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‘Living shorelines’ use oyster shells and marsh grass to reverse coastal erosion

Americans who live along coastlines are watching their land disappear and property threatened as climate change causes sea levels to rise. While homeowners often rely on expensive seawalls and bulkheads to slow the erosion, a growing number are building “living shorelines,” which can reverse its effects. Hari Sreenivasan reports from Florida in partnership with Climate Central as part of our ongoing series “Peril and Promise: the Challenge of Climate Change.”

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  • HARI SREENIVASAN:

    On a muggy summer day, almost a dozen workers and volunteers form a bucket brigade. They pass 20 to 30 pound bags of trucked in oyster shells onto waiting rowboats.

    Then they transport them down the shore, piling the bags strategically in the shallow water next to the marsh.

    About 200 bags of oyster shells are used to build each 20 foot artificial reef, a form of green infrastructure known as a living shoreline.

    Rachel Gwin is the restoration coordinator for the Choctawhatchee Basin Alliance, or CBA, a nonprofit environmental organization building this living shoreline at a waterfront home on Florida’s panhandle.

    So without these reefs, what’s happening to this shore?

  • RACHEL GWIN:

    Without these reefs, this marsh area, which is a really good, healthy salt marsh, it would just eventually keep eroding.

  • HARI SREENIVASAN:

    Traditionally, seawalls, built of concrete, wood, or hardened plastic have been used to lock shorelines in place and prevent erosion. A living shoreline is an alternative, which protects the land behind it from erosion by reducing the wave energy. As the waves are knocked down by the artificial reef, sand and other sediment is trapped behind it, rebuilding the shore, and allowing vegetation to grow.

  • RACHEL GWIN:

    With the living shorelines – each site is different, especially with the sediment movement if it’s sandier or silty – but you could start to build back shoreline. And with the marsh grasses growing out, it can help reclaim a bit of your shoreline while stabilizing.

  • HARI SREENIVASAN:

    So all this is new?

  • JENNIFER MCPEAK:

    All of it is new in the last two-and-a-half years.

  • HARI SREENIVASAN:

    On the other side of the bay, homeowner Jennifer McPeak’s property has been transformed since the CBA installed a living shoreline.

  • JENNIFER MCPEAK:

    Prior to having this protection, this whole shoreline was scrubbed clean. It was just sand. There wasn’t one blade of vegetation on the entire length of the shoreline. And that was making the erosion far worse.

  • HARI SREENIVASAN:

    You’re watching your land your backyard disappear?

  • JENNIFER MCPEAK:

    We were watching our biggest investment fall into the ocean. Yes.

  • HARI SREENIVASAN:

    McPeak and her husband wanted what many of their neighbors had: a seawall. They even started the process of getting a permit from the state’s Department of Environmental Protection, or DEP.

  • JENNIFER MCPEAK:

    We had signed on the dotted line we’re putting in a seawall. And the representative from the DEP said, “have you ever heard of a living shoreline” and I said no. She said, “well contact these folks over at the Choctawhatchee Basin Alliance and ask them about it because I think you guys would be a really good candidate.”

  • HARI SREENIVASAN:

    It took almost a year to get the permits from the state and federal government to build the living shoreline. And it cost about $3,0000 – about a quarter of what an 80 foot seawall would have. The CBA subsidizes the cost with grants, labor, and oyster shells, which are collected from local restaurants.

    Are you surprised at how fast it’s taken?

  • JENNIFER MCPEAK:

    Shocked. shocked. We just had to protect the shoreline a little bit to give a chance for these grasses to gain a foothold and with it all this life and that’s been the biggest thrill for us. This isn’t just grass and some reefs, this thing is teeming with life.

  • HARI SREENIVASAN:

    The bags of oyster shells create a whole new habitat. Research shows that living shorelines attract more marine life and plants than seawalls.

    What kind of things do you see here?

  • JENNIFER MCPEAK:

    Oh my gosh. Every kind of crab you can imagine. We’ve got hermit crabs, stone crabs, blue crabs, fiddler crabs, marsh crabs. I sound like that guy from Forrest Gump with the shrimp, but it’s me with the crabs!

  • HARI SREENIVASAN:

    McPeak’s living shoreline is one small example of what’s been tried on a larger scale to protect shorelines all around the gulf.

    Here in Pensacola, Florida, just like the rest of the Southeast, or much of the Eastern seaboard, coasts have to deal with large storms and hurricanes. But there’s a growing body of research that suggests living shorelines, like this one, are more resilient through storms than hardened shorelines like seawalls.

  • DARRYL BOUDREAU:

    It looks today as good, if not better, than before the hurricane.

  • HARI SREENIVASAN:

    Darryl Boudreau is the watershed coordinator for The Nature Conservancy. He showed us a 30 acre living shoreline project in downtown Pensacola called Project Greenshores. The first part was completed in 2003, one year before Hurricane Ivan hammered the region.

  • DARRYL BOUDREAU:

    Hurricane Ivan was a Category 3 hurricane. It was basically a direct hit. It washed away the road on I-10, further up the bay that’s how powerful that storm was. But the road behind Project Greenshores was really not damaged

  • HARI SREENIVASAN:

    The experience with Project Greenshores in Pensacola is not unique. In North Carolina, researchers documented how living shorelines like this one were barely damaged after Hurricane Irene in 2011. While about 100 yards away, this hardened shoreline had to be completely replaced.

    And then there’s sea level rise. Climate Change is expected to push seas in this region up between two and five feet over the next 80 years.

  • We’ve got two different strategies to deal with sea level rise:

    got a solid wall and you’ve got this marsh. What’s going to do better?

  • DARRYL BOUDREAU:

    I would say over time the marsh is going to do better. The seawall is sort of a fixed point. So it’s a fixed height. It’s a fixed location. With sea level rise,the water levels are going to increase. And the only way to adapt a hardened structure is to come back with a higher structure.

  • HARI SREENIVASAN:

    Project Greenshores was funded by the federal government, the state, and private sources, including the local utility provider. Another phase of the project is currently being developed using money from the BP oil spill. Boudreau says it was designed to be an example of what a living shoreline could be.

    But with more than 14,000 miles of the nation’s nearly 100,000 miles of tidal shoreline already hardened with infrastructure like seawalls, living shorelines currently represent a tiny fraction of America’s coasts.

  • DARRYL BOUDREAU:

    It takes educating the community, because they see a softer solution they just say how does that protect it? But once they have it put into the neighbor’s house and they say hey their property is not eroding. And look at the wildlife that this attracts. That’s how you get that change and you win people over.

  • HARI SREENIVASAN:

    So seeing is believing.

  • DARRYL BOUDREAU:

    Seeing is believing

  • JUST CEBRIAN:

    We don’t have the research that shows us how to do it all, yet.

  • HARI SREENIVASAN:

    Just Cebrian is a marine ecologist with the Dauphin Island Sea Lab and the University of South Alabama.

  • JUST CEBRIAN:

    So that’s Dauphin Island, right there…

  • HARI SREENIVASAN:

    He took us to a living shoreline project by an uninhabited barrier island off the coast of Alabama. Funded with money from the stimulus plan in 2009, researchers installed bagged oyster shells, but also a commercial product known as ReefBLK – a metal triangle filled with oyster shells. And concrete Reef Balls, like these, which are submerged under water.

    Cebrian says fish and marine invertebrates love the habitat, but none of the reef designs have completely prevented erosion. The reefs are too far from the shoreline.

  • JUST CEBRIAN:

    We are still losing the shoreline very quickly.

  • HARI SREENIVASAN:

    However, at a nearby site, the state and the federal government funded this project to install these trapezoidal concrete blocks to help rebuild a narrow peninsula damaged by Hurricane Katrina. Since the nearly one mile of artificial reef was installed in 2010, the shore has grown dramatically, creating a vibrant ecosystem.

  • JUST CEBRIAN:

    So it’s a very healthy environment. We have documented that oysters can settle here. And also a lot of birds will come over to hang out here as well. And also there’s a lot of fish that come to these blocks because they find a structure. So all in all, combining marshes with pyramids is a very effective way to create living shorelines

  • HARI SREENIVASAN:

    And there’s a lot of research behind this. Before these concrete pyramids were deployed in the water, they were tested here, at a wave pool at the nearby University of South Alabama. Engineers tested scale models of the design. Here they can adjust the size and frequency of the waves to simulate real world conditions.

    Bret Webb is a professor of coastal engineering and has consulted on dozens of living shorelines on the Gulf Coast.

  • BRET WEBB:

    The testing allowed us to say, number one, that that the original size structure would not really work well for that site, that they were going to need to be a little bit bigger. The other thing that allowed us to say is we don’t need three rows of these structures, we could just have two rows.

  • HARI SREENIVASAN:

    Webb says researchers, including engineers and ecologists, are still figuring out what works. And that one size does not fit all. Even with customization, Webb says, living shorelines are not appropriate for all waterfronts.

  • BRET WEBB:

    There are also certain cases where somebody just absolutely needs vertical, you know, structure. Along city waterfronts and things like that where you’ve got wharfs and marinas or maybe ports and harbors, going to a natural shoreline there is really somewhat counterproductive.

  • HARI SREENIVASAN:

    But back on the banks of the choctawhatchee bay in florida, oyster reef living shorelines like this one have been very effective at protecting land from erosion and building natural habitat. as a final step, the team plants supplementary grass along the shore.

  • BUTCH RICHARD:

    Fishing is going to get good out here…

  • HARI SREENIVASAN:

    Homeowner Butch Richard, a retired Air Force pilot, is optimistic the shore on the far side of his property will start to build back up after years of erosion.

  • BUTCH RICHARD:

    Once you get that grass going, and going into the water, towards the water, then you’re making big progress

  • HARI SREENIVASAN:

    The CBA has built more than two miles of living shorelines around the Choctawhatchee Bay. And the group says the idea is gaining traction; there is currently a one year long waiting list to have an oyster shell living shoreline installed.

Editor’s Note: Peril and Promise is an ongoing series of reports on the human impact of, and solutions for, Climate Change. Lead funding for Peril and Promise is provided by Dr. P. Roy Vagelos and Diana T. Vagelos. Major support is provided by Marc Haas Foundation.

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