Stimulation of heterotrophic and autotrophic metabolism in the mixing zone of the Kuroshio Current and northern South China Sea : implications for export production

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Huang, Yibin and Laws, Edward and Chen, Bingzhang and Huang, Bangqin (2019) Stimulation of heterotrophic and autotrophic metabolism in the mixing zone of the Kuroshio Current and northern South China Sea : implications for export production. Journal of Geophysical Research: Biogeosciences, 124 (9). pp. 2645-2661. (https://doi.org/10.1029/2018JG004833)

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Abstract

To evaluate the influences of the Kuroshio Current intrusion on the biogeochemistry of the northern South China Sea (NSCS), we conducted field observations of the responses of microbial metabolism to the intrusions of the Kuroshio Current into the NSCS. We used an isopycnal mixing model to quantitatively assess the extent of the Kuroshio intrusion into the NSCS and found that bacterial abundance, production, and growth efficiency were unimodal functions of the fraction of Kuroshio water. Values were maximal at ~60% Kuroshio water and decreased monotonically as the percent of Kuroshio water deviated from 60%. The patterns of gross primary production and nitrate concentration were similar, but the peaks occurred at ~50% Kuroshio water. The Kuroshio intrusion, however, had little impact on bacterial and community respiration. The observed elevation of nitrate concentrations at ~50% Kuroshio water was quantitatively consistent with estimates of the amount of inorganic nitrogen released by remineralization of dissolved organic nitrogen by bacteria. Based on these observations, we hypothesize that dissolved organic matter (DOM) in the Kuroshio water stimulates bacterial activity, and catabolism of the DOM releases inorganic nutrients that stimulate primary production in the NSCS basin. The concomitant elevation of net community production subsequently enhances export production and thereby strengthens the biological pump in the nitrogen‐limited NSCS basin. Recognition of this mechanism underscores the role of horizontal currents in regional carbon and nitrogen cycles and broadens understanding of the processes that sustain export production in the oligotrophic ocean.

ORCID iDs

Huang, Yibin, Laws, Edward, Chen, Bingzhang ORCID logoORCID: https://orcid.org/0000-0002-1573-7473 and Huang, Bangqin;
  • Item type:Article
    ID code:69497
    Dates:
    Date
    Event
    30 September 2019
    Published
    16 August 2019
    Published Online
    17 July 2019
    Accepted
    Notes:Accepted for publication in Journal of Geophysical Research: Biogeosciences. Copyright 2019 American Geophysical Union. Further reproduction or electronic distribution is not permitted.
    Subjects:Science > Mathematics > Probabilities. Mathematical statistics
    Department:Faculty of Science > Mathematics and Statistics
    Depositing user: Pure Administrator
    Date deposited:26 Aug 2019 15:57
    Last modified:19 Nov 2024 20:16
    URI:https://strathprints.strath.ac.uk/id/eprint/69497
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