The Retrospective Analysis of Aquatic Ecosystem Modification of Russian Large Lakes under Antropogenic Impacts pp. 309-324
Authors: (Tatyana I. Moiseenko, Andrey N. Sharov, Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia)
Abstract: The retrospective analysis of aquatic ecosystem long-term changes in the Russian large lakes: Ladoga, Onega and Imandra are given. The lakes in past were oligotrophic, similar in their origin, water chemistry and fauna. The ecosystems transformed under the impact of pollution with toxic matters and nutrients. There are three stages of ecosystem quality: background parameters, degradation and recovery trends after the decrease of the toxic stress. On the stage of degradation species abundance and community biodiversity were decreased. Eurybiontic species abundance and biomass were increased due to lack of competitive connections in toxic conditions and biogenic inflow. Small forms of organisms (r-strategists), providing more rapid biomass turnover in ecosystem, dominated in the formed plankton communities. On the stage of decrease of the toxic pollution, the lakes recolonization with northern species is proceeding, that‘s approved by replacement of dominating complexes, increasing index of plankton community biodiversity and rising of individual mass of organisms of communities. Accumulated nutrients in ecosystems are efficiently utilized by upper trophic level. The ecosystem state after decrease of the toxic impact indicate formation of its mature and more stable modification, which differs from a natural one.