Toxic effects of estradiol E2 on development in the European tree frog (Hyla arborea)

Karim Ghali, Julien Leuenberger, Michel Ansermet, Nicolas Perrin, Christophe Dufresnes


Oestrogenic hormones are a major environmental threat to aquatic wildlife. Here we report on chronic toxic effects of larval exposure to the naturally excreted oestrogen 17β-estradiol (E2), in the European tree frog (Hyla arborea), by means of an experimental setting and long-term monitoring. Larval survival was significantly lower in treated tanks when compared to controls, as more treated larvae died during metamorphosis. Morphometric data suggested an impact on froglet phenotypes, with treated individuals being heavier (but not different in size) than control ones. Survival during juvenile growth was also significantly lower for exposed frogs, which after two and a half years of monitoring furthermore seemed to have developed slower. In addition to the well-documented impact on sexual differentiation and mating behaviour, the general toxicity of human-released oestrogens likely contributes to global amphibian declines, particularly for tree frogs which are threatened in many countries.

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