Spatio-temporal organization of phytoplankton in Peipsi lake

In the article, the results of the study of phytoplankton received at 16 stations of the Lake Peipsi in the spring (May), summer (August) and autumn (October) within the period of 2012–2015 were analyzed. 186 phytoplankton species were found. The list of mass taxa is given. It was noted that phytoplankton biomass had wide amplitude of annual average values in different lakes: Lake Peipsi/Chudskoe 2.1 ± 0.2 (0.3–23.0) mg / L; Lake Pihkva/Pskovskoe 5.4 ± 1.4 (0.4–34.0) mg / L and Lake Lämmijärv/Teploe 6.1 ± 1.2 (3.4–25.1) mg / l. According to species composition, structure and biomass of phytoplankton the lake belongs to the mesotrophic reservoirs with eutrophic features, as it was in previous years of observation. The water quality in the different parts of Lake Peipsi corresponded to conditionally pure water (1st quality class) and slightly polluted one(2nd quality class). Correlation between characteristics of phytoplankton and the environmental factors (temperature, water level, transparency, N and P concentration in water) was detected.