Guppy Sexual Behavior as an Effect Biomarker of Estrogen Mimics

There is widespread concern that some environmental chemicals can reduce the reproductive capability of humans and wildlife by mimicking natural estrogens and disrupting endocrine function. This potential threat to animal populations posed by xenoestrogens has, hardly surprisingly, been met by an intensive global effort to identify and develop biomarkers suitable for screening chemicals for estrogen mimicking capacity. Despite this effort, there are few biomarkers capable of linking exposure to xenoestrogens to impaired reproductive capability. The reproductive success of most animals depends strongly on the ability to perform the appropriate sexual behavior. The sexual display of the male guppy is strongly linked to reproductive success and is readily quantified under laboratory conditions. This preliminary study demonstrates that exposure of adult male guppies to water weakly contaminated with either natural estrogen (17β-estradiol) or the xenoestrogen (4-tert-octylphenol) causes a dramatic decrease in the rate and intensity of sexual display. It is concluded that quantitative analysis of the sexual display of male guppies holds great promise as a biomarker at the organismal level for the effects of estrogen mimicking xenobiotics.