Long-term variations of the trophic state index in the Narochanskie Lakes and its relation with the major hydroecological parameters

Abstract

Variations of the trophic status of lakes Batorino, Myastro, and Naroch were analyzed over a long period of 1978–2013. The lakes form a system of interconnected water bodies with a wide range of trophic states. In the period under consideration, the trophic conditions in the lakes varied from highly eutrophic (Lake Batorino) to oligotrophic (Lake Naroch), making it possible to analyze the long-term changes in the trophic state of the lakes with the use of different variants of evaluating the Carlson index (trophic state index, TSI), to assess the relationship between the three versions of the index with one another, with phytoplankton biomass, and with hydroecological characteristics, such as the concentrations of total N, seston, and organic matter and biochemical oxygen demand. The possibility to evaluate the index by other characteristics, including phytoplankton biomass, was also considered.