A LONG~ERM STUDY OF "MICROCELL " DISEASE IN OYSTERS WITH A DESCRIPTION OF A NEW GENUS, MIKROCYTOS (Go No), AND TWO NEW SPECIES, MIKROCYTOS MACKINI (SP. No) AND MIKROCYTOS ROUGHLEYI (SP. No)

• Main Authors: C. Austin Farley, Peter H. Wolf, Ralph A. Elstons
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: and Olympia oyster; O. lunda; in North America; Canada; Lunda; Crassostrea gigas
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.505.490; http://fishbull.noaa.gov/863/farley.pdf

Continuing long-tenn studies of oyster disease problems have been carried out over the past 26 years using field monitoring, gross, histologic, and ultrastructural pathologic methods. A microorganism of uncertain taxonomy was discovered in 1963 by J. G. Mackin in association with lesions and mortalities of Japanese oysters, Crassostrea gigas, from Denman Island, Britisll Columbia, Canada. Mackin coined the tenn "microcell " for this organism and described the parasite as 1-3,.m cells with small nuclei which occurred within vesicular connective tissue cells adjacent to characteristic abscesses. We are describing this organism as Mikrot:ytos mac1cini sp. n. in his honor. Similar appearing organisms were seen by the senior author in flat oysters, Ostrea edulis, from Milford, Connecticut, on three different occasions: 1) in oysters transferred from Milford. Connecticut, to Chincoteague Bay. Virginia; 2) in oysters transferred from Milford to Elkhorn Slough, California; and 3) in oysters trans-ferred from Milford to Oxford, Maryland, and held in recirculated sea water. The causative organism in these three episodes has been sIlown by electron microscopy to be Bonamia ostreae, the parasite that was implicated in recent mortalities in flat oysters in Europe. Similar organisms have also been seen in Olympia oysters, Ostrea lurida, from Oregon and in the Sydney rock oyster, Saccostrea commercialis, from Australia. Presence of the organism in the latter species is associsted with the winter mortalities originally described by T. C. Roughley, and the pathogen is here described as Mikrot:ytos roughleyi (sp. n.) in his honor. "Microcell " type parasites of oysters are associated with a complex of diseases that occur in Japanese oyster, Crassostrea gigas; Sydney rock oyster, Sac-costrea commercialis; flat oyster, Ostrea edulis;