Summer plankton communities of the Northern Dvina river and its tributaries

The work is a part of a comprehensive study of the rivers of the south-east of the Arkhangelsk region, carried out with the aim of developing aquaculture in inland waters. Qualitative and quantitative characteristics for the plankton communities state of the Northern Dvina River such as species composition, abundance, and biomass were obtained in the summer period of 2021. For tributaries these characteristics were obtained for the first time. The species diversity of phytoplankton and the saprobiological state of waters were assessed using indices. An assessment of the watercourses trophicity was carried out. 133 taxa of microalgae from eight systematic divisions, and nine zooplankter species of three taxonomic groups have been identified. The basis of the algoflora has been established to be diatoms, green algae, and cyanobacteria. Zooplankton communities were characterized as cladocerne-rotifers, with a significant predominance of cladocerans. The data obtained can be used for ecological monitoring of the region aquatic ecosystems, for assessing the fish productivity of water bodies, and calculating the damage to aquatic biological resources from economic activity.