Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 261:111-122 (2003) - doi:10.3354/meps261111 Response of coccolithophorid Emiliania huxleyi to elevated partial pressure of CO2 under nitrogen limitation Antoine Sciandra1,*, Jérome Harlay2, Dominique Lefèvre3, Rodolphe Lemée1, Peguy Rimmelin3, Michel Denis3, Jean-Pierre Gattuso1 1Laboratoire d¹Océanographie, Université Mixte de Recherche (UMR) 7093, Centre National de la Recherche Scientifique- Université Pierre et Marie Curie (CNRS-UPMC), BP 28, 06234 Villefranche-sur-mer Cedex, France 2Service d¹Océanographie Chimique et Géochimie des Eaux, Université Libre de Bruxelles, Campus Plaine, CP 208, Boulevard du Triomphe, 1050 Brussels, Belgium 3Laboratoire d¹Océanographie et de Biogéochimie, Centre d'Océanologie de Marseille, Université Mixte de Recherche (UMR) 6535, Centre National de la Recherche Scientifique (CNRS)-Université de la Méditerranée, Case 901, 13288 Marseille Cedex 9, France *Email: sciandra@obs-vlfr.fr ABSTRACT: Precipitation of calcium carbonate by phytoplankton in the photic oceanic layer is an important process regulating the carbon cycling and the exchange of CO2 at the ocean-atmosphere interface. Previous experiments have demonstrated that, under nutrient-sufficient conditions, doubling the partial pressure of CO2 (pCO2) in seawater‹a likely scenario for the end of the century‹can significantly decrease both the rate of calcification by coccolithophorids and the ratio of inorganic to organic carbon production. The present work investigates the effects of high pCO2 on calcification by the coccolithophore Emiliania huxleyi (Strain TW1) grown under nitrogen-limiting conditions, a situation that can also prevail in the ocean. Nitrogen limitation was achieved in NO3-limited continuous cultures renewed at the rate of 0.5 d-1 and exposed to a saturating light level. pCO2 was increased from 400 to 700 ppm and controlled by bubbling CO2-rich or CO2-free air into the cultures. The pCO2 shift has a rapid effect on cell physiology that occurs within 2 cell divisions subsequent to the perturbation. Net calcification rate (C) decreased by 25% and, in contrast to previous studies with N-replete cultures, gross community production (GCP) and dark community respiration (DCR) also decreased. These results suggest that increasing pCO2 has no noticeable effect on the calcification/photosynthesis ratio (C/P) when cells of E. huxleyi are NO3-limited. KEY WORDS: Calcification · Carbon fixation · Coccolith · Emiliania huxleyi · Nitrate · Alkalinity · CO2 Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 261. Online publication date: October 17, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.
Highlights
The depression of marine calcification by elevated pressure of CO2 (pCO2) was first demonstrated in tropical coralline algae (Agegian 1985) and has subsequently been identified in other photosynthetic and calcifying organisms and communities (Langdon et al 2000, Leclercq et al 2000, 2002)
The present work investigates the effects of high pCO2 on calcification by the coccolithophore Emiliania huxleyi (Strain TW1) grown under nitrogen-limiting conditions, a situation that can prevail in the ocean
Net calcification rate (C ) decreased by 25% and, in contrast to previous studies with N-replete cultures, gross community production (GCP) and dark community respiration (DCR) decreased. These results suggest that increasing pCO2 has no noticeable effect on the calcification/photosynthesis ratio (C /P) when cells of E. huxleyi are NO3-limited
Summary
The depression of marine calcification by elevated pCO2 was first demonstrated in tropical coralline algae (Agegian 1985) and has subsequently been identified in other photosynthetic and calcifying organisms (reviewed by Gattuso et al 1999a) and communities (Langdon et al 2000, Leclercq et al 2000, 2002). Benthic calcification represents a significant component of the oceanic precipitation of calcium carbonate, the extent and significance of this response were unknown until recently, when it was shown that calcification of coccolithophorids, the major group of marine calcifying organisms, is inhibited at elevated pCO2 (Zondervan et al 2001). Calcification is a source of CO2 to the water column (Ware et al 1992, Frankignoulle et al 1994). It increases the sea–air CO2 gradient and counteracts the uptake of CO2 by the ocean. The magnitude of the decrease in calcification is highly vari-
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