Impacts of Port Activities on the Health of Sciades herzbergii in the Amazon, Brazil

The harbor area of São Luís hosts the largest cargo complex in the Amazon region and is one of the most important port systems in Latin America. The rapid expansion of port infrastructure and associated activities can generate significant environmental pressures on aquatic ecosystems. However, information on contaminant effects on estuarine fish in Amazonian port areas remains limited. Histopathological biomarkers provide an effective approach for detecting sublethal impacts of environmental contamination in aquatic organisms. This study evaluated gill and hepatic lesions in the estuarine catfish Sciades herzbergii to assess the effects of environmental stressors in the harbor area of São Luís, Maranhão, Brazil. A total of 76 individuals were collected in 2018 at two sampling sites: the harbor area (A1) and Crab Island (A2), during both dry and rainy seasons. Gills and livers were processed using standard histological procedures to identify lesions associated with contaminant exposure. Morphometric measurements included total length (Lt), total weight (Wt), and gonad weight (Wg). Gill lesions were more frequent in fish collected at A1, particularly during the rainy season, and occurred in both sexes. Necrosis was especially prevalent in male individuals. In contrast, specimens from A2 showed a lower frequency of gill lesions. Liver analyses revealed a higher occurrence of histopathological alterations in fish from the harbor area during the rainy season, whereas no hepatic lesions were detected in individuals from Crab Island. These results indicate that S. herzbergii inhabiting the harbor region are exposed to environmental stressors, especially during the rainy season.