Bioindicators and Biomarkers of Environmental Pollution in the Middle-Lower Basin of the Suquía River (Córdoba, Argentina)

Abstract

The Suquía River middle-lower basin (Córdoba, Argentina) is subject to a strong anthropogenic impact because it receives pollutants from different sources. Recent studies have shown the importance and the need of approaching the monitoring process of water quality from integral perspectives, through the utilization of chemical as well as biological methods. The main goal of this study was to evaluate the fish species Jenynsia multidentata as a bioindicator of environmental pollution in the middle-lower basin of the Suquía River using biotransformation and antioxidant enzymes as well as gill and liver histopathology as biomarkers. We also studied the fish assemblage characteristics through the fish species pattern variation and the application of a Biotic Index based on fish data. Our study also included the analysis of a Water Quality Index, heavy metal concentrations in sediment and water and pesticide concentrations in sediment. The chemical analyses of the middle-lower Suquía river basin revealed a water quality degradation gradient. Fish assemblage structure changed with increasing water pollution, showing a simpler structure at the most polluted area. According to the Bioitc Index, the variation pattern of fish assemblages reflected the aquatic environment deterioration. Both molecular and histopathological biomarkers perceived the same trend in relation to water quality. However, enzymes discriminated with acuter precision between seasons. Besides, each enzyme presented different sensibility. At tissue level, the histopathological analysis detected chronic contamination at both stations and seasons. The present work that comprises different levels of biological organization together with chemical analyses generated particular although complementary information, evidencing the same trend of aquatic contamination. Thus, the development of integral investigations gives a comprehensive approach and becomes the most effective tool to construct policies both preventive and palliative. Our study constitutes a good model to be applied in other endorheic basins of South America.