The Occurrence of a Haplosporidian in Tomales Bay, California

Katkansky, S; Warner, R

Entire Text: Adult American oysters (Crassostrea virginica) are trucked to California for sale on local markets. Large quantities are commonly held for several months in Tomales Bay, approximately 60 miles north of San Francisco. Routine histological monitoring of these oysters commenced in the spring of 1967 in conjunction with a Pacific oyster (Crassostrea gigas) mortality study. The sporozoan Minchinia costalis is a serious oyster pathogen which has been identified as the etiologic agent of certain oyster epizootics on the Atlantic' coast of the United States in recent years (J. L. Wood and J. D. Andrews, Science 136, 710-711,1962). Numerous plasmodial stages of a morphologically identical haplosporidan were noted in oysters (C. virginica) in July, 1967, and in July, 1968, from a group placed in Tomales Bay in October, 1966. Spores were present in one oyster from the July, 1967, collection. It is not known j certain when sporulation initiated due the sequence of events involved in transplantation from the East to West coast Plasmodia were noted in another oyster December 1968, from a group planted Tomales Bay in June, 1967. A total of infected oysters (four moribund and ti living) have been observed. All such infected stocks originated from the vicinity of New Haven, Connecticut. Sporulation of this haplosporidan has been observed to occur in oysters in males Bay, but plasmodia have been noted in oysters that have been there for months. It is evident that this pathogen able to survive on the West coast for e. tended periods. Thus far, we have 111 observed infections to be spread to adjacent stocks of C. gigas.

The Occurrence of a Haplosporidian in Tomales Bay, California

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