Aquatic environments contaminated by industrial effluents and urban sewage present as common characteristic the release of xenobiotics complex mixture that potentially affects important aspects related with physiological aspects in fish. In the present work, fish specimens, Astyanax aff. fasciatus and Oreochromis niloticus, were used to evaluate the anthropogenic impact in two lakes (Lake Park and Cedeteg) situated in Guarapuava City, southern of Brazil. The occurrence of morphological changes in gills and liver associated with somatic indexes (Hepatosomatic-HSI and Condition Factor-CF) were used as biomarkers, and two reference sites were used. According to the results, individuals from both studied sites presented morphological damages in gills (aneurysms, hyperplasia, lamellar fusion and neoplasia) and liver (necrosis and leukocyte infiltration). The lesion indexes for liver and gills studied in both lakes were significantly impacted when compared with reference sites, but individuals from Lake Park were more affected. The HSI in both species was not different, but the CF in A. fasciatus decreased in both studied sites. These results suggest that the morphological findings found in the present study were developed due to the urban sewage release, reinforcing the importance of histopathological investigation in biomonitoring programs to evaluate the water quality and environmental assessment.

Cylindrospermopsin is a potent toxicant for eukaryotic cells produced by several cyanobacteria. Recently, primary hepatocyte cultures of Neotropical fish have been established, demonstrating to be a quite efficient in vitro model for cellular toxicology studies. In the current study, a protocol for culture of Prochilodus lineatus hepatocytes was established and utilized to investigate the cellular responses to purified cylindrospermopsin exposure. Hepatocytes were successfully dissociated with dispase, resulting in a cell yield of 6.36 × 10(7)cells g(-1) of liver, viability of 97% and attachment on uncoated culture flasks. For investigation of cylindrospermopsin effects, hepatocytes were dissociated, cultured during 96 h and exposed to three concentrations of the toxin (0.1, 1.0 or 10 μgl(-1)) for 72 h. Cylindrospermopsin exposure significantly decreased cell viability (0.1 and 1 μgl(-1)) and multixenobiotic resistance mechanism, MXR (all exposed groups), but increased reactive oxygen/nitrogen species levels (all exposed groups) and lipid peroxidation (10 μgl(-1)). On the other hand no significant alterations were observed for other biochemical biomarkers as 2GSH/GSSG ratio, protein carbonyl levels and DNA strand breaks or glutathione S-transferase and glucose 6-phosphate dehydrogenase activities. In conclusion, hepatocytes might be made sensitive to cylindrospermopsin, at least in part, due to reduction of xenobiotics and endobiotics efflux capacity by MXR. Additionally, the toxin exposure suggests important issues regarding hepatocytes survival at the lowest cylindrospermopsin concentrations.

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The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.