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

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.

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.

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.

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 damage.