[en] The role of calcifying phytoplanktonic organisms in ocean carbon biogeochemistry
and in climate change has received increasing attention in the marine community. The
quantification of the production of biogenic calcium carbonate and associated organic
matter in the photic zone and of their fate during settling is essential for a better assessment
of the oceanic carbon cycle. In the framework of the Belgian global change
programme, we conducted a field experiment on board the R/V Belgica in Spring
2002 along the Northern Bay of Biscay margin during successive coccolithophorid
Emiliania huxleyi (Ehux) blooms. We aim, in particular, at quantifying the role of
calcifying phytoplanktonic organisms in sequestering carbon.
With near real-time transmission of remote sensing data during the survey, we were
able to track the position and evolution of the various coccolithophore blooms along
the shelf break. Bio-optical measurements were performed for modelling purpose and
for calibration of the recently launched MERIS Sensor. During the field campaign,
special attention was paid to the precise determination of the dissolved inorganic
carbon chemistry. Primary production and rate of calcification were measured using
C14 incorporation experiments and the organic to inorganic particulate carbon ratio
quantified. Phytoplankton speciation was determined by microscopic examination,
flow cytometry and HPLC pigment analyses. Zooplankton grazing experiments on
phytoplankton were also performed. Suspended particles were characterised by their
chemical composition and morphology. Th234 was used to quantify particle residence
times and particulate organic carbon fluxes in surface waters. The results indicate
significant particle export during the sampling period, with particle residence times in
the upper 80 m ranging from 15 to 45 days.
In this presentation, we will integrate the results obtained from remote sensing, biooptical
investigation, water chemistry and process studies to elucidate the coupling of
primary production and calcification during Ehux blooms and its importance in the
marine biogeochemical cycle of carbon.
Chou, Lei; Laboratoire d’Océanographie Chimique et Géochimie des Eaux, Faculté des Sciences, Université Libre de Bruxelles, B-1050 Brussels, Belgium
Harlay, Jérôme ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Roevros, Nathalie; Laboratoire d’Océanographie Chimique et Géochimie des Eaux, Faculté des Sciences, Université Libre de Bruxelles, B-1050 Brussels, Belgium
Wollast, Roland; Laboratoire d’Océanographie Chimique et Géochimie des Eaux, Faculté des Sciences, Université Libre de Bruxelles, B-1050 Brussels, Belgium
Delille, Bruno ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Aerts, Katrien; Micro and Trace Analysis Centre (MiTAC), Universiteit Antwerpen, B-2610 Antwerp, Belgium
Lapernat, Pascale-Emmanuelle; Laboratorium voor Ecologie en Systematiek,ECOL, Vrij Universiteit Brussel, B-1050 Brussels, Belgium