Biogeochemical and microbiological evidence for methane-related archaeal communities at active submarine mud volcanoes on the Canadian Beaufort Sea slope

Abstract

In this study, we investigated lipid biomarker patterns and phylogenic (check this) identities of key microbes mediating anaerobic oxidation of methane (AOM) in active mud volcanos (MVs) on the continental slope of the Canadian Beaufort Sea. The enriched δ13C values of total organic carbon (TOC) as well as lipid biomarkers such as archaeol and biphytanes (BPs) relative to δ13CCH4 values suggested that the contribution of AOM-related biomass to sedimentary TOC was in general negligible in the Beaufort Sea MVs investigated. However, the δ13C values of sn-2- and sn-3-hydroxyarchaeol were more negative than CH4, indicating the presence of AOM communities, albeit in a small amount. The ratio of sn-2-hydroxyarchaeol to archaeol and the 16S rRNA results indeed indicated that archaea of the ANME-2c and ANME-3 clades were involved in AOM. Accordingly, it appears that CH4 is, to a limited extent, being oxidized in the Beaufort Sea MVs investigated. In near future, further studies are needed to investigate the diversity and distribution of AOM communities and to characterize their habitats in the uppermost surface sediments of Beaufort Sea MV systems.