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The Big Blue Sea

USC College microbiologist Douglas Capone: “The closer we look at the oceans, the more important the tiniest organisms appear to be.”

Photo/Eva Emerson

A USC College marine microbiologist was among the select group of scientists elected fellows of the American Academy of Microbiology this year.

Douglas Capone, the William and Julie Wrigley Chair in Environmental Studies and professor of biology, was formally recognized for the honor at a May 26 ceremony held by the American Society of Microbiology in New Orleans.

The AAM is the leadership group within the American Society for Microbiology, the world’s oldest life science organization.

The academy selected Capone on the basis of his outstanding work in marine microbial ecology and biogeochemistry.

Capone’s work has revolutionized understanding of the marine nitrogen cycle, leading to radical revisions in the calculations of the global marine nitrogen budget.

Specifically, Capone was cited for revealing the critical – and quantitatively important – role nitrogen-fixing microbes play in the movement of nitrogen through marine ecosystems.

He was also recognized for his pioneering research on plankton, most notably the cyanobacteria Trichodesmium, the oceans’ most conspicuous nitrogen fixer. This group of tiny marine algae can transform atmospheric nitrogen gas into a form readily used by other living things, thus providing essential nutrients for marine life.

“The closer we look at the oceans, the more important the tiniest organisms appear to be,” Capone said.

Capone’s work, which ranges from the molecular scale to the global, has had broader implications. Fixed nitrogen is a limiting nutrient for plants. By increasing levels of fixed nitrogen in the seas, Trichodesmium and other nitrogen fixers may boost the growth of marine algae that take in carbon dioxide.

In theory, that could increase the ocean’s ability to remove carbon dioxide from the atmosphere, thus altering the carbon cycle and potentially, through a complex set of interactions, the world climate.

Capone is now investigating the interplay of limiting nutrient levels (nitrogen, iron and phosphates) in temperate and tropical oceans and the role of nitrogen fixers in altering the ocean’s levels of carbon sequestration. In addition, he continues to study microbes and nutrient cycling in a wide variety of environments: from mangrove forests and coral reefs to snow at the South Pole.

The Big Blue Sea

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