ZOOPLANKTON OF VARIOUS BEAVER PONDS IN PROTECTED TERRITORY OF KOSTROMA ZAVOLZHIE REGION

The paper examines structural features of hydrobiont communities in small watercourses of the European part of Russia under conditions of flow regulation by the Eurasian beaver. The research was conducted in the territory of the M.G. Sinitsyn State Nature Reserve "Kologrivsky Forest", where direct anthropogenic impact on the watercourses is excluded. The parameters of zooplankton development were used as an indicator of the impact of beaver activities. A comparison of the abiotic conditions and the main characteristics of zooplankton communities in flowing and beaver-regulated sections of small watercourses is presented. It is shown that in zoogenically transformed conditions, compared to flowing areas, the water transparency, pH and specific electrical conductivity are lower, and the temperature and BOD5 are higher. Zooplankton in conditions of flow regulation by beavers is characterized by an increase in comparison with flowing sections, zooplankton is characterized by: greater specific species richness, increased abundance, biomass, higher values of the Shannon species diversity index and saprobity, but lower values of the Pielou index. An original classification of beaver ponds is presented, based on the morphological features of the floodplain of watercourses, the size of the spill, the time of existence of ponds and the duration of residence of beaver families. The abiotic characteristics of each type of pond and the features of the development of zooplankton communities were analyzed. Based on the features of qualitative composition, quantitative characteristics, and the ratio of taxonomic and ecological groups of planktonic invertebrates, two diametrically different types of beaver ponds were identified: ponds on river sections with high floodplains and perennial ponds on streams. In ponds on river sections with high floodplains the structure of zooplankton communities is characterized by typical features of the consequences of zoogenic eutrophication, in perennial ponds on streams — of anthropogenic eutrophication. Ponds of other types present modifications of the processes of zooplankton communities organization under the influence of zoogenic factors.