The Occurrence of Protogonyaulax spp. in Ofunato Bay, in Association with the Toxification of the Scallop Patinopecten yessoensis

Abstract

The abundance of Protogonyaulax and the toxicity of the scallop Patinopecten yessoensis were monitored at two stations in Ofunato Bay, Iwate Prefecture. In spring and summer, P. tamarensis appeared and in autumn, P. catenella. The ratio of the toxicity level of scallop to the number of Protogonyaulax plankton cells varied even in the same species. The toxin, once accumulated in the scallop, was not easily eliminated. The toxicity level in the shellfish did not markedly increase when the Protogonyaulax cell density reached the maximum. The maximum level was attained about one week later, when most of the Protogonyaulax had already disappeared. © 1982, The Japanese Society of Fisheries Science. All rights reserved.