Meeting Abstract
Chronic exposure to xenoestrogens can result in endocrine disruption concomitant with reproductive impairment in aquatic organisms. Combined field and laboratory studies are necessary to understand the complex interactions between environmental variables and functional endocrine outcomes. Using western mosquitofish (Gambusia affinis), we assessed morphological and molecular effects of low level exposure to endocrine disrupting chemicals (EDCs) in natural- and laboratory-exposure settings. We collected male and female G. affinis (N = 20) from five Verde River watershed sites in central Arizona differing in point and nonpoint pollution sources including wastewater treatment plant effluent, mining leachate and agricultural discharges. We assessed morphological, gonopodial and vitellogenin (Vtg) concentration differences among the populations. We then exposed male and female G. affinis (N =20-24) collected from a reference site to a 30-day water exposure from Verde River sites previously identified as containing EDCs, and assessed gonopodial and Vtg differences among groups. Last, we exposed a reference and a Verde River population of male G. affinis (N = 10-12) to 0 or 1 nM ethinyl estradiol (EE2) for seven days. The first study found significant differences in female fecundity and male incidence of detectable Vtg among Verde River sites; treatment of adults with water from sites inducing a Vtg response in males did not induce shifts in gonopodial morphology. Finally, EE2 treatment did not affect any measures between EE2 treatments, but site-related differences in gonadosomatic index (P < 0.0071) and gonopodial R4:R6 ratio (P < 0.0001) were significant. Our results suggest that understanding existing population differences when testing wild species is critical in assessing the consequences of exposure to EDCs.
