Effects of the synthetic estrogen 17α-ethinylestradiol on Heterandria formosa populations: Does matrotrophy circumvent population collapse?

Aquat Toxicol. 2020 Dec:229:105659. doi: 10.1016/j.aquatox.2020.105659. Epub 2020 Oct 19.


Feminization responses have been observed in some wild populations of fish living in rivers and streams, some of which have been shown to arise as a consequence of exposure to sewage treatment (STP) effluent discharges and the endocrine disrupting chemicals (EDCs) they contain which mimic or antagonize the actions of steroid hormones. The synthetic estrogen, 17α-ethinylestradiol (EE2), commonly used in oral contraceptives, is present in surface waters receiving STP effluents at concentrations ranging from non-detectable to 5 ng/L. Despite extensive evidence that EE2 negatively affects the reproductive health of fishes, relatively little is known about effects at the population level - and especially so for live-bearing fishes. To investigate the potential for such impacts, populations of the least killifish (Heterandria formosa) were exposed to 0 or 5 ng/L EE2. Exposures were started with newborn fish and continued for seven months. Chronic exposure to 5 ng/L EE2 caused significant reductions in population size, in abundances of newborns and males, and in population growth rates. The exposure also resulted in a female-biased sex ratio. However, individuals' survival rates were not affected. This study showed that chronic exposure to 5 ng/L EE2 negatively affected population dynamics in a live-bearing fish, demonstrating that the levels of EE2 detected near STPs have the potential to impact wild populations of these fish.

Keywords: 17α-ethinylestradiol (EE(2)); Aquatic toxicology; Endocrine disruption; Estrogens; Fish; Fish populations.

MeSH terms

  • Aging / physiology
  • Animals
  • Animals, Newborn
  • Cyprinodontiformes / growth & development*
  • Ethinyl Estradiol / toxicity*
  • Female
  • Male
  • Population Density
  • Sex Ratio
  • Taiwan
  • Water Pollutants, Chemical / toxicity


  • Water Pollutants, Chemical
  • Ethinyl Estradiol