| Overview This project will study
the physiology, toxicology, ecology and oceanography of toxic
Pseudo-nitzschia 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. Recent studies
suggest that the seasonal Juan de Fuca eddy, a nutrient rich retentive
feature off the Washington coast serves as a "bioreactor" for
the growth of phytoplankton, including diatoms of the genus Pseudo-nitzschia.
Existing ship of opportunity data are consistent with the working
hypothesis that the seasonal Juan de Fuca eddy is an initiation
site for toxic Pseudo-nitzschia that impact the Washington coast
and that upwelling sites adjacent to the coast are less likely
to develop toxicity.
The long term project goal is to develop a mechanistic basis
for forecasting toxic Pseudo-nitzschia bloom development here
and in other similar coastal regions in Eastern Boundary upwelling
systems.
Specific study objectives are:
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To determine the physical/biological/chemical factors that
make the Juan de Fuca eddy region more viable for growth and
sustenance of toxic Pseudo-nitzschia than the nearshore upwelling
zone;
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To determine the combination of environmental factors that
regulate the production, accumulation, and/or release of domoic
acid (DA) from Pseudo-nitzschia cells in the field;
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To determine possible transport pathways between DA initiation
sites and shellfish beds on the nearby coast.
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Satellite-derived sea surface temperature,
particulate DA (µg/L) and total Pseudo-nitzschia cell numbers
(106 cells/L) in surface seawater July 1997 (after Trainer et
al. LO, 47(5), 2002). Spatial patterns show a coincidence of colder
temperature, higher DA and greater numbers of Pseudo-nitzschia
cells offshore of Juan de Fuca Strait. The colder offshore water
is indicative of the Juan de Fuca eddy. Colder water along the
Washington coast is indicative of local wind-driven upwelling. |
