Meeting Abstract
Zostera marina eelgrass, an important foundation species for many temperate coastal marine ecosystems in the North Pacific and North Atlantic, is nevertheless vulnerable to pathogens. In particular, the protist Labyrinthula zosterae, which causes eelgrass wasting disease, has at times swept through eelgrass populations with devastating effects. Although L. zosterae has not recently caused widespread epidemics, it continues to be present at low but varying levels in eelgrass beds, including those in Washington State. Knowing the factors which can affect its spread is important for management of eelgrass. The eelgrass isopod Pentidotea resecata is a common inhabitant of eelgrass in Washington State, with high abundance in Padilla Bay. P. resecata lives and feeds on eelgrass and, as an accomplished swimmer, travels from blade to blade. In this laboratory study we tested whether P. resecata serves as a vector for spreading wasting disease by its travel among and feeding on the eelgrass blades. During 12-day laboratory experiments, eelgrass blades exposed only to seawater developed virtually no wasting. Blades placed near infected blades developed substantially more wasting lesions. Allowing the isopods to travel back and forth between the blades further increased the prevalence of wasting, while the greatest incidence was produced by direct contact of infected blades with the clean blades. These results indicate that, in conjunction with other important variables, P. resecata can serve as a vector for the spread of eelgrass wasting disease.
