Articles | Volume 4, issue 1
Earth Syst. Sci. Data, 4, 47–73, 2012

Special issue: MAREDAT – Towards a world atlas of marine plankton functional...

Earth Syst. Sci. Data, 4, 47–73, 2012

  31 Aug 2012

31 Aug 2012

Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates

Y.-W. Luo1, S. C. Doney1, L. A. Anderson2, M. Benavides3, I. Berman-Frank4, A. Bode5, S. Bonnet6, K. H. Boström7, D. Böttjer8, D. G. Capone9, E. J. Carpenter10, Y. L. Chen11, M. J. Church8, J. E. Dore12, L. I. Falcón13, A. Fernández14, R. A. Foster15, K. Furuya16, F. Gómez17, K. Gundersen18, A. M. Hynes19,*, D. M. Karl8, S. Kitajima16, R. J. Langlois20, J. LaRoche20, R. M. Letelier21, E. Marañón14, D. J. McGillicuddy Jr.2, P. H. Moisander22,**, C. M. Moore23, B. Mouriño-Carballido14, M. R. Mulholland24, J. A. Needoba25, K. M. Orcutt18, A. J. Poulton26, E. Rahav4, P. Raimbault6, A. P. Rees27, L. Riemann28, T. Shiozaki16, A. Subramaniam29, T. Tyrrell23, K. A. Turk-Kubo22, M. Varela5, T. A. Villareal30, E. A. Webb9, A. E. White21, J. Wu31, and J. P. Zehr22 Y.-W. Luo et al.
  • 1Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
  • 2Department of Applied Ocean Science and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
  • 3Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, 35017, Las Palmas de Gran Canaria, Spain
  • 4The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
  • 5Instituto Español de Oceanografía, Centro Oceanográfico de A Coruña, 15080 A Coruña, Spain
  • 6IRD-INSU-CNRS, Laboratoire d'Océanographie Physique et Biogéochimique, UMR 6535, Centre d'Océanologie de Marseille, Aix Marseille Université, France
  • 7Department of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden
  • 8School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, Hawaii 96822, USA
  • 9Department of Biological Sciences and Wrigley Institute for Environmental Studies, University of Southern California, Los Angeles, California 90089, USA
  • 10Romberg Tiburon Center, San Francisco State University, Tiburon, California 94920, USA
  • 11Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
  • 12Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
  • 13Laboratorio de Ecología Bacteriana, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico
  • 14Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, 36310 Vigo, Spain
  • 15Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany
  • 16Department of Aquatic Bioscience, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
  • 17Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia, P.O. Box 22085, 46071 Valencia, Spain
  • 18Department of Marine Science, University of Southern Mississippi, Stennis Space Center, Mississippi 39529, USA
  • 19MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
  • 20Leibniz Institute for Marine Sciences, Duesternbrooker Weg 20, 24105 Kiel, Germany
  • 21College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA
  • 22Ocean Sciences Department, University of California, Santa Cruz, California 95064, USA
  • 23University of Southampton, National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK
  • 24Department of Ocean, Earth & Atmospheric Sciences, Old Dominion University, Norfolk, VA 23529, USA
  • 25Division of Environmental and Biomolecular Systems, Oregon Health & Science University, Portland, Oregon 97239, USA
  • 26National Oceanography Centre, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK
  • 27Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK
  • 28Marine Biological Section, University of Copenhagen, 3000 Helsingør, Denmark
  • 29Lamont Doherty Earth Observatory, Palisades, New York 10964, USA
  • 30Marine Science Institute, University of Texas at Austin, Port Aransas, Texas 78382, USA
  • 31Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA
  • *currently at: Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
  • **currently at: Department of Biology, University of Massachusetts Dartmouth, North Dartmouth, Massachusetts 02747, USA

Abstract. 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).