Y.-W. Luo, Woods Hole Oceanographic Institution
S.C. Doney, Woods Hole Oceanographic Institution
L.A. Anderson, Woods Hole Oceanographic Institution
M. Benavides, Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria
I. Berman-Frank, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University
A. Bode, Instituto Español de Oceanografía, Centro Oceanográfico de A Coruña
S. Bonnet, Centre d'Océanologie de Marseille
K. H. Boström, Linnaeus University
D. Böttjer, University of Hawaii
D.G. Capone, University of Southern California
E.J. Carpenter, San Francisco State University
Y.L. Chen, National Sun Yat-sen University
M.J. Church, University of Hawaii
J.E. Dore, Montana Sate University
L.I. Falcón, Universidad Nacional Autónoma de México
A. Fernández, Universidade de Vigo
R.A. Foster, Max Planck Institute for Marine Microbiology
K. Furuya, University of Tokyo
F. Gómez, Universidad de Valencia
K. Gundersen, University of Southern MississippiFollow
A.M. Hynes, Woods Hole Oceanographic Institution
D.M. Karl, University of Hawaii
S. Kitajima, University of Tokyo
R.J. Langlois, Leibniz Institutefor Marine Sciences
J. LaRoche, Leibniz Institute for Marine Sciences
R.M. Letelier, Oregon State University
E. Marañón, Universidade de Vigo
D.J. McGillicuddy Jr., Woods Hole Oceanographic Institution
P.H. Moisander, University of California, Santa Cruz
C.M. Moore, University of Southampton
B. Mouriño-Carballido, Universidade de Vigo
M.R. Mulholland, Old Dominion University
J.A. Needoba, Oregon Health & Science University
K.M. Orcutt, University of Southern Mississippi
A.J. Poulton, National Oceanography Centre
E. Rahav, Bar-Ilan University, Israel
P. Raimbault, Aix Marseille Université
A.P. Rees, Plymouth Marine Laboratory
L. Riemann, University of Copenhagen
T. Shiozaki, University of Tokyo
A. Subramaniam, Lamont Doherty Earth Observatory
T. Tyrell, University of Southampton
K.A. Turk-Kubo, Univresity of California, Santa Cruz
M. Varela, Instituto Español de Oceanografía
T.A. Villareal, University of Texas at Austin
E.A. Webb, University of Southern California
A.E. White, Oregon State University
J. Wu, University of Miami
J.P. Zehr, University of California, Santa Cruz

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Marine Science


Ocean Science and Engineering


Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (52–73) Tg N yr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4–3.1) Tg C from cell counts and to 89 (43–150) Tg C from nifH-based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 ± 9.2 Tg N yr−1, 18 ± 1.8 Tg C and 590 ± 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70%. It was recently established that the most commonly applied method used to measure N2 fixation has underestimated the true rates. As a result, one can expect that future rate measurements will shift the mean N2 fixation rate upward and may result in significantly higher estimates for the global N2 fixation. The evolving database can nevertheless be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models, keeping in mind that future rate measurements may rise in the future. The database is stored in PANGAEA (doi:10.1594/PANGAEA.774851).

Publication Title

Earth System Science Data





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