Diarrhetic shellfish poisoning (DSP) has emerged as a significant and expanding seafood safety threat in coastal regions across the United States. The harmful algal species Dinophysis produces toxins known to cause DSP that can accumulate in shellfish. Little is known about the environmental and biological drivers of Dinophysis growth and toxin production. We will develop a nationwide network of Imaging FlowCytobots (IFCBs) optimized for monitoring Dinophysis blooms and determine how growth rates and toxin production are influenced by the environment. Our results will help address regional management needs.

Why We Care
Toxin-producing species of dinoflagellates in the genus Dinophysis have threatened the safety of shellfish consumers in Asia and Europe for decades. Only in the last decade has DSP become a human health threat in the U.S., and recent observations of more intense Dinophysis spp. blooms may signal expansion of this species into new regions. Since it was first detected on the coast of Texas in 2008, Dinophysis ovum has been detected frequently and has resulted in the closures of shellfish harvesting to prevent DSP. Since 2011, closures due to DSP from D. acuminata and D. fortii have also occurred at multiple sites in Puget Sound, Washington. Toxin levels in shellfish exceeding FDA regulatory limits have been reported in New York and Massachusetts due to D. cf. acuminata. Maine closed shellfish harvesting in 2016 due to a novel toxin produced by D. norvegica, and monitoring programs in the DELMARVA region have recently detected toxin-producing species of Dinophysis. Emergence of Dinophysis in Maine and the Mid-Atlantic disclose a relatively new area of concern, with evidence of an approaching tipping point.

Despite this immediate threat to human and ecosystem health, little is known of the environmental and biological drivers of Dinophysis growth and toxin production in the U.S.

What We Are Doing

We aim to:

1. 1. Develop a nationwide network of IFCBs optimized for monitoring and providing early warning of Dinophysis spp. blooms;
   2. Investigate environmental and biological drivers of Dinophysis spp. blooms and toxicity in situ within and across regions;
   3. Quantify rates of growth and toxin production of Dinophysis spp. to a range of environmental and biological factors using controlled laboratory experiments;
   4. Develop informative markers for species identification and investigate physiological responses among Dinophysis spp. to environmental and biological factors;
   5. Determine toxicity of the novel DSP toxin dihydro-DTX1 recently detected in Maine waters;
   6. Evaluate the potential for climate change to expand the threat of DSP in the U.S.; and
   7. Partner with state, tribal, and industry groups to address management needs, disseminate results, and aid regional management programs.

This project will improve shellfish management and response to Dinophysis spp. blooms. The integration of new and enhanced IFCB-based early warning systems into harmful algal bloom monitoring programs will inform management decisions in the Gulf of Mexico, Chesapeake Bay, Long Island Sound, Puget Sound, the Gulf of Maine, and the Nauset Marsh Estuary (Massachusetts). Coastal resource managers will also gain a better understanding of the physiological responses, vertical distribution, seasonality, and average concentrations of DSP toxins in Dinophysis spp. and the biological and environmental controls of growth and toxin production.

Dr. Juliette Smith of the Virginia Institute of Marine Science leads this project. Co-investigators are Drs. Lisa Campbell (Texas A&M University), Christopher Gobler (Stony Brook University), Vera Trainer (NOAA/NMFS/NWFSC), Stephanie Moore (NOAA/NMFS/NWFSC), Jonathan Deeds (US FDA), and Michael Brosnahan (Woods Hole Oceanographic Institution).

The project is funded through the NCCOS Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program.