N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean
Nitrogen (N) is an essential element for life and controls the magnitude of primary productivity in the ocean. In order to describe the microorganisms that catalyze N transformations in surface waters in the South Pacific Ocean, we collected high-resolution biotic and abiotic data along a 7000 km tr...
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ftdoajarticles:oai:doaj.org/article:1da527c498c54b46bf89e9d29b9f41e9 2023-05-15T13:38:29+02:00 N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean Eric J. Raes Jodie van de Kamp Levente Bodrossy Allison A. Fong Jessica Riekenberg Bronwyn H. Holmes Dirk V. Erler Bradley D. Eyre Sarah-Sophie Weil A. M. Waite 2020-05-01T00:00:00Z https://doi.org/10.3389/fmars.2020.00389 https://doaj.org/article/1da527c498c54b46bf89e9d29b9f41e9 EN eng Frontiers Media S.A. https://www.frontiersin.org/article/10.3389/fmars.2020.00389/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2020.00389 https://doaj.org/article/1da527c498c54b46bf89e9d29b9f41e9 Frontiers in Marine Science, Vol 7 (2020) N2 fixation nitrification latitudinal trends GO-SHIP nifH marine biogeography South Pacific Ocean Science Q General. Including nature conservation geographical distribution QH1-199.5 article 2020 ftdoajarticles https://doi.org/10.3389/fmars.2020.00389 2022-12-31T03:07:21Z Nitrogen (N) is an essential element for life and controls the magnitude of primary productivity in the ocean. In order to describe the microorganisms that catalyze N transformations in surface waters in the South Pacific Ocean, we collected high-resolution biotic and abiotic data along a 7000 km transect, from the Antarctic ice edge to the equator. The transect, conducted between late Austral autumn and early winter 2016, covered major oceanographic features such as the polar front (PF), the subtropical front (STF) and the Pacific equatorial divergence (PED). We measured N2 fixation and nitrification rates and quantified the relative abundances of diazotrophs and nitrifiers in a region where few to no rate measurements are available. Even though N2 fixation rates are usually below detection limits in cold environments, we were able to measure this N pathway at 7/10 stations in the cold and nutrient rich waters near the PF. This result highlights that N2 fixation rates continue to be measured outside the well-known subtropical regions. The majority of the mid to high N2 fixation rates (>∼20 nmol L–1 d–1), however, still occurred in the expected tropical and subtropical regions. High throughput sequence analyses of the dinitrogenase reductase gene (nifH) revealed that the nifH Cluster I dominated the diazotroph diversity throughout the transect. nifH gene richness did not show a latitudinal trend, nor was it significantly correlated with N2 fixation rates. Nitrification rates above the mixed layer in the Southern Ocean ranged between 56 and 1440 nmol L–1 d–1. Our data showed a decoupling between carbon and N assimilation (NO3– and NH4+ assimilation rates) in winter in the South Pacific Ocean. Phytoplankton community structure showed clear changes across the PF, the STF and the PED, defining clear biomes. Overall, these findings provide a better understanding of the ecosystem functionality in the South Pacific Ocean across key oceanographic biomes. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Austral Pacific Southern Ocean The Antarctic Frontiers in Marine Science 7 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
N2 fixation nitrification latitudinal trends GO-SHIP nifH marine biogeography South Pacific Ocean Science Q General. Including nature conservation geographical distribution QH1-199.5 |
spellingShingle |
N2 fixation nitrification latitudinal trends GO-SHIP nifH marine biogeography South Pacific Ocean Science Q General. Including nature conservation geographical distribution QH1-199.5 Eric J. Raes Jodie van de Kamp Levente Bodrossy Allison A. Fong Jessica Riekenberg Bronwyn H. Holmes Dirk V. Erler Bradley D. Eyre Sarah-Sophie Weil A. M. Waite N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
topic_facet |
N2 fixation nitrification latitudinal trends GO-SHIP nifH marine biogeography South Pacific Ocean Science Q General. Including nature conservation geographical distribution QH1-199.5 |
description |
Nitrogen (N) is an essential element for life and controls the magnitude of primary productivity in the ocean. In order to describe the microorganisms that catalyze N transformations in surface waters in the South Pacific Ocean, we collected high-resolution biotic and abiotic data along a 7000 km transect, from the Antarctic ice edge to the equator. The transect, conducted between late Austral autumn and early winter 2016, covered major oceanographic features such as the polar front (PF), the subtropical front (STF) and the Pacific equatorial divergence (PED). We measured N2 fixation and nitrification rates and quantified the relative abundances of diazotrophs and nitrifiers in a region where few to no rate measurements are available. Even though N2 fixation rates are usually below detection limits in cold environments, we were able to measure this N pathway at 7/10 stations in the cold and nutrient rich waters near the PF. This result highlights that N2 fixation rates continue to be measured outside the well-known subtropical regions. The majority of the mid to high N2 fixation rates (>∼20 nmol L–1 d–1), however, still occurred in the expected tropical and subtropical regions. High throughput sequence analyses of the dinitrogenase reductase gene (nifH) revealed that the nifH Cluster I dominated the diazotroph diversity throughout the transect. nifH gene richness did not show a latitudinal trend, nor was it significantly correlated with N2 fixation rates. Nitrification rates above the mixed layer in the Southern Ocean ranged between 56 and 1440 nmol L–1 d–1. Our data showed a decoupling between carbon and N assimilation (NO3– and NH4+ assimilation rates) in winter in the South Pacific Ocean. Phytoplankton community structure showed clear changes across the PF, the STF and the PED, defining clear biomes. Overall, these findings provide a better understanding of the ecosystem functionality in the South Pacific Ocean across key oceanographic biomes. |
format |
Article in Journal/Newspaper |
author |
Eric J. Raes Jodie van de Kamp Levente Bodrossy Allison A. Fong Jessica Riekenberg Bronwyn H. Holmes Dirk V. Erler Bradley D. Eyre Sarah-Sophie Weil A. M. Waite |
author_facet |
Eric J. Raes Jodie van de Kamp Levente Bodrossy Allison A. Fong Jessica Riekenberg Bronwyn H. Holmes Dirk V. Erler Bradley D. Eyre Sarah-Sophie Weil A. M. Waite |
author_sort |
Eric J. Raes |
title |
N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
title_short |
N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
title_full |
N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
title_fullStr |
N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
title_full_unstemmed |
N2 Fixation and New Insights Into Nitrification From the Ice-Edge to the Equator in the South Pacific Ocean |
title_sort |
n2 fixation and new insights into nitrification from the ice-edge to the equator in the south pacific ocean |
publisher |
Frontiers Media S.A. |
publishDate |
2020 |
url |
https://doi.org/10.3389/fmars.2020.00389 https://doaj.org/article/1da527c498c54b46bf89e9d29b9f41e9 |
geographic |
Antarctic Austral Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Austral Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Frontiers in Marine Science, Vol 7 (2020) |
op_relation |
https://www.frontiersin.org/article/10.3389/fmars.2020.00389/full https://doaj.org/toc/2296-7745 2296-7745 doi:10.3389/fmars.2020.00389 https://doaj.org/article/1da527c498c54b46bf89e9d29b9f41e9 |
op_doi |
https://doi.org/10.3389/fmars.2020.00389 |
container_title |
Frontiers in Marine Science |
container_volume |
7 |
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1766106729192357888 |