Re-examination of the relationship between marine virus and microbial cell abundances

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Marine viruses are critical drivers of ocean biogeochemistry, and their abundances vary spatiotemporally in the global oceans, with upper estimates exceeding 108 per ml. Over many years, a consensus has emerged that virus abundances are typically tenfold higher than microbial cell abundances. However, the true explanatory power of a linear relationship and its robustness across diverse ocean environments is unclear. Here, we compile 5,671 microbial cell and virus abundance estimates from 25 distinct marine surveys and find substantial variation in the virus-to-microbial cell ratio, in which a 10:1 model has either limited or no explanatory power. Instead, virus abundances are better described as nonlinear, power-law functions of microbial cell abundances. The fitted scaling exponents are typically less than 1, implying that the virus-to-microbial cell ratio decreases with microbial cell density, rather than remaining fixed. The observed scaling also implies that viral effect sizes derived from ‘representative’ abundances require substantial refinement to be extrapolated to regional or global scales.

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Author information


  1. School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

    • Charles H. Wigington
    •  & Joshua S. Weitz
  2. Department of Mathematics and Statistics, Northern Arizona University, Flagstaff, Arizona 86011, USA

    • Derek Sonderegger
  3. Department of Biological Oceanography, Royal Netherlands Institute for Sea Research (NIOZ), 1790 AB Den Burg, Texel, The Netherlands

    • Corina P. D. Brussaard
  4. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, 1090 GE, Amsterdam, The Netherlands

    • Corina P. D. Brussaard
  5. Department of Microbiology, The University of Tennessee, Knoxville, Tennessee 37996, USA

    • Alison Buchan
    •  & Steven W. Wilhelm
  6. Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

    • Jan F. Finke
    •  & Curtis A. Suttle
  7. Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA

    • Jed A. Fuhrman
  8. Department of Biology, Indiana University, Bloomington, Indiana 47405, USA

    • Jay T. Lennon
  9. Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000, Helsingør, Denmark

    • Mathias Middelboe
  10. Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

    • Curtis A. Suttle
  11. Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

    • Curtis A. Suttle
  12. Program in Integrated Microbial Diversity, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada

    • Curtis A. Suttle
  13. Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey 08540, USA

    • Charles Stock
  14. Sir Alister Hardy Foundation for Ocean Science, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK

    • William H. Wilson
  15. Plant and Soil Sciences, Delaware Biotechnology Institute, Delaware Technology Park, Newark, Delaware 19711, USA

    • K. Eric Wommack
  16. School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

    • Joshua S. Weitz


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C.H.W. developed the code and implemented all scripts, analysed data, performed statistical analysis and contributed to writing the manuscript. D.S. developed and reviewed the code, analysed data, performed statistical analysis and provided feedback on the manuscript. A.B., J.F., J.T.L., M.M., C.A.S., C.S., W.H.W. and K.E.W. contributed to the design and implementation of the study, the assessment and collection of data sets, and provided feedback on the manuscript. C.P.D.B. and J.F.F. contributed to the assessment and collection of data sets and provided feedback on the manuscript. S.W.W. co-led the design of the study, led the data collection and assessment component, and contributed to writing the manuscript. J.S.W. co-led the design of the study, led the code and statistical analysis component, and wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Steven W. Wilhelm or Joshua S. Weitz.

Supplementary information

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    Supplementary Information

    Containing Supplementary Text, Tables 1-6, Figures 1-6 and References

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    Supplementary Data 1

    Supplementary Dataset