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

Research output: Contribution to journalArticle

Authors

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

Colleges, School and Institutes

External organisations

  • Center for Marine Environmental Studies, Ehime University
  • Key Laboratory of Marine Environment and Ecology, Ministry of Education of China, Ocean University of China
  • Laboratory for Marine Ecology and Environmental Sciences, Qingdao National Laboratory for Marine Science and Technology

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.

Details

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