Microbial control of diatom bloom dynamics in the open ocean

Boyd, P W
Strzepek, Robert
Chiswell, Steve
Chang, Hoe
DeBruyn, Jennifer M
Ellwood, Michael
Keenan, Sean
King, A.L.
Maas, Elisabeth W
Nodder, Scott D
Sander, Sylvia G
Sutton, Phillip
Twining, B.S.

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Publication date

February 2016

DOI

10.1029/2012GL053448

Publisher

American Geophysical Union (AGU)

Journal

Geophysical Research Letters

Abstract

Diatom blooms play a central role in supporting foodwebs and sequestering biogenic carbon to depth. Oceanic conditions set bloom initiation, whereas both environmental and ecological factors determine bloom magnitude and longevity. Our study reveals another fundamental determinant of bloom dynamics. A diatom spring bloom in offshore New Zealand waters was likely terminated by iron limitation, even though diatoms consumed <1/3 of the mixed-layer dissolved iron inventory. Thus, bloom duration and magnitude were primarily set by competition for dissolved iron between microbes and small phytoplankton versus diatoms. Significantly, such a microbial mode of control probably relies both upon out-competing diatoms for iron (i.e., K-strategy), and h...