biostudies-literatureUnknown7(3)Yanagawa KSediment-hosting hydrothermal systems in the Okinawa Trough maintain a large amount of liquid, supercritical and hydrate phases of CO(2) in the seabed. The emission of CO(2) may critically impact the geochemical, geophysical and ecological characteristics of the deep-sea sedimentary environment. So far it remains unclear whether microbial communities that have been detected in such high-CO(2) and low-pH habitats are metabolically active, and if so, what the biogeochemical and ecological consequences for the environment are. In this study, RNA-based molecular approaches and radioactive tracer-based respiration rate assays were combined to study the density, diversity and metabolic activity of microbial communities in CO(2)-seep sediment at the Yonaguni Knoll IV hydrothermal field of the souThe ISME journal555-67https://www.ebi.ac.uk/biostudies/studies/S-EPMC3578575biostudies-literatureMetabolically active microbial communities in marine sediment under high-CO(2) and low-pH extremes.PMC3578575Haeckel MBoetius ASunamura MHoshino TUrabe TNakamura Kde Beer DFutagami TYanagawa KTerada TInagaki FRehder GMorono YfalseMetabolically active microbial communities in marine sediment under high-CO(2) and low-pH extremes.Sediment-hosting hydrothermal systems in the Okinawa Trough maintain a large amount of liquid, supercritical and hydrate phases of CO(2) in the seabed. The emission of CO(2) may critically impact the geochemical, geophysical and ecological characteristics of the deep-sea sedimentary environment. So far it remains unclear whether microbial communities that have been detected in such high-CO(2) and low-pH habitats are metabolically active, and if so, what the biogeochemical and ecological consequences for the environment are. In this study, RNA-based molecular approaches and radioactive tracer-based respiration rate assays were combined to study the density, diversity and metabolic activity of microbial communities in CO(2)-seep sediment at the Yonaguni Knoll IV hydrothermal field of the sou2013-01-01T00:00:00Z2013 Mar2026-05-03T14:09:24.546Z2026-04-07T19:14:46.041ZS-EPMC35785752309640010.1038/ismej.2012.124