Abiotic features of Sukhyi and Grygorivskyi Estuaries' ecosystems as seaport water areas (northwestern part of the Black Sea)

Abstract

The article studies the location, origin and abiotic features of the ecosystems of Sukhyi and Grygorivskyi Estuaries that were transformed into water areas of Chornomorsk and Yuzhnyi, the major seaports of Ukraine, in the second half of the 20th century. It also presents a comparison of the abiotic conditions of such ecosystems based on the analysis of published data and additional database materials of the Institute of Marine Biology of the National Academy of Sciences of Ukraine.
 The construction of permanent and deep watercourses in the water areas of the estuaries alongside with large-scale dredging works led to their transformation into narrow sea bays with the depths significantly exceeding those in the adjacent sea. The construction of berths included levelling the coastline, changing the bottom profile and increasing the water volumes by more than three times. Now the volumes amount to 45–55 million m3 in Sukhyi Estuary and 60–70 million m3 in Grygorivskyi Estuary. The current abiotic features of the estuaries' ecosystems are determined by the processes occurring in Odesa sea region of the northwestern part of the Black Sea where such estuaries are located. The estuaries' hydrochemical regime depends on the yearly meteorological features, the intensity of water exchange with the sea, the amount of biogenic matter coming from natural (surface runoff, precipitation) and anthropogenic sources and the intra-aquatic processes of new organic matter production and destruction. Dredging activities resulted in emergence of the conditions for halocline and thermocline formation that hamper vertical water exchange. The formation of zones with extreme values of dissolved oxygen was also noted during the research. The maximum values in the surface layers result from photosynthesis development, while the minimum values in the bottom layers are caused by accumulation and destruction of dead organic matter. This information can be used to forecast the consequences arising from similar anthropogenic interference in the functioning of coastal marine ecosystems.