Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean
The western tropical South Pacific (WTSP) Ocean has been recognized as a global hotspot of dinitrogen (N2) fixation. Here, as in other marine environments across the oceans, N2 fixation studies have focused in the sunlit layer. However, studies have confirmed the importance of aphotic N2 fixation ac...
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ftarchimer:oai:archimer.ifremer.fr:53118 2023-05-15T13:50:50+02:00 Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean Benavides, Mar Shoemaker, Katyanne M. Moisander, Pia H. Niggemann, Jutta Dittmar, Thorsten Duhamel, Solange Grosso, Olivier Pujo-pay, Mireille Hélias-nunige, Sandra Bonnet, Sophie 2018 application/pdf https://archimer.ifremer.fr/doc/00420/53118/54070.pdf https://archimer.ifremer.fr/doc/00420/53118/54076.pdf https://archimer.ifremer.fr/doc/00420/53118/56814.pdf https://archimer.ifremer.fr/doc/00420/53118/56815.pdf https://doi.org/10.5194/bg-2017-542 https://archimer.ifremer.fr/doc/00420/53118/ eng eng Copernicus GmbH info:eu-repo/grantAgreement/EC/FP7/625185/EU//DIADOM https://archimer.ifremer.fr/doc/00420/53118/54070.pdf https://archimer.ifremer.fr/doc/00420/53118/54076.pdf https://archimer.ifremer.fr/doc/00420/53118/56814.pdf https://archimer.ifremer.fr/doc/00420/53118/56815.pdf doi:10.5194/bg-2017-542 https://archimer.ifremer.fr/doc/00420/53118/ Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. info:eu-repo/semantics/openAccess restricted use CC-BY Biogeosciences (1726-4170) (Copernicus GmbH), 2018 , Vol. 15 , N. 10 , P. 3107-3119 text Publication info:eu-repo/semantics/article 2018 ftarchimer https://doi.org/10.5194/bg-2017-542 2021-09-23T20:30:24Z The western tropical South Pacific (WTSP) Ocean has been recognized as a global hotspot of dinitrogen (N2) fixation. Here, as in other marine environments across the oceans, N2 fixation studies have focused in the sunlit layer. However, studies have confirmed the importance of aphotic N2 fixation activity, although until now only one had been performed in the WTSP. In order to increase our knowledge of aphotic N2 fixation in the WTSP, here we measure N2 fixation rates and identify diazotrophic phylotypes in the mesopelagic layer along a transect spanning from New Caledonia to French Polynesia. Because non-cyanobacterial diazotrophs presumably need external dissolved organic matter (DOM) sources for their nutrition, we also identified DOM compounds using Fourier Transform Ion Cyclotron Mass Spectrometry (FTICRMS). N2 fixation rates were low (average 0.63 ± 0.07 nmol N L−1 d−1), but consistently detected across all depths and stations, representing ~ 6–88 % of photic N2 fixation. N2 fixation rates were not significantly correlated to DOM compounds. The analysis of nifH gene amplicons revealed a wide diversity of non-cyanobacterial diazotrophs, majorly matching clusters 1 and 3. Interestingly, a distinct phylotype from the major nifH subcluster 1G dominated at 650 dbar, coinciding with the oxygenated Sub-Antarctic Mode Water (SAMW). This consistent pattern suggests that the distribution of aphotic diazotroph communities is to some extent controlled by water mass structure. While the data available is still too scarce to elucidate the distribution and controls of mesopelagic non-cyanobacterial diazotrophs in the WTSP, their prevalence in the mesopelagic layer and the consistent detection of active N2 fixation activity at all depths sampled during our study suggest that aphotic N2 fixation may contribute significantly to fixed nitrogen inputs in this area. Article in Journal/Newspaper Antarc* Antarctic Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Antarctic Pacific |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
description |
The western tropical South Pacific (WTSP) Ocean has been recognized as a global hotspot of dinitrogen (N2) fixation. Here, as in other marine environments across the oceans, N2 fixation studies have focused in the sunlit layer. However, studies have confirmed the importance of aphotic N2 fixation activity, although until now only one had been performed in the WTSP. In order to increase our knowledge of aphotic N2 fixation in the WTSP, here we measure N2 fixation rates and identify diazotrophic phylotypes in the mesopelagic layer along a transect spanning from New Caledonia to French Polynesia. Because non-cyanobacterial diazotrophs presumably need external dissolved organic matter (DOM) sources for their nutrition, we also identified DOM compounds using Fourier Transform Ion Cyclotron Mass Spectrometry (FTICRMS). N2 fixation rates were low (average 0.63 ± 0.07 nmol N L−1 d−1), but consistently detected across all depths and stations, representing ~ 6–88 % of photic N2 fixation. N2 fixation rates were not significantly correlated to DOM compounds. The analysis of nifH gene amplicons revealed a wide diversity of non-cyanobacterial diazotrophs, majorly matching clusters 1 and 3. Interestingly, a distinct phylotype from the major nifH subcluster 1G dominated at 650 dbar, coinciding with the oxygenated Sub-Antarctic Mode Water (SAMW). This consistent pattern suggests that the distribution of aphotic diazotroph communities is to some extent controlled by water mass structure. While the data available is still too scarce to elucidate the distribution and controls of mesopelagic non-cyanobacterial diazotrophs in the WTSP, their prevalence in the mesopelagic layer and the consistent detection of active N2 fixation activity at all depths sampled during our study suggest that aphotic N2 fixation may contribute significantly to fixed nitrogen inputs in this area. |
format |
Article in Journal/Newspaper |
author |
Benavides, Mar Shoemaker, Katyanne M. Moisander, Pia H. Niggemann, Jutta Dittmar, Thorsten Duhamel, Solange Grosso, Olivier Pujo-pay, Mireille Hélias-nunige, Sandra Bonnet, Sophie |
spellingShingle |
Benavides, Mar Shoemaker, Katyanne M. Moisander, Pia H. Niggemann, Jutta Dittmar, Thorsten Duhamel, Solange Grosso, Olivier Pujo-pay, Mireille Hélias-nunige, Sandra Bonnet, Sophie Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
author_facet |
Benavides, Mar Shoemaker, Katyanne M. Moisander, Pia H. Niggemann, Jutta Dittmar, Thorsten Duhamel, Solange Grosso, Olivier Pujo-pay, Mireille Hélias-nunige, Sandra Bonnet, Sophie |
author_sort |
Benavides, Mar |
title |
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
title_short |
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
title_full |
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
title_fullStr |
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
title_full_unstemmed |
Aphotic N2 fixation along an oligotrophic to ultraoligotrophic transect in the Western Tropical South Pacific Ocean |
title_sort |
aphotic n2 fixation along an oligotrophic to ultraoligotrophic transect in the western tropical south pacific ocean |
publisher |
Copernicus GmbH |
publishDate |
2018 |
url |
https://archimer.ifremer.fr/doc/00420/53118/54070.pdf https://archimer.ifremer.fr/doc/00420/53118/54076.pdf https://archimer.ifremer.fr/doc/00420/53118/56814.pdf https://archimer.ifremer.fr/doc/00420/53118/56815.pdf https://doi.org/10.5194/bg-2017-542 https://archimer.ifremer.fr/doc/00420/53118/ |
geographic |
Antarctic Pacific |
geographic_facet |
Antarctic Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Biogeosciences (1726-4170) (Copernicus GmbH), 2018 , Vol. 15 , N. 10 , P. 3107-3119 |
op_relation |
info:eu-repo/grantAgreement/EC/FP7/625185/EU//DIADOM https://archimer.ifremer.fr/doc/00420/53118/54070.pdf https://archimer.ifremer.fr/doc/00420/53118/54076.pdf https://archimer.ifremer.fr/doc/00420/53118/56814.pdf https://archimer.ifremer.fr/doc/00420/53118/56815.pdf doi:10.5194/bg-2017-542 https://archimer.ifremer.fr/doc/00420/53118/ |
op_rights |
Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. info:eu-repo/semantics/openAccess restricted use |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/bg-2017-542 |
_version_ |
1766254162504318976 |