Biological interpretation of the third main factor influencing the long-term dynamics of hydro-ecological parameters of the three Naroch lakes under variable nutrient loading in 1978-2015
T. I. Kazantseva1, B. V. Adamovich2, T. M. Mikheeva2
1Zoological Institute of RAS, St. Petersburg, Russia
2Belarusian State University, Minsk, Belarus
Keywords: lake ecosystems, long-term dynamics, trophic state, cyclic components, PCA method, SSA method, interpretation of main factors, Naroch lakes
Abstract
The results of continuous monitoring of the Naroch lakes system, which includes eutrophic Lake Batorino, mesotrophic Lake Myastro and oligo-mesotrophic Lake Naroch, were used to study the question of what factors most affect the long-term dynamics of the state of the lake ecosystem that is under variable load of biogenic elements. The set of continuous series of seasonal mean values of eight parameters of each ecosystem for 1978-2015 was analyzed by methods of singular spectrum analysis (SSA) and principal component analysis (PCA). The third principal component (F3) which contributed 8,2 %, 9,8 % and 13,3 % respectively to the dynamics of ecosystems of Lake Batorino, Myastro and Naroch turned out to be connected with biomasses of phyto- and zooplankton, as well as with the parameters characterizing processes of destruction and biochemical decomposition of organic matter. Comparison of statistical relationships and periods of the dominant cyclic components of the principal components F3 and associated parameters of ecosystems allowed us to conclude that the interpretation of the third main factor under conditions of variable load of biogenic elements depends on the characteristics of a particular ecosystem. For ecosystems that are not deficient in nutrients, it can be interpreted as the transfer of created primary organic matter to consumers of the next trophic level, related to 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 nutrients, it is this available amount of nutrients that is the third main factor affecting its long-term dynamics.
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