Assessment of the Impact of Some Rivers of the Black Sea Region on the Coastal Marine Environment in Their Plume Zones

The paper assesses the impact of water quality of some rivers located within the Black Sea coastal zone in the Sochi area on the ecological security and status of the Black Sea coastal line. The relevance of the study is determined by the lack of a unified methodological approach to establishing parameters for assessing the ecological condition of water bodies within the Black Sea coastal area. The study is the first to consider a unified river-sea system in the context of integrated monitoring of natural water quality. The research is based on biological methods (biotesting, bioindication) to evaluate the state of biological communities and processes in combination with the analysis of geological aspects. This allows a detailed study of the influence of various factors on the marine environment ecological safety. It was revealed that the marine environment has the highest levels of toxicity in the inflow zones of small rivers, which are subject to significant complex impacts from municipal solid waste landfills and industrial enterprises located in their catchment areas. In the marine plumes of rivers classified as medium, which are important for water management, recreation and fisheries in the region, seawater has a lower toxic effect as a result of significant dilution. Thus, small rivers inflows can cause similar negative impacts on the quality of the marine environment and the status of coastal biocenoses as runoff from larger watercourses. The study results can contribute to the development of new approaches for the assessment and monitoring of the environmental security of the coastal marine environment, based on the concept of the ecological system integrity in the context of interdependencies associated with the pollutants and nutrients transfer between qualitatively different environments and associated with them river and cjastal marine hydrobiocenoses.