Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects

M. Lévy, D. Iovino, Laure Resplandy, P. Klein, G. Madec, A. M. Tréguier, S. Masson, K. Takahashi

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

The sensitivity of an idealized bio-physical model of seasonally varying subtropical and subpolar gyres to increased horizontal resolution is presented. Switching from mesoscale-resolving (1/9°) to submesoscale-resolving (1/54°) allows the emergence of a denser and more energetic vortex population sustained by submesoscale physics. The experiments display a global decrease in phytoplankton abundance of ~10-20% as the resolution is refined. This result contrasts with previous studies, which suggested that eddy-driven vertical fluxes of nutrients locally boost phytoplankton growth at mid-latitudes in the open ocean. The explanation is that the long-term (50. years) modification of the large-scale, or basin-scale, circulation and distribution of nutrients by submesoscale processes (remote effects), not taken into account by previous studies because of their much shorter time integration, balance the local, small-scale effects. More precisely, dynamical remote effects (involving only the physics) affect the location of the boundary between the two gyres as well as the large-scale mixed-layer depth (MLD) and thermocline depth. Biological remote effects result from the dynamical remote effects that strongly modify the physical-biological interactions at all scales, including at large scales. These biological remote effects involve changes of the nutricline depth. In the mid-latitude subpolar gyre, phytoplankton decrease in abundance at higher resolution is due to the shallower MLD and nutricline, which promote zooplankton grazing; in the subtropical gyre, it is due to deeper MLD and nutricline, which diminishes regenerated production. In addition, remote effects modulate the dynamical supplies of nutrients to the euphotic layer through a combination of changes in mean advection, eddy advection and vertical mixing.

Original languageEnglish (US)
Pages (from-to)77-93
Number of pages17
JournalOcean Modelling
Volume43-44
DOIs
StatePublished - Jan 17 2012

All Science Journal Classification (ASJC) codes

  • Computer Science (miscellaneous)
  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Atmospheric Science

Keywords

  • Grazing
  • Large-scale
  • Nutricline
  • Phytoplankton
  • Primary production
  • Submesoscale
  • Thermocline

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  • Cite this

    Lévy, M., Iovino, D., Resplandy, L., Klein, P., Madec, G., Tréguier, A. M., Masson, S., & Takahashi, K. (2012). Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects. Ocean Modelling, 43-44, 77-93. https://doi.org/10.1016/j.ocemod.2011.12.003