Articles | Volume 13, issue 21
Biogeosciences, 13, 5983–6001, 2016
Biogeosciences, 13, 5983–6001, 2016

Research article 02 Nov 2016

Research article | 02 Nov 2016

Growth of the coccolithophore Emiliania huxleyi in light- and nutrient-limited batch reactors: relevance for the BIOSOPE deep ecological niche of coccolithophores

Laura Perrin1, Ian Probert2, Gerald Langer3, and Giovanni Aloisi4 Laura Perrin et al.
  • 1Sorbonne Universités, UPMC Univ. Paris 06-CNRS-IRD-MNHN, LOCEAN-IPSL, 75252 Paris, France
  • 2CNRS-UPMC Université, Paris 06 FR2424, Roscoff Culture Collection, Station Biologique de Roscoff, 29680 Roscoff, France
  • 3The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, Devon, PL1 2PB, UK
  • 4LOCEAN, UMR 7159, CNRS-UPMC-IRD-MNHN, 75252 Paris, France

Abstract. Coccolithophores are unicellular calcifying marine algae that play an important role in the oceanic carbon cycle via their cellular processes of photosynthesis (a CO2 sink) and calcification (a CO2 source). In contrast to the well-studied, surface-water coccolithophore blooms visible from satellites, the lower photic zone is a poorly known but potentially important ecological niche for coccolithophores in terms of primary production and carbon export to the deep ocean. In this study, the physiological responses of an Emiliania huxleyi strain to conditions simulating the deep niche in the oligotrophic gyres along the BIOSOPE transect in the South Pacific Gyre were investigated. We carried out batch culture experiments with an E. huxleyi strain isolated from the BIOSOPE transect, reproducing the in situ conditions of light and nutrient (nitrate and phosphate) limitation. By simulating coccolithophore growth using an internal stores (Droop) model, we were able to constrain fundamental physiological parameters for this E. huxleyi strain. We show that simple batch experiments, in conjunction with physiological modelling, can provide reliable estimates of fundamental physiological parameters for E. huxleyi that are usually obtained experimentally in more time-consuming and costly chemostat experiments. The combination of culture experiments, physiological modelling and in situ data from the BIOSOPE cruise show that E. huxleyi growth in the deep BIOSOPE niche is limited by availability of light and nitrate. This study contributes more widely to the understanding of E. huxleyi physiology and behaviour in a low-light and oligotrophic environment of the ocean.

Short summary
Coccolithophores are calcifying marine algae that play an important role in the oceanic carbon cycle. Deep niches of coccolithophores exist in the ocean and are poorly understood. Laboratory cultures with the coccolithophore Emiliania huxleyi were carried out to reproduce the environmental conditions (light–nutrient limitation) of a deep niche in the South Pacific Ocean. Physiological modelling of experimental results allows us to estimate the growth rates of coccolithophores in this niche.
Final-revised paper