Soft shell clams (Mya arenaria) have historically played key ecological roles in the Chesapeake Bay, notably as biofilters, sediment burrowers, and significant prey items. Unfortunately, their natural populations have been severely depleted, which could be due, in part, to diseases caused by parasites and cancers. In response to this depletion, strategic efforts to culture Mya arenaria have emerged, like at the Patuxent Environmental and Aquatic Research Laboratory at Morgan State University. Introducing the culturing of M. arenaria in Maryland holds the potential for significant expansion of the shellfish industry. The inclusion of M. arenaria as a cultured shellfish species could contribute to the economic value of the region, but the current disease threats are not well understood.
This research focuses on examining the parasites, pathogens, and transmissible cancers affecting 1-year-old hatchery-grown (“young”) and wild 2-year-old (“adult”) M. arenaria. Clams were assessed for the prevalence and intensity of Perkinsus spp., Vibrio parahaemolyticus, and Disseminated Neoplasia (DN).
The study involved a 9-week outplant experiment, initiated in April 2024, across three distinct rivers within the Chesapeake Bay, MD. This approach tested how environmental conditions (water temperature, salinity, and dissolved oxygen), along with different life stages, affect infection levels in M. arenaria. Preliminary findings indicate differences in mortality and infection levels across the study sites and life stages. Mortality was higher in the Chester River, which had elevated water temperatures and lower salinity (Figure 1). There were great differences in disease impacts between young and adult M. arenaria, based on infection prevalence and intensity of Perkinsus spp. and Vibrio parahaemolyticus. Disease patterns also varied across sample sites. Further analysis of these results is ongoing, including testing site and age patterns for DN, characterizing Vibrio toxicity, and comparing overall disease impacts across sites.
This research provides a comprehensive, up-to-date analysis of diseases affecting M. arenaria, with the goal of supporting the potential introduction into the aquaculture industry.