Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Type Article
Date 2016-05
Language English
Author(s) Rembauville M.1, Meilland J.2, Ziveri P.3, 4, Schiebel R.2, 5, Blain S.1, Salter I.1, 6
Affiliation(s) 1 : Univ Paris 06, Sorbonne Univ, CNRS, Observ Oceanol,Lab Oceanog Microbienne LOMIC, F-66650 Banyuls Sur Mer, France.
2 : Univ Angers, UMR CNRS 6112, LPG BIAF Bioindicateurs Actuels & Fossiles, 2 Blvd Lavoisier, F-49045 Angers, France.
3 : Univ Autonoma Barcelona, ICREA ICTA, Edifici Z,Carrer de les Columnes S-N, E-08193 Barcelona, Spain.
4 : ICREA, Catalan Inst Res & Adv Studies, Barcelona 08010, Spain.
5 : Max Planck Inst Chem, Hahn Meitner Weg 1, D-55128 Mainz, Germany.
6 : Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Handelshafen 12, D-27570 Bremerhaven, Germany.
Source Deep-sea Research Part I-oceanographic Research Papers (0967-0637) (Pergamon-elsevier Science Ltd), 2016-05 , Vol. 111 , P. 91-101
DOI 10.1016/j.dsr.2016.02.017
WOS© Times Cited 23
Keyword(s) Foraminifer, Coccoliths, Export, Carbonate counter-pump, Kerguelen Plateau, Southern Ocean
Abstract

We report the contribution of planktic foraminifers and coccoliths to the particulate inorganic carbon (PIC) export fluxes collected over an annual cycle (October 2011/September 2012) on the central Kerguelen Plateau in the Antarctic Zone (AAZ) south of the Polar Front (PF). The seasonality of PIC flux was decoupled from surface chlorophyll a concentration and particulate organic carbon (POC) fluxes and was characterized by a late summer (February) maximum. This peak was concomitant with the highest satellite-derived sea surface PIC and corresponded to a Emiliania huxleyi coccoliths export event that accounted for 85% of the annual PIC export. The foraminifer contribution to the annual PIC flux was much lower (15%) and dominated by Turborotalita quinqueloba and Neogloboquadrina pachyderma. Foraminifer export fluxes were closely related to the surface chlorophyll a concentration, suggesting food availability as an important factor regulating the foraminifer's biomass. We compared size-normalized test weight (SNW) of the foraminifers with previously published SNW from the Crozet Islands using the same methodology and found no significant difference in SNW between sites for a given species. However, the SNW was significantly species-specific with a threefold increase from T quinqueloba to Globigerina bulloides. The annual PIC:POC molar ratio of 0.07 was close to the mean ratio for the global ocean and lead to a low carbonate counter pump effect (similar to 5%) compared to a previous study north of the PF (6-32%). We suggest that lowers counter pump effect south of the PF despite similar productivity levels is due to a dominance of coccoliths in the PIC fluxes and a difference in the foraminifers species assemblage with a predominance of polar species with lower SNW.

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