Hi! I’m Emily Pierce and I’ve been interning at the Coastal Studies Institute with Dr. Lindsay Dubbs this semester. I had a lot of freedom when deciding the focus of my internship and eventually deciding to take on a project with the Pine Island Audubon Sanctuary here on the Outer Banks with the help of the director there Robert Fearn.
My goal was to use natural vegetation from the Pine Island shoreline and create some sort of experimental shoreline protection feature to help prevent erosion at a lower cost than most popular shoreline protection strategies. Because the Pine Island Shoreline is on the
Albermarle Sound with shallow waters and changing wind patterns, the main cause of erosion is the frequently changing water level; in order to target this problem, the first step was to plan and research protection measures that can move with the changing water level.
After a lot of literature review and consultation with Lindsay, I decided to model my project after a floating breakwater structure, but mine would be made out of bundles of natural vegetation like cordgrass. Because there was such little precedent on using bundled vegetation for erosion protection, I also wanted to conduct floatation and decomposition experiments to get an idea of how feasible and long lasting a protection measure like this would be.
With some help from Lindsay, Lab technicians Claire and Ted, and my peers I was able tocollect cordgrass from Pine Island on several occasions to be used for creating bundles and testing floatation and decomposition over time. The Vegetation was bundled into rolls about 30 centimeters in diameter and 3 meters long using natural twine. Test bundles
Photo by Brett Wells
were placed into the water off the dock at the Coastal Studies to start the floatation study. It became clear that the bundles wouldn’t be able to float for extended periods once being waterlogged, so we decided to add two pool noodles as core for each bundle.
Bundles were placed at two locations on Pine Island, one receiving north eastern winds and the other receiving south western winds, on October 23rd. Bundles were placed using steel stakes and secured with rope so they were able to float. In order to measure the success of the protection measure PVC pipe was also placed in front of and behind the bundles to be used a reference point for measuring sediment accretion. The distance between the bundles and the shoreline was also measured to help provide a reference for determining success of the bundles in preventing erosion.
When the bundles were placed at Pine Island, water was also collected from the sound to be used in the decomposition study. In order to determine how long the grass can function and what it produces as it decomposes, subsamples of cordgrass in sound water, just sound water, and distilled water were placed in separate glass containers and subjected to environmental conditions using an incubator. Small amounts from each sample are being filtered periodically to get data on total organic carbon and chlorophyll A.
While its likely that I won’t be able to make far reaching conclusion on the success of using vegetation bundles as a shoreline protection measure before the semester ends, my project does represent a unique approach that could provide some interesting information for the future of shoreline protection.
I’d like to extend a big thanks to Lindsay for not only hoping to guide me through this project, but also for introducing me to joys of field research and the beauty of an imperfect process from start to finish. While it of course comes with frustration, working on something that has little prior research or application is absolutely an exciting experience that I’m ever grateful for.