December 7, 2002

The ability of the ocean to buffer the effects of global warming may hinge upon the interactions of tiny marine organisms at various temperatures according to a marine scientist at Rutgers, The State University of New Jersey.

Kay D. Bidle, a postdoctoral research associate at Rutgers Institute of Marine and Coastal Sciences, studied how water temperature and marine bacteria affect the interaction of silicon and carbon in diatoms, the oceans’ most common form of phytoplankton. His findings were published in a paper, “Regulation of Oceanic Silicon and Carbon Preservation by Temperature Control on Bacteria,” in the Dec. 6 issue of the journal “Science.”

“Scientists recently discovered that phytoplankton, microscopic plants that float freely thoughout the oceans, play just as big a role as land-dwelling plants in removing carbon dioxide from the atmosphere,” said Bidle, noting that carbon dioxide is the prime suspect in the global warming phenomenon.

“Diatoms are the most important group of phytoplankton for removing carbon from the atmosphere and it’s the silicon in diatoms that makes carbon removal possible. This is the first time that that anyone has presented the relationship between carbon and silicon in diatoms. What we’ve found is that temperature dramatically influences how well diatoms can do this.”

Under laboratory conditions, Bidle studied how carbon and silicon in diatoms are recycled by marine bacteria in temperatures found in equatorial waters vs. polar waters. He found that a coating of carbon surrounds and protects silicon in diatoms. In cold water, like that found near Antarctica, slower bacterial action allows more carbon to remain attached to the silicon. As the diatoms sink in the cold water, they take the carbon with them to the ocean bottom. The carbon can remain there for thousands of years away from the atmosphere. Even small increases in temperature cause bacteria to quickly eat the coating. The diatoms dissolve more readily and carbon recycles back to the surface ocean instead of being sequestered in deep waters.

Bidle said his research illustrates a possible global warming Catch 22 — the warmer the ocean, the less able it is to pull carbon out of the atmosphere, which in turn may set the stage for even warmer ocean temperatures. Also, temperature change in cold water regions like Antarctica could have especially disruptive effects on the balance of atmospheric carbon.

Co-authors of the paper include Maura Manganelli of Italy’s National Institute for Occupational Safety and Prevention, and Farooq Azam of the Scripps Institute of Oceanography.

This text derived from http://www.eurekalert.org/bysubject/atmospheric.php

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