Jeremy Island Oyster Castles
A series of new condominiums appeared recently along the shores of a tiny island in Cape Romain, and Marine Restoration Specialist Joy Brown of The Nature Conservancy couldn’t be happier.
In fact, Brown and some partner “architects” are responsible for the building boom. They’ve been working on a pilot project to erect castle-like structures ─ you might call them mini-condos for oyster larvae ─ to stimulate natural growth of threatened oyster reefs near McClellanville.
Constructed basically of recycled oyster shells and concrete, the “oyster castles” provide a hard surface to which microscopic oyster larvae, or “spat,” can attach and begin to grow their own reef structures. Without them, the “spat” can sink into the mud and die. This is a concern because nearly half of South Carolina’s oyster reefs have disappeared in the past century.
Oysters not only help the environment by filtering impurities from coastal waters, but they build important reef habitats for fish, shrimp, crabs, and other marine life as well. In addition, oyster reefs can help slow erosion and protect shorelines.
So last year on a breezy summer morning at low tide, Brown, officials from the S.C. Department of Natural Resources (DNR), and a group of TNC volunteers donned mud boots and gloves to place the roughly 25-pound shell blocks to designated sites for deployment around the marsh. DNR is under contract to monitor the castles and co-authored the grant that’s funding the project.
“We make assessments of the oysters that are living on the castles, and we do that photographically,” said Peter Kingsley-Smith, associate marine scientist for shellfish restoration and management with DNR’s Marine Resources and Research Institute. “We bring those photos back and put them into image analysis. We also are monitoring changes in the shoreline around the castles by comparing them to nearby control areas. That is to investigate whether these castles are protecting the shoreline from erosion.”
During the quarterly assessments, scientists also look for sediment changes. When they discuss oyster “recruitment,” it means new life added to the habitat.
“So far, oyster recruitment and growth have exceeded our expectations,” Brown said. “The castles at this point are almost completely covered. The goal is to get them back into a natural state. They are on their way to looking like that.”
Brown is optimistic about prospects for replication at compatible sites but cautioned that the success of any approach depends on very specific conditions that vary from environment to environment.
“I am looking at trying to do a project with oyster castles in Winyah Bay this year,” she said. “Winyah Bay is totally different from Jeremy Island. It’s an estuary with a different history of oyster population as well as pollutants. Each system has its own characteristics, and that influences how you approach the project.”
A related pilot project, launched last October, is the collaborative Oyster Shell Recycling Program. TNC, DNR, the U.S. Fish and Wildlife Service (USFWS), Fisher Recycling LLC, and the College of Charleston are working together with Charleston-area restaurants to keep discarded oyster shells out of landfills and, instead, return them to estuaries, where they can be put to good use restoring ailing reef systems.
Historically, oyster shells have been difficult to reclaim for reef restoration, forcing DNR officials for the past eight years to import, at considerable cost, about 40,000 bushels of shell per year from Texas and North Carolina. This project, funded in part by an $8,000 USFWS grant, is the first coordinated effort to target local restaurants as a source for shells.
“Oyster shells are an essential ecosystem in our marine environment,” Brown explained. “This project will allow us to reduce the amount of shell brought in from out of state that is used to replenish the oyster population in South Carolina.”
In the first four months of operation, the project garnered 48,500 pounds of shell from seven participating restaurants.