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Identifying unexpected causes of climate change

Photoset-smA long time ago, back in the days before air conditioning or paved roads, the Everglades covered roughly a third of Florida.

In an effort to control flooding, and expand land for farming crops and grazing cattle, white settlers carved trenches to drain the Everglades into the Gulf of Mexico. Now, the once seemingly endless swath of grass and marsh is but a fraction of its original size.

But that is not all that has changed. Less easily seen is the effect the changing global climate had on Florida’s illustrious wetland. Rising global temperatures are changing the interactions between different microorganisms in peat lands in tropical and subtropical wetlands, such as the Everglades.

Andrew Ogram, professor of soil and water science and Genetics Institute faculty member, studies this phenomenon.

“We’re trying to learn how this complex chain of interactions is affected by changes in nutrient additions,” Ogram said.

By nutrient additions, Ogram refers to fertilizer runoff. The region south of Lake Okeechobee, Ogram’s study site, is a powerhouse for sugarcane production.

Rainwater or other vehicles carry the fertilizer off the fields, and into the nearby wetlands. Next, the fertilizer does what comes naturally– stimulates the foliage to grow.

Why is this a problem?

After the foliage in the wetland eventually ends its lifecycle, much of it turns into peat, or partially decomposed organic matter.

Peat contains microorganisms. Billions per gram.

“These specific microorganisms produce methane,” Ogram said.

As these microorganisms perform their metabolic processes, converting food into energy and so on, just as human do, they give off methane– just as we exhale carbon dioxide. Except methane is 24 times more potent a greenhouse gas than carbon dioxide.

Fertilizer causing plants to grow more abundantly has increased the amount of peat, which in turn has increased the amount of microorganisms, thereby increasing the amount of methane produced.

“It’s a very complex chain reaction between different groups of microorganisms that produce the methane,” Ogram said. “There are some very significant changes in, not only the magnitude of methane that’s produced, but the ways the methane is produced.”

Ogram and his research staff are attempting to understand the interactions between these microorganisms, as well as the significance of the increased production of substances such as methane. By better understanding these systems, scientists can better predict how human activities will affect the production of greenhouse gases.

In order to better understand how nutrient additions affect methane production by microorganisms, Ogram and his team study an alternate system in Panama. Fertilizer run-off is relatively non-existent in this “control” area, which enables Ogram to assess how much methane is produced in a peat land that has not been influenced by fertilizer.

In addition to his research in the Everglades and Panama, Ogram is also studying how rising sea levels are affecting ground water. He does this along the Yucatan Peninsula with colleagues from the Department of Geological Sciences and the UF Water Institute. Both projects are funded by the National Science Foundation.

As global climates rise, oceans undergo “thermal expansion.” The waters expand, as they grow warmer. With two-thirds of the Earth covered in water, such a minor change becomes significant.

The pressure of the increased ocean waters pushes on groundwater inland along the coast. As the seawater mixes with the groundwater, and pushes it backward along these underground channels, the chemistry of the coastal groundwater changes. In turn, this alters the interactions between the microorganisms responsible for nutrient cycling within the water.

As a member of the Genetics Institute faculty, Ogram studies these bacteria by looking at the DNA and RNA.

He has noticed some fairly significant changes, particularly with how nitrogen and phosphorous are cycled. Ogram analyzes the genetics of the microorganisms because simply looking at them under a microscope is not sufficient. He analyzes their DNA and RNA to determine how active they are, and to which groups they belong.