Acute exposure to 17α-ethinylestradiol alters boldness behavioral syndrome in female Siamese fighting fish

The role of anthropogenic sources in generating, maintaining, and influencing behavioral syndromes has recently been identified as an important area of future research. Endocrine disrupting chemicals are prevalent and persistent in aquatic ecosystems worldwide. These chemicals are known to have marked effects on the morphology and behavior of exposed individuals and, as such, may serve as a potential influence on behavioral syndromes. However, both the effects of exposure on behaviors beyond courtship and aggression and how exposure might affect behavioral variation at the individual level are understudied. To address this question, we examined boldness behavior in female Siamese fighting fish in three different assays (Novel Environment, Empty Tank, Shoaling) both before and after they were exposed to the estrogen mimic, 17α-ethinylestradiol (EE2). EE2 influences courtship, aggression, and boldness in males of this species but its effects have not been examined in females, to our knowledge. Females were tested multiple times in each assay before and after exposure so that behavioral consistency could be examined. A behavioral syndrome for boldness and activity level occurred across the three assays. The reductions in boldness and loss of the behavioral syndrome that resulted from EE2 exposure were surprising and suggest that the effects of EE2 exposure on female behavior and physiology should be examined more frequently. This study is one of the first to examine the effects of EE2 in females as well as on correlated behaviors and emphasizes the importance of examining the effects of endocrine disrupting chemicals on individual behavioral variation and consistency.