Document Type



Virginia Institute of Marine Science

Publication Date



Special Reports in Applied Marine Science and Ocean Engineering (SRAMSOE) No. 360


In accordance with the Rational Plan for Testing Application of Non-Native Oyster Species (VIMS 1996) we conducted a field experiment to examine survival, growth and disease susceptibility of Crassostrea ariakensis (=rivularis) in relation to salinity in Virginia. The performance of triploid C. ariakensis in comparison with that of diploid C. virginica, (n = 250, age = 2 years, mean shell height = 60- 64 mm) was evaluated at replicate sites within low, medium, and high salinity regimes (respectively, < 15‰, 15-25‰, > 25‰) in Chesapeake Bay and the Atlantic Coast. During the course of this study, from June 1998 to September 1999, there was a severe oyster disease epizootic prevailing in Chesapeake Bay. At the end of the study C. ariakensis exhibited lower disease prevalence and intensity and superior survival and growth than C. virginica. At low salinity sites cumulative mortality in C. ariakensis (14%) was significantly lower than that in C. virginica (81%). At medium and high salinity sites, cumulative mortality in C. ariakensis was less than 16% whereas all C. virginica were dead by the end of the experiment. After one year of deployment, mean shell height of C. ariakensis at low, moderate, and high salinity sites, was respectively 96 mm, 125 mm, and 140 mm. In comparison, mean shell height of C. virginica was respectively 72 mm, 85 mm, and 75 mm. Prevalence and intensity of Perkinsus marinus infections were significantly lower in C. ariakensis than in C. virginica. During the second summer of disease exposure, prevalence in C. ariakensis ranged form 0-28% whereas prevalence in C. virginica was 100% at all sites. Only light infections were present in C. ariakensis whereas heavy infections were found in C. virginica. MSX was absent in C. ariakensis and present in C. virginica. Mud worms were present in both oyster species but infestations were low and did not appear to affect condition or growth. In summary, wide salinity tolerance and low disease susceptibility were associated with high survival and growth of C. ariakensis in Chesapeake Bay and the Atlantic Coast of Virginia.



Oysters, Salinity, Native Species, Non-Native, Fisheries



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