Molecular methods for the detection of anaerobic oxidation of methane associated with marine gas hydrates
Abstract
Anaerobic gas hydrate-bearing sediments of Hydrate Ridge at the Cascadia margin are characterized by intense sulfate reduction driven by the anaerobic oxidation of methane (AOM). The overall process involves a syntrophic consortium consisting of archaea anaerobically oxidizing methane and sulfate-reducing bacteria (SRB) scavenging an extracellular carbon intermediate that still waits to be elucidated. The carbon flow of methane via AOM into microbial biomass is indicated by very low carbon isotope values of specific archaeal and bacterial lipids. Specific lipid biomarkers include fatty acids (e.g., C16:1ω5c, cyC17:0ω5,6) derived from SRB and phytanyl glycerol diethers (archaeol and sn-2-hydroxyarchaeol) produced by methanotrophic archaea. Depth profiles of the biomarkers match in active seeping areas with high AOM activity and are also correlated with aggregate numbers of the AOM consortia. Moreover, biomarker profiles are in good agreement with rate measurements of sulfate reduction and AOM. The combination of all of these parameters is a powerful tool for the analysis and description of AOM, which is probably also of high interest for the detection of other important biogeochemical processes.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....5327E