Alligators at GA’s Okefenokee have mercury in them. Where’s it coming from?
AI-generated summary reviewed by our newsroom.
- Researchers found Okefenokee alligators have 8x more mercury than coastal sites.
- Coal-fired plant emissions likely source of mercury via rainwater deposition.
- EPA rollback of 2024 mercury limits raises concerns over environmental safety.
In a first-of-its-kind study, researchers from ecology schools at University of Georgia and Clemson University measured mercury in alligators across habitat hotspots in the Southeast.
It was more prevalent in the Peach State’s gators than you might expect, particularly in one place.
The harmful toxin was found to be eight times higher in alligators in the Okefenokee Swamp than in the other two alligator sites: Jekyll Island, Georgia, and Yawkey Wildlife Center, South Carolina.
In the year spent on this study, Kristen Zemaitis, who led the project and graduated from UGA, pulled out 800 alligators in all three of these areas to take blood and tissue samples to reveal levels of mercury in their body.
“It’s very safe, we have a well-trained team of people that know what they are doing,” Zemaitis said. “It’s not like wrestling alligators that you see on TV.”
After they hog tie the gator, those involved in the study get them onto land and tape their snout shut. Then a handful of people sit on the gator, especially their powerful and dangerous tail.
Zemaitis was doing turtle research at Jekyll Island when she was approached by the Okefenokee Swamp to start a research program for the under-researched 10,000 plus gators roaming throughout the swamp.
Working near Brunswick, Zemaitis saw there were consistently warnings and advisories posted near the waterways to avoid fishing because of mercury and other contaminants.
“Brunswick is known for its superfund sites, which are plants that had really bad chemicals and got caught and got into trouble and now have to spend tons of money to fix or remediate what was released into the environment,” she said.
Glynn County, including the city of Brunswick, hosts four Superfund sites on the National Priorities List, including LCP Chemicals and Wood Preserving Site.
She compared Jekyll Island gators, Yawkey gators and Okefenokee gators because their habitats are so varied.
“Okefenokee is inland, it’s fresh water, Jekyll and Yawkey are both barrier islands and animals have a lot of access to marsh and those are different water chemistries with different pH levels,” she explained.
She believes the mercury showed up higher in the gators in Okefenokee partly because of the acidic swampy environment that allows the mercury–which could be occurring naturally in the swamp already from volcanic rock – to be more bioavailable or integrate into the body more easily. Scientists call this methylation.
“So there might be mercury in other environments (such as salt water) that just is not being methylated as easily, the microbes and acidity in the water definitely increase that and exacerbate it more,” she said.
Mercury in the food chain
Mercury can get into anything that is living in the water, including plants, dragonfly larvae, fish and frogs, and then eventually go up the food chain, according to Zemaitis.
Consuming fish is the most common way it can accumulate in people.
“(Mercury) can cause severe health issues, not just for wildlife, but for humans as well,” Zemaitis said. “It’s really, really bad for reproduction.”
That means pregnant or breastfeeding moms should be more careful. Children should be wary too.
“It’s also really bad for children, and accumulates faster,” she said. “It causes mobility issues, organ failure.”
An alligator with lots of mercury in them might be slow at hunting, or dopey, or act strange, she said.
While the levels were eight times higher at Okefenokee, mercury was still present in gators at the other two saltwater sites.
Fishing is allowed at Okefenokee, but Zemaitis said she would not “personally consume fish from the swamp.”
The research team’s findings about the higher mercury levels in Okefenokee leave them questioning about its source, aside from the amount that occurs naturally.
Where is the mercury coming from?
Aside from a few natural springs, the swamp receives 90% of its water from rain.
“So when it rains, there is mercury coming down from whatever anthropogenic release there was upwind … then getting rained down (into the swamp),” Zemaitis said.
Both Zemaitis and the project supervisor, professor James Byers of the Odum School of Ecology at UGA, believe the mercury is coming from smoke stacks in steam form and becoming part of the water cycle.
“In Georgia and many places in the world, that’s probably the number one human caused source of mercury in the environment–is from burning of coal,” Byers said. “Mercury persists with coal because you can’t get it out, it’s a byproduct.”
This theory is hard to prove, but Byers said it is the most likely source because it is the main place where anthropogenic mercury comes from.
“It’s usually older plants that are the biggest contributors, because they’re less efficient, they don’t have the scrubbers and things like that on the smoke stacks,” he said. “There are ways that plants can install mercury controls, but even those still release large amounts of mercury in the environment.”
A report in 2011 by Environment Georgia found two-thirds of all airborne mercury pollution in the United States came from the smokestacks of coal-fired power plants.
“Power plants generate more airborne mercury pollution than all other industrial sources combined,” he said.
The first standard limiting the release of mercury was adopted by the Environmental Protection Agency in 2012 which intended to reduce mercury levels by 90%. In 2024, the EPA updated the rule to make mercury limits and particulate matter even more stringent.
But just last month, new EPA Administrator Lee Zeldin announced a proposal that would reverse the 2024 changes and stick with 2012 standards.
“It’s just kind of maddening,” Byers said. “Because mercury and lead are both two highly toxic metals in our environment, and it seems like they’re so obvious and easy to control, and it’s just a matter of political will. We’ve done a good job with lead; we got it out of paint and gasoline. With mercury, there’s very little use of it now, industrially and coal-fired power plants, one of the main ones left.”
The two current coal power plants in Georgia are Plant Bowen, just outside Euharlee, and Plant Scherer, in Juliette.
Byer also said the study was funded from a combination of state agencies and private donations, including Americorp.
Americorps is the domestic Peace Corps program, and a lot of research in nature-oriented projects are funded by it, and it’s already been cut in half since Trump started.
Around 41% of AmeriCorps annual budget was rescinded by DOGE in April, about $400 million.
