Habitat conditions of aquatic bioresources in the Lower Don water area (2015–2024)
Authors:   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), Kosenko Yu. V. , Korablina I. V. ,   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), Gorgola L. G. ,   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), Baskakova T. E. ,   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), Elfimova N. S. ,   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”)
Published: December 2024

Background. The hydrochemical and toxicological regime of the Lower Don has a major impact on the habitat conditions of semi-anadromous fish species and the ecological state of the Azov Sea. Relevance. Currently, the Lower Don water area is a transformed natural ecosystem, the state of which has been significantly deteriorating in recent years. Environmental problems of the Lower Don are also associated with global natural climatic factors, such as changes in atmospheric circulation and a significant decrease in surface runoff observed from 2007 to the present. The aim of this work is to study the hydrochemical regime and toxicological state of the Lower Don water area in 2015–2024. Methods. This article presents the results of studies of the hydrochemical regime and pollution with priority toxicants in the ecosystem of the lower reaches of the Don River, from stanitsa Romanovskaya to its mouth at the Azov Sea, in the spring, summer, and autumn seasons for the period 2015–2024. Samples have been collected in compliance with the requirements of State Standard R 59024-2020, State Standard 17.1.5.01-80, and State Standard 31339-2006. Identification of the hydrochemical and toxicologocal parameters of the water, bottom sediments and aquatic organisms has been conducted according to the provisions of the guidelines developed and adopted for the monitoring environmental surveys at the federal level. Results. Concentrations of biogenic elements and total mineralization of water were favorable for the vital activity of aquatic organisms. Water in the lower reaches of the Don River is characterized by a high trophic status. Local pollution of the investigated area with priority toxicants has been found. Conclusion. The water areas most polluted with petroleum products are the mouth of the Temernik River, the site of the Rostov-on-Don city sewage outlet, and the Mokraya Kalancha River Branch, where their threshold level in bottom sediments is exceeded by 9–25 times. Localized elevated concentrations of polychlorinated biphenyls and petroleum products in water, as well as benz(a)pyrene in bottom sediments, further worsen the environmental conditions for aquatic organisms. The quality of aquatic bioresources caught in the Don River has been found satisfactory in terms of pollution, and their consumption does not pose a danger to human health.