Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 9, issue 9
Biogeosciences, 9, 3491–3512, 2012
https://doi.org/10.5194/bg-9-3491-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 9, 3491–3512, 2012
https://doi.org/10.5194/bg-9-3491-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 03 Sep 2012

Research article | 03 Sep 2012

Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

M.-C. Ciobanu1,2,3,4, M. Rabineau4, L. Droz4, S. Révillon4, J.-F. Ghiglione5, B. Dennielou6, S.-J. Jorry6, J. Kallmeyer7, J. Etoubleau6, P. Pignet1,2,3, P. Crassous8, O. Vandenabeele-Trambouze1,2,3, J. Laugier1, M. Guégan1, A. Godfroy1,2,3, and K. Alain1,2,3 M.-C. Ciobanu et al.
  • 1Université de Bretagne Occidentale (UBO, UEB), Institut Universitaire Européen de la Mer (IUEM) − UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Place Nicolas Copernic, 29280 Plouzané, France
  • 2CNRS, IUEM − UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Place Nicolas Copernic, 29280 Plouzané, France
  • 3Ifremer, UMR6197, Laboratoire de Microbiologie des Environnements Extrêmes (LMEE), Technopôle Pointe du diable, 29280 Plouzané, France
  • 4CNRS, IUEM − UMR 6538, Laboratoire Domaines Océaniques, 29280 Plouzané, France
  • 5CNRS, Observatoire Océanologique de Banyuls s/mer − UMR 7621, Laboratoire d'Océanographie Microbienne (LOMIC), 66650 Banyuls-sur-Mer, France
  • 6Ifremer, Géosciences Marines, 29280 Plouzané, France
  • 7Universität Potsdam, Earth and Environmental Sciences, Karl-Liebknecht Str. 25, 14476 Potsdam, Germany
  • 8Ifremer, Laboratoire Environnements Profonds, 29280 Plouzané, France

Abstract. An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion). Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG), within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG) and Halobacteria) within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria within Proteobacteria phylum, and also members of Bacteroidetes phylum. The second most abundant lineages were Actinobacteria and Firmicutes at the Gulf of Lion site and Chloroflexi at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: Alpha-, Gammaproteobacteria, Firmicutes and Actinobacteria. In molecular surveys, the Betaproteobacteria group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea levee. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence analyses (CCA) showed that the availability of electron acceptors and the quality of electron donors (indicated by age) strongly influenced the community structure. In contrast, within the Gulf of Lion core, characterized by a homogeneous lithological structure of upper-slope environment, most detected groups were Bacteroidetes and, to a lesser extent, Betaproteobacteria. At both site, the detection of Betaproteobacteria coincided with increased terrestrial inputs, as confirmed by the geochemical measurements (Si, Sr, Ti and Ca). In the Gulf of Lion, geochemical parameters were also found to drive microbial community composition. Taken together, our data suggest that the palaeoenvironmental history of erosion and deposition recorded in the Western Mediterranean Sea sediments has left its imprint on the sedimentological context for microbial habitability, and then indirectly on structure and composition of the microbial communities during the late Quaternary.

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