Ecological Risk Assessment Of Marine Gastropod Mollusks Population

In recent years, the toxic effects caused by Endocrine Disrupting Chemicals on the eco-environment have attracted more attention from people all over the world, especially the research results has been put into use in internationally environmental politics. As the metal compounds of endocrine disruptors chemical, TBT (tributyltin) was introduced to sea water artificially, which has posed a lot of threat to marine aquatic organisms, especially led to the imposex of some certain kind of marine female gastropod species and the migration of the sex ratio, which finally resulted in the decline of gastropod population and the damage of the marine food chain, as time passed, TBT did serious damage to the eco-environment in the end. The majority of TBT is from the antifouling paint of the dock. Normally, this kind of paint has the killing effects on the marine life, which attached to the outer surface of the ship hull can reduce the dock sailing resistance. In 1960s, TBT has been so appreciated and put into use that the existence of TBT was detected in the tissue of marine life, the sediment and sea water in the mid 1980s. At present, the use of such organic pollutants has been banned in foreign countries, detailed rules and regulations have been enacted and improved. However, except the restrictive regulations in Japan and Hong Kong, other countries in Asian have not yet made such regulations.Imposex of marine gastropod species has been used as a means of biological monitoring for organic tin compounds with the character of being simple and accurate. In this study Nucella lapillus and Thais clavigera Kuster distributed in Europe and Asia respectively were used as sensitive indicator organisms for testing TBT. Compared with other marine gastropod species, these two organisms distributed widely in the Northern Europe and southeastern coast of Asia are more sensitive to TBT, and more convenient to collect and monitor.At present, domestic and foreign researches focus mainly on the individual level of marine gastropod species or use them for biological monitoring of contaminated regions, While, the study of population decline of marine life resulted from pollution is lacking. This study is carried out based on the toxicology experimental data from literature reviews and the life circle of both Nucella lapillus and Thais clavigera Kuster. By using the intrinsic rate of increase resulted from TBT as the end point for evaluation, the aged-structure matrix model has been established, through detecting the distribution of exposure probability of the pollution concentration in Northern Europe and Southeast area, the quantitative predictions of population Value-at-risk has been made. With the Bootstrap re-sample statistical method, the Quantitative Calculation of population value-at-risk of each Country has been made, and with the power function, the effect relationship of these two populations to measure the Safe threshold values has been also established and applied to enact the rules of Water quality benchmark concentration to protect the marine gastropod species in these two regions. At the same time, this study also provides a theoretical foundation for restrictive laws related to the organic tin compound.