Interspecific transmission of Seagrass Wasting Disease from Pacific oysters, Crassostrea gigas, to eelgrass, Zostera marina

Abstract

In order to feed the growing population of the world in more sustainable ways, more governments and other actors are turning to the aquaculture of marine species to provide for the increasing need for sustenance. Oysters, specifically Crassostrea gigas, are an important aquaculture species, and have been introduced into many areas for this purpose, however welack understanding of their direct interactions with cohabiting species. One such species that commonly coccurs in areas with C. gigas is Zostera marina, eelgrass, which is affected by Seagrass Wasting Disease (SWD). The transmission dynamics of SWD from oysters to eelgrass needs more study. A laboratory experiment was conducted where Pacific oysters, C. gigas, were exposed to Labyrinthula zosterae and transferred over to tanks containing naive eelgrass to test if oysters were a vector for Labyrinthula zosterae. The resulting data shows that disease prevalence of directly inoculated treatments and oyster vectoring of disase were similar. Disease severity was also highest in the inoculated treatments, with direct inoculation being highest. Overall, the findings show that transfer of oysters from infected waters to non-infected waters can introduce disease and subsequent infection. These findings should be used to inform general aquaculture practices and the management and land use practices of oyster beds and possibly other farmed shellfish species.