WATER QUALITY ASSESSMENT OF THE BASIVKUT RESERVOIR BY PHYTOPLANKTON INDICATOR SPECIES

Abstract

The article analyzes the species composition, changes in abundance, biomass, information diversity of phytoplankton of theBasivkut Reservoir and evaluates water quality by indicator species. Phytoplankton of the Basivkut reservoir is represented by 121 species (125 intraspecific taxa (intraspecific taxa)) belonging to 8 divisions, 12 classes, 29 orders, 45 families and 84 genera. It is shown that phytoplankton of the Basivkut Reservoir is formed by Chlorophyta (40.0% of the total number of species), Bacillariophyta (27.2%), Cyanobacteria and Euglenozoa (12.8% each). There is a clearly insignificant representation of species of the departments Miozoa (3.2%), Ochrophyta (2.4%), Cryptophyta and Streptophyta (0.8% each). The highest generic coefficient was recorded for Euglenozoa (2.3). It was established that the biomass of phytoplankton varies from 0.8732 mg/dm3 (July) to 9.4828 mg/dm3 (October), and the number – from 4654 thousand cells/dm3 (June) to 14212 thousand cells/dm3 (August). The Shannon index varies from 0.62 bp/mg to 5.07 bp/mg (by biomass) and from 2.13 bp/ex to 4.50 bp/e (by abundance) The saprobity index varies from 1.74 to 2.14, which corresponds to III quality class (moderately polluted water). The core of thephytoplankton of the Basivkut Reservoir is formed by planktonic-benthic (43%) and planktonic (24%) species, slow-flowing in terms of water saturation with oxygen and rheophilicity (75%), indifferent in relation to salinity (85%) and pH (60%). Among the indicators of the temperature regime, algae of the temperate range and eurythermal are equally represented. The most  represented species are autotrophs that can withstand high concentrations of nitrogen-containing organic compounds (52%). The level of trophicity is dominated by mesoeutrophic species (30%), however, oligo-mesotrophic and m-mesotrophic species are represented (18% each). Species-indicators of organic pollution (according to the Watanabe system) are mainly represented by Eurysaphrobes (61%), which indicates moderately polluted water of the Basivkut Reservoir. According to the Pantle-Buksystem (as modified by Sladechek), the most numerous group is betamesosaprobionts (51%) and oligo-alpha-mesosaprobionts (18%). It was determined that the water of the Basivkut reservoir corresponds to the III quality class (moderately polluted) according to the level of organic pollution according to the Pantle – Buk system (in Sladechek’s modification).