Microbes dominate our planet, especially our oceans. The distinguishing feature of microorganisms is their small size, usually defined as less than 100 micrometers (µm); they are all invisible to the naked eye, however, their similarity may end there.
The discipline of microbial oceanography strives to understand, in a comprehensive and holistic sense, the role of microorganisms in the structure and function of marine ecosystems. Accordingly, microbial oceanographers make field observations of the distributions, abundances, diversity and metabolic activities of microorganisms in the sea and use this information to develop and test ecological hypotheses about the role that microbes play in global biogeochemical cycles, energy transduction and related ecosystem processes. This research requires a comprehensive understanding of ocean chemistry and physics as well as biology/microbiology.