Phytoplankton and phytoperiphyton in lake Khedo used for cages trout

Data are reported about the formation of phytoplankton and phytoperiphyton communities in Lake Khedo (Karelia republic, White Sea catchment) under the effect of effluent discharges from a trout farm. The purpose of this paper is to assess how informative phytoperiphyton structural parameters are, and to assess the feasibility of using them for biological monitoring of river quality. The influence of anthropogenic impacts on periphyton communities was analyzed in terms of species richness, species diversity, species ecology values, biomass and chlorophyll concentration. At present, effluents discharged into the lake from the trout farm cause no profound transformations in the structure of aquatic organism communities. The results of the chemical analysis of water indicate a low level of anthropogenic influence. Although a slight increase in the concentration of suspended matter and heavy metals in the water near the cages was recorded. The structure of algae communities is due primarily to specific hydrographic location and hydrological characteristics of lake. The composition and ratio of most common species of algae communities in the lake is typical for cold-water, oligotrophic reservoirs of the boreal and subarctic zones, with low mineralization, not experiencing a significant anthropogenic load. The biotic indices and hydrochemical indicators indicated mainly a low degree of pollution, so the lake waters could be classified as belonging to water purity class II. Relatively high values of the abundance and biomass of phytoplankton and phytoperiphyton, in the Lake Khedo comparing to the average values for the studied region make it possible to conclude on the favorable conditions in the lake and on the stability of communities.