02709nas a2200361   4500008004100000245014000041210006900181300000900250490000800259520161000267653002201877653001801899653002501917653001801942653001601960653001601976653002501992653002202017653002502039653001902064653002002083653001802103653002102121653003002142653001602172653002402188653002102212653002102233100001802254700002002272700002102292856003402313       2004                        eng d00aEnvironmental conditions and phytoplankton dynamics associated with Pseudo-nitzschia abundance and domoic acid in the Juan de Fuca eddy0 aEnvironmental conditions and phytoplankton dynamics associated w  a1-120 v2813 aThe Juan de Fuca eddy, located off the coasts of Washington (USA) and British Columbia (Canada), has been identified as a region that frequently contains relatively high levels of domoic acid (DA), d toxin produced by some members of the marine diatom genus, Pseudo-nitzschia. This seasonal eddy provides a unique environment to study the influence of nutrients on Pseudo-nitzschia abundance and DA accumulation in the field. Vertical sampling in the Juan de Fuca region was conducted in May, July and September of 2001 in an effort to determine environmental conditions and phytoplankton dynamics within the eddy compared to surrounding waters. The eddy was characterized by high primary productivity and high biomass in May and September relative to surrounding waters and was dominated by diatoms in the >5 mum size-fraction. In May, nitrate (NO3-) concentrations and the corresponding NO3- assimilation rates by phytoplankton within the eddy surface waters were relatively low. In contrast, in September, NO3- was high and NO3- assimilation rates increased by 7 times relative to those in May. DA was below detection levels at all stations in May and July. In September, Pseudo-nitzschia reached highest cell densities (-2 x 10(4) cells l(-1)) and particulate DA (-30 ng DA equivalents l(-1)) was detected in surface waters of the eddy. The presence of DA in healthy growing phytoplankton communities indicates a need to examine other environmental conditions that induce DA production in natural Pseudo-nitzschia populations than have previously been reported in nutrient-stressed laboratory studies.10aBacillariophyceae10aBatch culture10abiological processes10acarbon uptake10achlorophyll10adomoic acid10aharmful algal blooms10aJuan de Fuca eddy10amarine-phytoplankton10anitrate uptake10anitrogen uptake10aphytoplankton10aPseudo-nitzschia10apseudonitzschia-australis10arazor clams10asilicate limitation10avancouver-island10awashington coast1 aMarchetti, A.1 aTrainer, V., L.1 aHarrison, P., J.  u<Go to ISI>://00022554340000102502nas a2200265   4500008004100000245010000041210006900141260000800210300001200218490000700230520172800237653002801965653001601993653002602009653001502035653001802050653003302068653002102101100001802122700001602140700001702156700001302173700001602186856003402202       2006                        eng d00aDiscrimination of phytoplankton classes using characteristic spectra of 3D fluorescence spectra0 aDiscrimination of phytoplankton classes using characteristic spe  cFEB  a361-3690 v633 aThe discrimination of phytoplankton classes using the characteristic fluorescence spectra extracted from three-dimensional fluorescence spectra was investigated. Single species cultures of 11 phytoplankton species, representing 5 major phytoplankton divisions, were used. The 3D fluorescence spectra of the cultures grown at different temperatures (20 and 15 degrees C) and illumination intensities (140, 80 and 30 mu M m(-2) s(-1)) were measured and their feature extraction methods were explored. Ordering Rayleigh and Raman scattering data as zero, the obtained excitation-emission matrices were processed by both singular value decomposition (SVD) and trilinear decomposition methods. The resulting first principal component can be regarded as the characteristic spectrum of the original 3D fluorescence spectrum. The analysis shows that such characteristic spectra have a discriminatory capability. At different temperatures, the characteristic spectra of lsochrysis galbana, Platymonas helgolanidica and Skeletonema costatuma have high degrees of similarity to their own species samples, while the spectra similarities of Alexandrium tamarense, Prorocentrum dentatum, Pseudo-nitzschia-pungens, Chaetoceros curvisetus, Ch. Debilis, Ch. Didymus and Synechococcus sp. are not as significant as the other three species. C curvisetus, Ch. Debilis and Ch. Didymus, belonging to genus Chaetoceros, have identical spectra and cannot be discriminated at all. Regarding all six diatom species as one class, the average discriminant error rate is below 9%. It is worth mentioning that the diatom class can be distinguished from A. tamarense and P. dentatum, which belong to Dinophyta. (c) 2005 Elsevier B.V. All rights reserved.10a3d fluorescence spectra10achlorophyll10adiscriminant analysis10aexcitation10aphytoplankton10asingular value decomposition10aspectral feature1 aZhang, Q., Q.1 aLei, S., H.1 aWang, X., L.1 aWang, L.1 aZhu, C., J.  u<Go to ISI>://00023530010001702805nas a2200301   4500008004100000020001400041245008900055210006900144260001100213300001400224490000700238520195600245653001702201653001002218653001602228653001002244653002502254653003702279653002802316653001602344653001802360653002402378653001602402100001802418700001802436700001502454856003402469       2008                        eng d  a0278-434300aAbiotic controls of potentially harmful algal blooms in Santa Monica Bay, California0 aAbiotic controls of potentially harmful algal blooms in Santa Mo  cOct 30  a2584-25930 v283 aDespite the increasing occurrence of harmful phytoplankton blooms along the North American west coast, records of phytoplankton populations and related environmental conditions are uncommon. In this study, twice monthly measurements in the upper 50m are used to assess physico-chemical conditions contributing to the growth of potentially harmful bloom taxa over two annual cycles (2004-2005) in the Santa Monica Bay, California. Results were compared to the predictions of the Intaglio model [Smayda, T.J., Reynolds, C.S., 2001. Community assembly in marine phytoplankton: application of recent models to harmful dinoflagellate blooms. journal of Plankton Research 23, 447-461.] of phytoplankton community assembly. Potentially harmful taxa were present in every surface sample and were numerically dominant during the largest observed blooms, contributing up to 92% of the total phytoplankton abundance >5 mu m. Large interannual variation was observed in the dominant taxa and bloom seasonality; Pseudo-nitzschia sp. dominated blooms in early 2004 (February and April), whereas Prorocentrum micans and Lingulodinium polyedrum blooms occurred in May and September of 2005, respectively. The Pseudo-nitzschia sp. blooms were associated with elevated nitrate, dissolved silicon and phosphate concentrations throughout the euphotic zone; the first bloom followed a strong upwelling and the second occurred during the onset of seasonal stratification. In contrast, the blooms of P. micans were associated with highly stratified, low nutrient waters. Multivariate analysis supports the roles of temperature, mixed-layer depth and nutrient concentrations as primary controls of bloom growth, following the conceptual Intaglio model. The strong presence of potentially harmful bloom species in the Santa Monica Bay during this study appears unusual in comparison to limited studies over the last several decades. (C) 2008 Elsevier Ltd. All rights reserved.10aAlgal blooms10abight10achlorophyll10acoast10acoastal oceanography10adiatom pseudonitzschia-australis10aecological associations10apedro basin10aphytoplankton10asouthern-california10aTemperature1 aShipe, R., F.1 aLeinweber, A.1 aGruber, N.  u<Go to ISI>://000260700400005