Extensive shellfish resources in the Gulf of Maine are frequently contaminated with toxins produced by the red tide dinoflagellate Alexandrium fundyense. Shellfish harvesting must be closed to protect public health. To minimize economic disruption, this project is developing models to predict toxic blooms and understand the transfer of toxins to shellfish in order to provide early warning. Protocols were developed for safe shellfish harvesting in areas too remote for routine monitoring.
Why We Care
The Gulf of Maine and Georges Bank experience annual blooms of Alexandrium fundyense (aka the New England red tide). A. fundyense produces potent neurotoxins that accumulate in shellfish and cause Paralytic Shellfish Poisoning (PSP) in human consumers. Near shore areas are monitored and shellfish harvesting is regulated by states in the region. In federal waters where routine monitoring is not feasible, large areas have been permanently or temporarily closed to shellfish harvesting, blocking access to a resource with a potential sustained harvesting value of $50-100 million per year. Since 1997 ECOHAB ( 1997, 2004, 2009 ) and MERHAB projects have supported research to understand the causes and impacts of toxic A. fundyenseblooms in the Gulf of Maine in order to better monitor and predict these blooms and minimize impacts to public health and coastal economies.
Our objectives were to establish a comprehensive regional-scale understanding of the factors influencing A. fundyense growth, the movement of cells and toxins around the Gulf and between the surface and the bottom, and their relationship to shellfish toxicity. By developing models to predict blooms and shellfish toxicity, both near shore and off shore harvesting closures can be minimized.
What We Did
GOMTOX has utilized a combination of large-scale oceanographic cruises, moored instruments and sediment traps, drifters, and satellite imagery to:
- investigate A. fundyense bloom dynamics in relation to environmental and oceanographic conditions;
- determine the pathways by which toxins are transferred from A. fundyense to shellfish in both nearshore and offshore Gulf of Maine and southern New England shelf waters;
- assess interannual to interdecadal variability in A. fundyense cell and cyst abundance, PSP toxicity and shellfish harvesting closures;
- incorporate field observations results from this study and those that preceded it into a suite of numerical models for hind casting and forecasting applications; and
- synthesize and disseminate the information and technology widely, emphasizing the need to transition scientific and management tools to the management community for operational use.
This project is part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program. The project is led by Dr. Donald Anderson, Woods Hole Oceanographic Institution. Co-principle investigators include Dennis McGillicuddy and Bruce Keafer, Woods Hole Oceanographic Institution; Ruoying He, North Carolina State University; V. Monica Bricelj, Rutgers University; Stacey DeGrasse , Jonathan Deeds, and Sherwood Hall, U.S. FDA; Benjamin Cowie-Haskell NOAA Marine Sanctuaries Division; James P. Manning, NOAA NMFS; Jennifer Martin, Canadian Department of Fisheries and Oceans; David Townsend, Neal Pettigrew, and Andrew Thomas, University of Maine, Orono; and Cynthia Pilskaln and Jefferson Turner, University of Massachusetts, Dartmouth. Associate investigators include Darcie Couture, Resource Access International, LLC; J. Michael Hickey and David Whittaker, Massachusetts Division of Marine Fisheries; and David H. Wallace, North Atlantic Clam Association.
Benefits of Our Work
We have produced a comprehensive understanding of the causes of A. fundyense blooms and the associated toxicity of nearshore and offshore shellfish across this highly complex region. Important hydrographic pathways and branch points have been identified, and key features and processes characterized. Conceptual models have been formulated to explain blooms and toxicity throughout the region, and sophisticated numerical models have been developed and tested that simulate physical, chemical, and biological processes at a highly detailed level over the region. A major breakthrough, based partly on another ECOHAB project, was that the abundance of seed-like cysts, deposited on the ocean bottom by the fall of one year, along with ocean conditions the next spring, determines the severity of the outbreak during the next bloom season.
Starting in 2008 the model has been used to issue Gulf of Maine HAB seasonal outlooks, similar to annual hurricane forecasts. In addition weekly forecasts of bloom intensity and location have been provided to state shellfish managers. A Prevention, Control, and Mitigation of HABs (PCMHAB) project is now funding the transfer of the model to the NOAA HAB Operational Forecasting System (HAB-OFS).
A pilot study for an onboard screening/dockside testing protocol was conducted as part of this project in order to facilitate safe harvesting of shellfish from federal waters where shellfish are sometimes contaminated with high levels of PSP toxins. The protocol was approved in October 2011 as a marine biotoxin control strategy by the Interstate Shellfish Sanitation Conference. Approval by the U.S. Food and Drug Administration followed on 2/26/12, prompting the Mid-Atlantic Fishery Management Council to request that NOAA National Marine Fisheries Service open a portion of federal waters closed to shellfish harvesting with the use of the protocol. On 12/16/12 NOAA announced a new rule, to take effect 1/1/13. The protocol allows fishing vessels with the appropriate license to harvest shellfish in federal waters, screen them for PSP toxins on board, and, if toxins are below the regulatory threshold, bring the shellfish to port where they are again tested for toxins in a lab that meets National Shellfish Sanitation Program standards before the shellfish can be sold.