Histological structure of gills of Prussian carp of the Samara River of the Dnipropetrovsk region

Purpose. To study the histological structure of the gill apparatus of the Prussian carp (Сarassius gibelio) from the point of view of the presence of pathologies with differentiation according to areas with different levels of anthropogenic pressure of the Samara River in the Dnipropetrovsk region. Methodology. The generalized sutdy results were obtained during 2019–2021. The study was conducted within three sampling sites with different types of human impact. The object of the study were age-6 Prussian carps of both sexes. Histological studies were performed in accordance with generally accepted methods. Gills were obtained by anatomical dissection from freshly caught fish. Photographs of histological specimens were taken using a digital camera “SciencelabT5005.17M” and an microscope “Ulab XY-B2TLED”. Measurements of the samples were performed using the “ScienceLabView7”. Statistical processing of the obtained data was carried out in MS Excel 2010. Findings. The conducted histological studies showed that pathological changes in the structure of the gill apparatus were observed in age-6 Prussian carps in all sampling sites of the Samara River. In particular, such pathologies as curvature of lamellae terminals, accumulation of mucus and hyperplasia of the epithelium of gill filaments, fusion of lamellae were found. Single cases of necrosis and twisting of lamellae threads were recorded. Most often, histopathological changes in the gill apparatus were observed in fish caught near the city Novomoskovsk. Organometric studies showed that there was no significant difference between the length and width of gill arches of Prussian carp from different sampling sites. The length and width of the lamellae of the gill apparatus was the largest in individuals sampled near the city Novomoskovsk, which may indicate a greater need for oxygen for the fish body in the specified area. The length of the respiratory lamellae was the lowest in Prissian carp sampled near the village of Novoselivka. The lowest width of the lamellae were found in fish from the village of Khashcheve. The obtained data give reason to conclude that the conditions of existence for Prussian carp are most favorable near the village of Novoselivka. Originality. For the first time the histological structure and pathology of the gills aparatus of Prussian carp in the conditions of the Samara River in the Dnipropetrovsk region was studied. Practical value. The obtained data on the histological changes of the gill apparatus of fish can be used to identify adaptive reactions, will allow assessing the impact of anthropogenic factors on hydrobionts, and will also provide the opportunity to monitor the morpho-physiological state of a specific population under the impact of pollutants of various origins.