Histopathological alterations in gills of two Patagonian reef fishes exposed to complex mixtures of anthropogenic contaminants.

Anthropogenic pollution is a major threat to coastal marine ecosystems. Due to their direct exposure to the surrounding water, fish gills are highly susceptible to contaminant-induced damage, making gill histopathology a valuable approach for evaluating the health status of fish populations in impacted environments. In this study, we evaluate gill histopathological alterations in two wild marine fishes, the rockfish Sebastes oculatus and the sandperch Pinguipes brasilianus. Fish were sampled at a site exposed to multiple anthropogenic sources of chemical contamination (exposed site: S. oculatus, n = 10; P. brasilianus, n = 9) and from two reference sites that do not receive urban, industrial, or other wastes (reference site: S. oculatus, n = 26; P. brasilianus, n = 12). Individuals from the exposed site showed higher prevalence of several gill lesions and higher histopathological damage, as indicated by higher histopathological index scores, than fish from reference sites. Despite these differences, most of the observed lesions corresponded to mild to moderate tissue damage, with severe alterations such as necrosis occurring at low prevalence. Overall, the observed alterations were consistent with tissue responses commonly associated with environmental stress and contaminant exposure. These findings indicate poorer gill conditions in fish from the impacted site and support the use of histopathological assessments for evaluating population health and detecting contamination-related effects in marine ecosystems.