Sewanee faculty member Thea Edwards has been named a Fulbright Scholar for the 2015-2016 year. She has been teaching courses and directing student research in the Biology Department since August 2014.
In January 2016, Edwards will travel to Botswana for eight months to study the effects of aquatic pollution on fish health in the Okavango Delta. The Okavango is an inland freshwater delta that floods during the dry season with rainwater draining south from mountains in Angola. This great natural event is the lifespring for magnificent herds of southern African wildlife that migrate annually to the flooded Okavango.
The Fulbright Program is America’s flagship international exchange and diplomacy program funded by the U.S. Department of State and partner countries. Each year, 800 faculty and experienced professionals are selected by review panels and the Fulbright Foreign Scholarship Board, a 12-member group appointed by the President of the United States. Fulbrighters receive teaching and/or research grants to work in any of 130 countries worldwide. Sewanee has nine current faculty previously selected for this prestigious program.
At the Okavango Research Institute (ORI), Edwards will collaborate with Senior Research Scholars Keta Mosepele and Mike Murray-Hudson, other ORI scientists, and students from the University of Botswana collecting tilapia fish along a growing pollution gradient in the Okavango. The pollution originates from a variety of sources including agricultural and mining runoff, aerial deposition from coal burning, and bioaccumulation of persistent pesticides. Particular pollutants include the insecticide DDT, a range of toxic heavy metals, and excess nitrate from fertilizers and sewage.
Edwards will use tilapia like canaries in a coal mine to study the environmental impacts of pesticides, heavy metals, and nitrogen pollution on fish reproductive health. Some pollutants, like DDT and nitrate, mimic or block animal hormone signaling. When tilapia are exposed to hormonally-active pollutants, their reproductive development can be delayed or impaired. Edwards will evaluate cell structure in tilapia gonads to determine fish fertility and make predictions about how chemical exposure works at the cellular level. Her results will provide new information about how human-made pollution and changes in land use are affecting the reproductive health of Okavango wildlife.
Another important group of pollutants in the Okavango ecosystem are heavy metals. Using equipment recently purchased by Sewanee, Edwards will measure heavy metal concentrations in Okavango tilapia tissues. This is important because heavy metals accumulate in fish and are transferred to people who eat those fish. Metal bioaccumulation causes a variety of adverse health effects in both fish and people.
Finally, Edwards will map nitrate pollution across portions of the flooded Delta. Elevated aquatic nitrate levels are associated with fertilizer and sewage runoff and result in algae blooms. When the algae die, their decomposition uses up oxygen in the water. This loss of oxygen kills fishes and other aquatic animals.
Edwards is currently working with Sewanee student Robert Corey, C'17, on a related project using tilapia caught in South Africa. Corey’s project is a collaboration with Dr. Louis Guillette at the Medical University of South Carolina and Drs. Jan Myburgh and Danny Govender at the University of Pretoria in South Africa.