Research Plan
The objectives of this project will be met with an integrated suite
of field and laboratory studies on two 21 day cruises per year, moored
bio/chem/physical sensors, GPS-tracked drifters as well as circulation
and biophysical modeling in a study area that includes both the eddy
and also a typical coastal upwelling region.
| 
Idealized initial large scale survey and
locations of three moored arrays. Locations of existing moorings,
wind measurement buoys, razor clam beaches, and ORHAB sampling
sites are also shown. The approximate location of the Juan de
Fuca eddy is drawn as a lightly shaded area. |
The key factors responsible for high cell densities of toxigenic Pseudo-nitzschia
spp. and the variable levels of cell toxicity will be 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 will be studied by following drogued patches of water
both from the eddy and from a nearshore upwelling region. Toxification
of coastal shellfish will be determined using beach sampling sites maintained
by the Olympic Region HAB program. A coupled biophysical model of the
region enhanced with assimilated survey data will be 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 Pseudo-nitzschia to
the coast under a variety of environmental and physiological conditions.
The sampling plan, moored sensor arrays at key locations and drifter
deployments will allow us to:
- Contrast the nutrient-rich eddy with nutrient-rich nearshore upwelling
areas. We will determine whether physical and biological factors that
control DA production differ significantly in the two regimes.
- Contrast healthy and aged natural assemblages of Pseudo-nitzschia
to compare and contrast the environmental controls on DA production
in cells at different stages of growth in situ.
- Determine the biophysical mechanisms of Pseudo-nitzschia advection
to the coast, resulting in shellfish toxification. Possible mechanisms
include the following scenarios: a) a healthy Pseudo-nitzschia population
is advected directly from the offshore eddy to coastal shellfish during
a storm event; b) an aged Pseudo-nitzschia population is advected
from the eddy to the coast where it becomes a "seed" population that
becomes toxic only when later supplied with nutrients from local coastal
upwelling; or c) the nearshore, "seed" population toxifies the coastal
shellfish directly after local upwelling followed by a storm. These
possibilities will be examined using the large scale pattern data
as well as the process data, in conjunction with the biophysical models,
which can be configured to show actual particle pathways.
