New Studies Find a Wealth of Oceanic Diversity

Scientists usually like to tout how much they know about a topic. But three new papers in the journal PLoS Biology underscore how much scientists don't know about life in the Earth's oceans.

By analyzing the DNA of microorganisms found in a range of water samples, the scientists found many new species and proteins.

The project began four years ago, when Craig Venter had an interesting idea. He's the geneticist and entrepreneur who helped sequence the human genome.

His new idea went like this: Get on your yacht (he has a very nice one); sail out into the ocean; take a water sample; and sequence all the DNA of the microorganisms in the sample.

So he did that, and the results were astonishing: The DNA revealed thousands of previously unknown organisms.

That led Venter to super-size his idea, sailing his yacht around the world and bringing samples back to the Venter Institute in Rockville, Md., where Douglas Rusch took over.

As in the first study, Rusch and his team sequenced the DNA of whatever microbes were in each sample.

"Only about 15 to 20 percent of our data can be associated with known microbes at all," Rusch says.

One thing that particularly surprised the researchers was the amount of variability there appeared to be even among microbes of the same species.

As impressive as Rusch's mountain of data is, marine biologist Edward DeLong says you can only learn so much by sequencing DNA.

"One shouldn't be misled by thinking that we'll be able to understand the nature of our world just by looking at genomes," DeLong says.

Instead, he says, the long-term value of the new study is that it combines genomics with detailed environmental information, allowing scientists to know exactly where the microbe was living when it was captured, whether it was in the open ocean or close to shore; in cold water or warm water.

The combination should help scientists get a better understanding of life in the oceans. And that's critical, because understanding ocean ecosystems — and microbes — is crucial for understanding the global climate.

DeLong says scientists are just developing the analytical tools that will help them make sense of the deluge of data pouring in. Doug Rusch says only one thing is clear at this point.

"In just about any way you can look at it," Rusch says, "the microbe world is far more complicated than we appreciated before."