Methanotroph community structure and processes in an inland river affected by natural gas macro-seeps

Determining how microbial communities utilise available energy sources in freshwater ecosystems is becoming more important at a time when anthropogenic activities are increasingly altering the availability of basal resources in aquatic food webs. Methane availability in aquatic ecosystems is usually associated with seasonal changes in methanogenesis. Unusually, however, several natural gas macro-seeps occur along the Condamine River in Queensland which can elevate water-column methane concentrations more than 3,000 times above levels recorded in unaffected reaches. In this study, we quantified the spatial and temporal variation in the rates of methane oxidation and methanotroph community composition, and the factors mediating this variation, in reaches with and without macro-seeps. We characterised the total microbial community and methanotroph community composition of benthic sediment through the amplification and sequencing of the 16Sv4 and particulate methane monooxygenase (pmoA) genes, respectively.