Revisiting the distribution of oceanic N-2 fixation and estimating diazotrophic contribution to marine production
|Author(s)||Tang Weiyi1, Wang Seaver1, Fonseca-Batista Debany2, 6, Dehairs Frank2, Gifford Scott3, Gonzalez Aridane G.4, 5, Gallinari Morgane7, Planquette Helene4, Sarthou Geraldine4, Cassar Nicolas1, 4|
|Affiliation(s)||1 : Duke Univ, Nicholas Sch Environm, Div Earth & Ocean Sci, Durham, NC 27708 USA.
2 : Vrije Univ Brussel, Analyt Environm & Geochem, B-1050 Brussels, Belgium.
3 : Univ North Carolina Chapel Hill, Dept Marine Sci, Chapel Hill, NC 27599 USA.
4 : Inst Univ Europeen Mer IUEM, Lab Sci Environm Marin LEMAR, IFREMER, UBO,CNRS,IRD,UMR 6539, F-29280 Brest, France.
5 : Univ Las Palmas Gran Canaria, Inst Oceanog & Cambio Global IOCAG, Las Palmas Gran Canaria 35214, Spain.
6 : Dalhousie Univ, Dept Biol, Halifax, NS B3H 4R2, Canada.
|Source||Nature Communications (2041-1723) (Nature Publishing Group), 2019-02 , Vol. 10 , N. 831 , P. 10p.|
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 cyanobacterial diazotrophs. N-2 fixation is best correlated to phosphorus availability and chlorophylla 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.