The Fish Part of Community of the Vychegda River in a Pulp and Paper Mill-Treated Wastewater Discharge Area

The paper presents the results of a study of the species diversity and individual developmental stability of common fish species from the Vychegda River in the discharge area of treated wastewater from one of the largest forestry industries in the European, northeastern area of Russia. In 2018–2020, the European perch, roach, and bleak prevailed in the catches of a standard set of nets with a mesh size of 10 to 60 mm in the littoral zone of the monitoring sites. These species are widespread representatives of the ichthyofauna in the Vychegda River basin. White-eye bream, asp, and pike-perch were also registered; their recent appearance became possible due to the construction of canals connecting the Northern Dvina River basin with other river systems. Indicators of species diversity (the number of species, their relative abundance, and Shannon index) in areas adjacent to local timber plots were similar to those observed at monitoring sites. The integral index for the assessment of individual development, which is based on fluctuating asymmetry, indicated the absence of a negative effect on the formation of bilateral morphological structures in early ontogenesis in fish that lived both in the industrial area and in the conditionally background area. To clarify the results, an additional study should be carried out to identify physiological disorders or the accumulation of heavy metals or other pollutants in fish tissues and organs.