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UGA researchers receive grant to study mysterious coastal phenomenon

The sudden population explosion of a single-celled organism named Thaumarchaeota in the coastal waters of the Southeastern United States baffled scientists.
Researchers at the University of Georgia have received a $727,000 grant from the National Science Foundation to study this phenomenon and its implications.
James Hollibaugh, a distinguished research professor of marine sciences, is the principal investigator for the project. He said the Georgia coast is an ideal place to do this research.
“So there’s something interesting and hopefully informative going on on the Georgia coast that makes it a key place to study this," he said. "[The Thaumarchaeota] seem to behave differently than at the other places that have been studied in more detail. So we’re trying to figure out what it is about water quality or the oceanography of the Georgia coast that leads to these bloom dynamics.”
Bradley Tolar, a graduate student in microbiology from Ocean Springs, Miss., has been involved in the research. He said the purpose of the three-year project that will be funded by the grant is to learn more about the organism.
“We’re studying a group of organisms that are relatively poorly understood,” Tolar said. “There are a few labs around the world that are studying them. Basically, they were discovered in 2005, so we know more than we did then, but it’s still not a lot. If you look at all the single-celled organisms in the ocean, this one group makes up 20 percent.”
Sapelo Island is the location of UGA’s Marine Institute, where researchers do environmental studies. The sudden boom in numbers of Thaumarchaeota could affect the availability of nitrogen and the fertility of coastal waters.
“Nitrogen is a problem in the coastal waters because if there’s too much of it, it leads to algal blooms," Hollibaugh said. "It could poison the dolphins and fish. When the algae die and hits the bottom, they rot and use up all the oxygen, and that kills all the stuff on the bottom.”
Hollibaugh said that more land being used for farming and suburban development has led to a greater amount of knowledge into the coastal zone.
“These organisms play a key role in this, in that they are the first step in a multistep pathway to get rid of that excess nitrogen, so they help clean up the coastal water by eliminating the excess nitrogen and bringing the productivity back to something more normal in the coastal waters,” Hollibaugh said.
Understanding how Thaumarchaeota lower nitrogen levels could help scientists prevent a dead zone from forming on the coast of Georgia, similar to the one at the mouth of the Mississippi River.
“The place that is having the most noteworthy problems right now is the mouth of the Mississippi River, where every year there’s this thing called the dead zone that covers hundreds of square miles,” Hollibaugh said. “It kills the shrimps, clams and everything that lives on the bottom."
Although the organism helps eliminate excess nitrogen, the sudden boom in numbers could lead to an overproduction of nitrous oxide, a greenhouse gas that could be more potent than carbon dioxide.
“So if for some reason worldwide they all decided to start producing this, it could have a really big impact,” Tolar said. “I don’t think that would ever happen, but it’s just another reason to find out more about them and what causes them to make this greenhouse gas, if there’s any way.”
The research project will consist of sampling cruises along the coast of the Southeastern United States to map populations of the organism and see how they change seasonally, as well as experiments to study the factors controlling their growth.
“One of the most important questions is why did they appear out of nowhere,” Tolar said. “We’re really wondering what environmental keys are causing them to become a thousand times more abundant. It’s almost spontaneous, so we’re really trying to find out what changes in the environment cause that.”

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