Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

Chao Zhang, Huiwang Gao, Xiaohong Yao, Zongbo Shi, Jinhui Shi, Yang Yu, Ling Meng, Xinyu Guo

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
119 Downloads (Pure)

Abstract

In this study, five on-board microcosm experiments were performed in the subtropical gyre, the Kuroshio Extension region of the northwest Pacific Ocean (NWPO), and the Yellow Sea (YS) in order to investigate phytoplankton growth following the addition of artificially modified mineral dust (AM dust) and various nutrients (nitrogen (N), phosphorus (P), iron (Fe), NCP, and NCPCFe). The two experiments carried out with AM-dust addition in the subtropical gyre showed a maximum chlorophyll a (Chl a/concentration increase of 1.7- A nd 2.8-fold, while the cell abundance of large-sized phytoplankton (<5μm) showed a 1.8- A nd 3.9-fold increase, respectively, relative to the controls. However, in the Kuroshio Extension region and the YS, the increases in maximum Chl a and cell abundance of largesized phytoplankton following AM-dust addition were at most 1.3-fold and 1.7-fold larger than those in the controls, respectively. A net conversion efficiency index (NCEI) newly proposed in this study, size-fractionated Chl a, and the abundance of large-sized phytoplankton were analysed to determine which nutrients contribute to supporting phytoplankton growth. Our results demonstrate that a combination of nutrients, N.P or NCPCFe, is responsible for phytoplankton growth in the subtropical gyre following AM-dust addition. Single nutrient addition, i.e., N in the Kuroshio Extension region and P or N in the YS, controls the phytoplankton growth following AM-dust addition. In the AM-dust-addition experiments, in which the increased N.P or P was identified to determine phytoplankton growth, the dissolved inorganic P from AM dust (8.6 nmol L-1/was much lower than the theoretically estimated minimum P demand (∼20 nmol L-1/for phytoplankton growth. These observations suggest that additional supply augments the bioavailable P stock in incubated seawater with AM-dust addition, most likely due to an enhanced solubility of P from AM dust or the remineralization of the dissolved organic P.

Original languageEnglish
Pages (from-to)749-765
Number of pages17
JournalBiogeosciences
Volume15
Issue number3
DOIs
Publication statusPublished - 7 Feb 2018

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes

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