International Census of Marine Microbes (ICoMM)

Built a cyberinfrastructure to index and organize what is known about microbes, the world's smallest organisms, which account for 90 percent of biomass in oceans.

Mitchell Sogin
Jan de Leeuw
Linda Amaral Zettler


Project Leaders:

Mitchell L. Sogin, Ph.D., The Marine Biological Laboratory at Woods Hole, Woods Hole, MA, USA

Jan W. de Leeuw, Ph.D., The Royal Netherlands Institute for Sea Research, Texel, The Netherlands

Linda Amaral Zettler, Ph.D., The Marine Biological Laboratory at Woods Hole, Woods Hole, MA, U.S.A.

Visit the ICoMM website.

The oceans worldwide are teeming with microbial life forms invisible to the naked eye. An estimated 3.6 x 1030 microbial cells of untold diversity account for > 90% of the total oceanic biomass. The number of viral particles may be one hundred fold greater. Rich, chemosynthetic microbial communities thrive at deep-sea hydrothermal vents. Abundant archaea, one of the two prokaryotic domains of life, populate oceanic midwaters. Very large populations of phytoplankton including diatoms, dinoflagellates, picoflagellates and cyanobacteria, the primary catalysts in carbon fixation, orchestrate the cycling of nitrogen and form the base of the traditional marine food web. The heterotrophic bacteria belonging to the SAR11 group dominate communities of ocean-surface bacterioplankton while nonphotosynthetic protists (usually single-cell eukaryotes) of unknown diversity control the size of picoplankton (plankton less than 2 µm) populations and regulate the supply of nutrients into the ocean's food webs. Microbes account for the preponderance of life's genetic and metabolic variation, but our understanding of microbial diversity and the evolution of its population structures in the oceans is only fragmentary.

The International Census of Marine Microbes (ICoMM) facilitated the inventory of this microbial diversity by implementing a strategy (1) to catalogue all known diversity of single-cell organisms inclusive of the Bacteria, Archaea, Protista and associated viruses, (2) to explore and discover unknown microbial diversity, and (3) to place that knowledge into appropriate ecological and evolutionary contexts.

Examples of the types of marine microbes included in the ICoMM initiative. From
the leftmost panel, a Synechococcus phage (J. Waterbury), filaments of the marine cyanobacterium Lyngbya(D. Patterson), the hyperthermophilic archaeon "GR1" (M. Holland), and a single-celled eukaryote called an acantharian (L. Amaral Zettler).

Examples of questions that ICoMM addressed include:

  • What governs the evolution of marine microbial lineages within complex marine communities?
  • Why do marine microbial consortia retain functionally equivalent but genetically distinct lineages?
  • Is there a marine microbial biogeography and if so, what are the principal drivers or restrictors?
  • How does genotypic diversity shape phenotypic diversity, and how does this diversity influence the functioning of marine ecosystems?

ICoMM had five major activities. The first was to support scientific working groups focusing on (1) open ocean and coastal systems, (2) benthic systems, (3) databases and (4) technology that was specifically required for a microbial census. The second was to develop the database resource microbis, which organizes morphological, molecular and contextual information for marine microbial diversity within a framework that integrates into OBIS. The third was to provide resources to facilitate and coordinate requests for research support from governmental and private foundations. The fourth was to facilitate education and outreach of ICoMM to make it visible to the general public and raise awareness of its goals. Finally, ICoMM supported small-scale, pilot projects that had the potential to shape larger-scale research initiatives in marine microbial diversity.

To be successful, ICoMM promoted international cooperation and forged linkages with existing CoML field projects for collecting samples, contextual information and new technologies. ICoMM recognized that projects completed over the past decade had an important impact on the census. Participation by principal investigators of such projects in the ICoMM initiative will accelerate progress and ultimately lead to an organized constituency for seeking funding from agencies and foundations. At the same time, ICoMM engaged the broader community of microbiologists with complementary interests in microbial diversity, evolution, biogeography and their functional roles in marine systems.

Visit the International Census of Marine Microbes website.