Ocean Plankton Gobbling Up Twice The Carbon As Previously Believed
March 18, 2013

Ocean Plankton Gobbling Up Twice The Carbon As Previously Believed

Lawrence LeBlond for redOrbit.com - Your Universe Online

Carbon dioxide is the leading driver of disruptive climate change on a global scale. And without the help of some organisms in the natural world the global climate could be a lot worse than it is now. Now, new research shows that trillions of plankton near the surface of warm waters are more carbon-rich than previously believed.

These researchers, led by scientists at the University of California-Irvine, suggest that the tiny Prochlorococcus, as well as other microbes in the sea, digest double the carbon previously estimated. The work, published online in Nature Geoscience, highlights the need for better models on the carbon dioxide levels found over the world´s oceans.

The new work upheaves a decades-old principle of marine science known as the Redfield ratio, named after famed oceanographer Alfred Redfield, who in 1934 concluded that from the top of the world´s oceans to the darker depths, both plankton and the materials they release contain the same ratio of carbon, nitrogen and phosphorous.

But the researchers found dramatically different ratios while investigating a variety of marine locations.

The team concluded that while the depth of the plankton is important, latitude plays an even bigger role. They found that far higher levels of carbon exist in warmer, nutrient-starved waters near the equator than in the colder, nutrient-rich Polar Regions.

"The Redfield concept remains a central tenet in ocean biology and chemistry. However, we clearly show that the nutrient content ratio in plankton is not constant and thus reject this longstanding central theory for ocean science," said lead author Adam Martiny, associate professor of Earth system science and ecology & evolutionary biology at UC Irvine. "Instead, we show that plankton follow a strong latitudinal pattern."

Martiny and his colleagues gathered large jars of marine water from the several regions over seven expeditions. They gathered samples from the Bering Sea, the North Atlantic, the mild Caribbean waters, and elsewhere. They implemented a sophisticated cell sorter aboard their research vessel to analyze the samples at a molecular level. They also compared their data with data from 18 published results from past marine voyages.

For the most part, Redfield´s ratio is an important staple of textbooks and research. But Martiny noted that a lot of research has pointed out that this long-term model may in fact be outdated. He said in recent years a few models have suggested that Redfield´s ratio was wrong.

Now, Martiny´s research team shows that real-world observations are backing up those models. These are important findings, he noted.

Funding for Martiny´s work was provided by the National Science Foundation (NSF), the US Dept. of Energy and the UCI Environment Institute.