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NCCOS Research Project

Interannual Variability of PSP Toxicity in Eastern Maine: Testing the Leaky Gyre Hypothesis and Improving Regional Forecasts and Management

Primary Contact(s): quay.dortch@noaa.gov
This project began in September 2015 and will end in August 2020

The Gulf of Maine is impacted annually by Alexandrium fundyense blooms which can result in paralytic shellfish poisoning. Paralytic shellfish poisoning (PSP) leads to significant economic impacts. The paralytic shellfish toxin distribution remains poorly understood. This project will investigate linkages between A. fundyense populations and PSP toxicity in the nearshore and offshore waters of the EGOM, to characterize the physical mechanisms that control that export, and to use this information to improve regional HAB management, modeling, and forecasting.

Why We Care

The Gulf of Maine (GOM) is a large continental shelf sea with extensive shellfish resources that are annually impacted by Alexandrium fundyense blooms and outbreaks of paralytic shellfish poisoning (PSP), leading to significant social and economic impacts every year, often totaling tens of millions of dollars in losses and sometimes more. Toxicity occurs in three main regions of the Gulf (the eastern and western Gulf of Maine [EGOM and WGOM], and Georges Bank) that are interconnected, but that can also behave independently due to large- scale oceanographic forcings. PSP toxin distribution in the EGOM remains poorly understood, despite the serious nature of the PSP in that region and its hydrographic connections to the west.

One major development from prior research programs is an A. fundyense population dynamics model that has been used to produce near-real-time weekly nowcasts and forecasts, and seasonal forecasts. That model is being transitioned for operational use by NOAA. Model skill is strongest in the WGOM, where A. fundyense cyst abundance in a “seedbed” or accumulation zone off mid-coast Maine has proven to be a primary driver of interannual PSP variability. Skill is weakest in the EGOM because the mechanisms responsible for interannual variability are not thought to relate to cyst abundances in that subregion but instead to the advection of established vegetative A. fundyense populations that originate in the Bay of Fundy (BOF) where there is a major cyst seedbed and a gyre that can be retentive for A. fundyense cells.

What We Are Doing

This project seeks to understand if the interannual variations of toxins in EGOM are controlled by upstream populations, for which there are two key sources of variability: (1) growing conditions, and (2) hydrodynamic leakiness of the BOF gyre. Neither of these aspects is adequately represented in existing models. They propose to investigate linkages between BOF A. fundyense populations and PSP toxicity in the nearshore and offshore waters of the EGOM, to characterize the physical mechanisms that control that export, and to use this information to improve regional HAB management, modeling, and forecasting. They will utilize a network of novel biosensors called Environmental Sample Processors (ESPs) to obtain data that would not be feasible with ship-based surveys.

Daily autonomous measurements at multiple locations will be augmented by satellite-tracked surface drifters released within the gyre, and by three targeted survey cruises to provide spatial context for the ESP observations. Measurements of nutrients and water column structure from NERACOOS ocean-observing buoys will also be obtained. All of this information will be incorporated into our existing regional Alexandrium model and hindcast simulations run to identify mechanisms underlying patterns in EGOM shellfish toxicity.

Dr. Donald Anderson of Woods Hole Oceanographic Institute leads this project. Co-leads are Dr. Dennis McGillicuddy (WHOI), Mr. Bruce Keafer (WHOI), Dr. David Townsend (University of Maine), Dr. Ruoying He (North Carolina State University), Dr. Richard Stumpf (NOAA/NOS), Mr. James Manning (NOAA/NMFS) and Dr. Jennifer Martin (Fisheries and Oceans Canada). The project is funded through the NCCOS Ecology and Oceanography of Harmful Algal Bloom (ECOHAB) Program.

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