Si and C interactions in the world ocean: Importance of ecological processes and implications for the role of diatoms in the biological pump

• Published in: Global Biogeochemical Cycles
• Main Authors: Ragueneau, Olivier, Schultes, Sabine, Bidle, Kay, Claquin, Pascal, Moriceau, Brivaëla
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Marine and Coastal Sciences (IMCS), Rutgers, The State University of New Jersey New Brunswick (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Physiologie et Ecophysiologie des Mollusques Marins (PE2M), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Marine Sciences Research center, Stony Brook University SUNY (SBU), State University of New York (SUNY)-State University of New York (SUNY)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: BIOGENIC SILICA DISSOLUTION; PARTICULATE ORGANIC-CARBON; TRANSPARENT EXOPOLYMER PARTICLES; PHYTOPLANKTON-DERIVED DETRITUS; SOUTHERN-OCEAN; MARINE SNOW; FECAL PELLETS; THALASSIOSIRA-PSEUDONANA; CELL-CYCLE; MICROBIAL AGGREGATION; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Archer; Southern Ocean
• Online Access: https://hal.univ-brest.fr/hal-00473808; https://hal.univ-brest.fr/hal-00473808/document; https://hal.univ-brest.fr/hal-00473808/file/2006GB002688.pdf; https://doi.org/10.1029/2006GB002688

International audience Diatoms play a major role in carbon export from surface waters, but their role in the transport of carbon to the deep sea has been questioned by global analyses of sediment trap fluxes which suggest that organic carbon fluxes and transfer efficiencies through the mesopelagic are tightly correlated with CaCO3 ( Klaas and Archer, 2002; Franc, ois et al., 2002). Here we explore the role of diatoms in the biological pump through a study of Si and C interactions from the molecular to the global scale. Recent findings on molecular interactions between Si and C are reviewed. The roles of bacteria, grazers and aggregation are explored and combined, to account for the extent of Si and C decoupling between surface waters and 1000 m, observed to be very homogeneous in different biogeochemical provinces of the ocean. It is suggested that the mesopelagic food web plays a crucial role in this homogeneity: Sites of high export are also sites where diatom C is being either remineralized or channeled toward the long-lived carbon pool most efficiently in the mesopelagic zone. The amount of carbon participating in the biological pump but not collected in sediment traps remains to be explored. It is also demonstrated that statistical analyses performed at global scales hide spatial variability in carrying coefficients, indicating a clear need to understand the mechanisms that control spatial and temporal variations in the relative importance of ballast minerals and other export mechanisms such as particle dynamics.