biostudies-literatureUnknown103(17)Ingalls AEAn ammonia-oxidizing, carbon-fixing archaeon, Candidatus "Nitrosopumilus maritimus," recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ. If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show thProceedings of the National Academy of Sciences of the United States of America6442-7https://www.ebi.ac.uk/biostudies/studies/S-EPMC1564200biostudies-literatureQuantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon.PMC1564200Ingalls AEShah SRAluwihare LIDruffel ERHansman RLPearson ASantos GMfalseQuantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon.An ammonia-oxidizing, carbon-fixing archaeon, Candidatus "Nitrosopumilus maritimus," recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ. If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show th2006-01-01T00:00:00Z2006 Apr2025-04-19T23:09:08.073Z2019-03-27T01:45:54ZS-EPMC15642001661407010.1073/pnas.0510157103