Microbes, macrofauna, and methane: A novel seep community fueled by aerobic methanotrophy

TitleMicrobes, macrofauna, and methane: A novel seep community fueled by aerobic methanotrophy
Publication TypeJournal Article
Year of Publication2013
AuthorsThurber AR, Levin L.A, Rowden A.A, Sommer S., Linke P., Kroger K.
JournalLimnology and Oceanography
Volume58
Pagination1640-1656
Date Published2013/09
Type of ArticleArticle
ISBN Number0024-3590
Accession NumberWOS:000327393800008
Keywordsanaerobic oxidation; cold-seep; fatty-acids; fluid-flow; habitat; heterogeneity; hikurangi; margin; mosby mud volcano; ne pacific; new-zealand; spatial heterogeneity
Abstract

During the discovery and description of seven New Zealand methane seep sites, an infaunal assemblage dominated by ampharetid polychaetes was found in association with high seabed methane emission. This ampharetid-bed assemblage had a mean density of 57,000 +/- 7800 macrofaunal individuals m(-2) and a maximum wet biomass of 274 g m(-2), both being among the greatest recorded from deep-sea methane seeps. We investigated these questions: Does the species assemblage present within these ampharetid beds form a distinct seep community on the New Zealand margin? and What type of chemoautotrophic microbes fuel this heterotrophic community? Unlike the other macro-infaunal assemblages, the ampharetid-bed assemblage composition was homogeneous, independent of location. Based on a mixing model of species-specific mass and isotopic composition, combined with published respiration measurements, we estimated that this community consumes 29-90 mmol C m(-2) d(-1) of methane-fueled biomass; this is > 290 times the carbon fixed by anaerobic methane oxidizers in these ampharetid beds. A fatty acid biomarker approach supported the finding that this community, unlike those previously known, consumes primarily aerobic methanotrophic bacteria. Due to the novel microbial fueling and high methane flux rates, New Zealand's ampharetid beds provide a model system to study the influence of metazoan grazing on microbially mediated biogeochemical cycles, including those that involve greenhouse gas emissions.

DOI10.4319/lo.2013.58.5.1640
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