Building Castles to Fight Sea-Level Rise

No, we’re not talking about putting up walls and towers and turrets.

We’re talking about building homes for baby oysters. (Awww.) Out of LEGO-like cement blocks.

Sounds like everything is awesome, doesn’t it?

Well, not quite.

A completed array of oyster castles at Chincoteague NWR. Credit: TNC.

In the mid-Atlantic region, water levels are rising at rates three to four times the global average for sea-level rise. Places like Chincoteague National Wildlife Refuge (NWR) and the entire Virginia coast are smack in the middle of this zone.

One innovative and natural method for combating the impacts of sea-level rise is to build oyster reefs to help buffer waves and create a better marine habitat.

Volunteers and project partners have been doing just that at Chincoteague NWR. Over multiple days in April and May, volunteers donned their waders and rolled up their sleeves to assemble thousands of cement blocks into oyster castles at two sites. These castles form the foundation of the oyster reefs.

Helping hands assemble castles to create oyster reefs at Chincoteague National Wildlife Refuge. Credit: Chelsi Burns/USFWS.

“The oyster reefs will provide natural benefits such as filtering water and nutrients and promoting sediment uptake, so they’re vital to our marine areas,” says Kevin Holcomb, USFWS wildlife biologist at Chincoteague NWR.

“But there is also growing scientific evidence that coastal habitats such as oyster reefs, tidal salt marshes and sea grass meadows can offer cost-effective risk reduction in the face of rising sea levels and future impacts.”

Watch a video of the project and see a photo slideshow (from Delmarva Now).

How does it work?

First, crushed oyster shells are laid down as a “bed” under the castle blocks. Oysters will settle on these beds and the spat (baby oysters) will cling to the castles, growing up the vertical columns. The castles weigh around 30 pounds each with windows for water to flow through. The whole system creates a functional habitat for oysters and other marine life, including fish like striped bass. And it provides a natural buffer to oncoming waves, reducing their impact on the shoreline.

Jenny Young hands of a castle block to Jenny Miller. Credit: Danny White/TNC.

When finished, there will be an estimated 1,400 feet of living shoreline oyster reefs at Tom’s Cove and 2,050 feet in Assateague Bay – two sites that were battered by Hurricane Sandy in 2012. (See photos of the damage.)

Using natural methods of coastal protection like oyster reefs, living shorelines and tidal marshes is a high priority for the USFWS. With $167 million in funding from the Disaster Relief Appropriations Act of 2013, USFWS is working on over 70 projects to restore areas hit hard by Hurricane Sandy and build in resiliency to help protect coastlines against future storms and the impacts of sea-level rise.

Our awesome partners in this work include The Nature Conservancy, the National Fish and Wildlife Federation, the National Park Service, the Virginia Department of Game and Inland Fisheries and the Virginia Marine Resources Commission.

Read a press release about the work.

Oyster spat. Credit: CSIRO Marine Research