A Regional West Coast Observing System for Toxigenic Pseudo-nitzschia: Lessening the Risk of Harmful Algal Toxins to Human Health

V. Trainer¹, B.M. Hickey², M.G. Foreman³, C.A. Scholin⁴

¹NOAA Fisheries Marine Biotoxins Program Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112 United States
²School of Oceanography University of Washington, Box 355351, Seattle, WA 98195 United States
³Institute of Ocean Sciences Fisheries and Oceans Canada, 9860 West Saanich Road, Sidney, BC V8L4B2
⁴Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039 United States

The presence of domoic acid, the toxin produced periodically by diatoms of the genus Pseudo-nitzschia, appears to be associated with topographically retentive regions off the North American west coast. A regional, integrated ocean observing system that monitors ocean conditions associated with harmful algal blooms (HABs) in selected locations could provide an early warning of toxic Pseudo-nitzschia blooms, thereby lessening their impacts on human health and west coast fisheries. The biological and physical processes of Pseudo-nitzschia bloom development, toxicity, and transport are currently being characterized in detail for one such feature, the Juan de Fuca eddy off the Washington/Vancouver Island coast. For example, we have learned that transport of cells from this eddy to the coast is strongly associated with downwelling-favorable wind events. Because circulation in retentive regions is generally more robust than in open coastal regions, these areas may better lend themselves to modeling of transport pathways. Numerical circulation models, forced with winds predicted several days into the future, such as with the MM5 atmospheric model, together with drifters deployed during key HAB development periods will be used to predict regional scale movement of toxigenic cells and in particular, their possible transport to the coast. Sensing platforms, placed in offshore areas that include likely initiation sites for HABs, will be used to collect both real-time and time series data needed to initialize, calibrate, and validate physical and biological models and associated forecasts. An integrated suite of sensors includes satellite, stationary sensor platforms measuring ocean water properties, currents, nutrients, toxins, and plankton assemblages including toxigenic cells that will add real-time elements to shore-based lab testing. Time-series data include preserved toxin and cells from automated water samplers, and plankton assemblage information from the FloCam, an in situ camera that provides plankton images. With the system fully in place, managers will be able to use the models and real-time data from drifters and moored arrays to forecast landfall of an identified bloom event with some accuracy. This will give them enough warning to minimize the impact on human health while at the same time allowing harvest of coastal resources, including razor clams and Dungeness crabs. This effort will be integrated with California Current observing system efforts such as PaCOOS.