The state of communities of aquatic invertebrates (plankton, benthos) in the conditions in the cage salmon farm
The results of the monitoring of the status of the biota in the artificial reservoir with functioning of cage salmon farm in one of the three reservoirs of the Republic of Komi presented. According to hydrochemical parametrs Nuvchim reservoir belongs to the category oligosaprobic water bodies, and water quality is assessed as «clean water». However, it was found that the content of organic substance in bottom sediments in the cage salmon farms zone was slightly increased. The composition, quantitative indices of development, distribution of Zooplankton and zoobenthos in this article discussed. The trophic status of the reservoir was estimated from oligo - to mesotrophic by quantitative indexes of water invertebrates's development. The composition of zoobenthos's taxonomic groups, species diversity of Zooplankton, quantitative indicators of biota's development and calculated indices assessing the quality of waters, indicate a prosperous condition of the ecosystem of the reservoir. In the zone of cage salmon farm the number of benthos's groups decreased (from 14 to 3 or complete absence), abundance and biomass both plankton and benthos reduced (0,5 - 0,7 times), the trophic status of the water body increased (trophic coefficient has increased in 1,2 - 1,9 times), the eutrophic species Polyarthra euryptera dominated. These facts indicate the presence of negative processes taking place in communities of aquatic organisms in this part of the reservoir.