EDWARDS, T. M.; EMRICH, R.; THOMPSON, H.; THRO, J. M.; CHAPMAN, L.; GUILLETTE, L. J.; University of Florida; University of Florida; University of Florida; University of Florida; University of Florida; University of Florida; ; : Reproductive physiology of Gambusia holbrooki collected from several Florida springs contaminated with varying amounts of nitrate.

Florida is well known for its more than 700 fresh water springs. These springs are often connected by underground streams that move water throughout the Floridian Aquifer. The movement allows transportation of agricultural runoff, which joins the groundwater at its source and may then disperse throughout the aquifer, only to resurface at the springs. This dispersal pattern is true of nitrate, a water-soluble component of fertilizer and animal wastes. Nitrate is becoming a significant environmental contaminant in several of Florida�s springs. Apart from the ecological impact of increased nutrients, nitrate may disrupt physiological processes as well. In vivo and in vitro, nitrate has been shown to affect multiple reproductive endpoints, including steroidogenesis and sperm quality. To investigate the impact of ecological nitrate on reproductive parameters in Gambusia holbrooki (eastern mosquitofish), we took advantage of the experimental opportunity afforded by Florida�s spring system, which includes several springs with replicated nitrate loads. Over a three week period in May 2003, we collected male and female mosquitofish from nine sites in central and north-central Florida and evaluated their reproductive status, including fecundity, sperm counts, and reproductive hormone concentrations. We also collected water quality data, including nitrate concentrations. Our discussion will focus on the effects of nitrate on reproductive physiology of mosquitofish, particularly in context of the many other environmental factors that may influence their reproduction.