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Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment

Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age....

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Autores principales: Walsh, Emily A., Kirkpatrick, John B., Pockalny, Robert, Sauvage, Justine, Spivack, Arthur J., Murray, Richard W., Sogin, Mitchell L., D'Hondt, Steven
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968545/
https://www.ncbi.nlm.nih.gov/pubmed/27287321
http://dx.doi.org/10.1128/AEM.00809-16
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author Walsh, Emily A.
Kirkpatrick, John B.
Pockalny, Robert
Sauvage, Justine
Spivack, Arthur J.
Murray, Richard W.
Sogin, Mitchell L.
D'Hondt, Steven
author_facet Walsh, Emily A.
Kirkpatrick, John B.
Pockalny, Robert
Sauvage, Justine
Spivack, Arthur J.
Murray, Richard W.
Sogin, Mitchell L.
D'Hondt, Steven
author_sort Walsh, Emily A.
collection PubMed
description Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age. At three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), richness decreases exponentially with increasing sediment depth. The rate of decrease in richness with increasing depth varies from site to site. The vertical succession of predominant terminal electron acceptors correlates with abundance-weighted community composition but does not drive the vertical decrease in richness. Vertical patterns of richness at the open-ocean sites closely match organic degradation rates; both properties are highest near the seafloor and decline together as sediment depth increases. This relationship suggests that (i) total catabolic activity and/or electron donor diversity exerts a primary influence on bacterial richness in marine sediment and (ii) many bacterial taxa that are poorly adapted for subseafloor sedimentary conditions are degraded in the geologically young sediment, where respiration rates are high. Richness consistently takes a few hundred thousand years to decline from near-seafloor values to much lower values in deep anoxic subseafloor sediment, regardless of sedimentation rate, predominant terminal electron acceptor, or oceanographic context. IMPORTANCE Subseafloor sediment provides a wonderful opportunity to investigate the drivers of microbial diversity in communities that may have been isolated for millions of years. Our paper shows the impact of in situ conditions on bacterial community structure in subseafloor sediment. Specifically, it shows that bacterial richness in subseafloor sediment declines exponentially with sediment age, and in parallel with organic-fueled oxidation rate. This result suggests that subseafloor diversity ultimately depends on electron donor diversity and/or total community respiration. This work studied how and why biological richness changes over time in the extraordinary ecosystem of subseafloor sediment.
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spelling pubmed-49685452016-08-08 Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment Walsh, Emily A. Kirkpatrick, John B. Pockalny, Robert Sauvage, Justine Spivack, Arthur J. Murray, Richard W. Sogin, Mitchell L. D'Hondt, Steven Appl Environ Microbiol Microbial Ecology Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age. At three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), richness decreases exponentially with increasing sediment depth. The rate of decrease in richness with increasing depth varies from site to site. The vertical succession of predominant terminal electron acceptors correlates with abundance-weighted community composition but does not drive the vertical decrease in richness. Vertical patterns of richness at the open-ocean sites closely match organic degradation rates; both properties are highest near the seafloor and decline together as sediment depth increases. This relationship suggests that (i) total catabolic activity and/or electron donor diversity exerts a primary influence on bacterial richness in marine sediment and (ii) many bacterial taxa that are poorly adapted for subseafloor sedimentary conditions are degraded in the geologically young sediment, where respiration rates are high. Richness consistently takes a few hundred thousand years to decline from near-seafloor values to much lower values in deep anoxic subseafloor sediment, regardless of sedimentation rate, predominant terminal electron acceptor, or oceanographic context. IMPORTANCE Subseafloor sediment provides a wonderful opportunity to investigate the drivers of microbial diversity in communities that may have been isolated for millions of years. Our paper shows the impact of in situ conditions on bacterial community structure in subseafloor sediment. Specifically, it shows that bacterial richness in subseafloor sediment declines exponentially with sediment age, and in parallel with organic-fueled oxidation rate. This result suggests that subseafloor diversity ultimately depends on electron donor diversity and/or total community respiration. This work studied how and why biological richness changes over time in the extraordinary ecosystem of subseafloor sediment. American Society for Microbiology 2016-07-29 /pmc/articles/PMC4968545/ /pubmed/27287321 http://dx.doi.org/10.1128/AEM.00809-16 Text en Copyright © 2016 Walsh et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Microbial Ecology
Walsh, Emily A.
Kirkpatrick, John B.
Pockalny, Robert
Sauvage, Justine
Spivack, Arthur J.
Murray, Richard W.
Sogin, Mitchell L.
D'Hondt, Steven
Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title_full Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title_fullStr Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title_full_unstemmed Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title_short Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment
title_sort relationship of bacterial richness to organic degradation rate and sediment age in subseafloor sediment
topic Microbial Ecology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968545/
https://www.ncbi.nlm.nih.gov/pubmed/27287321
http://dx.doi.org/10.1128/AEM.00809-16
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