ECOHAB2017: Cross-regional comparison of Dinophysis bloom dynamics, drivers, and toxicity
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Introduction: 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. Recently, harmful algal blooms (HAB) caused by Dinophysis spp. have emerged as 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, Maine, and Massachusetts due to blooms of D. cf. acuminata and most recently D. norvegica (ME). 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: Given the rapid increase in frequency of Dinophysis blooms on nearly every US coast, with clear regional variability in timing and species, it is essential that the drivers of Dinophysis success in coastal ecosystems be identified using a coordinated, nationwide effort. Such a cross-regional comparative study will identify not only potential drivers, but create a baseline for understanding how future climate and eutrophication scenarios will influence intensity, frequency, and toxicity of blooms. Objective: The goal of this project is to identify and quantify factors controlling Dinophysis blooms and DSP across the US as a means of developing optimized regional early warning systems and management plans. It is hypothesized that a combination of temperature, stratification, prey, and nutrient input combine to determine the success of Dinophysis in US coastal ecosystems. A carefully coordinated and collaborative study including high-resolution phytoplankton time series, field collections, and multi-factorial laboratory experiments using isolates of Dinophysis species from important shellfish harvesting sites in the US (Gulf of Mexico, Puget Sound, Long Island Sound and Chesapeake Bay), will be undertaken to address the following objectives: 1) Identify the environmental factors that control Dinophysis blooms and toxicity within and across regions; 2) Use isolates to characterize genetic variability and potential toxicity, under a variety of conditions; 3) Develop and optimize an early warning system for Dinophysis blooms and DTXs in US coastal regions; and 4) Partner with state and industry groups to closely match management needs, disseminate results, and aid regional management programs. Outcomes: Implementation of optimized DSP early warning systems will be a critical first step towards ensuring public safety while also minimizing negative economic impacts on local communities. The proposed work will also identify the environmental regulators of DSP toxin production and Dinophysis species success, providing the context with which to better understand, predict, and detect potential threats now and under future climate and nutrient management scenarios. As evidenced by the increasing frequency and duration of DSP-related harvesting closures, and unfortunately human illness events, there is a critical and urgent need to develop improved early warning systems for Dinophysis and DSP in Washington State, New York, Texas, and DELMARVA, serving as a template to guide ecoforecasting efforts in the rest of the U.S.
