Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin
In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is q...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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Copernicus GmbH
2013
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| Online Access: | http://hdl.handle.net/1721.1/82929 |
| _version_ | 1826213617923522560 |
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| author | Shah, S. R. Galy, V. McNichol, A. P. Eglinton, Timothy I. Griffith, David Richmond |
| author2 | Woods Hole Oceanographic Institution |
| author_facet | Woods Hole Oceanographic Institution Shah, S. R. Galy, V. McNichol, A. P. Eglinton, Timothy I. Griffith, David Richmond |
| author_sort | Shah, S. R. |
| collection | MIT |
| description | In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and [superscript 13]C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ[superscript 13]C values that are similar to suspended POC at all depths and are more [superscript 13]C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C[subscript 20–24]), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C[subscript 12] and iso-C[subscript 17]) are significantly depleted in [superscript 13]C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin. |
| first_indexed | 2024-09-23T15:52:07Z |
| format | Article |
| id | mit-1721.1/82929 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:52:07Z |
| publishDate | 2013 |
| publisher | Copernicus GmbH |
| record_format | dspace |
| spelling | mit-1721.1/829292022-10-02T04:41:25Z Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin Shah, S. R. Galy, V. McNichol, A. P. Eglinton, Timothy I. Griffith, David Richmond Woods Hole Oceanographic Institution Griffith, David Richmond In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and [superscript 13]C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ[superscript 13]C values that are similar to suspended POC at all depths and are more [superscript 13]C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C[subscript 20–24]), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C[subscript 12] and iso-C[subscript 17]) are significantly depleted in [superscript 13]C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin. National Science Foundation (U.S.) (OPP-0424864) 2013-12-13T20:18:47Z 2013-12-13T20:18:47Z 2013-11 2013-09 Article http://purl.org/eprint/type/JournalArticle 1726-4189 http://hdl.handle.net/1721.1/82929 Shah, S. R., D. R. Griffith, V. Galy, A. P. McNichol, and T. I. Eglinton. “Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin.” Biogeosciences 10, no. 11 (November 7, 2013): 7065-7080. en_US http://dx.doi.org/10.5194/bg-10-7065-2013 Biogeosciences http://creativecommons.org/licenses/by/3.0/ application/pdf Copernicus GmbH Copernicus GmbH |
| spellingShingle | Shah, S. R. Galy, V. McNichol, A. P. Eglinton, Timothy I. Griffith, David Richmond Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title | Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title_full | Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title_fullStr | Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title_full_unstemmed | Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title_short | Prominent bacterial heterotrophy and sources of [superscript 13]C-depleted fatty acids to the interior Canada Basin |
| title_sort | prominent bacterial heterotrophy and sources of superscript 13 c depleted fatty acids to the interior canada basin |
| url | http://hdl.handle.net/1721.1/82929 |
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