Although many environmental hormones, including persistent organic pollutants, have been banned in Taiwan, environmental residues are still a concerned issue. Gastropod snails are known to be the most sensitive bioindicators to reproductive-related environmental hormones. In the sand bottom ecosystem, the moon snails are one of the most important 2nd consumer. In this project, concentrations of environmental hormones, i.e., organotins, alkylphenols and Hg were determined in gastropod snails. And, the reproductive abnormalities of snails were correlated to the environmental hormones. The evaluation included the status of moon snail fishery, examination of snails’ reproductive structure and determining the concentrations of the environmental hormones.
A decrease trend in moon snail fishery has been found. However, due to a lack of detail description in trawling methodology, the decrease trend can not be certain. In the lined moon snail Natica lineate, there was a significant defference among sites in the ratio of normal to abnormal male penis which ranged from 20 to 50%. In the bladder moon snail Neverita didyma, significant difference among sites in the ratio of normal to abnormal male penis has also found and the ranges were 9-58%. In the oyster drill Thais clavigera, the percent imposex varied between 25-100% with significant difference among sites. In the ivory shell Babylonia areolata, the percent imposex was 7-18% and significantly differed between sites.
In the N. lineate and N. didyma, phenyltins was not detected and butyltin concentrations were high, i.e. 2527-3975 ng/g dry wt, with tributyltin as the major component. The concentrations of butyltins were higher in the hepatopancreas than in the foot and significant difference was found between the examined species. Nonylphenol (NP) was detected in all snail samples, with the concentrations of 572-2109 ng/g dry wt. In general, the foot had higher NP concentration than the hepatopancreas and there was no difference among species. The concentrations of total mercury (HG) in the foot and hepatopancreas ranged, respectively, from 42 to 554 and 211 to 1116 ng/g dry wt. Significant difference was observed in the concentrations of HG among species in both tissues. Additionally, the concentrations of organic HG were below the food safety limit (0.009-0.150 mg/kg wet wt).
According to the correlation analyses, there was no significant correlation between standardrized male penis length, standardrized female penis length or percent imposex and butyltins, NP or HG. Based on the results, it is likely that snails are affected by organotins and alkylphenols at concerned level, extra control actions are strongly suggested.