Journal of Oceanography

, Volume 60, Issue 1, pp 93–117

Nutrient and Plankton Dynamics in the NE and NW Gyres of the Subarctic Pacific Ocean

  • Paul J. Harrison
  • Frank A. Whitney
  • Atsushi Tsuda
  • Hiroaki Saito
  • Kazuaki Tadokoro
Article

DOI: 10.1023/B:JOCE.0000038321.57391.2a

Cite this article as:
Harrison, P.J., Whitney, F.A., Tsuda, A. et al. Journal of Oceanography (2004) 60: 93. doi:10.1023/B:JOCE.0000038321.57391.2a

Abstract

The western subarctic gyre (WSG) and the eastern Alaska Grye (AG) on each side of the subarctic North Pacific, have many similarities. In both gyres, macronutrients are generally high and chl is low, and hence both gyres are High Nitrate, Low Chlorophyll (HNLC) regions. Despite the general similarities between these two gyres, there are many important differences. The time series station established at Stn KNOT on the southwest edge of the WSG and two in situ mesoscale iron enrichment experiments at each of the gyres has provided more information on iron concentrations, the dual role of iron and silicate limitation and seasonal cycles in the gyres. There is more seasonality in many parameters at Stn KNOT than at Stn P. There is an increase in Chl and primary productivity at Stn KNOT in May followed by increased iron limitation in summer. Low DIC:NO3 ratios and high Si:NO3 ratios in the WSG, indicate lower calcification and higher diatom production than at Stn P. The sources of iron for these areas are still not clear, but horizontal transport of iron rich coastal water and vertical transport could be important sources at certain times of the year in addition to dust input. Satellite images show that chl-rich coastal waters occasionally extend to the vicinity of Stn KNOT and therefore Stn KNOT may not always represent conditions in the main part of the WSG. This review focuses mainly on a comparison of Stn KNOT and Stn P, two time series stations on the edge of two very large gyres. At present, we have a limited understanding of the temporal and spatial variability within each of these large gyres.

Subarctic Pacific Stn P Stn KNOT nutrients phytoplankton iron HNLC primary productivity silicate gyre 

Copyright information

© The Oceanographic Society of Japan 2004

Authors and Affiliations

  • Paul J. Harrison
    • 1
  • Frank A. Whitney
    • 2
  • Atsushi Tsuda
    • 3
  • Hiroaki Saito
    • 4
  • Kazuaki Tadokoro
    • 5
  1. 1.AMCE Program, Hong Kong University of Science and TechnologyClear Water BayHong Kong
  2. 2.Institute of Ocean Sciences, Fisheries and Oceans CanadaSidney, BCCanada
  3. 3.Oceanic Research InstituteUniversity of TokyoTokyoJapan
  4. 4.Tohoku National Fisheries Research InstituteShiogama, MiyagiJapan
  5. 5.Frontier Research System for Global ChangeYokahama, KanagawaJapan

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