Research Expeditions Performed by Marine Hydrophysical Institute in the Sivash Bay Waters in Spring and Autumn, 2018

55–60‰. Purpose. The results of the expeditionary studies performed by Marine Hydrophysical Institute in the Sivash Bay waters in spring and autumn, 2018 are considered in the paper. Its aim is to continue comprehensive investigation of the bay after the North Crimean channel was closed in 2014, and to evaluate dynamics of salinity, dissolved organic and total suspended matters in its waters affected by the changed anthropogenic and natural-climatic factors. Relevance of the studies carried out in the bay water area is conditioned by urgent necessity in developing and implementing a modern system of environmental monitoring of the bay. Methods and Results . The data obtained during two expeditions in spring and autumn, 2018 in the Sivash Bay waters including the present borders of the Eastern Sivash wetland are analyzed. At 13 stations, water salinity was determined by the refractometric and pycnometric methods, while the dissolved organic matter and the total suspended matter – by the «Kondor» biophysical complex. Conclusions. It is concluded that due to the fact that the North Crimean channel was closed in 2014, salinity of the Sivash Bay water continues to change and its ecosystem is being rebuilt. The observed salinity increase is not the same in different parts of the bay. The highest salinity values were observed in the Southern Sivash and amounted 92–93%, whereas at the same stations in 2016, this value constituted 55–60%. During the autumn survey, assessment of seasonal dynamics of the total suspended matter and the dissolved organic matter contents yielded high values of concentrations of these two parameters in the bay. In spring when the dissolved organic matter distribution is more monotonous, the slightly increased total suspended matter content was observed at the stations in the Southern Sivash. Bay, Eastern and Southern Sivash, Sea of Azov, seasonal salinity dynamics, total suspended matter, dissolved organic matter.