Seasonal Dynamics of Algal Flora of Lake Zasvitske (Rivne Region, Ukraine)

This study considers the algal flora of Lake Zasvitske (Rivne region, Ukraine). The author identifies 61 species of algae presented with 62 intraspecific taxa subdivided into nomenclatural types that belong to 8 divisions, 13 classes, 24 orders, 34 families and 51 genera. The paper demonstrates that Bacillariophyta, Chlorophyta, Cyanobacteria and Streptophyta play a significant role in lake phytoplankton development. According to the population, the Shannon diversity index varies from 2.13 bit/spec. (October) to 3.89 bit/spec. (July), and according to biomass this index varies from 1.63 bit/spec. (June) to 4.10 bit/spec. (July). In the lake phytoplankton, polydominant structure prevails. In Lake Zasvitske the phytoplankton core is developed with planktonic-benthic and planktonic species, slow-flowing species according to water saturation with oxygen and rheophilicity, indifferent species in relation to the density, pH level of the environment and water temperature, mesoeutrophic ones and species with wide amplitude according to the trophic level. Eurysaprobes (according to the Watanabe system) and beta-mesosaprobionts (according to the Pantle-Buk system as modified by Sladecek) are predominant among indicator species of organic water pollution.