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 particulate organic matter from the euxinic waters of the Black Sea. These strongly C-13-depleted biomarkers (up to -58 parts per thousand) provide evidence that archaea are consuming methane in euxinic waters. C-13-depleted archaeal compounds were absent from surface sediments, suggesting that the responsible organisms are in low abundance and leave no characteristic fingerprint in the sedimentary record. (C) 2001 Elsevier Science Ltd. All rights reserved.