Effects of maternal exposure to environmentally relevant concentrations of 17α-ethinyloestradiol in a live bearing freshwater fish, Xenotoca eiseni (Cyprinodontiformes, Goodeidae).

The viviparous teleost Redtail Splitfin (Xenotoca eiseni) is a live bearing fish that presents a novel freshwater model for investigating the effects of maternally derived micropollutants on vulnerable early developmental life stages. Here, adult female X. eiseni were exposed to 17α-ethinyloestradiol (EE2), a potent contraceptive oestrogen, at environmentally relevant concentrations, to investigate for effects on sex partitioning and development. Pregnant and non-pregnant females were exposed for four weeks to EE2 at measured concentrations of 0.9 and 3.4 ng/L EE2 and offspring from gravid females were kept in clean water for a further four weeks. Only pregnant females were seen to respond to 3.4 ng/L EE2 with an increase in the transcription of hepatic vitellogenins (vtgA, vtgB and vtgC). Offspring of exposed mothers showed no obvious effects on somatic growth, gonadal development, sex partitioning or development. However, there was a higher rate of deformities and developmental abnormalities in offspring of EE2-exposed females. The work presented provides the foundation for the development of X. eiseni as a new freshwater model for studies on maternal transfer of chemical pollutants in live bearing animals.