Institutions: Virginia Inst. of Marine Science, Texas A&M University, Stony Brook University, NOAA/NMFS/NWFSC, US FDA College Park, Woods Hole Ocean. Inst.

Investigators: Juliette Smith (lead), Lisa Campbell, Christopher Gobler, Vera Trainer, Stephanie Moore, Jonathan Deeds, Michael Brosnahan

Introduction to the Problem: Species of Dinophysis, known to produce toxins that cause diarrhetic shellfish poisoning (DSP), 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 US. Since first detected on the coast of Texas in 2008, D. ovum has been detected in six of the last eight years 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 been enforced annually at multiple sites throughout Puget Sound, WA, and toxin levels in shellfish exceeding FDA regulatory limits have been reported in New York and Massachusetts due to D. cf. acuminata. Most recently Maine has undergone closures as a result of D. norvegica (ME) and the unknown toxicity of novel toxin dihydro-dinophysistoxin-1 (dihydro-DTX1). Chesapeake Bay and the larger DELMARVA region (Delaware, Maryland, and Virginia) harbor toxin-producing species of Dinophysis. The region, however, provides contrast as a relatively new area of concern, with evidence of an approaching tipping point.

Rationale: DSP has emerged as a significant and expanding seafood safety threat in coastal regions across the country and observations of intensifying blooms in TX, WA, NY, and New England may signal further expansion into new regions. 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 US, species or subpopulation (strain) variation, and the relative toxicity of the novel dihydro-DTX1.

Objectives: 1) Develop a nationwide network of IFCBs that is 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 the toxicity of dihydro-DTX1; and 6) Evaluate the potential for climate change to expand the threat of DSP in the US; and 7) Partner with State, Tribal, and industry groups to address management needs, disseminate results, and aid regional management programs.

Outputs & Outcomes: This project is expected to improve shellfish management plans and response to Dinophysis spp, blooms. The integration of new and enhanced IFCB-based early warning systems into HAB monitoring programs will inform management decisions regarding resource allocation and shellfish bed closures/re-openings in Gulf of Mexico, Chesapeake Bay, Long Island Sound, Puget Sound, Gulf of Maine and Nauset Marsh Estuary. 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 their biological and environmental controls. Incorporation of a TEF (toxicity equivalency factor) and modified DSP quantification method for dihydro-DTX1 into management will result in more surgical closures, especially in the Gulf of Maine, and potentially in the Puget Sound and DELMARVA regions where D. norvegica is present but not currently dominant.

Institutions: Mote Marine Laboratory, New York University-Abu Dhabi, University of Maryland, Florida Fish and Wildlife Conservation Commission, Bigelow Laboratory for Ocean Sciences, University of South Florida

Investigators: Cynthia Heil (lead), Shady Amin, Patricia Glibert, Katherine Hubbard, Ming Li, Joaquín Martínez Martínez and Robert Weisberg

Blooms of the toxic dinoflagellate Karenia brevis occur almost annually in the eastern Gulf of Mexico (GoM). As exemplified by the recent 2017-2019 bloom, which killed nearly 600 sea turtles, more than 200 manatees and 150 dolphin, such events become the focus of intense public, political and media attention, are ecologically and economically devastating and also cause serious human health impacts. This prolonged current bloom, which coincided with several extreme events (Hurricane Irma and Tropical Storm Gordon) and an extremely wet summer, highlights the need to address two critical aspects of K. brevis bloom ecology: the role of extreme events in magnifying directly or indirectly the intensity and/or duration (i.e. expansion) of blooms, and the factors that ultimately lead to bloom decline.

An interdisciplinary team of 7 PIs from 6 institutions, building on prior K. brevis ECOHAB results and current ECOHAB efforts, will collaborate and apply new field, laboratory and modeling approaches to better understand interannual variation in blooms magnitude and expansion and the physical, chemical and biological factors associated with bloom decline. Three hypotheses will be addressed:

1) Interannual spatial and temporal variability in the magnitude of K. brevis blooms on the WFS is a function of physical factors, including deep-ocean interactions with the shelf slope, wind and precipitation patterns resulting from extreme events;

2) Nutrient supply supporting blooms varies with these extreme events both directly (more runoff of dissolved nutrients) increasing bloom intensity, and indirectly in supporting prey upon which K. brevis may feed, and that in turn gains a growth advantage and an ability to be sustained when inorganic nutrients become depleted; and

3) Bloom dispersal and termination is the result of specific physical, chemical and biological factors, acting alone or in concert.

To accomplish this, historical bloom analysis, measurements of the predominant physical forcing mechanisms acting on bloom expansion and termination, and laboratory and field measurements of nutrient supply, mixotrophy and associated bacterial and viral communities in later bloom stages will be undertaken. These data will populate new machine learning and mechanistic models of K. brevis, the latter to be developed within an open source physical and biogeochemical framework, and will incorporates mixotrophy and bacterial and viral dynamics.

It will be then applied in scenario testing and forecasting of the impacts of a) large scale climatological extreme events, b) microbial interactions, and c) mixotrophy on K. brevis blooms. Such knowledge is absolutely critical to–and required for–effective bloom management, including modeling efforts that allow for longer-term prediction than is possible with existing models, minimization of bloom-related economic damage to marine industries and tourism, and the development of targeted mitigation efforts.

Institutions: University of California San Diego, Monterey Bay Aquarium Research Institute, Southern California Coastal Water Research Project, NOAA

Investigators: Andrew E. Allen, Bradley Moore, Andrew Lucas, Clarissa Anderson, John Ryan, Jim Birch, Martha Sutula, Greg Doucette

Domoic acid (DA) is a potent neurotoxin produced by diatoms in the genus Pseudo-nitzschia (PN). In recent years, toxic PN blooms have occurred with increased frequency and duration. For example, conditions in 2015 resulted in the largest recorded PN bloom to date in the North Pacific. There is an urgent need to improve region-wide DA toxin risk management to safeguard public health, promote viable and sustainable fisheries, and protect living marine resources. In order to address this challenge, we propose a comprehensive research program to quantify the oceanographic and cellular factors that regulate and promote DA biosynthesis. Our recent discovery of the DA biosynthetic pathway in various PN species (Brunson et al., Science, 2018) coupled with recent breakthroughs in automated sampling and biogeochemical characterization of toxigenic blooms (Ryan et al., JGR, 2017) enables investigation of a range of hypotheses related to the oceanographic conditions and cellular physiology that underlie toxin production. We will undertake four primary research activities to increase our understanding of the factors that control the distribution and activity of the DA biosynthesis pathway and DA concentrations in the southern and central California Current System (CCS): 1) investigation into genetic, enzymatic, and physiological regulation of DA production in laboratory cultures; 2) comparative examination of the diversity and ecological genomics of PN in situ using state-of-the-art autonomous sampling and water column profiling technology; 3) optimization of leveraged projects aimed at ecological forecasting and mechanistic hindcast modeling of DA event in the ocean environment; and 4) synthesis of results into data products and outputs useful for management entities. We expect that this tightly integrated, multidisciplinary approach will result in a transformative new view of genetic, physiological, and oceanographic issues related to forecasting and mitigating the impact of future HAB events.