Diatoms preserved in surface sediments of the northeastern Kerguelen Plateau

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Armand, Leanne, Crosta, X., QUEGUINER, Bernard, Mosseri, J., Garcia, N.
• Other Authors: Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Laboratoire de MicrobiologiE de Géochimie et d'Ecologie Marines (LMGEM), Centre National de la Recherche Scientifique (CNRS)-Université de la Méditerranée - Aix-Marseille 2
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Southern Ocean; Chlorophyll a; Biogenic silica; Bacillariophyceae; Sediments; Fluff layer; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; Kerguelen; Antarc*; Antarctica; Sea ice
• Online Access: https://hal.archives-ouvertes.fr/hal-02105674; https://doi.org/10.1016/j.dsr2.2007.12.032

International audience An ''island mass effect'' was observed from the sedimentary distribution of diatoms on the northeastern Kerguelen Plateau. Five new samples placed in context to species distributions previously reported from the Permanently Open Ocean Zone (POOZ) revealed a plateau community dominated by three species/taxa: Fragilariopsis kerguelensis, Thalassionema nitzschioides f. nitzschioides and Chaetoceros Hyalochaete resting spores. Intermediate abundances of Thalassiosira antarctica were unique to the plateau sediment signature as were increased abundances of Eucampia antarctica v. antarctica. The off-plateau sediment sample contained typical POOZ sediment distributions dominated by F. kerguelensis, Thalassiosira lentiginosa and Thalassiothrix antarctica. The role of deposition from the surface waters to the sediments was investigated by comparison to the diatom thanatocoenose observed in surface waters. These results suggest that the use of sediment abundances of C. Hyalochaete resting spores and F. kerguelensis to determine past productivity events (such as wind-sourced iron enrichment of the Southern Ocean at the Last Glacial Maximum) is not straightforward. The elevated abundance of T. nitzschioides f. nitzschioides on the plateau did not indicate an iron-deplete regime but the converse. For the evaluation of paleo-productivity hypotheses for the open Southern Ocean, we suggest caution in the use of Subantarctic and Kerguelen Plateau sediment signatures, and emphasize that there is a need to also study Antarctic coastal and especially sea-ice melt-water stimulated blooms. r