Qualitative and quantitative composition of zoobenthos in the lower reaches of the Northern Dvina River in 2023

The article presents the results of a study of zoobenthos in the lower reaches of the Northern Dvina River in 2023, namely the spatial and seasonal dimensions of the taxonomic composition, abundance and biomass. Oligochaetes, chironomids and bivalve mollusks prevailed in terms of abundance in the studied areas, but bivalves dominatedin terms of biomass in all the sites. In general, zoobenthos abundances varied among sites in the surveyed area of the river in a fairly wide range (from 341 ind./m2 to 1718 ind./m2), with a maximum abundance at the railway bridge (left bank) over the Northern Dvina within the city of Arkhangelsk. The average abundance over the study period was 1123 ind./m2. Biomass values ranged from 13.6 g/m2 to 955.5 g/m2, with a maximum in the site within the City of Novodvinsk. The average biomass in 2023 was 267.3 g/m2. Zoobenthos in the lower reaches of the Northern Dvina River varied to different degrees between seasons