Effects of Exposure to Four Endocrine Disrupting-Chemicals on Fertilization and Embryonic Development of Barbel Chub (Squaliobarbus curriculus)

The toxicities of 4 common endocrine-disrupting chemicals （EDCs）, 17β-estradiol （E2）, p,p＇-dichlorodiphenyldi- chloro-ethylene （DDE）, 4-nonylphenol （NP） and tributyltin （TBT）, to sperm motility, fertilization rate, hatching rate and embryonic development of Barbel chub （Squaliobarbus curriculus） were investigated in this study. The duration of sperm motility was signifi- cantly shortened by exposure to the EDCs at the threshold concentrations of 10ngL-1 for E2 and TBT, 1 μgL l for NP and 100 μgL-1 for DDE, respectively. The fertilization rate was substantially reduced by the EDCs at the lowest observable effect concentrations （LOECs） of 10 ngL-1 for E2 and TBT and 10μgL-1 for DDE and NP, respectively. Of the tested properties of S. curriculus, larval deformity rate was most sensitive to EDC exposure and was significantly increased by DDE at the lowest experimental level of 0.1 μgL-1. Other EDCs increased the larval deformity rate at the LOECs of 1 ngL-1 for E2, 10ngL-1 for TBT and 1μgL-1 for NP, re- spectively. Despite their decreases with the increasing EDC concentrations, the hatching rate and larval survival rate of S. curriculus were not significantly affected by the exposure to EDCs. The results indicated that all the 4 EDCs affected significantly and nega- tively the early life stages of the freshwater fish S. curriculus. Overall, E2 and TBT were more toxic than NP and DDE, while DDE might be more toxic to larval deformity rate than to other measured parameters. Thus, the 4 EDCs showed potential negative influ- ences on natural population dynamics of S. curriculus. Our findings provided valuable basic data for the ecological risk assessment of E2, DDE, NP and TBT.

The toxicities of 4 common endocrine-disrupting chemicals(EDCs),17-estradiol(E2),p,p'-dichlorodiphenyldichloro-ethylene(DDE),4-nonylphenol(NP) and tributyltin(TBT),to sperm motility,fertilization rate,hatching rate and embryonic development of Barbel chub(Squaliobarbus curriculus) were investigated in this study.The duration of sperm motility was significantly shortened by exposure to the EDCs at the threshold concentrations of 10 ng L 1for E2 and TBT,1 μg L 1for NP and 100 μg L 1 for DDE,respectively.The fertilization rate was substantially reduced by the EDCs at the lowest observable effect concentrations(LOECs) of 10 ng L 1for E2 and TBT and 10 μg L 1for DDE and NP,respectively.Of the tested properties of S.curriculus,larval deformity rate was most sensitive to EDC exposure and was significantly increased by DDE at the lowest experimental level of 0.1 μgL 1.Other EDCs increased the larval deformity rate at the LOECs of 1 ng L 1for E2,10 ng L 1for TBT and 1 μg L 1for NP,respectively.Despite their decreases with the increasing EDC concentrations,the hatching rate and larval survival rate of S.curriculus were not significantly affected by the exposure to EDCs.The results indicated that all the 4 EDCs affected significantly and negatively the early life stages of the freshwater fish S.curriculus.Overall,E2 and TBT were more toxic than NP and DDE,while DDE might be more toxic to larval deformity rate than to other measured parameters.Thus,the 4 EDCs showed potential negative influences on natural population dynamics of S.curriculus.Our findings provided valuable basic data for the ecological risk assessment of E2,DDE,NP and TBT.