The Biological Pump and Seasonal Variability of pCO<sub>2</sub> in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron - Sorbonne Université Access content directly
Journal Articles Journal of Geophysical Research. Oceans Year : 2018

The Biological Pump and Seasonal Variability of pCO2 in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron

Abstract

Iron is known to limit primary production in the Southern Ocean (SO). To cope with the lack of this micronutrient, diatoms, a dominant phytoplankton group in this oceanic region, have been shown in cultures to have developed an original adaptation strategy to maintain efficient growth rates despite very low cellular iron quotas, even in low light conditions. Using a global ocean biogeochemical model, we explored the consequences of this physiological adaptation for the biological pump and the seasonal variability of both surface chlorophyll concentrations and surface partial pressure of carbon dioxide (pCO2) in this key region for global climate. In the model, we implemented a low intracellular Fe:C requirement in the SO for diatoms uniquely. This results in an increase of 10% in the relative contribution of diatoms to total SO primary production. The biological pump is also strengthened, which increases the biological contribution to the seasonal evolution of pCO2 relative to the thermodynamic component. Therefore, the seasonal evolution of both surface chlorophyll and surface pCO2 is significantly impacted, with a marked improvement, in our model, in the SO polar zone compared to the observations. Our model study underscores the potentially important consequences that this adaptive physiological behavior of diatoms could have on marine biogeochemistry in the SO. It is thus critical to improve our understanding of the physiology of this key phytoplankton group, in particular in the SO.

Domains

Oceanography
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Dates and versions

hal-01959020 , version 1 (18-12-2018)

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Renaud Person, Olivier Aumont, Marina Lévy. The Biological Pump and Seasonal Variability of pCO2 in the Southern Ocean: Exploring the Role of Diatom Adaptation to Low Iron. Journal of Geophysical Research. Oceans, 2018, 123 (5), pp.3204-3226. ⟨10.1029/2018JC013775⟩. ⟨hal-01959020⟩
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