ФИТОПЛАНКТОН КАК КОМПОНЕНТ КОРМОВОЙ БАЗЫ МУНОЗЕРА (БАССЕЙН ОНЕЖСКОГО ОЗЕРА)

Abstract

The paper presents the results of a study of phytoplankton in Lake Munozero during the vegetation period in 2018. The seasonal dynamics of the biomass and abundance of algae in the southern and northwestern reaches experiencing different anthropogenic pressures has been considered. The reservoir stands out among other water bodies of the Republic of Karelia for its chemical and morphometric characteristics. It is characterized by high mineralization (up to 100 mg/l), isolation of the reaches, low color and content of nutrients and organic compounds. There have been identified 147 taxa of the algoflora with a rank lower than the genus, belonging to 9 divisions. The structure of algocenoses in terms of species richness and quantitative development is determined by representatives of centric diatoms, cyanobacter, dinophytes, and chlorococcal greens, which is important for the formation of the fish food base. Average size of phytoplankton during 2018 in the northwestern reach reached 492 thousand cells/l, the average biomass was 0.468 g/m3. The average size of phytoplankton in the southern reach reached 589 thousand kg/l, the average biomass was 0.459 g/m3. The water quality in the northwestern and southern reaches by the value of the saprobic index corresponds to the III class of waters, but the biomass values characterize both parts of the reservoir as oligotrophic. Shannon's index, quantitative and structural characteristics of phytoplankton differ in the northwestern and southern reaches, seasonal dynamics is not typical for phytoplankton of the oligotrophic Karelian lake. According to the data on abundance and biomass of phytoplankton of Lake Munozero the value of commercial fish catch was calculated.