In situ monitoring of the Sinos River, southern Brazil: water quality parameters, biomarkers, and metal bioaccumulation in fish.

The Sinos River is an important water supply in Southern Brazil and receives industrial, agricultural, and domestic effluents which may affect aquatic biota. Water physicochemical and microbiological analyses, biomarker responses (scaled mass index (SMI), gill histopathology, and micronucleus and nuclear abnormality (MN and NA) frequencies), and metal bioaccumulation in muscle were assessed in the fish species Bryconamericus iheringii (Characidae) captured at three sampling sites (S1, S2, and S3) in four sampling periods. The mean values of five parameters (total phosphorus, thermotolerant coliforms, aluminum, iron, and lead) exceeded the limits established by the Brazilian legislation at the three sampling sites. Although physicochemical analysis indicated higher impacts at S3, in some samples, significantly higher MN frequencies and bioaccumulation of manganese in fish muscle were observed at S1, whereas low SMI and higher concentrations of aluminum and zinc in fish muscle were found at S2. Histopathological alterations in gills were observed in fish collected at the three sampling sites; however, no spatial differences were observed, indicating similar environmental conditions with respect to this biomarker. Moreover, temporal variation of biomarker responses and metal bioaccumulation were found at all sampling sites. Furthermore, the consumption of fish from the Sinos River should be avoided given the concentrations of chromium (all samples), cadmium, and lead in fish muscle above the threshold for safe human consumption.

Water quality parameters, biomarkers and metal bioaccumulation in native fish captured in the Ilha River, southern Brazil.

The Ilha River is one of the main tributaries of the Sinos River, southern Brazil, and it is located in an area characterized by low population density and presence of agricultural activities. Thus, this study aimed to assess the water quality of two sites of the Ilha River (source and mouth, S1 and S2 respectively) in five sampling periods using water physicochemical and microbiological analyses, biomarkers, such as condition factor, micronucleus test, gill histopathological analysis, and metal bioaccumulation in the native fish Bryconamericus iheringii. Mean values of BOD5, thermotolerant coliforms, aluminum, iron and lead exceeded the limits established by the Brazilian legislation for surface waters at both sampling sites. Significant higher micronucleus, nuclear abnormalities and mucous cells frequencies were found at S2 in, at least, one sampling period, whereas fish from S1 presented significant lower condition factor, higher frequencies of lamellar alterations and higher concentrations of chromium and nickel in muscle. Additionally, concentrations of cadmium, chromium and lead in fish muscle exceeded the limits considered safe for human consumption at both sites in at least one sampling period. Data from our study evidenced the mouth of the Ilha River suffers from point genotoxic effects, whereas the source is also contaminated by metals, despite being located in an area under minor anthropic activities.