Document Type



Virginia Institute of Marine Science

VIMS Department/Program

Institute History (VIMS)

Publication Date



VIMS 75th Anniversary Alumni Research Symposium


Virginia Institute of Marine Science, Gloucester Point, VA


Effective management of harmful algal blooms (HABs) within a region requires an understanding of species-specific HAB spatial and temporal distributions, bloom dynamics, as well as potential health impacts. In 2007, the southern Chesapeake Bay witnessed its first blooms of the HAB species Alexandrium monilatum. Since then, A. monilatum has bloomed in the region almost annually. A. monilatum produces the toxin ‘goniodomin A’ and is suspected in local mass mortalities of oyster larvae (Crassostrea virginica) grown for aquaculture and restoration projects. Representatives from Virginia’s multimillion dollar oyster aquaculture industry recently expressed great concern over A. monilatum impacts to their businesses; field and lab studies were designed to address these concerns. Sediment samples were collected from the southwest portion of the Chesapeake Bay in a systematic grid-sampling design to assess cyst (resting cell stage) distributions. Cysts were present in low densities at most sites, and cyst densities were high where blooms had been recorded in previous years. HAB toxicity bioassay methods developed at the Virginia Institute of Marine Science were modified to investigate adverse health impacts of five different A. monilatum cell density treatments on sub-adult oysters (~40-70 mm). Oysters delayed grazing when exposed to high densities (>1000 cells/mL) of A. monilatum. Data from the 2015 bloom season and additional bioassays will be presented. Results from these studies could aid in the prediction of A. monilatum bloom severity and health effects on wild and aquacultured oysters, enabling development of best management practices to minimize impacts to the Virginia oyster industry.


Poster, VIMS 75th Anniversary, Institute History, Alumni, Algal Blooms, Chesapeake Bay