MORPHOLOGICAL ANALYSIS AND PATHOLOGICAL CHANGES OF ERYTHROCYTES OF TOAD GOBY MESOGOBIUS BATRACHOCEPHALUS (PALLAS, 1814)

Abstract

The biological diversity of the Odessa Bay is primarily composed of fish from the Gobiidae family. These fish are crucial components of the marine ecosystem and are important targets for fishing. However, the characteristics of morphometric parameters and pathological changes in their blood are poorly described and mainly pertain to species of commercial significance. There is virtually no literature on the specifics of the blood of the toad goby, Mesogobius batrachocephalus (Pallas, 1814). This study presents the results of a morphological analysis and the investigation of pathological changes in erythrocytes and their nuclei in the toad goby caught during the spring-summer periods of 2022 and 2023 in the Black Sea (Odessa Bay). Blood samples were taken from the caudal vein and fixed using standard methodologies. According to the conducted research, the circulating blood of the toad goby contains both young and mature erythrocytes, as well as cells with pathological changes in the nucleus and the cell itself. Mature cells predominate in percentage, having higher average values of diameter, area, and volume compared to young cells. Meanwhile, young erythrocytes have slightly larger nuclear sizes and higher nuclear-cytoplasmic ratios. The morphometric parameters of erythrocytes in males and females are almost identical, with minor detected differences. Almost 40 % of the examined erythrocytes of the toad goby exhibited pathological changes in the nucleus or the cell itself. Gobies from Odessa Bay often show various forms of pathological changes on a single smear. The most common pathologies include bean-shaped nuclei, poikilocytosis, and festooned cell membranes. The high frequency and variety of pathological changes in the erythrocytes of the toad goby indicate significant negative environmental impacts in the Odessa Bay, predominantly of anthropogenic origin.