Altered non-reproductive behavior and feminization caused by developmental exposure to 17α-ethinylestradiol persist to adulthood in three-spined stickleback (Gasterosteus aculeatus).

The synthetic estrogen 17α-ethinylestradiol (EE), ubiquitous in the aquatic environment and commonly detected in sewage effluents, interferes with the endocrine system in multiple ways. Exposure during sensitive windows of development causes persistent effects on fertility, reproductive and non-reproductive behavior in mammals and fish. In the present study, three-spined stickleback (Gasterosteus aculeatus) were exposed to nominal 0 and 20 ng/L EE from fertilization to 7 weeks post-hatch. After 8 months of remediation in clean water three non-reproductive behaviors, not previously analyzed in developmentally EE-exposed progeny of wild-caught fish, were evaluated. Chemical analysis revealed that the nominal 0 and 20 ng/L exposure contained 5 and 30 ng/L EE respectively. Therefore, the use of control fish from previous experiments was necessary for comparisons. Fish exposed during development showed significant concentration-dependent reduction in anxiety-like behavior in the scototaxis (light/dark preference) test by means of shorter latency to first entrance to the white compartment, more visits in white, and longer total time in white compared to unexposed fish. In the novel tank test, developmental exposure significantly increased the number of transitions to the upper half of the aquaria. Exposure to EE during development did not alter shoal cohesion in the shoaling test compared with unexposed fish but fish exposed to 30 ng/L EE had significantly longer latency to leave the shoal and fewer transitions away from the shoal compared to fish exposed to 5 ng/L EE. Skewed sex ratio with more females, sex reversal in genetic males as well as intersex in males was observed after exposure to 30, but not 5 ng/L EE. In conclusion, EE exposure during development in three-spined stickleback resulted in persistent effects on anxiety-like behaviors. These long-term effects from developmental exposure are likely to be of higher relevance for natural populations than are short-term effects from adult exposure.