The impact of urbanization on the communities of macrophytes, phyto-, zooplankton and macrozoobenthos of the rivers of the Sukhona river basin

We considered the influence of urbanization of the catchment area and population density on water quality in lowland watercourses, using hydrochemical and hydrobiological indicators. The water quality was assessed for 4 groups of hydrobionts: macrophytes, phytoplankton, zooplankton, and zoobenthos, using the example of 6 tributary watercourses of the Sukhona River (the White Sea basin), For each of the 10 stations, a catchment area was built, within which the degree of urbanization of the catchment area, population density, and plowing were calculated. The water pollution index (estimated by hydrochemical indicators) increases with growing urbanization of the catchment area. The composition of aquatic flora and fauna of watercourses is determined by their territorial proximity, hydrological conditions and anthropogenic load. Quantitative indicators and species richness of planktonic organisms are determined primarily by the size of the river and do not depend on anthropogenic pressure on the catchment area. The species diversity and saprobity estimated for planktonic organisms are at the same level for all stations and also do not depend on anthropogenic load. Among macrophytes, only the number of hydrophyte species decreases with increasing urbanization of the catchment area. The species richness and diversity of zoobenthos significantly decreases with an increase in the proportion of settlements and population density in the catchment area. The water quality assessed by zoobenthos also deteriorates with increasing urbanization of the catchment area.