by Karen Knight | July 7, 2017
SHARK ISLAND – About a half mile from Avalon, marshes, which are a part of the New Jersey-Cape May Wetlands Wildlife area, have experienced a decrease in vegetation caused by:
* Rising sea levels
* Chronic pressure exerted by passing boats
Those 44 acres, which are home to oyster catchers, laughing gulls, egrets, herons, rails, and dowitchers, are experiencing a rejuvenation funded by a grant from the National Fish and Wildlife Foundation (NFWF).
The project to stabilize the green patches of marsh that act as a natural buffer against storms was made possible through a $3.4 million Hurricane Sandy Coastal Resiliency competitive grant from the NFWF. It covered design, planting, and monitoring.
In addition, the Army Corps of Engineer and the state Department of Transportation provided approximately $6.5 million in combination to implement the project.
“What has some environmentalists and state government officials worried is a decrease in the amount of marsh vegetation at wetlands near Avalon, Stone Harbor and Fortescue,” said David Golden, assistant director of New Jersey Division of Fish and Wildlife, “primarily caused by rising sea levels and chronic pressure exerted by passing boats. Without plants to hold the marsh in place, erosion accelerates, which in turn increases the risk of flooding in area coastal communities. Our project strives to increase the marsh elevation to an optimal range where vegetation, and the wildlife that depends on it, can flourish.”
The techniques that Golden and his team employed over the past three years is called “thin layer deposition,” which involves using recycled sand and salt dredged from navigation channels to boost the elevation of degraded marsh.
This approach clears waterways for boaters and is an economic way to reuse the sediments, most of which are lost from the marshes.
“Shark Island was selected because of its closeness to a dredging project already going on by the Army Corps of Engineers,” explained Jacquelin Jahn, project ecologist, GreenVest LLC, of Edison.
They along with the GreenTrust Alliance, the Nature Conservancy New Jersey, and Princeton Hydro were partners in the project.
By working close to an Army Corps’ dredging project, the marsh stabilization project was able to reuse dredged material to rebuild five marsh areas in the Intracoastal Waterway.
“The Nature Conservancy helped us to assess the sites, and we found that the pools of water in these marshes were expanding. Not only did this destroy the integrity of the marshes, but it was also destroying the nesting grounds of many of the birds and wildlife that are key to this area,” added Jahn.
To help contain the slurry that the Army Corps was dredging, the marsh project used 10-foot coconut fiber biodegradable logs for the perimeter.
The sediment was piped in and slowly built up so vegetation could grow through it.
“The thickness is important,” noted John Truscinski, coastal resilience manager, The Nature Conservancy New Jersey, “because you don’t want to block the plant growth. At four inches, the plants can grow through it. At eight inches, you have to replant everything, and that takes a lot longer.”
The Conservancy will continue monitoring the project, and Truscinski estimates that it will take five years before vegetation returns to the desired state. “It’s important to have the marshes because they slow down the effects of any major storm, like Sandy or Jonas, as we’ve already experienced,” he said. “We need to protect what we have so we have a buffer against flooding, wave energy and storm surges.”
To date, project coordinators have replenished 57.5 acres of wetlands across Avalon, Stone Harbor, and Fortescue.
The third project, in the Fortescue Wildlife Management Area in Delaware Bay, is not in a crowded area but is being closely monitored for the benefits to the communities of maintaining and improving the marshes.
For the most part, the work in the Stone Harbor-Avalon area was completed in February 2016, but the team will return this fall to remove some of the containment pieces that remain. They are seeking funds to extend their project further to continue monitoring its effectiveness.
“The work gives project coordinators the ability to examine the effectiveness of the thin layer deposition technique,” said Jahn. “The approach has already been used in other parts of the country, but this is the first time that experts and officials in New Jersey will be able to explore its viability, and potentially inform policies and regulations regarding its future use.”
(This article was published in the Cape May County Herald on July 7, 2017)