Vegetable communities in the lakes of Karelian isthmus central part as indicators of their ecological state

According to summer supervision in 2010-2012 the assessment of an ecological state of 20 polytypic lakes of Karelian Isthmus in hydrochemical parameters and structure of vegetable communities (phytoplankton, periphyton, macrophytes) is carried out. The trophic status of lakes and level of their saprobity are estimated. According to the content of the common phosphorus and chlorophyll a the trophic status of studied lakes fluctuates from oligotrophic to gipertrophic; the majority of lakes - mezotrophic. The increase in biogenic loading at lakes leads to increase in biomass of phytoplankton and decrease in its biodiversity. Changes of taxonomical structure of vegetable communities among increase in eutrophication of lakes are revealed.