Marine ecosystem community carbon and nutrient uptake stoichiometry under varying ocean acidification during the PeECE III experiment

• Published in: Biogeosciences
• Main Authors: Bellerby, R. G. J., Schulz, K. G., Riebesell, U., Neill, C., Nondal, G., Heegaard, E., Johannessen, T., Brown, K. R.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Ocean acidification
• Online Access: https://doi.org/10.5194/bg-5-1517-2008; https://www.biogeosciences.net/5/1517/2008/

Changes to seawater inorganic carbon and nutrient concentrations in response to the deliberate CO 2 perturbation of natural plankton assemblages were studied during the 2005 Pelagic Ecosystem CO 2 Enrichment (PeECE III) experiment. Inverse analysis of the temporal inorganic carbon dioxide system and nutrient variations was used to determine the net community stoichiometric uptake characteristics of a natural pelagic ecosystem perturbed over a range of p CO 2 scenarios (350, 700 and 1050 μatm). Nutrient uptake showed no sensitivity to CO 2 treatment. There was enhanced carbon production relative to nutrient consumption in the higher CO 2 treatments which was positively correlated with the initial CO 2 concentration. There was no significant calcification response to changing CO 2 in Emiliania huxleyi by the peak of the bloom and all treatments exhibited low particulate inorganic carbon production (~15 μmol kg −1 ). With insignificant air-sea CO 2 exchange across the treatments, the enhanced carbon uptake was due to increase organic carbon production. The inferred cumulative C:N:P stoichiometry of organic production increased with CO 2 treatment from 1:6.3:121 to 1:7.1:144 to 1:8.25:168 at the height of the bloom. This study discusses how ocean acidification may incur modification to the stoichiometry of pelagic production and have consequences for ocean biogeochemical cycling.