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

Repository

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

Show full record

Title: A multi-year study of summer diatom blooms in the North Pacific Subtropical Gyre
Author: Brown, Colbi Gabrielle, 1984-
Abstract: In 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.
Department: Marine Science Institute
Subject: Diatom blooms Phytoplankton blooms Diatom-diazotroph association Ocean blooms North Pacific Subtropical Gyre Ocean color data
URI: http://hdl.handle.net/2152/ETD-UT-2010-08-1757
Date: 2010-08

Files in this work

Download File: BROWN-THESIS.pdf
Size: 5.685Mb
Format: application/pdf
Download File: Colbi Brown Abstract.pdf
Size: 134.9Kb
Format: application/pdf

This work appears in the following Collection(s)

Show full record


Advanced Search

Browse

My Account

Statistics

Information