Occurrence of PSP-infested scallops in Ofunato Bay during 1976-1979 and investigation of responsible plankton.

Toxic specimens of the scallop Patinopecten yessoensis were collected from Ofunato Bay, Iwate Prefecture, in earlyor mid-summer during 1976-1979. The scallop specimens were dissected into various parts of organ and examined on distributin of the toxicity. Toxins were prepared from the digestive glands and examined on distributin of the toxicity. Toxins were prepared from the digestive glands and analyzed by TLC and electrophoresis. The highest toxicity was detected in digestive gland (19-110 MU/g), followed by rectum (12-83), foot (21-56), mantle (11-39), gill (3-13) and gonad (2-13). The lowest toxicity was found in adductor muscle (2-3 MU/g). Irrespective of the year of collection, the toxins contained gonyautoxins 1-4 as the major, and saxitoxin and neosaxitoxin as the minor. The culture of Protogonyaulax tamarensis OF-1 cells presented essentially the same toxin composition as toxic scallops, indicating the infestation of this plankton to scallops and other bivalves in Ofunato Bay in recent years.