Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 1445
Title: A Springtime Source of Toxic Pseudo-nitzschia cells on Washington's Razor Clam Beaches
Author: B. M. Hickey, Vera L. Trainer, P. Michael Kosro, N. G. Adams, Thomas P. Connolly, Nancy B. Kachel, Susan L. Geier
Publication Year: 2013
Journal: Harmful Algae
DOI: 10.1016/j.hal.2013.01.006
Keywords: harmful algal bloom,Pseudo-nitzschia,Heceta Bank,Juan de Fuca eddy

Concentrations of domoic acid (DA) above the regulatory limit in Washington coast razor clams are
usually higher on northern beaches from summer to fall. Recent field studies have confirmed that the
primary source of toxic Pseudo-nitzschia (PN) cells in those seasons is a semi-retentive topographically
trapped seasonal eddy located offshore and north of the clamming beaches. Another semi-retentive
coastal feature, Heceta Bank, that has been shown to support toxic PN cells in summer, is located south of
Washington’s clamming beaches. In this paper we present evidence to demonstrate that Heceta Bank,
although not a likely source of toxic cells to Washington in summer due to the prevailing southward
seasonal currents, may be a source of cells in springtime before the southward currents develop. In
contrast to summer and fall seasons, concentrations of DA in razor clams are typically higher at southern
beaches in spring. The likelihood of a southern source is explored using biological and transport data
surrounding a period of toxic razor clams in April 2005. In particular, satellite-derived chlorophyll data
confirm that a bloom occurred over Heceta Bank in March of that year, just prior to a period of strong
storm-driven northward transport. PN cells of the same species observed in the April bloom on
Washington beaches and in offshore waters were documented in Oregon offshore waters on the
northern edge of Heceta Bank. That species, P. australis, has been shown to be highly toxic in this region;
shore-based data show that razor clams on Oregon beaches were also toxic at the time when P. australis
was observed offshore. Both measured and modeled currents show that transport was more than
sufficient to move cells from the vicinity of Heceta Bank, Oregon to southern Washington beaches by the
time the toxic cells were observed on those beaches. The rapid transport was due in part to the presence
of the buoyant plume from the Columbia River, a common feature in winter and spring in nearshore
waters of the U.S. Pacific Northwest.
 2013 Elsevier B


Heceta Bank is a springtime source of toxic Pseudo-nitzschia to Washington State's razor clamming beaches.

Theme: Sustainable, safe and secure seafood for healthy populations and vibrant communities
Foci: Provide scientific support to ensure safe seafood for healthy populations and characterize how human activities and climate affect risks from pathogens, chemical contaminants and biotoxins
Official Citation:

Hickey, B.M., Trainer, V.L., Kosro, M.P., Adams, N.G., Connolly, T.P., Kachel, N.B., Geier, S.L. 2013. A springtime source of toxic Pseudo-nitzschia on razor clam beaches in the Pacific Northwest. Harmful Algae. doi: 10.1016/j.hal.2013.01.006.