International Census of Marine Microbes

Building 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.

Project Leaders:


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

Dr. Jan W. de Leeuw, The Royal Netherlands Institute for Sea Research, Texel, The Netherlands
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 ┬Ám) 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) will facilitate the inventory of this microbial diversity developing a strategy to (1) 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 questions that ICoMM will address 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 has five major activities. The first is to support scientific working groups focusing on (1) open ocean and coastal systems, (2) benthic systems, (3) databases and (4) technology that is specifically required for a microbial census. The second is to develop the database resource microbis, which will organize morphological, molecular and contextual information for marine microbial diversity within a framework that integrates into OBIS. The third is to provide resources that can facilitate and coordinate requests for research support from governmental and private foundations. The fourth is to facilitate education and outreach of ICoMM to make it visible to the general public and raise awareness of its goals. Finally, ICoMM will support small-scale, pilot projects that have the potential to shape larger-scale research initiatives in marine microbial diversity.


To be successful, ICoMM must promote international cooperation and forge linkages with existing and new CoML field projects for collecting samples, contextual information and new technologies. ICoMM recognizes that projects currently underway or completed over the past decade will have an important impact on the census. Participation by principal investigators of current 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 will engage the broader community of microbiologists with complementary interests in microbial diversity, evolution, biogeography and their functional roles in marine systems.



Visit the ICOMM website.
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