The Effects Of Early Life Stage Thyroid Disruption On Reproductive Behaviors In Fathead Minnows (Pimephales Promelas)

Abstract

Changes in thyroid hormones levels have been associated with alterations in somatic development and growth. However, recent studies have shown that alterations in thyroid hormone levels during early life stage development can lead to long-term changes in reproduction. Specifically, fathead minnows that have been exposed to propylthiouracil (PTU) experienced a 50% reduction in fecundity. The purpose of this study was to determine if early life stage thyroid disruption led to an alteration of reproductive behaviors in male fathead minnows. To accomplish this, larval fathead minnows were exposed to PTU and reproductive behaviors were quantified. Results showed that PTU-exposed fish demonstrated significantly fewer reproductive behaviors than those in the control group. This data provides an explanation for the previously observed 50% decrease in fecundity in the fathead minnows exposed to PTU and provides further evidence that early life stage thyroid disruption can interfere with the display of key and ecologically-relevant behaviors later in life.