A 13 C labelling study on carbon fluxes in Arctic plankton communities under elevated CO 2 levels

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 p C...

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Bibliographic Details
Published in:Biogeosciences
Main Authors: A. de Kluijver, K. Soetaert, J. Czerny, K. G. Schulz, T. Boxhammer, U. Riebesell, J. J. Middelburg
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2013
Subjects:
Ecology
QH540-549.5
Life
QH501-531
Geology
QE1-996.5
Arctic
Svalbard
Ny-Ålesund
Ny Ålesund
Ocean acidification
Phytoplankton
Zooplankton
Online Access:https://doi.org/10.5194/bg-10-1425-2013
https://doaj.org/article/952e3e9ff901433cb84c0b004f7b5109
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Summary: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 p CO 2 (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 with 13 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 CO 2 : grazing decreased and export increased with increasing p CO 2 . Nutrient addition halfway through the experiment increased the export, but not the production rates. Although mixotrophs showed initially higher production rates with increasing CO 2 , the overall production of POC (particulate organic carbon) after nutrient addition decreased with increasing CO 2 . Interestingly, and contrary to the low nutrient situation, much more material settled down in the sediment traps at low CO 2 . The observed CO 2 related effects potentially alter future organic carbon flows and export, with possible consequences for the efficiency of the biological pump.

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