Ecotoxicity Effects Of17β-Estradiol To Rare Minnows(Gobiocypris Rarus)

In recent years, in pace with report of environmental endocrine disrupting chemicals hazard with environmental beings and human health appeared frequently, environmental endocrine disrupting chemicals screening and its adverse effects in different levels of environmental beings have being paid close attention. In present study, rare minnows(Gobiocypris rarus) were exposed to17β-estradiol in acute toxicity test, short-term toxicity test on embryo and sac-fry stages, and sexual differentiation disruption assay, it researched endocrine disruption effect and biotoxicity of17β-estradiol to rare minnows on different life stages and different levels, and compared sensitivity of rare minnows were exposed to17β-estradiol in acute toxicity test, and short-term toxicity test on embryo and sac-fry stages. The main results are as follows:1. The LC50of adult rare minnows exposed to E2was3.39mg/L,95%confidence limits:2.72-4.47mg/L.2. The LC50of rare minnows exposed to E2in short-term toxicity test on embryo and sac-fry stages was1.13mg/L,95%confidence limits:0.94-1.39mg/L. Compared with control, the lethal effect on embryo was obvious in the treatments1.77,5.0mg/L E2(P<0.01).The lethal effect on larval was obvious in the treatments0.63,1.77mg/L E2(P><0.01). Comparison of the effects of E2on embryo and larval mortality, the effect of E2on larval was stronger than embryo. In the4th day, the hatching rate was decreased significantly at1.77mg/L E2treated groups (P<0.01). At0.63,1.77mg/L E2treated groups, the larval growth was inhibited significantly (P>0.01).3. Comparison of LC50between the acute toxicity test and short-term toxicity test on embryo and sac-fry stages, the embryo and sac-fry stages toxicity were stronger than adult acute toxicity, which indicated that the effect of E2in these two stages, sac-fry stages was more sensitive.4. Regard of the effects of E2on51dph of rare minnows, compare with control, the length increase was inhibited at259ng/L and1180ng/L (P<0.05, P<0.01).VTG concentrations in female fishes were decreased significantly at the8ng/L,48ng/L and259ng/L E2treated groups (P<0.01), while, in males were increased significantly at1180ng/L E2treated group (P<0.01). Based on histopathologic examination, no obviously difference in sex ratio was found between the treatment and control groups, however, intersex was found at48ng/L E2treatment group, and at259ng/L,1180ng/L E2treatment groups, male fish were appeared visibly depauperate. In conclusion,17β-estradiol performs estrogenic effects on gonads differentiation of the51dph juvenile of rare minnows, but rare minnows, which were taken as survival experimental prototype to screen and evaluate endocrine disrupters, need to be studied further.