Exposure to 17a-ethinyl estradiol impairs courtship and aggressive behaviour of male sand gobies (Pomatoschistus minutus)

Endocrine disrupting chemicals (EDCs), natural or manmade, are known to interfere with the endocrinology of organisms and also cause behavioural changes. The aim of this study was to test how 1–4 weeks exposure to 17a-ethinyl estradiol (EE2, 11 ng L1) affects nest building, courtship and aggressive behaviour of male fish. Our study species, the sand goby (Pomatoschistus minutus) exhibits a polygynous mating system, in which males compete for females and defend their nest against intruders. Nest takeovers are common in their nest-constrained habitat. In our experiment, control and EE2-exposed males were first allowed to build a nest and mate with non-exposed females. When the males had received eggs in their nest, three rival males were introduced into the test aquarium, and the males were left to compete for the nest site overnight. Courtship and aggressive defence behaviour were recorded using a video camera.