The Delaware Estuary Living Shoreline Initiative (DELSI) was created to address the increased loss of tidal salt marshes in the Delaware Estuary. In 2008, PDE with Rutgers University developed the DELSI Tactic to help stabilize these eroding shorelines using a combination of native wetland plants, natural structures, and intertidal shellfish to trap sediment and absorb waves. This unique living shoreline tactic provides an economical approach for communities in the Delaware Estuary to combat the erosion of tidal marshes which provide valuable services. Tidal marshes act as the estuary's kidneys by filtering water. When waters rise, marshes act like sponges, retaining floodwaters and buffering against powerful storm surges. They also provide spawning sites, foraging areas, and nesting grounds to fish, birds, and animals.
Tidal marshes act as the estuary's kidneys by filtering water. They also provide spawning sites, foraging areas, and nesting grounds to fish, birds, and animals. And when waters rise, marshes act like sponges, retaining floodwaters and buffering against powerful storm surges.
-Identify shorelines within the Delaware Estuary experiencing erosion
-Apply the best existing living shorelines tactics using native plants and shellfish in our unique design
-Provide educational materials and workshops to agencies, land owners, and communities
How can mussels stabilize and restore shorelines?
Within marshes of the mid-Atlantic region, ribbed mussels (Geukensia demissa) collectively outweigh all other animals combined. Like many bivalve shellfish, they are referred to as "ecosystem engineers" because they have the ability to build their own habitats and transform the landscape for other species. They can form clusters as dense as hundreds per square meter. Ribbed mussels bind to the roots of vegetation which helps to hold the marsh together. The mussels filter food from the water and fertilize marsh plants. As the plants grow, they trap sediment, helping the marsh grow vertically. DELSI is attempting to take advantage of this unique "mussel power."
Where is DELSI being implemented?
DELSI living shorelines have been installed at: Matt’s Landing in the Maurice River, NJ; along Nantuxent Creek Road at Money Island, Downe Twp, NJ; along the Lewes/Rehoboth Canal, Lewes DE; Indian River Marina, Rehoboth, DE; and at the Dupont Nature Center at Mispillion Harbor, Milford, DE. Additional areas of interest are currently being evaluated for future installations.
How is DELSI being implemented?
Treatments consisting of coconut-fiber logs and mats were first deployed in 2008 in areas experiencing various levels and types of erosion. Tests revealed that the logs can persist over long periods of time in lower energy areas, and that mussels attach to the fibers of these products similar to the way they attach to marsh plants. Monitoring data has shown that the logs are able to trap sediment, increasing the elevation of the treated areas, and marsh grasses can flourish behind the logs. PDE currently monitors the performance of each treatment to determine which attracts the greatest amount of ribbed mussels and which has the most benefits for marsh plants. Additionally, hybrid tactics consisting of the current DELSI design being deployed in tandem with an off-shore breakwater for use in moderate to high energy environments are currently being studied.
If you would like more information about this project, please contact the Restoration Coordinator or call (800) 445-4935.