Structure of microphytobenthos in the pelagic and littoral areas of Kyiv Reservoir

The paper considers the common features and differences in the microphytobenthos structure in the littoral and pelagic areas of Kyiv Reservoir. The findings may be used for more precise water quality assessment in the bottom layers of shallow and deep-water areas. The retrospective data overview shows that for 60 years of Kyiv Reservoir’s existence the bottom algal communities has been represented by polydominant complex of Bacillariophyta — Chlorophyta — Cyanobacteria. During the period of microphybenthos studies since 1966 to 1984 its species and intraspecies diversity varied within 104 species (146 ist) — 165 species (234 ist), and according to our field data includes 194 species (199 ist), which is indicative of the the bottom algal communities’ long-term stability. The microphytobenthos structure in the littoral and pelagic areas is similar at the highest taxonomic levels (phylum — order), and differences are evident at the family – species levels. The highest occurrence rate in the littoral area (17–100%) and pelagic area (33–100%) was observed for 22 species, among which pennate diatoms prevailed. Out of the total species number only 4 species had 100% occurrence rate both in the littoral and pelagic area. This is indicative of the distinctness of the microphytobenthos taxonomic composition in the littoral and pelagic areas and heterogeneity of its structure. The differences in the occurrence rate (%), multiple indices of Sørensen similarity, Kendall coefficient show more pronounced heterogeneity of micro-phytobenthos in the pelagic area. According to the ratio of indicator species of saprobity and Pantle-Buck indices in Sladeček modification the water quality of the areas under study is characterized as “moderately polluted”, β-mesosaprobic zone, 3rd class of water quality. The findings of the parallel studies on the taxonomic structure of bottom algal communities in Kyiv Reservoir show their distinctness in the littoral and pelagic areas, high diversity and important role in the autotrophic link functioning.