WASHINGTON — In an ocean teeming with life, scientists have discovered a barely inhabited sea floor desert.
Researchers curious about the limit to sea floor life turned to the deadest spot in the oceans, the South Pacific Gyre, explained University of Rhode Island oceanographer Steven D’Hondt.
Sediment cores from the region carried as few as 1,000 living cells per cubic centimeter, D’Hondt explained in a telephone interview.
By comparison, nearshore sediments can contain 1 billion living cells per CC and even offshore sediments can have 1 million per CC, he said.
The findings by D’Hondt and colleagues are reported in Tuesday’s online edition of Proceedings of the National Academy of Sciences.
The South Pacific Gyre is a massive area of ocean south of the Equator between South America and Australia. Slow-moving currents ring the region, leaving little organic matter to settle to the sea floor and keeping the water clear.
Similar gyres occur in other oceans, suggesting those regions too may produce little life at the sea floor.
The researchers also were surprised to find oxygen in the sediment in the gyre, unlike other regions where the sediments tend to lack oxygen.
“In most places, oxygen is gone just a few centimeters below the sea floor, but we found that oxygen goes many meters below the sea floor at these sites, and possibly all the way through the sediment to the underlying igneous rock,” D’Hondt said.
The research was supported by the National Science Foundation, National Aeronautics and Space Administration and Max Planck Institute for Marine Microbiology.
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PNAS: www/pnas.org
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