Contribution of deep dark fixation processes to overall CO2 incorporation and large vertical changes of microbial populations in stratified karstic lakes

Emilio O. Casamayor, Marc Llirós, Antonio Picazo, Albert Barberán, Carles M. Borrego, Antonio Camacho

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

We carried out a detailed study in five stratified lakes in the karstic regions of NE Spain along a redox gradient combining vertical profiles of inorganic carbon dioxide fixation and analysis of microbial (bacteria and archaea) community composition determined by 16S rRNA gene fingerprinting (DGGE), microscopic counts, and pigment analysis. High rates of non-photosynthetic (i.e., "dark") inorganic carbon incorporation were detected mostly at deeper layers after short-term in situ incubations at noon. Significant contribution of dark CO2 incorporation was observed at the whole lake level for the single time sampling, ranging between 4 and 19% of total carbon fixation measured, and up to 31% in the case of a meromictic basin. Good agreement was found between vertical patterns in redox conditions and the different microbial diversity descriptors (DGGE band sequencing, microscopic analysis, and pigment data), showing large vertical changes in microbial community composition covering a wide range of phylogenetic diversity. Cyanobacteria, Alpha and Beta-Proteobacteria, Actinobacteria, Flavobacteria and Flectobacillaceae were the most frequently recovered groups in the DGGE from oxygenated water masses. In anoxic waters, we found Beta-Proteobacteria mostly of the Rhodoferax group, Gamma-Proteobacteria (Chromatiaceae), Delta-Proteobacteria related to different sulfate reducing bacteria, Chlorobiaceae, and anaerobic Bacteroidetes spread among the Bacteroidales, Flavobacteriales and Saprospiraceae. However, as a whole, we did not find any significant correlation between dark fixation rates and either nutrient distribution and microbial community composition in the study lakes. All of this suggests that (1) different physiologies and ecologies are simultaneously contributing to the process (2) more sensitive methods are needed and more specific compounds measured and (3) some of the non-specialist microbial populations detected may carry out carbon dioxide assimilation in the dark under in situ conditions.

Original languageEnglish (US)
Pages (from-to)61-75
Number of pages15
JournalAquatic Sciences
Volume74
Issue number1
DOIs
StatePublished - Jan 2012
Externally publishedYes

Keywords

  • 16S rRNA
  • Archaea
  • Bacteria
  • DGGE
  • Dark carbon fixation
  • Karstic lakes
  • Photosynthetic sulfur bacteria
  • Primary production

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology
  • Water Science and Technology

Fingerprint

Dive into the research topics of 'Contribution of deep dark fixation processes to overall CO2 incorporation and large vertical changes of microbial populations in stratified karstic lakes'. Together they form a unique fingerprint.

Cite this