The reconstruction of hydrobiological data for lakes of Karelia

The factors which determined the variability of hydrochemical and hydrobiological pa-rameters of lakes of Karelia (in total 225 lakes) are analyzed. It is shown that oligo-mesotrophic lakes dominate among studied water bodies whereas the share of eutrophic lakes is low (about 10%). The biomass of phytoplankton and zooplankton was not exactly reconstructed by using the total phosphorous concentration as the argument in regression analysis due to high variability of these parameters. The hydrochemical and hydrobiological indexes were worked to classify the lakes of Karelia. The methods of prognoses of zooplankton biomass (with accuracy of 55–86%) and benthos biomass (with accuracy of 71–78%) on the base of the total phosphorous concentration were worked by using the contingency tables.