Biomarkers' Responses of Rhamdia quelen Exposed In Situ on a Brazilian River Located in Agricultural Areas

Aquatic environments are impacted by the use of pesticides in agricultural areas, and to evaluate its impact on wildlife, in situ exposure has become an alternative. In this study, the fish Rhamdia quelen was used as a bioindicator for the in situ experimental protocol. The fish were exposed for 96 h in three different sites at Vacacai river located in Southern Brazil. After exposure, the brain, gills, liver, and muscles were collected for biochemical assays. Biomarkers of oxidative damage, neurotoxicity, detoxification, and antioxidant parameters were analyzed. The calculation of the Integrated Biomarker Response Index (IBR) was used to assess the responses of the biomarkers as an integrated approach. The most significant biochemical changes were recorded in places close to agricultural crops and in urban areas. The main results show elevated levels of carbonyl proteins in the brain, gills, and liver. Disruptions in acetylcholinesterase activity in the muscle. Other results include changes in glutathione S-transferase activity in the muscle and liver of fish indicating potential contamination. Furthermore, R. quelen proved to be an excellent bioindicator for in situ experiments, since the biomarkers responded in a manner consistent with the characteristics of the environment in which they were inserted.