Skip to Main content Skip to Navigation
Journal articles

Contribution of picoplankton to the total particulate organic carbon concentration in the eastern South Pacific

Abstract : Prochlorococcus, Synechococcus, picophytoeukaryotes and bacterioplankton abundances and contributions to the total particulate organic carbon concentration, derived from the total particle beam attenuation coefficient (cp), were determined across the eastern South Pacific between the Marquesas Islands and the coast of Chile. All flow cytometrically derived abundances decreased towards the hyper-oligotrophic centre of the gyre and were highest at the coast, except for Prochlorococcus, which was not detected under eutrophic conditions. Temperature and nutrient availability appeared important in modulating picophytoplankton abundance, according to the prevailing trophic conditions. Although the non-vegetal particles tended to dominate the cp signal everywhere along the transect (50 to 83%), this dominance seemed to weaken from oligo- to eutrophic conditions, the contributions by vegetal and non-vegetal particles being about equal under mature upwelling conditions. Spatial variability in the vegetal compartment was more important than the non-vegetal one in shaping the water column particle beam attenuation coefficient. Spatial variability in picophytoplankton biomass could be traced by changes in both total chlorophyll a (i.e. mono + divinyl chlorophyll a) concentration and cp. Finally, picophytoeukaryotes contributed ~38% on average to the total integrated phytoplankton carbon biomass or vegetal attenuation signal along the transect, as determined by size measurements (i.e. equivalent spherical diameter) on cells sorted by flow cytometry and optical theory. Although there are some uncertainties associated with these estimates, the new approach used in this work further supports the idea that picophytoeukaryotes play a dominant role in carbon cycling in the upper open ocean, even under hyper-oligotrophic conditions.
Complete list of metadata

Cited literature [59 references]  Display  Hide  Download
Contributor : Publication Egu <>
Submitted on : Monday, October 15, 2007 - 8:00:00 AM
Last modification on : Wednesday, December 9, 2020 - 3:15:17 PM
Long-term archiving on: : Tuesday, October 9, 2012 - 12:46:36 PM


Explicit agreement for this submission


  • HAL Id : hal-00330328, version 1


C. Grob, O. Ulloa, Hervé Claustre, Y. Huot, G. Alarcón, et al.. Contribution of picoplankton to the total particulate organic carbon concentration in the eastern South Pacific. Biogeosciences, European Geosciences Union, 2007, 4 (5), pp.837-852. ⟨hal-00330328⟩



Record views


Files downloads