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Views from theTower AUTUMN 2024 | VOLUME 52 | NO. 3
Rehabilitating Drowning Marshes by Dr. Lenore Tedesco, Executive Director Salt marshes are an essential component that have fallen 2 to 3 feet below the ranges of coastal ecosystems, performing services for healthy marsh. The goal is to reestablish that benefit both wildlife and people. suitable levels of tidal flooding and allow They are among the most diverse habitats the marsh to flourish for decades to come, on Earth, rivaling coral reefs and tropical potentially offsetting sea level rise by more rain forests. They provide essential food, than 100 years. refuge, and nursery habitat for more than Placement area on Scotch Bonnet 75% of fish and shellfish and foraging Island, within the Cape May Coastal habitat for a variety of birds. Salt marshes Wetlands Wildlife Management Area remove carbon from the atmosphere and store it below ground, helping to reduce the impacts of climate change. Stone Harbor Blvd. There is also a lot of research that shows they absorb wave energy and reduce storm damage, protecting our coastal communities. A recent study showed that the back bay marshes of Ocean City reduce flood damages by 15% annually. We all also know they are majestic, calming, and beautiful. The Wetlands Institute With the documented loss of marshes right at the Institute (see Views From the Tower summer 2024 for info), we are taking action. Beginning in early October, the partnership of the U.S. Army Corps of Engineers (Philadelphia District), NJDEP, and The Wetlands Institute are initiating a beneficial use of dredged material project. Clean dredged sediment from the NJ Intracoastal Waterway will be used to increase the elevation of low marsh areas
Dredging will be in the vicinity of Nummy Island. A sand and mud slurry will be pumped though a floating pipeline and spread onto a section of marsh managed by NJDEP as part of the Cape May Coastal Wetlands Wildlife Management Area, just south of Stone Harbor Boulevard and adjacent to TWI. This placement will smother the existing marsh grasses, but the new surface is designed to be at appropriate elevations for new marsh grass colonization. Our experience on similar projects indicates that the muddy surface takes about one year to stabilize before it starts to recover. New grasses from the natural seedbank begin to grow in the second growing season. Planting does not seem to accelerate the recovery time of the placement areas; allowing natural recovery is typically the best approach.
We expect the construction phase to take 6-8 weeks, and have scheduled the project for later fall when there are much lower levels of wildlife usage of the marsh. This should help minimize short-term impacts while maximizing the long-term benefits.
Dredge material placement on Great Flats For the past several years, a large group of scientists and engineers have been planning and designing this project, and working to understand the marsh’s condition and needs. We have a strong commitment to monitoring and managing the site to ensure the best possible outcomes. This effort will provide important opportunities for natural resource managers, local municipalities, and state and federal partners to see first-hand how clean dredged materials can be used to rehabilitate drowning marshes. Stay up-to-date by scanning the code below, or visiting our website at wetlandsinstitute.org/scotchbonnet.
Channel dredging area, outlined in orange. Placement area is in white.
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