Dataset Information

Initiation and Development of a Toxic and Persistent Pseudo-nitzschia Bloom off the Oregon Coast in Spring/Summer 2015.

ABSTRACT: In spring/summer 2015, a toxic bloom by the diatom Pseudo-nitzschia (PN) occurred along the west coast of the United States which led to closures of the harvest of razor clams and Dungeness crabs. Twice monthly observations of temperature, salinity, nutrients, chlorophyll and phytoplankton species composition allowed us to track oceanographic conditions preceding and during the development of the bloom. PN cells were first detected during late winter 2015. A PN bloom was initiated following the onset of coastal upwelling in mid-April; subsequent peaks in May and June were sustained by episodic upwelling events and reached magnitudes of 105 cells/L and 106 cells/L, 40% and 90% of the total diatom abundance, respectively. The bloom temporarily crashed in July due to a lack of upwelling, but PN cells increased again in August due to a resumption of upwelling, albeit with lower magnitude. Macronutrient conditions prior to this bloom likely played a critical role in triggering the bloom and its toxicity (particularly silicic acid limitation stress). Nutrient stress preceding the toxic bloom was related to two oceanographic events: an anomalously warm and thick water mass that occupied the northern North Pacific from September 2014 through 2015 leading to a highly-stratified water column, and the drawdown of nitrate and silicic acid during an unusually intense winter phytoplankton bloom in February and early March 2015.

SUBMITTER: Du X

PROVIDER: S-EPMC5061394 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Publications

Initiation and Development of a Toxic and Persistent Pseudo-nitzschia Bloom off the Oregon Coast in Spring/Summer 2015.

Du Xiuning X Peterson William W Fisher Jennifer J Hunter Matt M Peterson Jay J

PloS one 20161012 10

In spring/summer 2015, a toxic bloom by the diatom Pseudo-nitzschia (PN) occurred along the west coast of the United States which led to closures of the harvest of razor clams and Dungeness crabs. Twice monthly observations of temperature, salinity, nutrients, chlorophyll and phytoplankton species composition allowed us to track oceanographic conditions preceding and during the development of the bloom. PN cells were first detected during late winter 2015. A PN bloom was initiated following the ...[more]

PMID: 27732630

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Project description:The toxic diatom genus Pseudo-nitzschia is a growing presence in the Gulf of Maine (GOM), where regionally unprecedented levels of domoic acid (DA) in 2016 led to the first Amnesic Shellfish Poisoning closures in the region. However, factors driving GOM Pseudo-nitzschia dynamics, DA concentrations, and the 2016 event are unclear. Water samples were collected at the surface and at depth in offshore transects in summer 2012, 2014, and 2015, and fall 2016, and a weekly time series of surface water samples was collected in 2013. Temperature and salinity data were obtained from NERACOOS buoys and measurements during sample collection. Samples were processed for particulate DA (pDA), dissolved nutrients (nitrate, ammonium, silicic acid, and phosphate), and cellular abundance. Species composition was estimated via Automated Ribosomal Intergenic Spacer Analysis (ARISA), a semi-quantitative DNA finger-printing tool. Pseudo-nitzschia biogeography was consistent in the years 2012, 2014, and 2015, with greater Pseudo-nitzschia cell abundance and P. plurisecta dominance in low-salinity inshore samples, and lower Pseudo-nitzschia cell abundance and P. delicatissima and P. seriata dominance in high-salinity offshore samples. During the 2016 event, pDA concentrations were an order of magnitude higher than in previous years, and inshore-offshore contrasts in biogeography were weak, with P. australis present in every sample. Patterns in temporal and spatial variability confirm that pDA increases with the abundance and the cellular DA of Pseudo-nitzschia species, but was not correlated with any one environmental factor. The greater pDA in 2016 was caused by P. australis - the observation of which is unprecedented in the region - and may have been exacerbated by low residual silicic acid. The novel presence of P. australis may be due to local growth conditions, the introduction of a population with an anomalous water mass, or both factors. A definitive cause of the 2016 bloom remains unknown, and continued DA monitoring in the GOM is warranted.

Dataset Information

Initiation and Development of a Toxic and Persistent Pseudo-nitzschia Bloom off the Oregon Coast in Spring/Summer 2015.

Publications

Initiation and Development of a Toxic and Persistent Pseudo-nitzschia Bloom off the Oregon Coast in Spring/Summer 2015.

Similar Datasets

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