David Karl, Ph.D.

In situ assessment of microbial biomass, activity and growth and elucidation of microbialy mediated biogeochemical cycles


The field of microbial oceanography is truly a sea of opportunity. My research interests revolve around energy and matter transformations ranging from solar energy capture to the major element cycles

David Karl, Ph.D.

Research Description

The field of microbial oceanography is truly a sea of opportunity. My research interests revolve around energy and matter transformations ranging from solar energy capture to the major element cycles, especially carbon and phosphorus. I have developed and employed analytical techniques to study ecological and biogeochemical processes in the sea with a focus on blue water oceanography. My team has, over the past two decades, helped to build the basic understanding of microbial and biogeochemical processes at the North Pacific benchmark site, Station ALOHA, a temporally dynamic ecosystem that is vulnerable to climate change. The microbial community at this oligotrophic location is complex, tightly coupled, and highly regulated; yet the detailed mechanisms of energy and mass transformations are not well known. My current research projects include an assessment of the net metabolic balance between photosynthesis and respiration, the production and cycling of reduced biogenic gases (methane, carbon monoxide, nitrous oxide, dimethyl sulfide and hydrogen), and environmental controls on the biological carbon pump in the open sea.

Research Impact

I consider myself fortunate to have had a career that coincided with the emergence of marine microbial ecology / microbial oceanography as a fundamental discipline in Oceanography (1972-present). Major benchmarks during this period include the discoveries of the three major forms of microbial life in the sea (Synechococcus, Prochlorococcus, SAR 11), the unexpected discovery of deep-sea hydrothermal vents, the launch of several ocean-sensing satellites that for the first time presented a true global ocean view, and the “-omics revolution,” to name a few.

Until the mid-1980s we were still trying to build the fundamental paradigms based on “snapshots” accumulated from field expeditions that were separated in space and in time. In 1986, I proposed a permanent ocean station where time-series measurements of relevant physical, chemical, and microbiological parameters could be sustained. In 1988, a team of oceanographers founded the Hawaii Ocean Time-series program that has obtained approximately monthly measurements of a broad range of parameters for the past 26 years. The program has also produced a number of fundamental scientific discoveries, including new microorganisms and metabolic pathways. In 2006, Ed DeLong and I became co-Directors of a new National Science Foundation Center of excellence in microbial oceanography (C-MORE) to promote and to pursue opportunities in microbial oceanography, from genomes to biomes. A new field-based research program, Simons Collaboration on Ocean Processes and Ecology (SCOPE), is just getting underway at Station ALOHA.

Media Press





related links

Marine Microbiology Initiative Science University of Hawaii Foundation Back


University of California, San Diego, Scripps Institution of Oceanography; Ph.D. degree, March 1978 - Major:  Oceanography

Florida State University, Tallahassee, Florida; M.S. degree, August 1974 - Major:  Biological Oceanography

State University College at Buffalo, New York; B.A. degree, December 1971, Magna cum laude - Major:  Biology



Recipient, Eckart Dissertation Prize, University of California, Scripps Institution of Oceanography, 1979

Recipient, Presidential Young Investigator Award, White House and National Science Foundation, 1984-1989

Recipient, Board of Regents Excellence in Research Award (Junior Faculty), University of Hawaii, 1985

Recipient, Board of Regents Excellence in Research Award (Senior Faculty), University of Hawaii, 1994

Recipient, G. Evelyn Hutchinson Medal, American Society for Limnology and Oceanography, 1998

Elected to Fellowship in the American Geophysical Union, Jan 1999

Recipient, A. G. Huntsman Medal for excellence in marine science, Royal Society of Canada, 2001

Distinguished Lecturer, 9th Annual W.S. Jardetzky Lecture, Lamont-Doherty Earth Observatory, February 2002

Designated a “Highly Cited Researcher” by the Institute for Scientific Information (ISIHighlyCited.com) in the category of Plant & Animal Science, March 2002

Recipient, American Geophysical Union Citation for Excellence in Referring, Geophysical Research Letters, Dec 2003

Recipient, Gordon and Betty Moore Foundation Investigator in Marine Microbiology, May 2004-2013; 2013-present

Recipient, Henry Bryant Bigelow Medal in Oceanography, Woods Hole Oceanographic Institution, October 2004

Designated David Packard Distinguished Lecturer and Recipient of the David Packard Medal in Oceanography, Monterey Bay Aquarium Research Institute, November 2005

Elected to the U.S. National Academy of Sciences, April 2006

Elected to Fellowship in the American Academy of Microbiology, May 2006

Summer Research Fellow, Harris Manchester College, Oxford University, U.K., July 2009

Co-recipient of the National Academy of Sciences Cozzarelli Prize for best paper of 2009 in areas of Physical Science and Mathematics

Honorary Doctor of Science degree, University of Chicago, June 2010

Recipient, Alexander Agassiz Medal, National Academy of Sciences, April 2013

Inaugural Recipient, Victor and Peggy Brandstrom Pavel Endowed Chair in Ocean and Earth Science and Technology, University of Hawaii, February 2014

Designated Roger Revelle Commemorative Lecturer, National Academies’ Ocean Studies Board, March 2014


2014 Karl, D. M.  Microbially mediated transformations of phosphorus in the sea:  New views of an old cycle.  Annual Reviews of Marine Science 6: 279-337.

2014 Karl, D. M.  Solar energy capture and transformation in the sea.  Elementa, doi: 10.12952/journal.elementa.000021.

2014 Wilson, S. T., D. A. del Valle, M. Segura-Noguera and D. M. Karl.  A role for nitrite in the production of nitrous oxide in the lower euphotic zone of the oligotrophic North Pacific Ocean. Deep-Sea Research Part I 85: 47-55.

2014 Karl, D. M. and W. H. Schlesinger (eds.), Biogeochemistry, 2nd edn., vol. 10 of Treatise on Geochemistry (Holland, H. D. and K. K. Turekian, Exec. Eds.), Elsevier, Oxford, UK, 649 pp.

2014 Luo, Y.-W., I. D. Lima, D. M. Karl, C. A. Deutsch and S. C. Doney.  Data-based assessment of environmental controls on global marine nitrogen fixation.  Biogeosciences 11: 691-708.

2014 Durham, B. P., J. Grote, K. A. Whittaker, S. J. Bender, H. Luo, S. L. Grim, J. M. Brown, J. R. Casey, A. Dron, L. Florez-Leiva, A. Krupke, C. M. Luria, A. H. Mine, O. D. Nigro, S. Pather, A. Talarmin, E. K. Wear, T. S. Weber, J. M. Wilson, M. J. Church, E. F. DeLong, D. M. Karl, G. F. Steward, J. M. Eppley, N. C. Kyrpides, S. Schuster, and M. S. Rappé.  Draft genome sequence of marine alphaproteobacterial strain HIMB11, the first cultivated representative of a unique lineage within the Roseobacter clade possessing an unusually small genome.  Standards in Genomic Sciences 9: 632-645.

2014 Robidart, J. C., M. J. Church, J. P. Ryan, F. Ascani, S. T. Wilson, D. Bombar, R. Marin III, K. J. Richards, D. M. Karl, C. A. Scholin and J. P. Zehr.  Ecogenomic sensor reveals controls on N2-fixing microorganisms in the North Pacific Ocean.  ISME Journal 8: 1175-1185.

2014 Duhamel, S., K. M. Björkman, J. K. Doggett and D. M. Karl.  Microbial response to enhanced phosphorus cycling in the North Pacific Subtropical Gyre.  Marine Ecology Progress Series 504: 43-58.

2014 Karl, D. M.  Roger Revelle Commemorative Lecture:  The contemporary challenge of the sea:  Science, society and sustainability.  Oceanography 27: 208-225.

2014 Böttjer, D., D. M. Karl, R. M. Letelier, D. A. Viviani and M. J. Church.  Experimental assessment of diazotroph responses to elevated seawater pCO2 in the North Pacific Subtropical Gyre.  Global Biogeochemical Cycles 28: 601-616.

2014 Laws, E. A., R. M. Letelier and D. M. Karl.  Estimating the compensation irradiance in the ocean:  The importance of accounting for non-photosynthetic uptake of inorganic carbon.  Deep-Sea Research 93: 35-40.

2014 Sharma, A. K., J. W. Becker, E. A. Ottesen, J. A. Bryant, S. Duhamel, D. M. Karl, O. X. Cordero, D. J.  Repeta and E. F. DeLong.  Distinct dissolved organic matter sources induce rapid transcriptional responses in coexisting populations of Prochlorococcus, Pelagibacter and the OM60 clade.  Environmental Microbiology 16: 2815-2830.

2014 Karl, D. M. and M. J. Church.  Microbial oceanography and the Hawaii Ocean Time-series programme.  Nature Reviews Microbiology 12: 699-713.

2014 del Valle, D. A. and D. M. Karl.  Aerobic production of methane from dissolved water-column methylphosphonate and sinking particles in the North Pacific Subtropical Gyre.  Aquatic Microbial Ecology 73: 93-105.

2014 Pörtner, H.-O., D. M. Karl, P. W. Boyd, W. L. Cheung, S. E. Lluch-Cota, Y. Nojiri, D. N. Schmidt and P. O. Zavialov.  Ocean systems.  In: Field, C.B. et al. (Eds.), Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. XXX-YYY, in press.

2014 Bidigare, R. R., F. R. Buttler, S. J. Christensen, B. Barone, D. M. Karl and S. T. Wilson.  Evaluation of the utility of xanthophylls cycle pigment dynamics for assessing upper ocean mixing processes at Station ALOHA.  Journal of Plankton Research, in press.

2014 Dore, J. E., M. J. Church, D. M. Karl, D. W. Sadler and R. M. Letelier.  Paired windward and leeward biogeochemical time series reveal consistent surface ocean CO2 trends across the Hawaiian Ridge.  Geophysical Research Letters, in press.

2015 Karl, D. M. and K. M. Björkman.  Dynamics of dissolved organic phosphorus.  In:  D. Hansell and C. Carlson, Eds., Biogeochemistry of Marine Dissolved Organic Matter, Academic Press, Burlington, MA, USA, pp. 233-334.

Affiliated Investigators