Occurrence and growth characteristics of the toxic dinoflagellate Gymnodinium catenatum Graham in Furue Bay, Nagasaki prefecture, Japan from winter to spring
2008
Yamatogi, T.(Nagasaki-ken. Inst. of Fisheries (Japan)) | Sakaguti, M. | Somekawa, K. | Nagata, S. | Maruta, H. | Ura, K. | Masuda, D. | Matsuyama, Y.
The unarmored chain-forming dinoflagellate Gymnodinium catenatum is one of the causative species responsible to paralytic shellfish poisoning (PSP) in western Japan. Since 1999, blooms of G. catenatum in Furue Bay (Nagasaki prefecture) have recurrently caused PSP in Pacific oyster Crassostrea gigas and short-necked clam Ruditapes philippinarum. In order to evaluate factors causing G. catenatum blooms, field surveys were carried out in this bay, from the initial to the end of the blooms of this species in 1999-2005. The motile cells of G. catenatum appeared from late fall to winter, and disappeared from winter to early spring. Cell density of G. catenatum was 19,700 cells/L at the maximum abundance in the water with water temperatures of 9.8-21.0degC, salinities of 28.8-35.5 psu. PSP concentration in oysters showed a time lag of a few weeks to the relative densities of G. catenatum. The clone culture of G. catenatum isolated from Furue Bay grew well within 10-30degC, and 16-36 psu, and the maximum growth rate was 0.30/day at 22.5degC and 24 psu. These results indicate a possibility that G. catenatum can form blooms all year round in Furue Bay and adjacent seas.
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