Jul 16, 2019 | Updated: 10:46 AM EDT

Sampling the World’s Oceans on a Global Scale Reveals the Complex Relationship between Viruses and Microbes

May 23, 2015 03:16 PM EDT


If you're going to study something as vast as the world's oceans, it helps if you have a large cadre of scientists to sift through the data. And that's just what an international research team, led by University of Arizona scientists, have done. They are rolling out the results of a three-year expedition in which they cataloged over 150,000 tiny ocean creatures, most of which are brand new discoveries.

You may not realize it, but all of life on earth depends on ocean microbes. They produce half the oxygen we breathe and are fundamental to the chemical reactions and energy transfers that underlie global ecological processes.

But they, like us, are susceptible to viral infections. These viruses can invade algae and interrupt the photosynthetic processes that produce much of the earth's oxygen and they can destroy food webs that ultimately depend on these tiny microbes.

So the UA team set out to catalog not only the vast oceanic organisms themselves, but the viruses that plagued them, in order to better understand these complex interactions that take place within our oceans.

"Ocean virus-microbe interactions have a huge impact on global biogeochemistry," Mathew Sullivan, one of the UA scientists involved in the project, said in a press release. "As they destroy microbial cells, they change the forms of nutrients available to other, larger organisms in ocean ecosystems. This recycling of nutrients through viral lysis is an important pathway that regulates how the oceanic ecosystem functions. Viral infections simultaneously reduce the amount of nutrients and materials available to larger organisms by killing microbial cells, but also stimulate microbial activity through the release of organic matter and nutrients, which provides increased biomass available for larger organisms including fish."

Sullivan, along with UA scientists Jennifer Brum, Simon Roux, and Julio Cesar Ignacio Espinoza led an international team in collaboration with the Tara Oceans Expedition, a French-based non-profit research organization that has spent the last 10 years scouring the oceans, collecting specimens and amassing data.

"The Tara Oceans expedition provided a platform for systematically sampling ocean biota from viruses to fish larvae, and in a comprehensive environmental context," Sullivan says. "Until now, a global picture of ocean viral community patterns and ecological drivers was something we could only dream of achieving."

And the result of all their global trawling? Around 35,000 bacteria, 150,000 single-celled plants and organisms, and about 5,000 viruses. Not surprising, considering the Tara vessel has traversed more than 180,000 miles of ocean.

The UA team's paper is one of five landmark studies that appear in the journal Science. They hope by collecting biological samples on a global scale, they can better understand the interactions between microbes and marine viruses.

"This is an incredible new way of doing science," Sullivan says. "At Tara Oceans, we are united by a common goal rather than a common funding source. These first papers show the world that we're capable of doing science at this scale, and yet they represent just the tip of the iceberg of what is hidden in these vast data sets. We've got years of work ahead of us."

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