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August 30 - September 19 2003 The second ECOHAB Pacific Northwest cruise took place in September 2003 aboard the R/V Wecoma. The Wecoma left Seattle at 10:00 AM PDT August 30 and returned to Seattle at 10:00 AM September 19. The chief scientist was Barbara Hickey and the cruise leader was Nicolaus Adams.
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The purpose of this cruise was to measure the physical, chemical and
physiological conditions under which the algae Pseudo-nitzschia
produce the toxin domoic acid, and when the toxin is released into the
environment. We attempted to observe the conditions under which the
released domoic acid moves toward the coast of Washington, where it
can be taken up by shellfish. Such occurrences lead to closure of beaches
to razor clam collection to avoid outbreaks of amnesiatic shellfish
poisoning. Measurements made included continuous surface water properties,
temperature, salinity, fluorescence, as well as discrete surface samples
for particulate and dissolved domoic acid, chlorophyll concentration,
and identification of phytoplankton species. In these surveys profile
data taken with the CTD (conductivity, temperature, depth) included
extra sensors that measured fluorescence, photosynthetically active
radiation (PAR), beam attenuation (light transmission), and oxygen concentration.
During CTD casts discrete samples were taken for chlorophyll and nutrient
analyses. An iron pump was used to measure iron concentration. On deck
incubations of phytoplankton for growth experiments, as well as shipboard
laboratory analyses of the plankton were conducted. Satellite tracked
drifters were released in the strait, near the Juan de Fuca eddy and
off the coast of Washington. The ship followed these drifters for several
days each, so that the same parcels of water could be resampled as they
aged, and thus measure in situ changes in the physical, chemical and
biologic constituents.