Pilot Oyster Reef Restoration Projects in Cape Romain National Wildlife Refuge
Joy Brown1, Peter Kingsley-Smith2, Ben Stone2 and Lowell Atkinson3
1 The Nature Conservancy, 2 SC Department of Natural Resources, 3 College of Charleston
2009 Sites
Jeremy Island/AIWW
Restoration Method: Oyster castle clusters
(13 units to a cluster)
Reef Dimensions: Each of the eight individual clusters
measures 3 feet wide, 3 feet long, and 2
feet high; clusters are separated from
each other by approximately 3 feet.
Install Date: July 2009
Jeremy Island/Casino Creek
The Value of Oyster Reef Restoration
2011 Sites
The Eastern Oyster has been called an ‘ecological engineer’ because of the vital role it
plays in coastal and estuarine habitats. Among the many benefits they provide, oysters –
through the formation of beds, flats, and reefs - have a positive impact on fishery support,
water quality, shoreline stabilization and storm protection. Self-sustaining oyster reefs
provide a source of refuge and food for over 130 marine species – including finfish and
shellfish - and therefore can help sustain commercial and recreational fishing harvests.
Also, a single oyster is capable of filtering nearly 50 gallons of water every day; in doing so,
they decrease the amount of suspended solids, excess nutrients, and contaminants found
in surface waters which improves the overall quality of our estuarine waters. Last, large
oyster reefs can decrease the force of waves approaching coastal and estuarine shorelines
and can therefore protect marsh environments from harmful storms, seasonal floods, and
boat wake while also stabilizing the shoreline.
Jeremy Island/AIWW
Restoration Method: Oyster castle segment
(contiguous group of clusters)
Reef Dimensions: The one segment measures roughly 50
feet long, 3 feet wide, and 2 feet high. This
reef was installed as an expansion to the
2009 AIWW reef.
Install Date: September 2011
Restoration Method: Oyster castle clusters
(13 units to a cluster)
Reef Dimensions: Each of the eight individual clusters
measures 3 feet wide, 3 feet long, and 2
feet high; clusters are separated from
each other by approximately 3 feet.
Install Date: July 2009
Jeremy Island/Skrine Creek
Restoration Method: Oyster castle segment
(contiguous group of clusters)
Reef Dimensions: The one segment measures roughly
50 feet wide, 3 feet wide, and 2 feet
high. This reef was installed an
expansion to the 2009 Skrine Creek
reef.
Install Date: September 2011
Jeremy Island/Skrine Creek
Restoration Method: Oyster castle clusters
(13 units to a cluster)
Reef Dimensions: Each of the eight individual clusters
measures 3 feet wide, 3 feet long, and 2
feet high; clusters are separated from
each other by approximately 3 feet.
Install Date: July 2009
2012 Site
Palmetto Plantation/AIWW
Restoration Method: Oyster castle segment
(contiguous group of clusters)
Reef Dimensions: The one segment, which is the largest
reef installed to date, measures roughly
60 feet long, 6 feet wide, and 3 feet high.
Install Date: July 2012
Tibwin Creek
Restoration Method: Bagged oyster shell mats
Reef Dimensions: The oyster mat measures 30 feet long,
10 feet wide, and roughly 1 foot high.
Two additional installations were required
to raise the reef to a suitable elevation.
Install Date: April 2009
Restoration Methods
Oyster Castles
Results: What do we know so far?
For all seven pilot projects conducted thus far, the success of the installations are being determined by the
project’s ability to: increase oyster reef habitat in the area, create good conditions for vegetative marsh growth
behind the reefs, and reduce erosion of the marsh bank adjacent and parallel to the reefs. So far, only the 2009
reefs have been thoroughly monitored over a period of two years, and analysis of these reefs show the following
results:
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•
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Oyster castles do provide a firm substrate that supports the development of a functioning
oyster reef habitat that could eventually become a self-sustaining reef system.
It was not confirmed that the 2009 reef projects had any measurable impact on reducing
erosion of the intertidal marsh.
It was not confirmed that the 2009 reef projects had any measurable impact on the growth
of marsh vegetation behind the reefs.
It is believed that the spacing between each castle formation explains the limited ability of the 2009 reef
projects to reduce erosion and promote marsh growth. These gaps separating each castle cluster allow
precious finer sediment and nutrients to escape the marsh bank instead of settling and assimilating to create
good conditions for marsh growth. In 2011, a new approach was adopted that utilized a single, linear
arrangement of oyster castles placed parallel to the waterline, and ongoing monitoring of those completed
projects should reveal that this configuration more effectively reduces bank erosion while promoting intertidal
marsh growth behind the reef structures.
Each oyster castle unit measures 12 inches wide and 12 inches high with a certain design that allows
multiple units to be stacked and interlocked into different configurations. An oyster castle consists of four
primary materials: limestone, cement, Pozzolan (micro-silica), and crushed oyster shell – a combination that
allows oyster larvae to attach to the structure and slowly grow into healthy, adult oysters. Over time, the
artificial reef structure – mostly made of cement and limestone – will gradually develop into a self-sustaining
oyster reef and a permanent addition to the intertidal marsh. As a relatively new approach, this technique has
been exclusively used in the Cape Romain National Wildlife Refuge and specifically Jeremy Island where its
effectiveness is still being monitored.
Bagged Oyster Shell Mats
Oyster shell - or cultch - can be found in large quantities along marsh banks and shorelines – especially in
the winter months, and effective shell recycling programs along the Atlantic and in the Gulf are being used to
build more self-sustaining oyster reefs in coastal and estuarine waters. To create an oyster bed or oyster reef,
recycled shells are packed into large mesh bags, which are then placed along the edge of the marsh or
coastline in rows; individual bags are typically secured to the marsh platform and to each other with steel rebar,
zip-ties, or other means. Over time, the mesh bags break down and disintegrate as new oysters grow and
create a self-sustaining reef structure. Bagged oyster shell mats represent a commonly used method for
oyster reef restoration that is common along the Atlantic and in the Gulf and have yielded proven results.
What are the next steps?
Through the use of linear oyster castle configurations, monitoring results should reveal that the oyster castles support
the surrounding ecosystem by creating good conditions for vegetative marsh growth, increase the overall area of intertidal
oyster reef habitat, and stabilize shorelines along the coast of South Carolina. However, alternative methods of oyster reef
restoration are being considered for future projects in Cape Romain National Wildlife Refuge and other nearshore areas,
and we hope to engage with any and all stakeholders as well as partners in other states to develop the best possible
techniques for effective restoration in the region. Ultimately, the success of these pilot projects will determine the long-term
feasibility of large-scale living shoreline projects along the South Carolina coast. By the year 2025, TNC hopes to work with
multiple partners and experiment with a variety of techniques to increase overall oyster abundance by 10% in the SeweeSantee-Winyah Bay Complex – an area vastly underrepresented by coastal and estuarine restoration activities.
Partners and Funding
Several organizations provided funding and support for the implementation of these reef projects including: Alcoa
Foundation, The Boeing Company, Coastal Expeditions, College of Charleston, National Oceanic and Atmospheric
Administration’s Community-Based Restoration Program (NOAA CRP), South Carolina Department of Natural Resources,
U.S. Fish and Wildlife Service (FWS), the Town of McClellanville, and the general public. Volunteers from partner
organizations as well as residents from the Charleston and McClellanville areas assisted with installing each of the pilot reef
projects. We acknowledge them for their generous support.