Comprehensive Assessment of the Ecological State of the Shahagachi Coastal Zone (Caspian Sea) using Genotoxic and Histopathological Markers of Fish

This study assessed the ecological status of the Shahagachi coastal area (Azerbaijan, Caspian Sea) using fish as bioindicators. The study was conducted on 16 specimens of mullet (Liza saliens) and 15 specimens of kutum (Rutilus frisii cutum). A comprehensive approach was employed to evaluate the condition of the fish, including a genotoxic analysis based on nuclear aberrations in erythrocytes and a histopathological analysis of the gills. The genotoxic analysis revealed pathologies in fish erythrocytes such as nuclear deformation, invagination, and displacement, and in some cases, micronuclei. However, the level of detected pathological cells in the blood of mullet (1.65±0.06%) and kutum (2.12±0.18%) remained within the physiological reference range (<5%). Histological examination of the gills of both species showed protective and adaptive changes, such as hyperplasia, curvature, and fusion of secondary lamellae, and an uneven distribution of secondary lamellar hyperplasia; parasitic infestations were also detected.An integrated assessment of the results indicated that the studied fish populations are experiencing a state of mild physiological stress. It was concluded that the environmental conditions in the Shahagachi area, while not causing critical damage, create unfavorable background conditions for aquatic organisms, which underscores the need for further monitoring to prevent ecosystem degradation.