Marine microorganisms (or microbes) comprise all microscopic life in the sea.
The diversity of marine microbial organisms is very high. A non-exhaustive classification is shown in Fig. 1. Microbes, mainly bacteria and protists, account for around 70% of the total marine biomass. Microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. They are also responsible for nearly all photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements. Marine microorganisms sequester large amounts of carbon and produce about half of the world's oxygen.
See the Wikipedia article Marine microorganisms for more details.
- Bar-On, Y.M., Phillips, R. and Milo, R. 2018. The biomass distribution on Earth. PNAS 115(25): 6506-6511
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