At the southern edge of Cannon’s Point Preserve on St. Simons Island, small crabs scurry across a thriving oyster reef adjacent to Taylors Creek. Native plants like muhly grass and saltmeadow cordgrass sway above the water, creating a lush green perimeter around the creek. Fish glide under the water’s surface, while birds skim above.
This is far from what the coastal edge used to look like, says Christi Lambert, director of coastal and marine conservation at The Nature Conservancy. Before 2015, the creek edge of mud and dirt was eroding, surrounded by debris from the abandoned Taylor Fish Camp.
“Isn’t it just beautiful now?” she says.
What transformed the area was a low-cost, nature-based solution to erosion exacerbated by climate change, a bio-engineering tool called living shorelines. The solution harnesses the inherent resiliency of native materials and habitats like oyster reefs and is touted by a diverse coalition of academics and conservation groups in Coastal Georgia as an alternative to traditional cement or wooden bulkheads common along the coast.
This living shoreline on St. Simons Island is one of eight in Georgia established on state-owned land between 2010 and 2020, with permits from the Georgia Department of Natural Resources Coastal Resources Divisions.
Living shorelines are proven to be environmentally beneficial and resilient against the effects of rising sea levels, but for decades, bulkheads have been the go-to technology for government agencies and private property owners in need of erosion protection along the coast.
Across Coastal Georgia, Lambert hopes that will change because living shorelines are not only resilient and better for the environment, but because they are cheaper as well. A 2013 report by the DNR concluded that living shorelines can cost around half as much as a bulkhead to install and maintain.
Bio-engineered infrastructure
Living shorelines are a type of nature-based infrastructure that combine biology with engineering. From North Carolina to Florida, scientists use them to reestablish the sloped shape of healthy shorelines at eroding coastal edges. When the shape is constructed, native plants and other species are introduced to help absorb and disperse the energy of waves that would normally cause erosion.
The sloped angle also aids that process, says Lambert. Traditional approaches, like seawalls and bulkheads, sit at a right angle like the wall of a bathtub. “If a wave hits that wall, it’s going to deflect and come right back at you,” she said. This can cause erosion in front of the bulkhead, rather than protect against it.
“Building these things is not as simple as it may sound,” she said.
Along the Georgia coast, scientists are using one of the most widely available natural materials for living shorelines: oyster shells.
Once laid in bulk, the empty shells attract oyster larvae, which settle and create an oyster reef. The reef eventually attracts more species, like crabs and marine worms, helping make the shoreline even more resilient.
As importantly, the multiple edges of oyster reefs deflect wave energy, and each oyster can filter up to 50 gallons of water per day, Lambert says.
Development in Georgia
Georgia’s first two living shorelines were built on Sapelo Island from 2010 to 2011, along Upper and Lower Post Office Creek. The two are similar to the one at Cannon’s Point, with foundations of oyster shells and plantings of native vegetation. Some of the shells were sourced from shell recycling centers in the area.
“The philosophy is that if you can imitate nature, that’s the best way to go,” Doug Samson, the reserve manager at Sapelo Island National Estuarine Research Reserve, said. “Keep hardened structures to a minimum and instead try to work with the shoreline and imitate something that would naturally be found in the environment.”
Georgia’s third living shoreline was finished on Little St. Simons Island in 2013 to replace the wooden bulkhead that was deteriorating and losing efficacy, said Scott Coleman, the ecological manager at Little St. Simons Island. It was built near Mosquito Creek, at the bank adjacent to the island’s main dock.
Cannon’s Point came next in 2015. Volunteers and students packed and placed 8,000 bags of oyster shells largely recycled from restaurants in the southeast and the St. Simons Land Trust Annual Oyster Roast. Some of the shells were 4500-year-old specimens found locally by archaeologists.
Stephanie Knox, preserve manager at Cannon’s Point, said the living shoreline has both enhanced and stabilized the edge of Taylor’s Creek. She said it has also been great for public engagement and learning, since it was the first living shoreline in Georgia accessible by car.
“It has been a phenomenal resource for the public,” Knox said.
Since 2015, living shorelines have been developed at Skidaway Island State Park, Tybee Island, Little St. Simons Island and Little Cumberland Island.
Extensive monitoring
Lambert said each of Georgia’s living shorelines have been adapted for slightly unique geographic characteristics in the coastline to account for differing water flows, shape and size, as well as the history and use of the site.
Ongoing research is underway at the sites by the University of Georgia Marine Extension and Georgia Sea Grant, DNR’s Coastal Resources Division, the College of Coastal Georgia and The Nature Conservancy in Georgia to assess the resiliency and environmental benefits of living shorelines.
One of the most vivid examples of their resilience is that they survived flooding and heavy winds from Hurricanes Hermine and Matthew in 2016 and Hurricane Irma in 2017, according to Coleman. “We didn’t notice any significant impacts from any of the storms, which is pretty remarkable,” he said.
Research has also found that living shorelines provide habitat benefits. Scientists with The Nature Conservancy and UGA Marine Extension and Georgia Sea Grant observed 43 different species of fish and seven species of crustaceans at the living shorelines on Little St. Simons and Sapelo Island, finding that they help increase species abundance and diversity.
Lambert said she thinks one of the key environmental attributes of living shorelines is that by using natural materials, they create connectivity between species in water, species on the oyster reefs and species on land. She said this can provide a clear path for otters, alligators and other species to migrate to higher ground as sea levels rise.
Future development
While the benefits of living shorelines are well-documented, methods for installing them are still being developed and refined.
One needed area of improvement: The bags that hold the oyster shells are made of plastic. Researchers are continuing to look into a material to hold the shells that isn’t plastic, but won’t deteriorate when placed along the shoreline.
For now, Georgia’s existing living shorelines provide a wealth of scientific exploration. At Cannon’s Point, students from the College of Coastal Georgia are studying the number of oyster larvae that are permanently attaching themselves to available oyster shells.
There are also hopes to develop more living shorelines along the coast, with one currently planned for the Honey Creek center in Waverly. A children’s book about living shorelines and oyster reefs is also being developed, in hopes of educating children and their families about the technology.
“We want it to be the first option, before thinking of bulkheads or seawalls,” Lambert said. “Not only do you have the erosive benefits, the habitat benefits and all the other benefits, but they’re also just beautiful to look at.”
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