Molecular Isotopic Tracing of Carbon Flow and Trophic Relationships in a Methane-Supported Benthic Microbial Community

A molecular isotopic study in cold-seep sediments from Kazan mud volcano in the eastern Mediterranean Sea indicates that a significant proportion of methane released in this environment is incorporated into biomass in methane-supported chemosynthetic microbial communities. Furthermore, extremely 13C depleted biomarkers (as much as $-111\perthousand$ Vienna Pee Dee Belemnite (VPDB)) have revealed pathways of methane-derived carbon flow through the microbial community and into eukaryotic biomass. Specifically, we are able to trace the flow of methane-derived carbon through anaerobic methane-oxidizing archaea into sulfate-reducing bacteria, as well as into aerobic methane-oxidizing bacteria. The methane-derived carbon is then incorporated into eukaryotic biomass through heterotrophy by bacterivorous ciliates.