Recent history of Lakes Bol’shoe and Zerkal’noe by diatom analysis

Diatom complexes from bottom sediments of two drainless lakes in the Sochi National Park (Krasnodar Krai) have been analyzed. The authors’ method of graphical analysis of diatom complexes has been applied. Two scenarios of transformations of their taxonomic structure have been established. Only one scenario is typical of Lake Zerkal’noe ecosystem. It is determined by external natural impact, the parameters of the state of the ecosystem remaining relatively stable. Two transformation scenarios have been identified in Lake Bol’shoe. The first of them is similar to the processes taking place in Lake Zerkal’noe ecosystem. The second scenario corresponds to transitional stages; it is governed by changes in the parameters of the ecosystem proper. This is due to both natural bogging processes and the increasing anthropogenic impact on lacustrine ecosystems.