"Before I joined this research project, I had no idea that many major cities in the United States let raw sewage flow into streams that border parks and homes. It just seems unsafe," says Greg Decker, a senior majoring in environmental studies.
This week, Decker is presenting Emory's research findings on mosquitoes and Atlanta creeks at the Ecological Society of America's annual meeting.
He was part of a team that monitored disease-carrying mosquitoes in Atlanta's Tanyard Creek, which until recently got occasional runoff known as combined sewer overflows (CSO). "The creek goes right by residential areas, a dog park and a jungle gym where children play. At times, we could smell the sewage," Decker says.
The researchers found that the Culex mosquito – a vector for West Nile Virus – thrived in the creek's waters, which were loaded with nitrogen and phosphorous. The mosquitoes were more populous, bred faster, and grew larger than those found in cleaner waters, such as Peavine Creek on campus.
In addition to lots of nutrients, the mosquitoes in Tanyard Creek had fewer predators. While the research began a year ago, the city recently built a catch basin near Tanyard Creek, designed to contain sewage runoff. "We're seeing more things that prey on mosquitoes now – fish, frogs and dragonfly larvae – and the mosquito population is down," Decker says.
The researchers are continuing to collect data on urban mosquito ecology in Atlanta and elsewhere. "If we can fully understand the mosquito's life cycle and how the environment affects it, we can better understand West Nile Virus and how to control it," Decker says.
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