Assessing the Ecological Condition of the Waters of the Sea of Azov Using Biochemical Parameters of the Round Goby (Neogobius melanostomus (Pallas, 1814)) Liver

Biochemical indices (albumin content, level of oxidized proteins (OP) and lipid peroxidation (LPO) products, activity of antioxidant enzymes (superoxide dismutase (SOD) and catalase), aminotransferases, and cholinesterase (ChE)) of the liver of the round goby Neogobius melanostomus from the Sea of Azov have been analyzed. The samples have been harvested from the central (CP), southern (SP), and southeastern (SEP) parts of the sea differing in anthropogenic load level. The intensification of LPO and protein oxidation processes, as well as the reorganization of the protein metabolism towards gluconeogenesis and detoxification reactions, are observed in the round goby liver from the SEP. This may indicate that, compared to the SP and CP, the SEP is characterized by a more expressed environmentally unfavorable state. The analysis of biochemical indices of the liver of fish from the SP and CP sites shows they are similar in complex pollution level, but changes in biochemical parameters such as inhibition of SOD activity and increased OP level are more expressed for samples harvested from the SP site. The results allow us to rank the investigated areas according to the increase in the complex pollution level in the following order: CP → SP → SEP. The reasons for the changes are discussed.