An ecological study of a massive bloom of toxigenic Pseudo-nitzschia cuspidata off the Washington State coast

作者：Trainer Vera L^*; Wells Mark L; Cochlan William P; Trick Charles G; Bill Brian D; Baugh Keri A; Beall Benjamin F; Herndon Julian; Lundholm Nina

来源：Limnology and Oceanography, 2009, 54(5): 1461-1474.

DOI：10.4319/lo.2009.54.5.1461

In September 2004 a large, nearly monospecific diatom bloom of Pseudo-nitzschia cuspidata off the coast of the state of Washington reached cell concentrations of 6.1 x 10(6) cells L(-1) and produced maximum particulate domoic acid (pDA), dissolved domoic acid (dDA), and cellular domoic acid concentrations of 43 nmol L(-1), 4 nmol L(-1), and 63 pg cell(-1), respectively. This bloom co-dominated the phytoplankton assemblage with the euglenoid Eutreptiella sp. in the Juan de Fuca eddy region, a known initiation site for toxigenic Pseudo-nitzschia blooms. Two isolates of P. cuspidata collected during separate cruises produced domoic acid (DA) in culture. During the September 2004 survey, 84% of the stations (n = 98) had detectable Pseudo-nitzschia and 78% had detectable pDA. There were no significant correlations between either pDA or cellular DA and ambient concentrations of macronutrients; however, when considering only those stations where Pseudo-nitzschia was present, pDA was positively correlated with chlorophyll a and negatively correlated with temperature (p <= 0.01) at both 1- and 5-m depths. Correlations between cellular DA concentrations and total bacteria or cyanobacteria abundances were not significant. Variable ratios of pDA: dDA in the eddy region suggest that DA release was under cellular regulation by Pseudo-nitzschia. Stations where dissolved Fe concentrations were limiting (<0.5 nmol L(-1)) had the highest Pseudo-nitzschia abundances and pDA and cellular DA values. These results provide enticing field evidence of the role of Fe limitation in controlling cellular DA levels.

• 出版日期2009-9