Evidence of endocrine alteration in the red mullet, Mullus barbatus from the NW Mediterranean

9 pages, 4 figures, 4 tables.Red mullet (Mullus barbatus) were collected from different sampling sites (NW Mediterranean) in spring and autumn, with the aim of assessing potential alterations of the endocrine system. Alkylphenols were measured in fish bile as an indicator of estrogenic exposure. Key enzymatic activities involved in both synthesis (ovarian 17β-hydroxysteroid dehydrogenases and P450 aromatase) and metabolism of steroids were assessed together with histological alterations of the gonads. During the spring sampling, delayed gamete maturation, intersexuality, fibrosis, and depressed ovarian P450 aromatase activity were observed in organisms from the most polluted sites. During the autumn sampling, those effects were less evident, indicating that fish might be more susceptible to endocrine disrupting chemicals during the reproductive period. Nonetheless, enhanced glucuronidation of testosterone and estradiol was observed. Overall, this work provides first evidences of significant alterations in the endocrine system of red mullet from highly impacted areas in the NW Mediterranean.This work was partially supported by the EC Project ENVK3-CT-2000-00025. R.M.-S. acknowledges a predoctoral fellowship from the Spanish Government. Dr. Rémi Thibaut acknowledges a I3P contract from the Spanish Government.Peer reviewe