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Diadromous marine and freshwater Atlantic salmon occurs in Karelia’s water bodies. Freshwater salmon populations are listed in the Red Data Books of the Russian Federation and the Republic of Karelia. Marine salmon occurs in relatively small Karelia’s rivers flowing into the White Sea. In the past few decades, the deleterious influence of economic activities on North European Russia’s valuable fish stock tends to increase. As a result of hydraulic construction and other types of human activities, the White Sea salmon stock has rapidly decreased. An efficient way of restoring its abundance is “farm” reproduction. In the Republic of Karelia, artificial salmon reproduction is carried out at Vyg and Kem fish farms. One of the methods used to improve fish production quality is to apply laser radiation to salmon eggs and juveniles during “farm” reproduction. Application of low-intensity laser radiation to fish in a certain dose range has been shown to improve the compensatory adaptation of organisms. As a result, death rate declines and fish samples grow more rapidly. To reconstruct and maintain the original structure of Atlantic salmon populations in Karelia’s water bodies, purpose-oriented fish breeding, which comprises farm reproduction, fish protection and the recultivation of spawning and growing grounds, is needed.

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The following paper assesses the current state of the phyto- and zooplankton and benthic communities of Lake Tulos, which geographically is a part of the Green Belt of Fennoscandia. The lake is located on the territory of the planned National Park Tulos. The species diversity, the ratio of major taxonomic groups and the structure, abundance and biomass of predominant aquatic organism species in the littoral and pelagic zones of the lake were studied. According to the obtained results (the level of quantitative development and the ratio of phytoplankton species during the growing season 2018) the waters of Lake Tulos can be assigned to the third quality class, grade 3a (fairly clean), which corresponds to the -mesosaprobic zone by the saprobity scale. According to Pantle-Bukk saprobity index calculated on the basis of zooplankton, the lakes water can be attributed to oligosaprobic - the 2nd class of quality, pure natural waters. Indices of abundance of macrozoobenthos correspond to the oligotrophic class, according to the ratio of its main groups, the lake belongs to the chironomid type of lakes. The reservoir has a high recreational potential, according to the ichthyofauna composition it belongs to the water bodies of the first fishery category. Lake Tulos is a reference water body convenient for environmental monitoring in near-border areas.