Evidence for anaerobic methane oxidation by archaea in euxinic waters of the Black Sea

C-13-depleted archaeal-derived ether-bound cyclic biphytanes occur in parti culate organic matter from the euxinic waters of the Black Sea. These stron gly C-13-depleted biomarkers (up to -58 parts per thousand) provide evidenc e that archaea are consuming methane in euxinic waters. C-13-depleted archa eal compounds were absent from surface sediments, suggesting that the respo nsible organisms are in low abundance and leave no characteristic fingerpri nt in the sedimentary record. (C) 2001 Elsevier Science Ltd. All rights res erved.