ECOHAB PNW: Ecology and Oceanography of Toxic Pseudo-nitzschia in the Pacific Northwest Coastal Ocean

University Of Washington, Seattle WA

Investigators

Abstract

This project is studying the physiology, toxicology, ecology and oceanography of toxic Pseudo-nitzschia (PN) species off the Pacific Northwest coast, a region in which both macro-nutrient supply and current patterns are primarily controlled by seasonal coastal upwelling processes. The long term project goal is to develop a mechanistic basis for forecasting toxic PN bloom development along the Pacific Northwest coast and in other similar coastal regions in Eastern Boundary upwelling systems. The objectives are being met with an integrated suite of field and laboratory studies on two 21 day cruises per year, moored bio/chem/physical sensors as well as circulation and biophysical modeling in a study area that includes both the eddy and also a typical coastal upwelling region. The key factors responsible for high cell densities of toxigenic PN spp. and the variable levels of cell toxicity are being investigated with on-deck incubation studies and comprehensive in situ measurements including macronutrients, micronutrients (Fe, Cu), bacteria and grazer abundance as well as photosynthetic radiation, stratification and velocity shear. Aging of blooms are being studied by following drogued patches of water both from the eddy and from a nearshore upwelling region. Toxification of coastal shellfish are being determined using beach sampling sites maintained by the Olympic Region HAB program. A coupled biophysical model of the region is being used to examine the potential for bloom generation in offshore eddy and nearshore upwelling regions (e.g., stratification, nutrient sources, strength and timing) as well as to assess transport pathways of toxic PN to the coast under a variety of environmental and physiological conditions.