The Ocean Microbiome: Metabolic Engine of the Marine Carbon Cycle

Abstract

Microorganisms are the foundation of the marine carbon cycle. Photosynthetic cyanobacteria and eukaryotic phytoplankton in the surface ocean use solar energy to convert carbon dioxide into energy-rich organic compounds (“carbon fixation”) that are then released when the organisms are grazed or lysed. This in turn fuels a dynamic community of heterotrophic bacteria in both the surface and deep oceans. Over a year, oceanic phytoplankton species fix as much carbon as do land plants.