Home – Home – Jornals – Contemporary Problems of Ecology 2022 number 4

Since the second half of the 70s of the twentieth century, the ecosystems of lakes Batorino, Myastro and Naroch have undergone stages of anthropogenic eutrophication, targeted deeutrophication and benthification caused by the introduction of the filter-feeding mollusk Dreissena polymorpha Pallas. The set of continuous series of seasonal mean values of eight parameters of each ecosystem obtained in 1978-2015 were analyzed by mathematical-statistical methods of principal components (PCA) and singular spectra (SSA). The analysis showed that the complex long-term dynamics of the set of selected characteristics of the ecosystems of Lake Batorino and Lake Myastro during this period of time was described by three main components by 92 % and 90 % respectively, and the ecosystem of Lake Naroch - by five main components by 94 %. A biological interpretation of these principal components was proposed, i. e. a hypothesis was put forward as to which factors had the greatest influence on the ecosystem dynamics in those years. The first main factor which determined the dynamics of the ecosystems of lakes Batorino, Myastro and Naroch by 63, 65 and 43 % respectively, was interpreted as the resistance of the lake ecosystem to variable biogenic load, which is inversely related to the trophicity of the reservoir. The second main factor, whose contribution to the dynamics of the Naroch lakes ecosystem parameters (in the same order) amounted to 21, 15 and 22 %, was interpreted as solar radiation activity. The interpretation of the third main factor depends on the properties of a particular ecosystem. For ecosystems which are not deficient in biogenic elements (Lakes Batorino and Myastro, the contribution of the factor to the ecosystem dynamics was 8 and 10 %), it can be interpreted as the transfer of the created primary organic matter to consumers of the next trophic level, associated with the structure of the food chain in the ecosystem. For an ecosystem in which the process of primary production formation is limited by the available amount of biogenic elements (Lake Naroch, 13 % contribution of the third main factor to ecosystem dynamics), it is this available amount of nutrients that is the third main factor affecting its long-term dynamics. The fourth main factor, which determined the dynamics of Lake Naroch ecosystem by 9 %, is also connected with the process of primary production formation. Only the fifth main factor, which determined the dynamics of the ecosystem of Lake Naroch during the time period under consideration by 7 %, controls the transfer of primary production to consumers of the first trophic level. Thus, the conducted statistical study not only confirmed empirically established regularities in the functioning of lake ecosystems, but also for the first time allowed us to obtain quantitative assessments of significance of each main factor for ecosystem development in specific circumstances, depending on the degree of trophicity of water body.