The Explorers - At the coast
On Sapelo Island, the bug spray won’t save you. Jennifer Glass and her students received that wisdom from a local scientist as they prepared for a long day of field work on this remote barrier island on the Georgia coast.
The surprise bite, the slap of skin that always comes too late, the never-ending itch to scratch — mosquitos, horseflies, red bugs and no-see-ums are ubiquitous in this swampland. This is the baseline for scientific research in Georgia’s coastal marsh. For Glass’ four-woman team of biogeochemists, the bugs are but background noise. These scientists have traveled 300 miles from Georgia Tech’s urban campus to this muddy hotbed of ecological research. They are here to get dirty.
Their mission: Slog through the marsh and remove chunks of the soil, called cores, to slice up and take back to their lab in Atlanta. Glass is an assistant professor in the School of Earth and Atmospheric Sciences at Georgia Tech. She specializes in the hidden chemistry of microbes that recycle Earth’s nutrients. Her lab is searching the marsh for new organisms and new routes of action in these chemical cycles. Sapelo’s soil and water are filled with unique microbes, and ecologists have been coming here for decades to study the natural environment.
This is more than just a curious quest in the name of basic science. Some of these microbes produce greenhouse gases such as methane and nitrous oxide, both of which are many times more potent than carbon dioxide, the heat-trapping gas that’s linked to climate change. Learning more about how microbes produce some gases and consume others could answer questions about the Earth’s ability to cope with greenhouse gas emissions.
So on a muggy July morning, Glass and her three students donned knee-high rubber boots and set off into the marsh.
Video: Sapelo Island research expedition
Photos: Sapelo Island research
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The marsh is located on the island’s coast, between land and open saltwater, where tides regularly flood. The marsh is filled with grasses and shrubs, which trap sediments and create a muddy but stable ecosystem that filters nutrients and supports wildlife in the water and on land.
This is one of the best parts of our job,” Glass said. “This is what environmental science is all about. Getting out and taking your own samples and getting to know an environment.”
Walking in the marsh is hard work. The mud sucked the team’s rubber boots into the ground, making each step an intricate process. Stride, sink ankle-deep into the mud, yank foot free without losing a boot, repeat. The slog churned up the soil, releasing more sulfur into the air.
“Sulfur is driving a lot of the chemistry in the salt marsh,” Glass said. “You can smell it in the air and in the water. It’s everywhere.”
As they walked farther, their nervous laughter grew louder as the mud’s suction grew stronger. Fiddler crabs shuffled about on top of the mud with envious ease. When the team reached the tidal levee — where tides have piled ocean silts and sands between land and sea, creating a microbe-dense location — they started working on their first core.
“Coring is just what it sounds like, nothing fancy,” Glass said. “You take a plastic pipe and you hammer it into the salt marsh. The hardest part is getting it back up. It gets stuck down there."
The three-foot-long PVC pipe easily sank into the soil. It did not easily come out. The team twisted, turned, and yanked on the pipe, but they couldn’t free it with the core of mud inside intact.
“Ladies, I’m very sorry, but I think you’ll have to dig it out,” Glass said.
And with that, the students plunged their hands into the soil, elbow deep, and began digging.
On Sapelo Island, tourism isn’t as dominant as on some of Georgia’s popular barrier islands. Vacationers flock to the state’s famed Golden Isles; Jekyll Island, St. Simons Island, Little St. Simons Island and Sea Island. But Sapelo, only accessible by boat or airplane, remains largely wild.
No one can visit the island unannounced. Visitors must be part of a tour, a guest of a resident or visiting one of the research stations on the island.
Sapelo Island is a state-protected barrier island in southeastern Georgia, along the state’s coast. Some 97 percent of the island is owned by the state and managed by the Georgia Department of Natural Resources. Private landowners, about 100 total, make up the remaining percentage. Most of the island’s permanent residents live in the Hog Hammock community, home to African-Americans of Gullah Geechee descent, who have been living here for generations. They are direct descendants of slaves brought from West Africa in the 19th century to work on the island. This community was in relative isolation for so long that they developed a culture that has preserved much of their African linguistic and cultural heritage. The same ferry that shuttles scientists to the island also carries residents of Hog Hammock to the mainland for work and school.
For decades, Sapelo Island was privately owned and closed to the public. Tobacco heir R.J. Reynolds Jr. purchased the island during the Great Depression. He was interested in agricultural experimentation and founded the Sapelo Island Research Foundation in 1949, which funded the research of Eugene Odum, a University of Georgia professor and pioneer in the field of ecology. Odum’s 1958 paper “The Ecology of a Salt Marsh” painted a portrait of the fragility of the cycle of nature in the wetlands. The paper was well-received among scientists and helped launch the modern ecology movement.
Having established a scientific presence on Sapelo, UGA created its Marine Institute (UGAMI) in the 1950s to support research here using buildings from Reynolds’ experimental dairy farm. (The main UGAMI lab is called "the barn.") Visiting scientists from faraway countries have been coming to Sapelo to study its salt marsh ever since. (A team from the Netherlands was at UGAMI at the same time as Glass’ team.) Resident scientists from UGA work here year round.
“This is a historic site, in many ways, but particularly for science. It’s really become one of those ecosystems around the country where scientists come back over and over again to study,” Glass said. “This facility is just amazing in terms of its historical relevance and its physical beauty.”
Glass' team has come to UGAMI, in part, to study the methane cycle. Methane is a greenhouse gas that’s 25 times more potent than carbon dioxide. Burning fossil fuels releases methane, as do microorganisms in wetlands such as Sapelo’s marsh.
Some organisms in the marsh are also thought to eat methane using unique chemistry that involves iron and manganese. Scientists have characterized the salt marsh’s geochemistry through the years, so researchers have a good idea where to look for theses microbes. What scientists don’t know is precisely how microbes use iron and manganese in their metabolism. Glass lab is taking samples from zones in the marsh that have these metals and methane in order to unravel the pathways at play.
That’s why these four women are knee-deep in mud — to look for organisms that no one has ever seen and that eat methane in a way no one fully understands.
On Sapelo Island, researchers work for everything they get. They load and unload their gear on and off the ferry, and then onto an old truck that they drive themselves — with a manual transmission — to the dorms.
There’s no cook for visiting researchers, so scientists must bring and cook their own food, even after a long day in the field. The dorms are utilitarian. Bunk beds, two desks, and set of chest of drawers are all that each room holds. The private bathrooms almost feel like a luxury, but the water smells of sulfur. Even after washing the marsh off in the shower, the smell of sulfur lingers.
For half of Glass team, this is their introduction to field work. It’s old-school science for a new generation of scientists. They are a diverse group of women with backgrounds that are underrepresented in science. There’s Amanda Cavazos, a first-year Ph.D. student from South Texas with a penchant for the oboe. Then there’s Melissa Warren, a master’s student whose love of mountain biking has her wearing a wrist brace for the entire trip —not that it slowed her down digging into the mud. And Chloe Stanton, a second-year undergraduate Earth Sciences major with a passion for playing in the orchestra; she strode into the marsh with the confidence of someone with years of field experience. For all of them, this was their first trip to Sapelo Island.
“This is going to be an adventure, because I’ve never been here before,” Glass said during the morning meeting with her team before their first day in the field.
One goal of the trip was to introduce the students to a field sampling site they can return to throughout their careers.
"There’s no better way to understand a place or process than to go there and experience it firsthand,” Cavazos said. “The trip to Sapelo allowed me to do just that."
In addition to the marsh, the team also collected water samples from the ferry dock to learn about the Earth’s nitrogen cycle. Each summer, a unique bloom of microbes forms here, and the Glass lab wants to learn how they produce nitrous oxide, the potent greenhouse gas. Water below the dock was pumped into big jugs. Some water was filtered and quickly treated to preserve any genetic material and then frozen in a giant container of liquid nitrogen that the team took with them. This tells what organisms are present. The unfiltered water tells the scientists what nutrients these organisms are working with. Compared to the marsh, this part of their field work was a breeze.
“That was pretty mild field sampling,” Glass said. “We had a nice hard surface.”
Long days in the field under the South Georgia sun are capped with short nights back at the dorms. A quick shower, a couple of hours for dinner and conversation, and then eyes start to get heavy and people start to turn in just after 9 p.m.
Nights on Sapelo aren’t exactly quiet. There is very little car traffic on the island, and the hum of work carts around the research station dies down after sunset. But the bugs sing loudly at night, creating a soundtrack for Sapelo Island.
“It feels like we’re a thousand miles away from Atlanta,” Glass said.
Back to the Marsh
Elbow deep in the mud, Chloe Stanton is fishing for the bottom of the core while Melissa Warren works a shovel down the other side.
“I’ve found the bottom!” Stanton said.
She squats lower, and with one final heave yanks the core free from the mud to the cheers from the rest of her team. The core was free, but Stanton was stuck. She passed the sample off to Warren to carry it safely to solid ground, then began the slow process of pulling her feet from the mud’s grip.
"Being stuck in a salt marsh with a tube full of mud held high like a trophy is not a scenario I imagined I would find myself in, but it's times like these that make me so happy I do what I do," Warren said.
Next it was Amanda Cavazos' turn. She ventured even farther into the marsh to find a different spot to pull a core. Solid ground was out of the question at this point.
“Oh, this is going to be fun,” Cavazos, sinking into the marsh as she prepared to hammer the pipe into the muck.
Stanton worked the shovel while Cavazos got her hands dirty. This time, it was Cavazos who pulled the core from the mud and held it head-high to cheers.
The grunt work was now behind them, but their day was far from done. The cores were sealed and driven back to the lab. In a coordinated and precise effort, the team sliced the mud into pieces that were just a few inches thick. Then their work shifted indoors, to the UGAMI’s lab, where everyone grew quiet as they quickly worked to preserve pore water samples from the mud cores, careful to log which sample came from what location and what depth.
Hours in the field turned into hours in the lab as the sun set over the research station. On Sapelo Island, it’s easy to get lost in your work and lose track of time, especially when you’re covered in mud.
“Look at my watch,” Stanton said. It was caked in grime. “I was just thinking, ‘What time is it?’”