Liver biomarkers response of the neotropical fish Aequidens metae to environmental stressors associated with the oil industry

The Acacias River in Colombia receives large volumes of industrial effluents mostly derived from the oil industry. To contribute to the study of the possible effects of industrial wastewaters on the aquatic environment and particularly on fish populations, a native neotropical fish, Aequidens metae was used as a sentinel species. Wild specimens of A. metae were caught at three different places of the Acacias River taking as reference the point of discharge of an oil industry effluent; upstream, downstream, and at the vicinity of the discharge pipe. A fourth sampling site was chosen as a reference site away from urban settlements. Samplings were performed twice, during the rainy and dry seasons. After anesthesia animals were weighted and measured, and humanely sacrificed. Livers were extracted, frozen on site and transported to the laboratory. Condition indices were calculated. Total protein content and the detoxification 7-ethoxyresorufin-O-deethylase (EROD) enzyme activity were estimated. Histopathological alterations were also evaluated. Water quality was estimated through the measurement of several variables. Results obtained evidenced that the highest induction in EROD activity and the strongest histological alterations in liver of the monitored fish appeared during the dry seasons at the discharge site and downstream to this point.The authors wish to thank the students and research assistants of the Research Group BioTox for their valuable participation during the sampling procedures. This study was funded by Colciencias, ANH and Universidad de los Llanos Project number 112272151869, contrato 162-2016, grant 721–2015 “Convocatoria para la formación de recurso humano en Colombia en el área de hidrocarburos, a través de proyectos de investigación”).Peer reviewe

Acute effects on hepatic biomarkers in the freshwater native fish Aequidens metae exposed to polycyclic aromatic hydrocarbons

14 Pág.BACKGROUND AND OBJECTIVES: Polycyclic aromatic hydrocarbons are present in all environmental matrices. Polycyclic aromatic hydrocarbons-rich wastewater from the oil industry is discharged into natural water bodies. Detritivorous fish shown the effects of pollutants in water. Biomarkers of effect make it possible to demonstrate exposure to xenobiotics such as polycyclic aromatic hydrocarbons. The aim of the present study was to evaluate the hepatic and erythrocyte response in Aequidens metae, a detritivorous fish, exposed to polycyclic aromatic hydrocarbons in terms of morphological, biochemical, and genotoxic changes. METHODS: Juveniles of Aequidens metae were exposed to 50 microgram per gram body weight of beta-naphthoflavone, 100 microgram per gram of naphthalene, 50 microgram per gram of phenanthrene and 10 microgram per gram of benzo[a]pyrene, for 72 hours. Water quality variables, total protein content, 7-ethoxyresorufin-O-deethylase activity, liver histopathological changes and genotoxic alterations in peripheral blood were measured during the assay. FINDINGS: In polycyclic aromatic hydrocarbons-exposed fish, analysis of liver tissue revealed parenchymal lesions and changes in the number and shape of hepatocyte nuclei. On the other hand, only fish exposed to benzo[a]pyrene shown significant increase in the 7-ethoxyresorufin-O-deethylase activity compared to solvent control. In peripheral blood erythrocytes, increased presence of nuclear abnormalities was higher in fish exposed to phenanthrene, followed by benzo[a]pyrene, beta-naphthoflavone, and naphthalene. CONCLUSION: It is concluded that Aequidens metae is a suitable bioindicator for polycyclic aromatic hydrocarbons monitoring in aquatic ecosystems. Phenanthrene reveals for the first time a greater genotoxic effect than benzo[a]pyrene at sublethal concentrations. Juveniles of Aequidens metae exposed to concentrations of polycyclic aromatic hydrocarbons close to those found in the environment showed health-compromising damageThis study was funded by Colciencias, Agencia Nacional de Hidrocarburos (ANH) and Universidad de los Llanos with the project number [112272151869, contract 1622016, grant 721–2015] “Convocatoria para la formación de recurso humano en Colombia en el área de hidrocarburos, a través de proyectos de investigación”) and by the Pontificia Universidad Javeriana, under the following research grant: Project ID 8572.Peer reviewe