Reconstructing the Zooplankton Composition of a Former Oligotrophic Lake

This is the authors' abstract. We don't add key points for this paper.

Lake Maly Terenkul in the Southern Urals was oligotrophic about 100 years ago, but after years of pollution from domestic waste, it has become a eutrophic–polytrophic body of water with a massive growth of cyanobacteria. The lake was not studied during the period of oligotrophy. An attempt was made to theoretically reconstruct the composition of the main components of zooplankton—rotifers, copepods, and cladocerans—that inhabited the lake a century ago. For this purpose, materials on the autecology of rotifers and crustaceans were used based on scales of trophic and thermal indicator properties of species previously developed by the author. It has been shown that trophic status is a key factor determining the composition of zooplankton, which is formed in interaction with the fauna of neighboring lakes. An algorithm for the theoretical reconstruction of lake fauna is proposed that includes the determination of the potential trophic status of the water body, an analysis of the current composition of zooplankton and identification of the reasons for its formation in the observed form, the identification of potential sources of immigration into the water body (and especially the “parent” water body, immigration from which had a decisive influence on the formation of zooplankton), and adoption of the composition of its fauna as the basis for reconstruction.