Zooplankton of Varvara Water Reservoir
The aim of article is a comprehensive study of the zooplankton in Varvara water reservoir. Methods. The collection of materials was carried out according to the methods adopted in hydrobiological research (plankton). Apstein’s net and nets of various sizes were used. Results. In 2019-2020 in Varvara water reservoir, 39 species and 2 subspecies related to zooplankton were recorded. 19 species of them belong to rotifera ( S. pectinata, P. vulgaris L. luna, A. priodonta, L. quadridentata, L. lunaris, T. tetractis, L. ovalis, B. quadridentatus, B. bennini, B. falcatus, B. diversicornis, B. calyciflorus, B. angularis, P. patulus, K. cochlearis, K. quadrata, F. longiseta, H. mira) , 11 species and 1 subspecies belong to cladocera (D. longispina, D. l. hyalina, S. vetulus, M. brachiata, C. reticulata, S. mucronata, M. hirsuticornis, G. testudinaria, Ch. sphaericus, P. aduncus, A. affinis, B. longirostris) , 9 species and 1 subspecies belong to copepoda ( Arct. acutulobatus, M. fuscus, M. albidus, E. serrulatus, E. m. macruroides , P. f. fimbriatus, C. vicinus A. gigas, M. gracilis, T. dybowskii). The quantitative development of zooplankton in Varvara water reservoir was uneven. Thus, the maximum abundance and biomass of zooplankton was recorded in the spring of 2019 (51771 ind. - 10952,00 mg per 1 m<sup>3</sup> of water), the minimum abundance and biomass in January 2020 (3847 ind./ m<sup>3</sup> - 750,04 mg/m<sup>3</sup>). Conclusion. The density maxima of rotifers and nauplial stages of copepods correlate with the maximum quantitative development of many ciliates of bacteriophages.