Current State of the Habitats and Communities of Invertebrates in the Right-Bank Tributaries of the Mezen River (Kyma and Sula Rivers)

The paper presents for the first time the results of a comprehensive cadaster study of the right-bank tributaries of the Mezen River (Kyma and Sula rivers) in autumn 2021. The characteristics of the habitat state for aquatic biota and the results of the study of plankton and zoobenthic communities are presented. According to the chemical composition, the waters of the surveyed rivers belong to the hydrocarbonate class of low mineralization and the neutral type according to the pH value. Our results indicate the absence of a noticeable anthropogenic impact on the studied watercourses. The phytoplankton community is characterized by high taxonomic diversity, while the zooplankton and zoobenthic communities, by low taxonomic diversity. Different dynamics of phytoplankton, zooplankton, and zoobenthos in terms of abundance, biomass, and taxonomic composition has been found. According to the fishery standards, the parameters of zooplankton in the Mezen River tributaries allows us to classify them as poor in terms of fodder base for planktivorous fish. According to the zoobenthos parameters, the Kyma River may be characterized as exceeding the average level in terms of fodder base for benthophagous fish, the Sula River, close to the average level. The data on the taxonomic composition and quantitative indicators of the development of hydrobionts in the right-bank tributaries of the Mezen River are the starting point for environmental monitoring of the state of these water bodies.