Seasonal variation of paralytic and amnesic shellfish toxicities in bivalves and microalgae in Haiphong area, Vietnam
2006
Huyen, Nguyen Thi Minh | Thuoc, Chu Van | Ogata, Takehiko | Sato, Shigeru | Takata, Yoshinobu | Kodama, Masaaki | Fukuyo, Yasuwo
Monitoring survey was conducted to know the distribution and seasonal variation of PSP and ASP toxicities in bivalves and the abundance of toxic microalgae in Haiphong area, Vietnam. Sampling was carried out at the stations in Cat Ba and Do Son every two weeks from February 2002 to March 2004. Low levels of PSP and DA were detected in shellfish samples from both stations, showing seasonal and yearly variation. Toxicity of plankton samples also showed fluctuation, though the clear correlation could not be observed with the shellfish toxicities. HPLC or LC-MSMS analysis provided clear evidence of shellfish contamination with these toxins and indicated the existence of causative microalgae for these toxicities in this area. Several species of Alexandrium such as A. minutum, A. tamiyavanichii, A. ostenfeldii, A. tamarense were found, though the abundance of them was very low. On the other hand, massive bloom of Pseudo-nitzschia occurred in January at both stations. However, these blooms did not always cause the increase of DA level both in plankton and shellfish samples.
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