1Hiroshima Prefectural Institute of Public Health and Environment, Minami, Hiroshima 734-0007, 2Hiroshima Prefectural Fisheries Experimental Station, Ondo, Hiroshima 737-1207, Japan
The differences of accumulation and elimination of paralytic shellfish toxins among oyster Crassostrea gigas, scallop Patinopectem yessoensis and mussel Mytillus edulis were investigated in relation to the density of Alexandrium tamarense in Kure Bay, the Seto Inland Sea, Japan. The rates of elimination of the toxins differed markedly from species to species. In the absence of the causative plankton, the oyster eliminated the toxin rapidly which became less than the detectable level after two weeks, and the toxin in the mussel became nondetectable after one month. However, the scallop retained a fairly high level of toxin even after three months. The maximum toxicity level of oyster was lower than that of scallop and mussel. The toxin compositions of oyster, scallop and mussel were analyzed by means of high-performance liquid chromatography. The toxin compositions were different among the species. The ratios of potent carbamate toxins GTX1 and GTX4 in scallop and mussel were higher than those in oyster, and scallop contained higher proportions of GTX2 and neoSTX which were not easily metabolized or eliminated. These results suggest that the differences of the toxin compositions among bivalves affect the toxicity level and the rates of elimination.