lake is referred to the basins of low and average productivity class and characterized as low and average basin on feeding. The lake contains the reserve for growing of plankton eater-fish. The calculation of prospective fish production by means of plankton recycling has shown that the basin allows to grow additionally from 12.4 to 107.2 kg/ha or from 50.21 to 434.0 tons of fish.