OVERVIEW:

Each summer, extensive areas of Maine coastline are closed to shellfish harvesting due to Alexandrium, a toxic dinoflagellate, costing millions of dollars in lost commercial revenue and monitoring efforts. Unlike the harmful algal blooms of other coastal waters, Alexandrium is dangerous even as just a minor part of the phytoplankton community, at concentrations too low to be detectable with current remote sensing technology. However, extensive previous research has shown that these organisms are widespread, have strong spatial and temporal patchiness, are associated with specific temperature and nutrient regimes, and are transported by local physical processes. The waters of the Gulf of Maine, especially those close to shore, are optically complex due to varying amounts, sources and characteristics of colored dissolved matter, suspended sediment, and varying concentrations and diversity of phytoplankton. A systematic investigation of the capability of multispectral satellite data to isolate and monitor the oceanic habitat of Alexandrium has not been carried out. In this proposal, we use NASA multispectral and SST data and new hyperspectral field data to bio-optically classify different Gulf of Maine surface water masses, identify those water masses that are preferred Alexandrium habitat, track these water masses and map their interaction with, and impact on, coastal shellfish harvesting sites. We bring a multi-institution and multi-disciplinary team to address this problem. The global ocean color community is poised to transition to the next generation of space-borne ocean color data from hyperspectral optical sensors. NASA's focus in this effort is the PACE mission, expected to launch in the next 5-6 years. Maine's ocean scientists and environmental resource managers need to transition to this level of data complexity to remain competitive and fully reap the benefits of these data for Maine applications and priorities. This proposal builds both instrument and intellectual infrastructure with hyperspectral data, while addressing a Maine technology priority and interfacing with a critical marine resource sector. Our overarching goal is to use NASA's satellite-based measurements of coastal ocean bio-optical and hydrographic characteristics to define, isolate and track those water masses most closely associated with Alexandrium and coastal shellfish toxicity. The research involves a combined retrospective and real-time analysis of existing field 2 observations and multispectral satellite data and 3 years of new fieldwork that leverages an existing, separately funded project, and introduces a project-purchased hyperspectral instrument. This instrument will be deployed on a ship and will emulate PACE, allowing unprecedented spectral resolution of Gulf of Maine surface waters to better discriminate optical water types. Both efforts are supported by numerical modeling of circulation to view interannual and spatial variability in flow trajectories and the forcing that drives these, and GIS modeling to map and model the interaction between these parcels and DMR sampling sites, coastal shellfish beds and both state and municipal stakeholders.