Person R. auteur aut IRD Aumont Olivier auteur aut IRD Lévy Marina auteur aut IRD text journalArticle eng text/pdf born digital access 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 (pCO(2)) 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 pCO(2) relative to the thermodynamic component. Therefore, the seasonal evolution of both surface chlorophyll and surface pCO(2) 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. specialized Southern Ocean diatoms physiological adaptation biological pump pCO(2) seasonal variability OCEAN AUSTRAL 036 123 5 3204-3226 2018 2169-9275 https://www.documentation.ird.fr/hor/fdi:010073197 10.1029/2018jc013775 2169-9275 [F B010073197] https://www.documentation.ird.fr/hor/fdi:010073197 https://www.documentation.ird.fr/intranet/publi/2018/07/010073197.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2018-09-03 2023-07-11 fdi:010073197 fre