Researching Salt Marsh Habitat Loss

Graduate Student Leads Project in Conjunction with Sustainable Aquaponics Research Center

Salt marshes in south Georgia are in constant need of restoration due to rising sea levels. Georgia Southern University graduate student Alexander Gregory is leading a project on the Armstrong Campus to address the loss of marsh habitats by researching Spartina alterniflora, the dominant plant in Georgia salt marshes.

Gregory, along with Sustainable Aquaponics Research Center (SARC) Senior Scientist Heather Joesting, Ph.D., is building an aquaponics garden to research the ideal growth conditions of Spartina and eventually become the first producer of locally grown Spartina for coastal marsh restoration projects.

“When you look out into the marsh, you see a sea of green – and most of that green is Spartina. Being a plant in the salt marsh is tough – the soil is salty with very little oxygen and the daily tides create a cycle of inundation and exposure,” said Joesting. “Spartina has developed some very unique adaptations to ‘tolerate’ these stresses, and as such is one of the only plant species that can grow in these habitats.”

The professor explained that Spartina is often planted as part of salt marsh restoration projects to stabilize and capture sediment. However, there is no local source in Georgia for the plants so coastal managers have to purchase them from out-of-state plant nurseries.

“Salt marsh habitats provide numerous ecosystem services, including coastal protection from storms, carbon sequestration and maintenance of commercial fisheries,” she stated. “Spartina is critical in stabilizing and accumulating sediment to facilitate marsh horizontal and vertical growth.”

Like the current aquaponics garden on the Armstrong Campus in Savannah that is used to grow vegetables, the garden in this project uses fish waste to fertilize the Spartina, which is grown in water. The water is then cleaned by the plants and recirculated into the fish tank. Due to the versatility of Spartina, the garden will be able to use freshwater or marine fish in the growing process, which will cut the cost of buying salt to maintain fish growing conditions in marine aquaculture. The project, which encompasses a multitude of scientific disciplines and research techniques, has so far provided seven undergraduate research students with experience in field and lab data collection, as well as other research skills that will be relevant to their post-graduation goals.

“This project incorporates information I’ve learned in courses like organic chemistry, plant biology and microbiology, just to name a few,” said Gregory. “There are so many organisms involved in this project, which is key to ecology. We want to understand all of the abiotic and biotic factors that are interacting to create the conditions we see. The knowledge that I brought with me at the beginning of this project pales in comparison to the knowledge I have gained actively planning and executing the work for it.”

While the research on the Spartina garden has been going on since last fall, the work is continuing this summer. The team is currently monitoring plant survival and completing the fish-garden recirculating system at the aquaponics facility on the Armstrong Campus. The researchers are also collecting data in the garden and completing analyses in the lab.

Gregory said the project has the potential to make a large impact on various scientific industries, such as conservation, living shorelines, aquaculture, traditional nursery practices, environmental biology and chemistry. He hopes to use the multidisciplinary aspects of the project in the next step of his professional or academic career.

“I think this project will have some pretty big implications for conservation of our salt marshes in Georgia and the economic and environmental costs of aquaculture,” Gregory said. “I think that the way this project ties together so many different threads is really amazing. I hope by the end of this project I have touched on and used competencies from many of these fields so that I can either get into a Ph.D. program or make myself a strong contender for the jobs that are out there.” — Kyle Dawson