1. A 13C labelling study on carbon fluxes in Arctic plankton communities under elevated CO2 levels.
- Author
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de Kluijver, A., Soetaert, K., Czerny, J., Schulz, K. G., Boxhammer, T., Riebesell, U., and Middelburg, J. J.
- Subjects
PLANKTON ,OCEAN acidification ,BICARBONATE ions ,FOOD chains ,DISSOLVED organic matter ,DETRITUS - Abstract
The effect of CO
2 on carbon fluxes (production, consumption, and export) in Arctic plankton communities was investigated during the 2010 EPOCA (European project on Ocean Acidification) mesocosm study off Ny Ålesund, Svalbard.13 C labelled bicarbonate was added to nine mesocosms with a range in pCO2 (185 to 1420 μatm) to follow the transfer of carbon from dissolved inorganic carbon (DIC) into phytoplankton, bacterial and zooplankton consumers, and export. A nutrient--phytoplankton--zooplankton--detritus model amended with13 C dynamics was constructed and fitted to the data to quantify uptake rates and carbon fluxes in the plankton community. The plankton community structure was characteristic for a post-bloom situation and retention food web and showed high bacterial production (∼ 31% of primary production), high abundance of mixotrophic phytoplankton, low mesozooplankton grazing (☤ 6% of primary production) and low export (∼ 7% of primary production). Zooplankton grazing and export of detritus were sensitive to CO2 : grazing decreased and export increased with increasing pCO2 . Nutrient addition halfway through the experiment increased the export, but not the production rates. Although mixotrophs showed initially higher production rates with increasing CO2 , the overall production of POC (particulate organic carbon) after nutrient addition decreased with increasing CO2 . Interestingly, and contrary to the low nutrient situation, much more material settled down in the sediment traps at low CO2 . The observed CO2 related effects potentially alter future organic carbon flows and export, with possible consequences for the efficiency of the biological pump. [ABSTRACT FROM AUTHOR]- Published
- 2013
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