The role of planktonic foraminifera in the marine carbon cycle at high latitudes (Southern Indian Ocean).!!

• Main Author: Meilland, Julie
• Other Authors: Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Université d'Angers, Ralf Schiebel
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Planktic foraminifera; Indian Ocean; Southern Ocean; Biological carbon pump; Foraminifères planctoniques; Océan Indien; Océan Austral; Pompe biologique du carbone; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Austral; Indian; Planktonic foraminifera
• Online Access: https://tel.archives-ouvertes.fr/tel-02117881; https://tel.archives-ouvertes.fr/tel-02117881/document; https://tel.archives-ouvertes.fr/tel-02117881/file/pdf2star-1556092086-thesemeilland.pdf

Planktonic foraminifera contribute to the marine biological carbon pump by generating organic (cytoplasm) and inorganic (shell) carbon fluxes. In this study, we characterized LPF total abundances, assemblages and test morphometry (minimum diameter) along 19 stations sampled by stratified plankton net (Multinet), during three consecutive austral summers (2012-2014) in the Southern Indian Ocean (30°S-60°S, 50°E-80°E). By demonstrating the efficiency of CPR for LPF sampling, we analysed population dynamic between 19 multinet sampling stations, showing the effect of frontal position on LPF production. To better constrain the impact of those organisms in the biological carbon pump at high latitudes, we have quantified the individual protein-biomass and test calcite mass of more than 2000 LPF. Differences in size-normalized protein-biomass and in size-normalized weight between years, species, and water bodies suggest that environmental parameters affect the production of planktonic foraminifera organic and inorganic carbon to varying degrees. Consequently, planktonic foraminifera are assumed to affect the biological carbon pump, depending on ecological conditions and biological prerequisites. The applicability of planktonic foraminifera tests as proxy of the past biological carbon pump in high latitudes would hence critically depend on the effect exerted by changing in ecological conditions, and the presence of different species. This study proposes a first estimation of planktonic foraminifera Corg and Cinorg standing stock and fluxes in the Southern Indian Ocean. Les foraminifères planctoniques vivants (LPF) contribuent à la pompe biologique du carbone océanique en générant des flux de Corg (cytoplasme) et de Cinorg (test calcaire). Dans cette étude, la morphométrie des tests, les abondances et les compositions spécifiques des assemblages de LPF dans l'océan Indien Sud (30°S-60°S, 50°E-80°E), ont été caractérisées à partir de la collecte par filet à plancton stratifié (Multinet) sur 19 stations échantillonnées ...