Meeting Abstract
Fish habitats are increasingly contaminated with estrogenic compounds, including 17β estradiol (E2). E2 causes adverse effects on the reproductive system of male fish; however, the effects of E2 on other aspects of fish metabolism are not well known. Our objective is to evaluate the effects of E2 exposure on the basal and stressed metabolic rate and morphological changes in body shapes of sunfish. Fish were held individually in ten gallon tanks under two treatments with varying estradiol concentrations (40 and 80 ng/l) and one control treatment (no E2). The duration of E2 exposure was 21 days, with E2 being replenished every week based on its half-life. Basal and maximum aerobic scopes were measured using close respirometry and a chase protocol at the beginning and at the end of the experiment. Lateral pictures of the fish were also taken at these two time points. Our working hypotheses are that (1) fish subjected to E2 exposure would experience stress and thus increased oxygen consumption, and (2) male dimorphic characters would become less noticeable in exposed fish. Our results show that in the control group the basal metabolic rate decreased after 21 days; whereas in the estradiol exposed groups, it did not. Although maximum oxygen consumption did not alter, the aerobic scope also increased in control individuals but not in exposed individuals. We observed the reduction in operculum size and decrease in head size in exposed individuals but not in the control. Contrary to our hypothesis, aerobic scope increased only in control males which could be related to aggressive male displays and higher allocation of resources to gonad development. E2 exposure caused some morphological changes in male related characters in sunfish which eroded male dimorphic characters. Our research highlights negative effects of estradiol that are more widespread than simple gonadal alterations.
