Meeting Abstract

P3.30  Sunday, Jan. 6  Evaluating naturalized populations of western mosquitofish, Gambusia affinis, in the Verde River watershed for biomarkers of endocrine disruption HEALY, F.*; PARK, D.; BERGAMINI, R.; DANIELS, K.; PROPPER, C.R.; Northern Arizona Univ., Flagstaff fh52@nau.edu

Invertebrate and vertebrate aquatic organisms exhibit a number of responses to xenobiotics, making them excellent bioindicators of environmental contamination. Rivers in the arid Southwest may be particularly vulnerable to chemical pollution as there is limited availability of surface water for dilution effects. Based on a prior study of benthic macroinvertebrate community structure in the Verde River watershed, Arizona, we identified five sites that may represent different pollution loads and a site that receives only spring-fed water. To determine whether these sites may also affect endocrine function in aquatic vertebrates, we used naturalized populations of western mosquitofish (Gambusia affinis) as a bioindicator for estrogenic or androgenic markers of pollution. There were no significant intrasex differences in anal fin lengths among all sites, suggesting that fish raised in these waters did not experience feminization or masculinization during development. However, body length in females and mass in males differed among sites, but these were not related to predicted pollution levels. The lack of differences in anal fin length suggests that there is no overt disruption of androgen activity in these sampled reaches. However, the differences in body size and mass may be related to complex biotic and abiotic interactions within the watershed. Our results suggest that water in the areas sampled may not affect androgenic activity in these fish. Furthermore, this study illustrates that within a watershed’s geographic microscales there are differences in population traits. These differences need to be taken into account when trying to find correlations between pollution and physiological outcomes in natural populations.