| The frequency, intensity and geographic distribution of poisoning and death events caused by the harmful algae toxins have increased recently. However, the system of food safety regulations and monitoring for shellfish has not been established or proposed in China. And the research on shellfish poisoning in market shellfish is relatively seldom, which threatened the life and health of human beings. The work on monitoring the toxin of shellfish in Shenzhen seafood wholesale market, which is one of the distributing centers of aquatic products in China, is significant. Therefore, the contents of PSP and DSP in 247 samples collected from 16 shellfish species in the seafood wholesale market of Luohu in Shenzhen two times one month during November 2007 to October 2008 were determined in order to understand the consistency of temporal, spatial and species distribution of the two toxins. The conclusions can be drawn as follows:Part one: Contaminated characteristics of PSP.Firstly, certain PSP toxins were detected in Shenzhen market shellfish. The main contaminated species were Patinopecten yessoensis and Chlamys nobilis, especially Patinopecten yessoensis. The highest PSP concentration that reached 23.84 Mu/g at April 24th in 2008 was almostly 6 times as the public healthy safety standard (4MU/g). Secondly, high PSP toxin production showed at spring and winter, it is higher risk that people eat shellfeish in spring. Lastly, shellfish from Dalian, Guangdong coast and Fujian waters were contaminated by PSP. Samples from Dalian were the most toxic ones, followed Guangdong coast.Part two: Contaminated characteristics of DSP.Firstly, DSP toxins were highly detected in Shenzhen market shellfish, with the positive rate was 44.94% and over-standard rate was 31.17%. Secondly, high diversity of contaminated shellfish, which is 11 species, was found. Among these 11 species, Paphia undulata and Patinopecten yessoensis were the most contaminated species. Thirdly, positive rate and the over-standard rate of samples changed in different seasons. Lastly, shellfish from several waters were all contaminated by DSP, especially in Aotou waters of Guangdong. The results of the present study will provide basic data and theoretical basis for the development of marine aquaculture, the food safety of shellfish and the establishment of shellfish poisoning monitoring program, and provide scientific references for the policy of related management.
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