Distributions of particulate Heme b in the Atlantic and Southern Oceans—Implications for electron transport in phytoplankton

Authors

  • Martha Gledhill,

    Corresponding author
    1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
    2. Chemical Oceanography, Helmholtz Centre for Ocean Research (GEOMAR), Kiel, Germany
    • Corresponding author: M. Gledhill, Chemical Oceanography, Helmholtz Centre for Ocean Research (GEOMAR), DE-24148 Kiel, Germany. (mgledhill@geomar.de)

    Search for more papers by this author
  • Eric P. Achterberg,

    1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
    2. Chemical Oceanography, Helmholtz Centre for Ocean Research (GEOMAR), Kiel, Germany
    Search for more papers by this author
  • David J. Honey,

    1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
    Search for more papers by this author
  • Maria C. Nielsdottir,

    1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
    2. Department of Ocean, Earth, and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia, USA
    Search for more papers by this author
  • Micha J. A. Rijkenberg

    1. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK
    2. Royal Netherlands Institute for Sea Research, Den Burg, Netherlands
    Search for more papers by this author

Abstract

[1] Concentrations of heme b, the iron-containing component of b-type hemoproteins, ranged from < 0.4 to 5.3 pM with an average of 1.18 ± 0.8 pM (± 1σ; n = 86) in the Iceland Basin (IB), from < 0.4 to 19.1 pM with an average of 2.24 ± 1.67 pM (n = 269) in the tropical northeast Atlantic (TNA) and from 0.6 to 21 pM with an average of 5.1 ± 4.8 pM (n = 34) in the Scotia Sea (SS). Heme b concentrations were enhanced in the photic zone and decreased with depth. Heme b concentrations correlated positively with chlorophyll a (chl a) in the TNA (r = 0.41, p < 0.01, n = 269). Heme b did not correlate with chl a in the IB or SS. In the IB and SS, stations with high-chlorophyll and low-nutrient (Fe and/or Si) concentrations exhibited low heme b concentrations relative to particulate organic carbon (< 0.1 μmol mol−1), and high chl a:heme b ratios (> 500). High chl a:heme b ratios resulted from relative decreases in heme b, suggesting proteins such as cytochrome b6f, the core complex of photosystem II, and eukaryotic nitrate reductase were depleted relative to proteins containing chlorophyll such as the eukaryotic light-harvesting antenna. Relative variations in heme b, particulate organic carbon, and chl a can thus be indicative of a physiological response of the phytoplankton community to the prevailing growth conditions, within the context of large-scale changes in phytoplankton community composition.

Ancillary