Perkinsus-Marinus Susceptibility And Defense-Related Activities In Eastern Oysters Crassostrea-Virginica - Temperature Effects



Poorly documented, but apparently sporadic oyster Crassostrea virginica mortality in the coastal lagoons Carmen, Machona and Mecoacan at the southern extreme of the Gulf of Mexico in Tabasco, Mexico, has been attributed by local oystermen to pollution resulting from oil refinery operations. In September 1992 we sampled oysters in these lagoons to investigate the potential for disease-induced mortality from the oyster pathogen Perkinsus marinus. Prevalence of P. marinus was 100% at Lodazal, a high salinity (31 ppt) site in Carmen lagoon and 60% at Rio San Felipe, a low salinity (15 ppt) site. At Los Jimenez, a high salinity (32 ppt) site in Machona lagoon with previous high mortality, prevalence of P. marinus was 90% and weighted prevalence, a measure of intensity, was 3.1, a high value associated with heavy infections and mortality. Samples collected at the Buena Vista aquaculture facility in Mecoacan lagoon revealed 60 to 100% prevalence of P. marinus, although most infections were low intensity. P. marinus is a potential source of oyster mortality in these coastal lagoons; more intensive sampling is necessary to determine the mortality attributable to P. marinus.