EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Bacterial abundance, growth and community composition in oligotrophic, metal-rich running waters of Southern New Caledonia

Chiaki Motegi1, Yvan Bettarel2, Aurélie Dufour3, Xavier Mari4, Christophe Migon5, Emma Rochelle-Newall6, Olivier Pringault4, Jean-Pascal Torréton7, and Markus Weinbauer5
Chiaki Motegi et al.
  • 1Atmosphere and Ocean Research Institute, The University of Tokyo, Japan (
  • 2Institut de Recherche pour le Développement (IRD) MARBEC, Université Montpellier, Montpellier, France
  • 3Mediterranean Institute of Oceanography (MIO), Marseille, France
  • 4Institut de Recherche pour le Développement (IRD), Mediterranean Institute of Oceanography (MIO), Marseille, France
  • 5LOV, Station Zoologique, Villefranche-sur-mer, France
  • 6Institut de Recherche pour le Développement (IRD)-Sorbonne Université, Paris, France
  • 7IRD-CNRS-CIRAD office in Southern Africa

The basic bacterial ecology and diversity was investigated in five running water systems of Southern New Caledonia. These running waters were characterized by potential P-limitation and high concentrations of Ni, Fe, Mn, Cr and Co. The low concentrations of dissolved organic carbon, bacterial and viral abundance, bacterial production and growth efficiency support the characterization of the running waters as oligotroph to ultraoligotroph. Despite these similarities, there were strong differences (<50% similarity) in bacterial community composition between some habitats based on 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) fingerprints. The high coverage of sequenced DGGE bands found for Betaproteobacteria is typical for freshwater systems, however, we found also a strong representation of Gammaproteobacteria. Indeed the three bands found at all stations were related to Limnohabitans (Comamonadaceae) and Alteromonadaceae. Strong differences were also found between the free-living and the attached bacterial fraction with Gammaproteobacteria dominating in two systems. A higher representation of Gammaproteobacteria seems typical for metal-rich freshwater habitats. Consistent with fresh water habitats, majority of phylotypes detected in the sediment was affiliated to proteobacteria. Also, none of the sequences showed a 100% identity with data bases, and 10 of the 22 and 2 of the 23 sequences had similarities higher than 97% in the freshwater and sediment. This could indicate specific adaptations of the community composition either due to the high metal concentrations or due to the geographical isolation of the New Caledonia. 

How to cite: Motegi, C., Bettarel, Y., Dufour, A., Mari, X., Migon, C., Rochelle-Newall, E., Pringault, O., Torréton, J.-P., and Weinbauer, M.: Bacterial abundance, growth and community composition in oligotrophic, metal-rich running waters of Southern New Caledonia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12701,, 2021.