Ovarian responses to 17ɑ-ethinylestradiol in a marine livebearer, the Southern crested weedfish

Pharmaceuticals are fast becoming a major source of environmental pollution. Many pharmaceuticals are endocrine disruptors and can thus interfere with the endocrine system of exposed organisms, leading to a suite of behavioural and physiological alterations. While numerous studies have shown that exposure to pharmaceutical contaminants can disrupt the reproductive ecology of oviparous fishes, far less attention has been given to understanding the impacts on viviparous fishes, despite their ecological and evolutionary importance. Here, we investigated the impacts of the pharmaceutical contaminant 17ɑ-ethinylestradiol (EE2) on the reproductive biology of a marine livebearer, the Southern crested weedfish (Cristiceps australis). Adult weedfish were exposed to one of three nominal concentrations of EE2 (0, 30, and 300 ng/L) for 14 days. We then assessed the impacts of exposure on morphology of both sexes, and female gametogenesis. In doing so, we found no differences in the body length, weight, or condition of fish between treatment groups. We additionally found no differences in gonadosomatic index (GSI) or gametogenesis between exposed and unexposed females. In contrast to reports in other taxa, our findings suggest that short-term exposure to EE2 does not produce detectable effects on weedfish growth and reproduction. However, the extent to which exposure duration influences these responses is unknown. Ultimately, these results emphasise the importance of assessing the effects of EE2 on a diverse range of organisms if we are to gain a more comprehensive understanding of its ecological impacts.