Effects of an endocrine disrupter on courtship and aggressive behaviour of male three-spined stickleback, Gasterosteus aculeatus

Oestrogenic endocrine-disrupting chemicals released into the environment have the potential to affect animal behaviour. This study examined the relationship between plasma levels of gonadal steroids and behaviour and the effects of exogenous hormonal perturbation on the behaviour of nesting male three-spined stickleback. Plasma gonadal steroid concentrations were related to levels of nesting and aggressive behaviours: levels of oestradiol were negatively related to courtship behaviours while levels of 11-ketotestosterone were negatively related to nesting behaviours. The behaviour of male three-spined stickleback exposed to environmentally relevant concentrations of an endocrine disrupter differed from the behaviour of control males. Control males increased their aggressive response to a live male conspecific over time, while males exposed to ethinyl oestradiol decreased their aggressive response. This study offers further evidence that low levels of endocrine-disrupting chemicals in the environment may exert subtle yet important effects on animal behaviour. (C) 2001 The Association for the Study of Animal Behaviour.