Undergraduate Honors Theses

Thesis Defended

Fall 2012

Document Type



Ecology and Evolutionary Biology

First Advisor

Dr. David O. Norris


The impact of a class of chemicals termed endocrine- disrupting chemicals (EDCs) has become a growing concern in light of recent studies elucidating their effects. They disrupt vertebrate hormone signaling and cause damage at very low concentrations. The zebrafish (Danio rerio) has been studied as a model organism. Thus far little data exists on effects of endocrine disrupting chemicals (EDCs) on zebrafish during the pre-hatching time period. It is known that EDCs affect neuronal and enzymatic function and disrupt endogenous hormone balance, but it is not known how early exposure with affect later reproductive fitness. I exposed zebrafish to environmentally relevant doses (1 and 10 ng/L) of 17β- estradiol in the post-fertilization, pre-hatching time period. Subsequently the exposed zebrafish were transferred to clean water and raised to sexual maturity. They were then bred with unexposed zebrafish and data on their fertility was collected. Exposure to steroidal estrogen during the pre-hatching period of time at 1 ng/L and 10 ng/L concentrations did not significantly affect zebrafish length, hatching, number of eggs produced, or egg fertilization.