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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 10, issue 1 | Copyright

Special issue: Arctic ocean acidification: pelagic ecosystem and biogeochemical...

Biogeosciences, 10, 555-566, 2013
https://doi.org/10.5194/bg-10-555-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 29 Jan 2013

Research article | 29 Jan 2013

Ocean acidification shows negligible impacts on high-latitude bacterial community structure in coastal pelagic mesocosms

A.-S. Roy1, S. M. Gibbons2,3, H. Schunck1, S. Owens2,8, J. G. Caporaso2,4, M. Sperling1,9, J. I. Nissimov5, S. Romac6, L. Bittner6, M. Mühling10, U. Riebesell1, J. LaRoche1,*, and J. A. Gilbert2,7 A.-S. Roy et al.
  • 1GEOMAR Helmholtz Center for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany
  • 2Argonne National Laboratory, Institute for Genomic and Systems Biology, 9700, S. Cass Ave. Lemont, IL 60439, USA
  • 3Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL 60637, USA
  • 4Department of Computer Science, Northern Arizona University, Flagstaff, AZ 86001, USA
  • 5Plymouth Marine Laboratory, Prospect Place, Plymouth, Devon, PL1 3DH, UK
  • 6CNRS, UMR7144 (Paris 6), Université Pierre et Marie Curie, Station Biologique de Roscoff, Place Georges Teissier, 29682, Roscoff, France
  • 7Department of Ecology and Evolution, University of Chicago, 5801 South Ellis Avenue, Chicago, IL 60637, USA
  • 8Computation Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
  • 9Alfred-Wegener-Institute, Am Handelshafen 12, 27570, Bremerhaven, Germany
  • 10Institute of Biological Sciences, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
  • *present address: Dalhousie University, 5850 University Avenue, Halifax, NS, B3K 6R8, Canada

Abstract. The impact of ocean acidification and carbonation on microbial community structure was assessed during a large-scale in situ costal pelagic mesocosm study, included as part of the EPOCA 2010 Arctic campaign. The mesocosm experiment included ambient conditions (fjord) and nine mesocosms with pCO2 levels ranging from ~145 to ~1420 μatm. Samples for the present study were collected at ten time points (t–1, t1, t5, t7, t12, t14, t18, t22, t26 to t28) in seven treatments (ambient fjord (~145), 2 × ~185, ~270, ~685, ~820, ~1050 μatm) and were analysed for "small" and "large" size fraction microbial community composition using 16S RNA (ribosomal ribonucleic acid) amplicon sequencing. This high-throughput sequencing analysis produced ~20 000 000 16S rRNA V4 reads, which comprised 7000 OTUs. The main variables structuring these communities were sample origins (fjord or mesocosms) and the community size fraction (small or large size fraction). The community was significantly different between the unenclosed fjord water and enclosed mesocosms (both control and elevated CO2 treatments) after nutrients were added to the mesocosms, suggesting that the addition of nutrients is the primary driver of the change in mesocosm community structure. The relative importance of each structuring variable depended greatly on the time at which the community was sampled in relation to the phytoplankton bloom. The sampling strategy of separating the small and large size fraction was the second most important factor for community structure. When the small and large size fraction bacteria were analysed separately at different time points, the only taxon pCO2 was found to significantly affect were the Gammaproteobacteria after nutrient addition. Finally, pCO2 treatment was found to be significantly correlated (non-linear) with 15 rare taxa, most of which increased in abundance with higher CO2.

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