Fish histopathology as biomarker to evaluate water quality

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.