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

• Published in: Nature
• Main Authors: Boyd, PW, Law, CS, Wong, CS, Nojiri, Y., Tsuda, A., Levasseur, M., Takeda, S., Rivkin, R., Harrison, PJ, Strzepek, R., Gower, J., McKay, RM, Abraham, E., Arychuk, M., Barwell-Clarke, J., Crawford, W., Crawford, D., Hale, M., Harada, K., Johnson, K., Kiyosawa, H., Kudo, I., Marchetti, A., Miller, W., Needoba, J., Nishioka, J., Ogawa, H., Page, J., Robert, M., Saito, H., Sastri, A., Sherry, N., Soutar, T., Sutherland, N., Taira, Y., Whitney, F., Wong, SKE, Yoshimura, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2004
• Subjects: Gulf of Alaska; Subarctic; Alaska
• Online Access: http://repository.ust.hk/ir/Record/1783.1-21715; https://doi.org/10.1038/nature02437; http://lbdiscover.ust.hk/uresolver?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rfr_id=info:sid/HKUST:SPI&rft.genre=article&rft.issn=0028-0836&rft.volume=428&rft.issue=6982&rft.date=2004&rft.spage=549&rft.epage=553&rft.aulast=Boyd&rft.aufirst=PW&rft.atitle=The+decline+and+fate+of+an+iron-induced+subarctic+phytoplankton+bloom; http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=LinksAMR&SrcApp=PARTNER_APP&DestLinkType=FullRecord&DestApp=WOS&KeyUT=000220540100039; http://www.scopus.com/record/display.url?eid=2-s2.0-11144353699&origin=inward

Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters(1-5). However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown(1-5). 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(6,7), and also for proposed geo-engineering schemes to increase oceanic carbon sequestration(3,8).