Project: ECOHAB - Pacific Northwest

ECOHAB-PNW is a 5-year multi-disciplinary project that will study the physiology, toxicology, ecology
and oceanography of toxic Pseudo-nitzschia species off the Pacific Northwest coast.

This program studies 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 program 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:
- 1.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;
- 2. 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;
- 3. To determine possible transport pathways between DA initiation sites and shellfish beds on the nearby coast.

The scientific operations of this study included obtaining multi-disciplinary data from a large scale grid,
sampling water properties while following a drifter, deployment of surface drifters, satellite imagery,
laboratory studies using water collected at selected sites, and numerical modeling of both the circulation
and chlorophyll concentration. Water samples included macronutrients, iron, particulate and dissolved domoic
acid, Pseudo-nitzschia species and numbers. Experiments were done to estimate growth and grazing rates.
Moored arrays were deployed to provide time series of currents and water properties from May to October,
each year from 2003-2006. Numerical modeling studies on a fine scale grid focused on the seasonal development
of the Juan de Fuca eddy and its change in structure during selected wind conditions. Conditions favorable
to release of phytoplankton from the eddy region were assessed.

After four years of field work the research team is able to describe a possible sequence of events necessary
to ingestion of domoic acid by coastal shellfish:
(1) Plankton must become concentrated in the bloom source region. ECOHAB PNW studies suggest this requires
a period of downwelling-favorable or lightly fluctuating winds.
(2) Next the plankton must undergo stress sufficient to cause an increase in cellular toxin: in the Juan de Fuca
eddy region toxin can be found on any survey of the region in both early and late summer within a 21 day time scale.
(3) Patches of toxic plankton must then escape from the offshore source region. For the Juan de Fuca eddy region
escape is favored during upwelling-favorable wind conditions that allow the geostrophic constraint of the eddy
circulation pattern to be broken.
(4) The patch must move alongshore to sites with shellfish populations, and
(5) must retain its toxicity during the time period of transport. For a toxic source in the Juan de Fuca eddy
this requires southward advection across the shelf, as occurs during periods of upwelling-favorable winds in
summer and early fall. ECOHAB PNW studies show that toxin can be maintained in the 7-14 days required for
transport. For an Oregon source such as Heceta bank to impact the Washington shelf, this requires northward
advection across the shelf, as occurs during periods of downwelling-favorable winds in spring.
(6) Last, the toxic patch must move onshore to coastal beaches and/or estuaries,
(7) where it must remain there for a period sufficient for significant ingestion by shellfish.

Cruises/Platforms:
Cruise = ECOHAB-PNW cruises, numbered sequentially from
Cruise_1 - Cruise_6 as ECOHAB_1 - ECOHAB_6.

Cruise_1=ECOHAB_1, R/V Wecoma, W0306A, June 2-23, 2003 Cruise Report
Cruise_2=ECOHAB_2, R/V Wecoma, W0308C, August 30 - September 19, 2003 Cruise Report
Cruise_3=ECOHAB_3, R/V Atlantis, AT11-17, September 8-28, 2004 Cruise Report
Cruise_4=ECOHAB_4, R/V Atlantis, AT11-30, July 7-27,2005 Cruise Report
Cruise_5=ECOHAB_5, R/V Melville, TUIM14MV, September 2-22, 2005 Cruise Report
Cruise_6=ECOHAB_6, R/V Thomas G. Thompson, TN200, Sept. 11- Oct. 4, 2006 Cruise Report