Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin

Bell, J. B., Aquilina, A., Woulds, C., Glover, A. G., Little, C. T.S., Reid, W. D.K., Hepburn, L. E., Newton, J. and Mills, R. A. (2016) Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin. Royal Society Open Science, 3(9), 160284. (doi:10.1098/rsos.160284) (PMID:27703692) (PMCID:PMC5043311)

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Abstract

Despite a number of studies in areas of focused methane seepage, the extent of transitional sediments of more diffuse methane seepage, and their influence upon biological communities is poorly understood. We investigated an area of reducing sediments with elevated levels of methane on the South Georgia margin around 250 m depth and report data from a series of geochemical and biological analyses. Here, the geochemical signatures were consistent with weak methane seepage and the role of sub-surface methane consumption was clearly very important, preventing gas emissions into bottom waters. As a result, the contribution of methane-derived carbon to the microbial and metazoan food webs was very limited, although sulfur isotopic signatures indicated a wider range of dietary contributions than was apparent from carbon isotope ratios. Macrofaunal assemblages had high dominance and were indicative of reducing sediments, with many taxa common to other similar environments and no seep-endemic fauna, indicating transitional assemblages. Also similar to other cold seep areas, there were samples of authigenic carbonate, but rather than occurring as pavements or sedimentary concretions, these carbonates were restricted to patches on the shells of Axinulus antarcticus (Bivalvia, Thyasiridae), which is suggestive of microbe–metazoan interactions.

Item Type:Articles
Additional Information:This work was funded by the NERC ChEsSo consortium (Chemosynthetically driven Ecosystems South of the Polar Front, NERC grant no. NE/DOI249X/I). C.W. was supported by a bursary from Antarctic Science Ltd. J.B.B. was funded by an NERC PhD Studentship (NE/L501542/1). Isotopic analyses were funded by the NERC Life Sciences Mass Spectrometry Facility (EK246-01/15).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Newton, Dr Jason
Authors: Bell, J. B., Aquilina, A., Woulds, C., Glover, A. G., Little, C. T.S., Reid, W. D.K., Hepburn, L. E., Newton, J., and Mills, R. A.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Royal Society Open Science
Publisher:The Royal Society
ISSN:2054-5703
ISSN (Online):2054-5703
Published Online:28 September 2016
Copyright Holders:Copyright © 2016 Elsevier
First Published:First published in Royal Society Open Science 3(9):160284
Publisher Policy:Reproduced under a Creative Commons License

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