Revisiting the distribution of oceanic N2 fixation and estimating diazotrophic contribution to marine production

• Published in: Nature Communications
• Main Authors: Tang, Weiyi, Wang, Seaver, Fonseca-Batista, Debany, Dehairs, Frank, Gifford, Scott, Gonzalez, Aridane G., Gallinari, Morgane, Planquette, Hélène, Sarthou, Géraldine, Cassar, Nicolas
• Other Authors: Nicholas School of the Environment, Duke University Durham, Analytical, Environmental and Geo- Chemistry, Vrije Universiteit Brussel (VUB), University of North Carolina System (UNC), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Oceanografía y Cambio Global (IOCAG), Université de Las Palmas de Gran Canaria Espagne (ULPGC), ANR-12-PDOC-0025,BITMAP,Biodisponibilité du fer et des métaux traces dans les particules marines(2012), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: DINITROGEN-FIXATION; GAS-EXCHANGE; NITROGEN-FIXATION; N2 FIXATION; ACL; COASTAL; ACETYLENE; RATES; ATLANTIC TIME-SERIES; CAVITY RING; CARBON-CYCLE; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; North Atlantic
• Online Access: https://hal.science/hal-02322624; https://hal.science/hal-02322624/document; https://hal.science/hal-02322624/file/Tang%20et%20al%202019.pdf; https://doi.org/10.1038/s41467-019-08640-0

International audience Marine N 2 fixation supports a significant portion of oceanic primary production by making N 2 bioavailable to planktonic communities, in the process influencing atmosphere-ocean carbon fluxes and our global climate. However, the geographical distribution and controlling factors of marine N 2 fixation remain elusive largely due to sparse observations. Here we present unprecedented high-resolution underway N 2 fixation estimates across over 6000 kilometers of the western North Atlantic. Unexpectedly, we find increasing N 2 fixation rates from the oligotrophic Sargasso Sea to North America coastal waters, driven primarily by cyano-bacterial diazotrophs. N 2 fixation is best correlated to phosphorus availability and chlorophyll-a concentration. Globally, intense N 2 fixation activity in the coastal oceans is validated by a meta-analysis of published observations and we estimate the annual coastal N 2 fixation flux to be 16.7 Tg N. This study broadens the biogeography of N 2 fixation, highlights the interplay of regulating factors, and reveals thriving diazotrophic communities in coastal waters with potential significance to the global nitrogen and carbon cycles.