CO2-dependent carbon isotope fractionation in dinoflagellates relates totheir inorganic carbon fluxes
Hoins, M.; Eberlein, T.; Van de Waal, D.B.; Sluijs, A.; Reichart, G.-J.; Rost, B. (2016). CO2-dependent carbon isotope fractionation in dinoflagellates relates totheir inorganic carbon fluxes. J. Exp. Mar. Biol. Ecol. 481: 9–14. https://dx.doi.org/10.1016/j.jembe.2016.04.001 In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more |   |
| Author keywords | CCM; CO2 uptake; HCO3 uptake; Leakage |
| Authors | | Top | - Hoins, M.
- Eberlein, T.
- Van de Waal, D.B.
| - Sluijs, A.
- Reichart, G.-J., more
- Rost, B.
| |
| Abstract | Carbon isotope fractionation (ep) between the inorganic carbon source and organic matter has been proposed tobe a function of pCO2. To understand the CO2-dependency of ep and species-specific differences therein, inorganiccarbon fluxes in the four dinoflagellate species Alexandriumfundyense, Scrippsiella trochoidea, Gonyaulax spiniferaand Protoceratium reticulatum have been measured by means of membrane-inlet mass spectrometry. In-vivoassays were carried out at different CO2 concentrations, representing a range of pCO2 from 180 to 1200 µatm.The relative bicarbonate contribution (i.e. the ratio of bicarbonate uptake to total inorganic carbon uptake)and leakage (i.e. the ratio of CO2 efflux to total inorganic carbon uptake) varied from 0.2 to 0.5 and 0.4 to 0.7,respectively, and differed significantly between species. These ratios were fed into a single-compartmentmodel, and ep values were calculated and compared to carbon isotope fractionation measured under the sameconditions. For all investigated species, modeled and measured ep values were comparable (A. fundyense,S. trochoidea, P. reticulatum) and/or showed similar trends with pCO2 (A. fundyense, G. spinifera, P. reticulatum).Offsets are attributed to biases in inorganic flux measurements, an overestimated fractionation factor for theCO2-fixing enzyme RubisCO, or the fact that intracellular inorganic carbon fluxes were not taken into accountin the model. This study demonstrates that CO2-dependency in ep can largely be explained by the inorganiccarbon fluxes of the individual dinoflagellates. |
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