Learning from a living shoreline in Delaware Bay
An innovative project made possible by Hurricane Sandy resilience funding delivers results
A deep-freeze never looked so good to Danielle McCulloch Prosser.
As she scanned iced-over Delaware Bay from the New Jersey shore one day in January 2018, McCulloch Prosser saw structures protruding through its frozen surface.
Part of a unique “living shoreline” project off The Nature Conservancy’s Gandys Beach Preserve, the structures — breakwaters made of concrete and materials formulated to attract larval oysters — were withstanding the frigid onslaught.
“Those breakwaters did not budge,” said McCulloch Prosser, a coastal biologist with the U.S. Fish and Wildlife Service, “and that was great news for Delaware Bay.”
Tackling erosion in Delaware Bay
That the breakwaters stood up to Delaware Bay’s extreme conditions is just one takeaway from the Gandys Beach “living shoreline,” a coastal resilience project that’s the product of collaboration by the Service, The Nature Conservancy in New Jersey, Partnership for the Delaware Estuary, Rutgers University’s Haskin Shellfish Research Laboratory, Stevens Institute of Technology, and others.
The roughly 8.5-acre project was paid for with $880,000 in federal funds for Hurricane Sandy resilience distributed through a grant from the National Fish and Wildlife Foundation.
It includes long-term study of the breakwaters’ performance to guide communities, regulators, nonprofit organizations, and public agencies doing similar work. And it’s yielding a trove of information about how nature-based approaches can protect and bolster Delaware Bay and places like it.
“This is a living laboratory,” said Joshua Moody, restoration programs manager with Partnership for the Delaware Estuary, which is studying changes in plants and elevation at the site. “So many partners are working at this site, and there are so many different types of monitoring being done. What we’re learning at Gandys Beach radiates out to other projects, too.”
Mirroring nature
Unlike concrete seawalls and stone riprap, which degrade over time and can hinder ecological processes, nature-based approaches can help protect vulnerable locations while also maintaining a naturally sloping shoreline allowing ecological processes.
In the case of Gandys Beach, the project had two primary goals: stem erosion to protect vulnerable beach habitat for the threatened red knot, a migratory shorebird that’s federally listed as threatened, and bolster the wild oyster population in Delaware Bay.
To succeed, the project team members needed to consider many factors.
They needed hard structures that would withstand the intense wave energy at the site, while also attracting baby oysters and mimicking the role natural oyster reefs play in shoreline protection.
They also needed something inexpensive that could be placed in the water by volunteers, as the equipment needed to build and transport larger structures to the site was too costly.
Finally, it was critical that the chosen approach not hamper horseshoe crabs moving from Delaware Bay onto Gandys Beach to spawn. Red knots rely on the site as a resting and feeding spot during their spring migrations, and horseshoe crab eggs fuel these and other migratory shorebirds for their journey from the tip of South America to their Arctic breeding grounds.
The project team decided to use interlocking Oyster Castle® blocks to create a series of 10–foot by 30-foot breakwaters with gaps for wildlife passage along the site’s shoreline.
In 2015 and 2016, volunteers helped install the blocks along with bags of clam and oyster shells to protect about 2,750 feet of shoreline.
Seeing signs of success
Site monitoring soon got underway — with many positive early returns.
“We quickly saw a lot of natural oyster recruitment on the castles,” McCulloch Prosser said. “There are natural oyster reefs in Delaware Bay that provide oyster larvae that can adhere to nearby structures. If you build it, they will come.”
The survival rate for new oysters during the first three years after breakwaters were built was more than 75%, which McCulloch Prosser called “hugely successful.”
Critically, gaps between the breakwaters appeared to provide plenty of room for the horseshoe crabs to maneuver to the beach. The structures were also withstanding the extreme conditions of Delaware Bay.
Needing to adapt
Still, erosion remained a challenge.
To provide adequate oyster habitat, the breakwaters had been situated low in the intertidal area. This means they are submerged at mid-high tide, and, when underwater, they are not as effective at reducing wave energy.
Additionally, in one location near a small peninsula, Partnership for the Delaware Estuary found that erosion was, in fact, intensifying, damaging the beach.
The erosion near the peninsula needed immediate action, and following the principles of adaptive management, team members went through the steps of diagnosing the problem and adjusting to remedy it.
They brought in Sovereign Consulting, a firm with extensive coastal experience, to help.
Sovereign found that the breakwaters near the peninsula were increasing erosion because they were funneling wave energy along the edge rather than intercepting it. The firm offered a design alternative that relied on a series of smaller, pyramid-like structures, which they then installed.
There were almost-immediate signs of success: Sediment began to fill in near the peninsula only a few days after the changes were made.
Monitoring of the project will continue through 2022, and more fine-tuning may be necessary. Nonetheless, in fall 2020, the American Shore and Beach Preservation Association recognized this adaptive management project as one of three Best Restored Shores in the nation.
Building resilience
Although the work at Gandys Beach isn’t over, its many takeaways about living shoreline materials, site dynamics, permitting and more are seminal for New Jersey, said Adrianna Zito-Livingston, coastal projects coordinator for The Nature Conservancy in New Jersey.
Gandys Beach and other projects supported with Hurricane Sandy resilience and restoration funds have provided valuable hands-on experience with nature-based approaches, including living shorelines, to protect and restore vulnerable sites, she said. In particular, the project location adjacent to a preserve rather than critical infrastructure is a safe place to try such techniques without putting people and property at risk.
Importantly, the substantial increase in real-world experience with living shorelines has also helped address regulatory hurdles. New Jersey is editing its regulations to facilitate ecologically responsible shoreline protection.
Conventional solutions like concrete seawalls and stone riprap are no longer the only available option; there is an increasing number of cases where state regulators ask landowners to demonstrate why a living shoreline won’t work for sites before permitting a bulkhead.
In the aftermath of Hurricane Sandy, and because of major commitments of resources to restoration, the discussion about using nature to protect things that matter has changed almost completely, Zito-Livingston said.
“We’re now in a place where we’re regularly having conversations about nature-based solutions with communities,” Zito-Livingston said. “We’re not just telling them they need them; they’re coming to us for input on projects they’re already forming.
“I think that’s a strong measure of success.”
