Ten years of data collected by Italian researchers suggest that approximately 65% of DNA present in the world's oceans is found in deep-sea sediments, and 90% of that DNA is extracellular. This suggests the deep, extracellular organic material provides a major contribution to the cycling of phosphorus, the authors report in last week'sScience.

The researchers propose that the main source of DNA originates from dead cells in the surface layers of the oceans, and pelagic-benthic coupling processes control the extracellular DNA distribution in world ocean sediments. In other words, phytoplankton, cyanobacteria, and other dead organisms, free or attached to aggregates -- the so-called marine snow -- travel through the water column to the deep-sea bed, where their DNA is deposited.

"Our study shows that the concentration of DNA in deep-sea sediments worldwide is extremely high," study co-author Roberto Danovaro of the Marine Science Institute of the University of Ancona...

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