Through the use of a DNA technique called 454 tag sequencing, researchers working on the International Census of Marine Microbes -- part of a 10-year plan which aims to catalogue marine species before the oceans are depleted -- found more than 20,000 kinds of microorganisms in a single liter of seawater. The water was expected to contain between 1,000 and 3,000 organisms.
Previously, molecular studies estimated that more than 500,000 kinds of marine microorganisms existed, but Dr. Mitchel Sogin, director of the Marine Biological Laboratory in Massachusetts, said these new results "blow away all previous estimates of bacterial diversity in the ocean."
While only 5,000 marine microbes have been named and formally described by scientists, Sogin said these new findings mean that there could be between 5 million and 10 million bacterial species in the world's oceans.
Scientists say these organisms are crucial to life on earth. "Microbes constitute the vast majority of marine biomass, and are the primary engines of the Earth's biosphere," Sogin said. "They are the oldest life forms, the primary catalysts of energy transformation, and fundamental to the biogeochemical cycles that shape our planetary atmosphere and environment."
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