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

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 Geor...

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Autores principales: Bell, James B., Aquilina, Alfred, Woulds, Clare, Glover, Adrian G., Little, Crispin T. S., Reid, William D. K., Hepburn, Laura E., Newton, Jason, Mills, Rachel A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5043311/
https://www.ncbi.nlm.nih.gov/pubmed/27703692
http://dx.doi.org/10.1098/rsos.160284
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author Bell, James B.
Aquilina, Alfred
Woulds, Clare
Glover, Adrian G.
Little, Crispin T. S.
Reid, William D. K.
Hepburn, Laura E.
Newton, Jason
Mills, Rachel A.
author_facet Bell, James B.
Aquilina, Alfred
Woulds, Clare
Glover, Adrian G.
Little, Crispin T. S.
Reid, William D. K.
Hepburn, Laura E.
Newton, Jason
Mills, Rachel A.
author_sort Bell, James B.
collection PubMed
description 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.
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spelling pubmed-50433112016-10-04 Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin Bell, James B. Aquilina, Alfred Woulds, Clare Glover, Adrian G. Little, Crispin T. S. Reid, William D. K. Hepburn, Laura E. Newton, Jason Mills, Rachel A. R Soc Open Sci Earth Science 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. The Royal Society 2016-09-28 /pmc/articles/PMC5043311/ /pubmed/27703692 http://dx.doi.org/10.1098/rsos.160284 Text en © 2016 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
spellingShingle Earth Science
Bell, James B.
Aquilina, Alfred
Woulds, Clare
Glover, Adrian G.
Little, Crispin T. S.
Reid, William D. K.
Hepburn, Laura E.
Newton, Jason
Mills, Rachel A.
Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title_full Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title_fullStr Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title_full_unstemmed Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title_short Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin
title_sort geochemistry, faunal composition and trophic structure in reducing sediments on the southwest south georgia margin
topic Earth Science
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5043311/
https://www.ncbi.nlm.nih.gov/pubmed/27703692
http://dx.doi.org/10.1098/rsos.160284
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