碩士 / 國立臺灣大學 / 漁業科學研究所 / 87 / Purple clam is a kind of shellfish of high economic importance in Taiwan. Since the paralytic shellfish poisoning (PSP) incidents due to the ingestion of contaminated purple clam occured in 1986 and 1991, the consumption and aquaculture industry of purple clam has been declining. According to the long term survey of toxic shellfish monitoring, it was noted that most of the toxic cases were related to one of the purple clam species, Hiatula rostrata, but none to H. diphos, another popular species cultured. In this research we used a high performance liquid chromatography for PSP toxin analysis in Alexandrium minutum, known as the toxin producing organism responsible for the PSP in Taiwan, and purple clams. Accumulation and detoxification of toxins in these two hiatula species were compared after continously feeding with toxic A. minutum for 24 days and nontoxic Isochrysis and Pavlova for another 24 days. Toxin metabolism and translocation in the purple clams were also studied and compared between two species.
The result showed that both Hiatula species accumulated the toxins according to the amount of filtered A. minutum cells. Although H. diphos showed a higher rate in toxicity increase than H. rostrata, both species showed a similar level of highest toxicity in the experiment period. Most of the ingested algal toxins remained in the digestive glad of the clam. Some of the toxins were translocation to muscle tissue after several days. It was found that were the same feeding behavior H. diphos showed toxicity in muscle the earlier than H. rostrata. There was a consitency on dates when the digestive gland and muscle showed their highest toxicity. However H. rostrata showed it's highest toxicity in muscle one sampling period after the date that the digestive gland had its highest toxicity. Generally, GTX-Ⅰand GTX-Ⅱwer more stable that the after two, GTX-Ⅲ and GTX-Ⅳ in the clam tissue due to the result that GTX-Ⅲ and GTX-Ⅳ remained almost the same concentration in the tissue during feeding period.
From the monitoring survey of toxic purple clam cultured in different areas along the south western coast of Taiwan it was noticed that the toxic clams were all from Tungkang of Pingtung. They had toxicities exceeding the safety level in several occasions. During the study period there seems no significant seasonal variation of the occurrence of toxic clam due to the widely ditsribution of the toxic specimens in almost every months of the year. There was a coincidence to show the toxic clams were H.rostrata and cultured mainly in Tungkang area and nontoxic ones were H. diphos, cultured elsewhere. Since our result showed no significant difference in toxin accumulation removal between these two Hiatula species, we speculated the geographic distribution of toxic clams was due the different environment and different culture behavior that brought the blooming of toxic algae and contaminated the clams.
| Identifer | oai:union.ndltd.org:TW/087NTU03451002 |
| Date | January 1999 |
| Creators | 黃振平 |
| Contributors | 周宏農 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 58 |
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