| Organotin compounds are regarded as the most toxic material ever deliberately introduced into the sea and also the only one metal compound in known endocrine disrupting chemicals. Tributyltin(TBT) and triphenyltin(TPT) have been reported to induce imposex in gastropods. And the ocean ecological environment has been seriously threatened by these kinds of compounds. The origin of organotin compounds is mainly from antifouling paints used as biocidal additives in marine environment. Xiamen and Hong Kong all have the well developed shipping industry, which brings about more serious organotin compounds pollution in these two areas. Because of the easy identifiability, irreversibility and particularity to organotin compounds, imposex in gastropods has been considered as an effective indicator to marine organotin compound pollution. Additionally to the most abundant quantity, easy collection and widespread distribution of Thais clavigera, the imposex level of Thais clavigera is used to indicate the organtin compounds pollution. In this paper, exposure experiment to TBT was firstly carried on in order to validate that TBT could cause imposex in Thais clavigera. Secondly, the imposex level of Thais clavigera had been investigated in Xiamen and Hong Kong sea area. Together analyzing with the past concentration of organotins in marine environment, the organotin compounds pollution had been evaluated in these two areas. Besides, according to the variation of hormone level in Thais clavigera from the exposure and field experiment, the endocrine interference mechanism of imposex induced by organotins was preliminary discussed in the end.By the exposure to TBT, females in all exposed groups(0.5,1,2,5μg/L) developed into imposex after one month. And the imposex level tended to more serious over the exposure time. 120 days later, the number of females in all exposed groups showed a sharp decrease and the rest were males almost. This phenomenon was likely be connected with the selective mortality on female. In general, the imposex had been proved to happen when Thais clavigera was exposed to TBT for a long period. According to the field research of the imposex in Thais clavigera in Xiamen and Hong Kong, it was found that the imposex level was more serious in Hong Kong. sea area. And T. clavigera in all 6 sites in Hong Kong exhibited 100% of IOI. Especially for the two areas adjacent to Shen Zhen, the percent of sterilization was up to 78.94% and 52.17% respectively. Besides, IOI of Thais clavigera in 5 of 17 sites in Xiamen was up to 100%. At Bao Zhu Yu Islet where located in an enclosed type of Ma Luan Gulf, it showed the most serious imposex level. Moreover, a decreased imposex level trend was found from the inner to the outer of Xiamen Western Harbour, which were accordant with the concentrations of organotins before. Meanwhile, it also showed a good correlationship between the imposex degree and the organotins contamination as well as shipping activities.By studying the variation results of testosterone and estradiol, there was relatively a good positive relationship between the imposex level and the testosterone level in females from the field research in Xiamen. Besides, it also showed a positive trend in Hong Kong area. Anyway, this result provided an evidence for the endocrine interference mechanism that organotins induced imposex by increasing the testosterone levels in organism.Generally, this research provided a scientific basis for the restriction of organotin compounds and a protection of coastal zone. Meanwhile, it provided a reference for further studying the mechanism of imposex caused by organotins and hopefully contributes to the relevant toxicological study in future. |
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