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The decline and fate of an iron-induced subarctic phytoplankton bloom


Boyd, PW and Law, CS and Wong, CS and Nojiri, Y and Tsuda, A and Levasseur, M and Takeda, S and Rivkin, R and Harrison, PJ and Strzepek, R and Gower, J and McKay, RM and Abraham, E and Arychuk, M and Barwell-Clark, J and Crawford, W and Crawford, D and Hale, M and Harada, K and Johnson, K and Kiyosawa, H and Kudo, I and Marchetti, A and Miller, W and Needoba, j and Nishioka, J and Ogawa, N and Page, J and Robert, M and Saito, H and Sastri, A and Sherry, N and Soutar, T and Sutherland, N and Taira, S and Whitney, F and Wong, S-KE and Yoshimura, T, The decline and fate of an iron-induced subarctic phytoplankton bloom, Nature, 428, (6982) pp. 549-553. ISSN 0028-0836 (2004) [Refereed Article]

Copyright Statement

Copyright 2004 Nature Publishing Group

DOI: doi:10.1038/nature02437


Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.

Item Details

Item Type:Refereed Article
Keywords:iron, subarctic, phytoplankton, bloom
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Oceanic processes (excl. in the Antarctic and Southern Ocean)
UTAS Author:Boyd, PW (Professor Philip Boyd)
UTAS Author:Strzepek, R (Dr Robert Strzepek)
ID Code:147705
Year Published:2004
Web of Science® Times Cited:372
Deposited By:Australian Antarctic Program Partnership
Deposited On:2021-11-11
Last Modified:2021-12-21

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