A multi-year study of summer diatom blooms in the North Pacific Subtropical Gyre

dc.contributor.advisorVillareal, Tracy Alanen
dc.contributor.committeeMemberBuskey, Edward J.en
dc.contributor.committeeMemberErdner, Deanaen
dc.creatorBrown, Colbi Gabrielle, 1984-en
dc.date.accessioned2010-12-22T22:48:55Zen
dc.date.accessioned2010-12-22T22:49:07Zen
dc.date.accessioned2017-05-11T22:20:57Z
dc.date.available2010-12-22T22:48:55Zen
dc.date.available2010-12-22T22:49:07Zen
dc.date.available2017-05-11T22:20:57Z
dc.date.issued2010-08en
dc.date.submittedAugust 2010en
dc.date.updated2010-12-22T22:49:07Zen
dc.descriptiontexten
dc.description.abstractIn the North Pacific Subtropical Gyre, a nearly-annual phytoplankton bloom forms near the subtropical front at ~30° N. Mixed communities of nitrogen-fixing diatom symbioses (diatom-diazotroph associations) increase 10²-10³ fold in these blooms. In July 2008 (31.46˚N 140.49˚W) and August 2009 (25.18 °N 154 °W), two blooms were sampled to determine diatom-diazotroph association species composition, physical, and chemical characteristics of the water column. In both 2008 and 2009, the dominant diatom-diazotroph association was the Hemiaulus hauckii-Richelia intracellularis symbiosis. The 2009 subtropical front bloom was missed; however, another bloom closer to Hawaii was sampled where diatom-diazotroph association abundance was 10-fold lower (10² cells Lˉ¹) than 2008 despite surface chlorophyll a values that were 3 times greater. Both blooms showed substantial changes in phytoplankton size structure with the >10 μm size chlorophyll a fraction increasing from 10 to 40 % in 2008. In the 2009 bloom, the non-symbiotic pennate diatom Mastogloia woodiana numerically dominated (>150,000 cells Lˉ¹) and formed aggregates that resulted in substantially higher % of netplankton chlorophyll a fractions. Summer open ocean blooms from the two years share a common trend of Hemiaulus dominance of the diatom-diazotroph association population and size structure changes. However, non-symbiotic species can dominate the overall bloom, and diatom-diazotroph association species may not be responsible for the chlorophyll a increase. These two years may represent different types of blooms or temporal changes within summer diatom blooms. The increased biomass in the larger-size fraction suggests these blooms are potential sites for carbon export from the surface layer.en
dc.description.departmentMarine Scienceen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-08-1757en
dc.language.isoengen
dc.subjectDiatom bloomsen
dc.subjectPhytoplankton bloomsen
dc.subjectDiatom-diazotroph associationen
dc.subjectOcean bloomsen
dc.subjectNorth Pacific Subtropical Gyreen
dc.subjectOcean color dataen
dc.titleA multi-year study of summer diatom blooms in the North Pacific Subtropical Gyreen
dc.type.genrethesisen

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