Contrasted geographical distribution of N$_2$ fixation rates and $nif$H phylotypes in the Coral and Solomon Seas (southwestern Pacific) during austral winter conditions

Sophie Bonnet; Martine Rodier; Kendra A. Turk-Kubo; Cyril Germineaud; Christophe E. Menkès; Alexandre Ganachaud; Sophie Cravatte; Patrick Raimbault; Ellen Campbell; Fabien Quéroué; Géraldine Sarthou; Anne Desnues; Christophe Maes; Gérard Eldin

doi:10.1002/2015gb005117

Journal articles

Contrasted geographical distribution of N$_2$ fixation rates and $nif$H phylotypes in the Coral and Solomon Seas (southwestern Pacific) during austral winter conditions

Sophie Bonnet ¹ Martine Rodier ^{2, 3} Kendra A. Turk-Kubo ⁴ Cyril Germineaud ^{5, 3} Christophe E. Menkès ⁶ Alexandre Ganachaud ^{7, 5} Sophie Cravatte ¹ Patrick Raimbault ¹ Ellen Campbell ⁵ Fabien Quéroué ⁸ Géraldine Sarthou ⁸ Anne Desnues ¹ Christophe Maes ^{9, 10} Gérard Eldin ⁵

1 MIO - Institut méditerranéen d'océanologie

2 EIO - Ecosystèmes Insulaires Océaniens (UMR 241)

3 IRD - Institut de Recherche pour le Développement

4 UCSC - University of California [Santa Cruz]

5 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales

6 PEPS - Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs

LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques

7 OLVAC - Océan du Large et Variabilité Climatique

LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales

8 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)

9 LPO - Laboratoire de physique des océans

10 IFREMER Centre de Bretagne - Institut Français de Recherche pour l'Exploitation de la Mer - Brest

Abstract : Biological dinitrogen (N$_2$) fixation and the distribution of diazotrophic phylotypes were investigated during two cruises in the Coral Sea and the Solomon Sea (southwestern Pacific) during austral winter conditions. N$_2$ fixation rates were measurable at every station, but integrated (0-150 m) rates were an order of magnitude higher in the Solomon Sea (30 to 5449 $\mu$mol N m$^{-2}$ d$^{-1}$ compared to those measured in the Coral Sea (2 to 109 $\mu$ mol N m$^{-2}$ d$^{-1}$. Rates measured in the Solomon Sea were in the upper range (100-1000 mu mol N m$^{-2}$ d$^{-1}$ or higher than rates compiled in the global MARine Ecosystem biomass DATa database, indicating that this region has some of the highest N$_2$ fixation rates reported in the global ocean. While unicellular diazotrophic cyanobacteria from group A (UCYN-A1 and UCYN-A2) and the proteobacteria $\gamma$-24774A11 dominated in the Coral Sea and were correlated with N$_2$ fixation rates (p < 0.05), $Trichodesmium$ and UCYN-B dominated in the Solomon Sea and were correlated (p < 0.05) with N$_2$ fixation rates. UCYN-A were totally absent in the Solomon Sea. The biogeographical distribution of diazotrophs is discussed within the context of patterns in measured environmental parameters.

Keywords : Cyanobacteria Cultures Optical NORTH-ATLANTIC North-Atlantic numerical-model Dinitrogen-fixation Trichodesmium SPP. nitrogen-fixation Diversity Ocean Iron Sensitivity ACL

Document type :

Journal articles

Domain :

Physics [physics] / Physics [physics] / Geophysics [physics.geo-ph]

Environmental Sciences / Biodiversity and Ecology

Sciences of the Universe [physics] / Ocean, Atmosphere

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https://hal.archives-ouvertes.fr/hal-01496543
Contributor : Françoise Pinsard <>
Submitted on : Tuesday, April 6, 2021 - 11:28:22 AM
Last modification on : Wednesday, April 7, 2021 - 3:32:41 AM

Contrasted geographical distribution of N$_2$ fixation rates and $nif$H phylotypes in the Coral and Solomon Seas (southwestern Pacific) during austral winter conditions

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Contrasted geographical distribution of N$_2$ fixation rates and $nif$H phylotypes in the Coral and Solomon Seas (southwestern Pacific) during austral winter conditions

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