Organic carbon isotopic composition of phytoplankton and sea-surface pCO2 reconstructions in the Southern Indian Ocean during the last 50,000 yr (original) (raw)

1996, Organic Geochemistry

3Universit6 P. and M. Curie, INRA, Lab. Biog6ochimie des isotopes stables 4, place Jussieu 75252, Paris, Cedex 05, France, 4LODYC, Universit6 P. and M. Curie 4, place Jussieu 75252, Paris, Cedex 05, France, 5LPCM, Univiversit6 P. and M. Curie 4, place Jussieu 75252, Paris, Cedex 05, France and 6Department of Environmental Chemistry, CID-CSIC, Barcelona, Spain Almtraet--Simultaneous measurements of chlorophyll and carbon content, carboxylase activities in phytoplankton, isotopic composition of suspended particulate organic carbon (POC), and pCO_, in surface sea-water in the south Indian Ocean indicate that plankton populations have different carbon metabolisms on both sides of the subtropical convergence (STC). North of STC. communities are dominated by mixo/heterotrophic organisms while south of the STC, physiological or biomass parameters are diagnostic of autotrophic phytoplankton. Only phytoplankton ~5~C values, in the southern part, showed a strong correlation with [CO_,(aq)] in surface waters which permitted a relationship between these parameters.