Hazards of the endocrine disruptors on mullets (Chelon labrosus) from the basque coast (Bay of Biscay) applying a biomarker based approach

Abstract

Biomonitoring programs are essential tools to evaluate the biological quality status of aquatic environments. Recently, several compounds with endocrine disruption ability have been included in the list of priority substances and therefore, implementation of biomarkers assessing the presence and the effects of such substances are required. In the present work we applied a battery of chemical and biological markers in order to study the effects of endocrine disruptors in four thicklip grey mullet (Chelon labrosus) populations from the Basque Country (Bay of Biscay) inhabiting differently polluted estuaries: Arriluze and Pasaia are marinas located in highly industrialized and densely populated areas, Plentzia is a leisure and touristic town and Gernika is located in the Biosphere Reserve of Urdaibai. Chemical analyses of fish bile were performed in order to determine the uptake of endocrine disruptors. Liver, gonad and brain samples were collected for the study of expression levels of genes associated with reproduction and development such as vtg, cyp19a1 and a2, er and rxr. Histological analysis of gonads was performed to identify possible gametogenic alterations such as intersex gonads. Results indicated clear pollution-dependent responses among four estuaries. Endocrine disruption effects were very marked in mullets from Gernika and Plentzia; these two populations showed high vtg gene expression levels in male mullets together with high alkylphenol metabolites in the bile. Bisphenol A was also present at high concentration in mullets from Gernika. cyp19a2 was upregulated in male mullets from Plentzia. Intersex fish were found in Gernika and Pasaia, the last ones showing high hormone metabolites in bile. The combination of chemical and biomarker approaches in biomonitoring programmes can be a valuable tool to be implemented within the framework of the new water policies.