Endocrine disruption of phenanthrene in the protogynous dusky grouper Epinephelus marginatus

FABIANA L. LO NOSTRO; RODRIGO H. DA CUÑA; MARIANA FRIAS DE CAMPOS; RENATA GUIMARAES MOREIRA

Gothenburg

Simposio; 8TH International Symposium on Fish Endocrinology; 2016

ISFE

The dusky grouper, Epinephelus marginatus (Serranidae: Perciformes) is a protogynous hermaphrodite, living on rocky bottoms. These fish mature first as female and then ovaries are replaced by testis, based on a complex social structure. As a hermaphrodite species, they maintain high levels of plasma steroids, even when juveniles, as substrates for sex inversion. In many tropical and temperate regions, overfishing and environmental degradation have been depleting wild dusky grouper populations. These fish are exposed to marine pollution, from the vessel traffic and oil spill during cargo handling. Polycyclic aromatic hydrocarbons (PAH) such as phenanthrene (Phe) are the main crude oil components and are toxic to fish, acting as endocrine disruptors (ED), negatively impacting reproduction. This study investigated the effect of Phe as ED on gonadal steroidogenesis in E. marginatus juveniles. After the LC50 determination, two experiments were designed to evaluate the effects of Phe in E. marginatus steroidogenesis. An in vivo sublethal exposure (96 h) to Phe was carried out at two concentrations (0,1 mg/L and 1 mg/L); exposure to the vehicle (ethanol; EtOH) was also performed. Plasma levels of 17B-estradiol (E2), testosterone (T) and 11-ketotestosterone (11-KT) were measured by ELISA. Gonads, liver and spleen were processed for histological analysis. In an in vitro bioassay, gonad fragments were incubated with Phe (50 µM) or EtOH. Steroid levels in the culture media were measured by ELISA. The in vivo exposure to Phe triggered an increase of the area of the hepatocytes, increased number of melanomacrophagic centers and hemosiderosis in the spleen; EtOH also induced similar effects on spleen. E2 and T levels did not change neither in plasma nor in vitro media. Phe sharply reduced 11-KT levels in vitro and in vivo. In plasma, EtOH also decreased 11-KT levels. Considering the importance of 11-KT in fish developing ovaries, phenanthrene seems to disrupt steroidogenesis in juvenile grouper, possibly being able to cause dysfunctions during sex change.