Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise)
N 2 fixation rates were measured during the KEOPS2 cruise in the HNLC area of Southern Ocean and in naturally iron-fertilized waters (Kerguelen Island 49.25° S, 69.58° E) using the 15 N isotopic technique. We detected N 2 fixation within the mixed layer at all stations, from the surface to 140 m dep...
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ftcopernicus:oai:publications.copernicus.org:bgd27881 2023-05-15T18:24:52+02:00 Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) González, M. L. Molina, V. Florez-Leiva, L. Oriol, L. Cavagna, A. J. Dehairs, F. Farias, L. Fernandez, C. 2018-09-26 application/pdf https://doi.org/10.5194/bgd-11-17151-2014 https://www.biogeosciences-discuss.net/bg-2014-576/ eng eng doi:10.5194/bgd-11-17151-2014 https://www.biogeosciences-discuss.net/bg-2014-576/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bgd-11-17151-2014 2019-12-24T09:53:55Z N 2 fixation rates were measured during the KEOPS2 cruise in the HNLC area of Southern Ocean and in naturally iron-fertilized waters (Kerguelen Island 49.25° S, 69.58° E) using the 15 N isotopic technique. We detected N 2 fixation within the mixed layer at all stations, from the surface to 140 m depth. The data shows high variability with rates ranging between 0.42 and 20.11 nmol N L −1 d −1 . The highest rates were concentrated in the euphotic layer and maximum values were obtained north of polar front (station F-L), which coincide with a positive N * ([NO 3 ]–16[PO 4 ]), high chlorophyll concentration and dissolved iron. N 2 fixation rates were also obtained in stations with moderate (A3-2; E-4W) and also low (R-2) iron levels as well as Chl a , suggesting that beside the microbial biomass, its composition/structure is a driving factor controlling N 2 fixation activities. Molecular analysis showed a diazotrophic community dominated by heterotrophic bacterioplankton. Size fractioned experiments indicated that most of N 2 fixating activities came from <5 μm community and it was on line with molecular analysis revealing a low diversity diazotrophic community dominated by heterotrophic bacterioplankton. This study shows for first time N 2 fixation is occurring in the Southern Ocean, at rates exceeding previous reports for high latitudes. Our findings suggest an indirect role of dFe in the regulation of N 2 fixation through the enhancement of regenerated primary production and the availability of phytoplankton-derived dissolved organic matter, which in turn may stimulate heterotrophic bacterioplankton. Text Southern Ocean Copernicus Publications: E-Journals Kerguelen Kerguelen Island ENVELOPE(69.500,69.500,-49.250,-49.250) Southern Ocean |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
N 2 fixation rates were measured during the KEOPS2 cruise in the HNLC area of Southern Ocean and in naturally iron-fertilized waters (Kerguelen Island 49.25° S, 69.58° E) using the 15 N isotopic technique. We detected N 2 fixation within the mixed layer at all stations, from the surface to 140 m depth. The data shows high variability with rates ranging between 0.42 and 20.11 nmol N L −1 d −1 . The highest rates were concentrated in the euphotic layer and maximum values were obtained north of polar front (station F-L), which coincide with a positive N * ([NO 3 ]–16[PO 4 ]), high chlorophyll concentration and dissolved iron. N 2 fixation rates were also obtained in stations with moderate (A3-2; E-4W) and also low (R-2) iron levels as well as Chl a , suggesting that beside the microbial biomass, its composition/structure is a driving factor controlling N 2 fixation activities. Molecular analysis showed a diazotrophic community dominated by heterotrophic bacterioplankton. Size fractioned experiments indicated that most of N 2 fixating activities came from <5 μm community and it was on line with molecular analysis revealing a low diversity diazotrophic community dominated by heterotrophic bacterioplankton. This study shows for first time N 2 fixation is occurring in the Southern Ocean, at rates exceeding previous reports for high latitudes. Our findings suggest an indirect role of dFe in the regulation of N 2 fixation through the enhancement of regenerated primary production and the availability of phytoplankton-derived dissolved organic matter, which in turn may stimulate heterotrophic bacterioplankton. |
format |
Text |
author |
González, M. L. Molina, V. Florez-Leiva, L. Oriol, L. Cavagna, A. J. Dehairs, F. Farias, L. Fernandez, C. |
spellingShingle |
González, M. L. Molina, V. Florez-Leiva, L. Oriol, L. Cavagna, A. J. Dehairs, F. Farias, L. Fernandez, C. Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
author_facet |
González, M. L. Molina, V. Florez-Leiva, L. Oriol, L. Cavagna, A. J. Dehairs, F. Farias, L. Fernandez, C. |
author_sort |
González, M. L. |
title |
Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
title_short |
Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
title_full |
Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
title_fullStr |
Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
title_full_unstemmed |
Nitrogen fixation in the Southern Ocean: a case of study of the Fe-fertilized Kerguelen region (KEOPS II cruise) |
title_sort |
nitrogen fixation in the southern ocean: a case of study of the fe-fertilized kerguelen region (keops ii cruise) |
publishDate |
2018 |
url |
https://doi.org/10.5194/bgd-11-17151-2014 https://www.biogeosciences-discuss.net/bg-2014-576/ |
long_lat |
ENVELOPE(69.500,69.500,-49.250,-49.250) |
geographic |
Kerguelen Kerguelen Island Southern Ocean |
geographic_facet |
Kerguelen Kerguelen Island Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bgd-11-17151-2014 https://www.biogeosciences-discuss.net/bg-2014-576/ |
op_doi |
https://doi.org/10.5194/bgd-11-17151-2014 |
_version_ |
1766205848134090752 |