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Published February 2008 | public
Journal Article

Temporal evolution of methane cycling and phylogenetic diversity of archaea in sediments from a deep-sea whale-fall in Monterey Canyon, California

Abstract

Whale-falls represent localized areas of extreme organic enrichment in an otherwise oligotrophic deep-sea environment. Anaerobic remineralization within these habitats is typically portrayed as sulfidogenic; however, we demonstrate that these systems are also favorable for diverse methane-producing archaeal assemblages, representing up to 40% of total cell counts. Chemical analyses revealed elevated methane and depleted sulfate concentrations in sediments under the whale-fall, as compared to surrounding sediments. Carbon was enriched (up to 3.5%) in whale-fall sediments, as well as the surrounding sea floor to at least 10 m, forming a 'bulls eye' of elevated carbon. The diversity of sedimentary archaea associated with the 2893 m whale-fall in Monterey Canyon (California) varied both spatially and temporally. 16S rRNA diversity, determined by both sequencing and terminal restriction fragment length polymorphism analysis, as well as quantitative PCR of the methyl-coenzyme M reductase gene, revealed that methanogens, including members of the Methanomicrobiales and Methanosarcinales, were the dominant archaea (up to 98%) in sediments immediately beneath the whale-fall. Temporal changes in this archaeal community included the early establishment of methylotrophic methanogens followed by development of methanogens thought to be hydrogenotrophic, as well as members related to the newly described methanotrophic lineage, ANME-3. In comparison, archaeal assemblages in 'reference' sediments collected 10 m from the whale-fall primarily consisted of Crenarchaeota affiliated with marine group I and marine benthic group B. Overall, these results indicate that whale-falls can favor the establishment of metabolically and phylogenetically diverse methanogen assemblages, resulting in an active near-seafloor methane cycle in the deep sea.

Additional Information

© 2008 International Society for Microbial Ecology. Received 13 August 2007; Revised 18 October 2007; Accepted 19 October 2007; Published online 24 January 2008. This study was supported by a Davidow grant to Caltech's Geological and Planetary Sciences division, US National Science Foundation (MCB-0454860 to SKG), and the Gordon and Betty Moore Foundation (to VJO). We thank the Tiburon pilots and Western Flyer crew and chief scientist R Vrijenhoek for allowing our participation in research cruises; S Johnson and WJ Jones for shipboard support; A Pernthaler for advice regarding FISH analyses; B Ussler for help with methane measurements; Patty Tavormina for QPCR data; Tsegereda Embaye for CARD FISH preparations and B Harrison for ARB assistance.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023