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Virginia Sea Grant funded research

Infectivity and Transmissibility to Crassostrea ariakensis of Pathogenic Bonamia sp. from Ostrea equestris: Evaluation of Crested Oysters as a Parasite Reservoir

Ryan B. Carnegie, Corinne Audemard, Eugene M. Burreson, (VIMS)

Our objectives during 2005 are to demonstrate, by injection challenge with purified parasite cells, the infectivity to C. ariakensis of C. ariakensis-pathogenic Bonamia sp. isolated from O. equestris; to describe the range of O. equestris in Virginia; and to determine the distribution of Bonamia spp. in O. equestris in Virginia. During 2006, we plan to demonstrate, through cohabitation of infected O. equestris with uninfected C. ariakensis, the direct transmissibility of the C. ariakensis-pathogenic Bonamia sp. from O. equestris to C. ariakensis; to demonstrate, through cohabitation of infected O. equestris with uninfected O. equestris, the direct transmissibility of the C. ariakensis-pathogenic Bonamia sp. between O. equestris; and to transfer our results to oyster culture industry and management agencies.

Our approach will include:

  • Identification of C. ariakensis-pathogenic Bonamia sp.-infected O. equestris in VIMS stocks.
  • Isolation of parasites from these O. equestris and determination of infectivity to C. ariakensis in controlled laboratory injection trials.
  • Identification of a second group of Bonamia sp.-infected O. equestris, and determination of the transmissibility of Bonamia sp. from O. equestris to uninfected C. ariakensis and O. equestris in controlled laboratory cohabitation trials.
  • Determination of the distribution of O. equestris in Virginia by dredge sampling at inlets along the Eastern Shore and shoals near the mouth of Chesapeake Bay.

The biggest threat to emerge to a Crassostrea ariakensis introduction on any scale has been a Bonamia sp. found to be pathogenic in C. ariakensis in North Carolina. Gauging the risk posed by this Bonamia sp. to C. ariakensis in Virginia will require an appreciation of the physical tolerances of the parasite and an identification of any possible parasite reservoirs. The small crested oyster Ostrea equestris is a likely reservoir candidate and appears to harbor C. ariakensis-pathogenic Bonamia sp. infections. It is an transmit Bonamia sp. to C. ariakensis; known that this oyster occurs anywhere north of Cape Hatteras, though several reports have suggested it does. Determining that Bonamia sp. isolated from O. equestris is infective in C. ariakensis and capable o will dem> may be used as a factor in assessing Bonamia sp limit of O. equestris will allow an assessment of how immediate the Bonamia sp. risk may be to C. ariakensis in Virginia waters.


Virginia Sea Grant • Virginia Institute of Marine Science
P.O. Box 1346 • Gloucester Point, VA 23062 • 804-684-7164 • 804-684-7161 (fax)

09-Oct-2008

vims