Oyster Reef Restoration
The Eastern Oyster (Crassostrea virginica) is native to the southeastern United States and lives in estuaries and marine coastal environments. The first stage in an oyster’s life cycle is the free-swimming larval stage. After about three weeks, the larva attaches to a hard substrate—surface area to attach to—such as prop roots, dock pilings, natural rock, and other oysters becoming an oyster spat—oysters that have just settled to the bottom. A large number of oysters often join together, thus forming an oyster reef (also referred to as oyster bed, oyster mat). Once attached to a surface, oysters will stay there for the remainder of their lives.
Oyster bed were an important resource for marine habitat and ecosystems. They provide a number of ecological, economical and recreational benefits to the environment and our lives. The Eastern Oyster acts as a keystone species by filtering estuaries and maintaining healthy, coastal ecosystems. Almost 95% of the seafood consumed in the United States spends a portion of its life in these estuaries. In addition, oyster reef also provide structured habitat in the form of refuge and hard substrate for a whole community of organisms. Without the oysters to solidify the benthic structure of the ecosystem, cascading impacts could cause large-scale transformations of oyster reef habits into unproductive shifting soft bottoms. This would result in significant changes in diversity and abundance of endemic marine species that were depending on the oyster reefs. Oyster reefs are able to survive in a wide range of reasonable salinity and temperature levels. Furthermore, oyster beds are efficient in filtering phytoplankton, pollutants, and suspended sediment from the water column. They consume nitrogen-containing compounds, and remove them from water. Oysters also limit the amount of phytoplankton in the water and improved water quality and other marine life. The oyster beds reduced competition and dissolved oxygen. On average, they filter about a gallon and a half of water per hour. Oyster beds further dissipate wave energy, acting as a breakwater, stabilize bottom sediments and reduce erosion. In the meantime, oyster reef improved the water quality, which increased recreation conditions for swimming, boating, surfing and sport fishing. According to the Southern Regional Aquaculture Center (SRAC), oysters in the southern part of the United States spawn when water temperatures are above 68 degrees. But they are affected more by the specific site where oyster restoration projects occur, the species of oysters used in a project, and if they are native to the surrounding area and disease free.
In addition to being a keystone species, oysters also serve as an indicator species—they are used to gather information on the overall health of the ecosystem. However, the majority of oyster populations have greatly declined within the last century due to over-harvesting, dredging, increased sedimentation, invasive species, pollution and disease. Preliminary field surveys revealed that native oysters are regularly reproducing and recruiting to local populations but suitable settlement habitat in the form of an oyster bed is lacking. In response to this decline, many oyster restoration projects have been put into place throughout the southeastern United States. The projects develop a long-term strategy of sustained productivity for oyster reefs and restore the ecological role they provide to nearby reef habitats.
The Nature Conservancy states that oyster restoration is crucial to creating a balanced, healthy ecosystem by being a beneficial nursery for various juvenile marine species, filtering impurities in the water, as well as preventing coastline erosion. Additionally, they contribute to better water flow patterns within estuaries.
As mentioned above, a common species of oysters used in oyster restoration is the Eastern American oyster (Crassostrea virginica), which is also called the American Oyster, Atlantic Oyster, Common Oyster, and Virginia Oyster. Since the early Americas, oyster beds have been beneficial for the Aboriginal North American Indians, who harvested oysters for subsistence purposes, and for the colonists that settled in the region. Since the 19th century oyster beds have been vital for commercial harvests and have generated substantial income. The oyster capital of the world was once New York City, where carts selling oysters were as common as hot dog stands are today. Unfortunately, there has been large declines of oyster beds in the coastal areas of the United States and around the world. It is estimated that more than 85% of oyster reefs are gone, making it the most threatened marine habitat in the world. Some reasons for this decline are overharvesting, dredging,filling and draining of wetland, pollution and other detrimental factors. As a result, this has spawned a need for oyster restoration projects in order to revitalize the depleted natural resource of the oyster population. There have been oyster reef restoration projects conducted in New York City for over five years and there is currently a plan to create 500 acres of oyster reefs by 2015 and 5,000 by 2050.
The first step in oyster restoration is to determine the locations for potential reefs. This is often done by comprehensive surveys that measure salinity levels, water quality, previous existence of oyster reefs, substrate conditions, prevalence of diseases, tidal range, oxygen concentration, algae concentration, prevalence of predators, accessibility and security.
Once the location is determined, cultch—fossilized shell, coral or other similar materials produced by living organisms designed to provide points of attachment for oysters—is often obtained from sustainable recycling programs. Used oyster and clam shells from farmers and restaurants are collected and disinfected by volunteers to be used in oyster restoration. Once returned to the water, these recycled shells provide substrate for oyster larval eggs to begin populating oyster beds laid out by volunteers programs such as those implemented in Southwest Florida, North Carolina, South Carolina, Georgia Southern California, and Alabama. The project will generate interest and excitement among community residents and environmental agency stakeholders, which will act as a catalyst for further expansion of restoration efforts.
The National Oceanic and Atmospheric Administration (NOAA) provide the following techniques for the construction of oyster reefs:
- Quickly distributing large amounts of shell with high pressure hoses to provide cultch for oysters. This technique work in areas that have known, reliable spat set.
- Constructing a linear reef of shell and rock to stabilize the shoreline while protecting sea grass plantings behind the reef. The grass plantings also enhance shoreline stability and provide additional habitat for organisms.
- Collecting and bagging oyster shells for use as cultch for spat set. Serving as habitat for oysters and other associated organisms, these bags of oyster shell will help establish new oyster reefs in intertidal areas.
- Using a hatchery to provide seed oysters in areas where spat set is nonexistent or unreliable. This will establish new reefs and improve water quality in the local area.
- Promote and implement a Public-Private Partnership to restore oyster beds in the Alamitos Bay. The aquaculture industry, public agencies, and environmental NGOs are natural partners for promoting the restoration of native oysters and their services. These groups could partner up to implement business plans to assist native oyster production that can be sold for market and in the process generate funds and seed oysters for habitat and population restoration.
- In order to reduce perverse incentives that make the restoration process more difficult, The Coastal Commission can implement a harvest moratorium on native oysters and an oyster industry compensation (buy out) program.
According to Anne Birch, director of The Nature Conservancy, creating an oyster mat is “a simple concept: [You] take a sheet of environmentally safe mesh, tie oyster shells to it and weight it to the bottom of the lagoon. Connected together, the mats then create a huge welcome mat to attract free-floating larvae. The larvae settle and produce the backbone of a new, healthy reef within as little as a year’s time.”
Commonly in the southeastern U.S., mangroves and other shoreline vegetation are often planted in conjunction with oyster restoration efforts to provide substrate – surface area to attach to – and reduce shoreline erosion resulting in less sediment deposits within estuaries.
Oyster restoration in public waters often requires permits and licenses from various agencies with requirements varying from state to state. Most often permits typically involve the U.S. Army Corps of Engineers, state natural resource agencies and state public health departments.
The desired outcome our organization hopes to achieve after evaluating numerous alternatives is to restore historic oyster reefs to produce a fully functioning, three-dimensional bed system that provides associated ecosystem services and biological functions, such as marine biodiversity, shoreline protection, sediment trapping, water quality improvement, and recreational fishing opportunities.
NOAA provides some of the major goals of an oyster restoration project:
- Augment commercial harvest
- Serve as habitat
- Improve water quality
- Increase or improve spat set in an area by creating oyster sanctuaries
- Maintain or increase biodiversity
- Restore ecological function
- Provide a barrier to prevent beach or shoreline erosion
- Protect and enhance sea grass restoration projects
As previously mentioned, intertidal oysters act as a keystone species by maintaining a healthy coastal ecosystem. They filter the water and increase water clarity by extracting organic and inorganic particles. The filtration capacity of an average adult oyster is estimated to be 50 gallons per day. Oysters not only clean the water, but also act as effective shoreline buffers by dissipating the energy caused by boat wakes and waves. Oyster reefs also support critical fisheries by providing habitat for numerous species of fish, crustaceans and shellfish.
The ecological value of reusing oyster shells for oyster restoration projects is vital not only for producing zero waste, but also for diversifying and increasing the number of oyster beds in a given area. In addition to environmental benefits, oyster restoration is also economically beneficial since coastal communities rely heavily on oysters for profit and subsistence.
Oyster beds provided a number of ecological, economical and recreational benefits to the environment and our lives. Oysters have been long recognized as an especially important component of a healthy and resilient estuarine ecosystem. This included providing structured habitat in the form of refuge and hard substrate for a whole community of organisms. Without the oysters to solidify the benthic structure of the ecosystem, cascading impacts on benthic could cause large-scale transformations of oyster reef habits into unproductive shifting soft bottoms. This would result in significant changes in diversity and abundance of endemic marine species that were depending on the oyster reefs. In addition, Oyster beds were efficient in filtering phytoplankton, pollutants, and suspended sediment from the water column. They consumed nitrogen-containing compounds, and removed them from water. Oysters also limit the amount of phytoplankton in the water and improved water quality and other marine life. The oyster beds reduced competition and dissolved oxygen. On average, they filtered about a gallon and a half of water per hour. Oyster beds further dissipate wave energy, acting as a breakwater, stabilize bottom sediments and reduce erosion. On the other hand, the most substantial economic benefits from oyster beds may result from harvest of other commercial species. Fishing, and agriculture harvesting have been employed by the local population for generations and it represented an important economic sources for Orange County. In the meantime, oyster beds improved the water quality which increased recreation conditions for swimming, boating, surfing and sport fishing. The water quality and habitat quality services result a boost in recreational tourism.
Environmental preventative issues
Some ancient reefs are used to make restorative oyster reefs in nearby sites. However, to reduce the risk of environmental damage when dredging, many projects tend to stay away from this method of transplanting. Another issue of environmental harm is placing invasive or newly introduced oyster species in an unknown habitat that can cause more harm than good. Therefore, it is important to correctly place oyster species in their respective habitats to prevent environmental harm to nearby oyster reefs. More information is available in local extension agencies within the state you live in.
Oyster reefs provide essential habitats for many ecological and economically important fish as well as invertebrate species. Healthy oyster populations improve the quality of water, which in turn improves commercial and recreational fishing, recreational boating, and ecotourism. All of these are beneficial to stimulating the economy for local communities. Not only does oyster restoration create additional jobs through the duration of projects, but it also safeguards many other jobs ranging from marine construction to scientific research jobs. Dr. Paul Zimba, Director of the Center for Coastal Studies at Texas A&M-Corpus Christi said, "Oysters are an important ecological and economic resource. They create habitats for fish and shellfish, filter and clean bay waters, protect shorelines from erosion, and are a valued commercial fishery element."
As stated earlier, oyster beds have been extremely profitable for commercial harvests in the 19th century; 10 million pounds per year were harvested during that time in the southeast alone. As a result, oyster restoration has become an important project in order to stabilize and stimulate economies in coastal communities of the United States. In addition to capitalistic economic profitability, there is a nature-based profitability for oyster restoration because they restore polluted waterways hindered by urbanization and other economic ecology issues.
The research in aquaculture has been a major contributor to the development of viable oyster strains to assist the commercial aquaculture industry and local ecosystems. The industry of aquaculture is booming with global profits exceeding $3,000,000,000 annually. Oyster restoration projects assist in the production of aquaculture harvests and have different procedural measures for different areas of the United States.
Aquaculture techniques vary geographically and represent regional differences. Some areas of the U.S. have enacted policies to lease out areas for aquaculture businesses to utilize the oyster-restored beds. These leasing policies will prove beneficial to job creation in coastal areas, improve the surrounding economy, and restore habitats where oyster restoration projects and commercial businesses occur.
All in all, aquaculture has and will continue to gain recognition for providing sustainable harvesting methods.
Oyster restoration has many recreational benefits. Improved water clarity and overall cleaner water greatly increases recreational fishing, boating and swimming. This allows locals and tourists to appreciate the environment around them.
In many parts of the southeastern United States volunteer efforts are responsible for oyster restoration. Community-based oyster restoration programs allow people to become knowledgeable on the important benefits oysters provide to an ecosystem. This volunteerism connects individuals with their environment as well as ensures the existence of oyster populations for future generations to appreciate. Areas of the southeastern United States, such as the coastal areas in the Gulf of Mexico, have a rich tradition related to oysters and other marine food that coastal areas provide. Oysters are part of the social culture in these areas and oyster restoration is a step towards preserving their traditions.
In addition to volunteering with oyster restoration projects, individuals with shoreline property—or those who have access to it—have the option of backyard shellfish gardening. This sustainable form of oyster harvesting allows for personal consumption or environmental enhancement and usually does not require special licenses or permits.
Specific examples in the southeastern United States
The Oyster Reef Restoration began in June 2009 and is expected to be completed by the fall of 2010. The project is funded by the National Oceanic and Atmospheric Administration (NOAA) as part of the American Recovery and Reinvestment Act of 2009. The goal of the project is to restore the important oyster habitat in the St. Lucie and Loxahatchee Estuaries, two of the largest brackish water systems on the east coast of Florida, where over the last 50 years oyster populations have declined by as much as 75%.
The Nature Conservancy recognizes the following partners who have or are currently working on oyster restoration projects:
- Brevard Zoo
- Brevard County Parks and Recreation
- Canaveral National Seashore Citizen volunteers
- Disney Friends for Change
- East Volusia County Mosquito Control
- Florida Coastal Management Program
- Indian River Lagoon National Estuary Program
- Marine Discovery Center
- Marine Resources Council
- Mosquito Lagoon Aquatic Preserve
- NOAA's Community-based Restoration Program
- Private donors
- RRI Energy
- Royal Caribbean Cruise Lines
- St. John's River Water Management District
- University of Central Florida
- U.S. Fish and Wildlife Service Coastal Program
Generating Enhanced Oyster Reefs in Georgia’s Inshore Areas (G.E.O.R.G.I.A.) is a volunteer-based program with the goal of enhancing stewardship and public awareness of oyster reef habitat along the Georgia coast, where previous oyster beds are essentially non-existent. The program recycles oyster shells from local seafood restaurants to use as cultch in new oyster reefs. Volunteers of the oyster reef building and monitoring are trained by the Marine Extension Service and building takes place every spring.
South Carolina Oyster Restoration and Enhancement (SCORE) is another volunteer oyster restoration movement. SCORE operates under the direction of the South Carolina Department of Natural Resources (SCDNR) and began in May 2001. The sites span approximately 200 miles (320 km) of the South Carolina coastline and have constructed 188 oyster reefs at 35 sites since the program began. According to SCORE’s website:
- Over 25,000 volunteer hours donated by more than 8,000 individuals
- Collected and processed more than 600 reef samples containing more than 300,000 spat in annual reef assessments
- Recycled and bagged over 20,000 bushels of oyster shell
- Returned more than 500 tons of oyster shell to the local waters by constructing almost 41,000 square feet (3,800 m2) of oyster reef footprint (about an acre)
- Approximately 25 teams of trained volunteers monitor water quality weekly at most sites
- Marsh grass is growing in behind many SCORE reefs
- SCORE received the prestigious Coastal America Partnership Award in 2004
The Eastern Oyster populations of the Tar-Pamlico and Neuse River basins have plunged 97% to 3% of historic numbers throughout the last century. In response to this drastic change, the Citizens’ Oyster Gardening Project (COGP) began. COGP is an environmental demonstration project that encourages oyster gardening aimed to reestablish populations of native Eastern Oysters in North Carolina through education and aquaculture methods. Educational workshops teach volunteers how to measure water quality and give information on oyster gardening techniques as well as necessary tools and materials. Advocacy through networking by volunteers is key to COGP’s success.
Project partners of COGP include:
- Carteret Community College’s (CCC) Aquaculture Technology Department
- Albemarle-Pamlico National Estuary Program (APNEP)
- Shellfish Gardeners of North Carolina (SGNC)
- The North Carolina Coastal Federation (NCCF)
- North Carolina National Estuarine Research Reserve Program (NCNERR)
- The Nature Conservancy (TNC)-Nags Head Woods Preserve
- North Carolina Sea Grant (NCSG)
- North Carolina Division of Marine Fisheries (NCDMF)
Southern California (Alamitos Bay, Orange County)
Oyster beds have suffered a large-scale depletion along the coast of Southern California. The EPA, Orange County Coast keeper and California Coastal Commission recognized that a large scale habitat restoration of oyster beds represented the primary means of improving degraded marine ecosystems. By this mean, they have asked Long Beach Management Group to assist in designing an oyster restoration project along the Orange County coast by utilizing public-private investments. The EPA authorized the disbursement of up to $89,100 to the Long Beach Management Group for the Alamitos Bay Native Oyster Restoration Project. The restoration of oyster beds in Orange County was hypothesized to have major positive effects on the resilience, biodiversity, and function of estuarine ecosystems. The long term goal was to protect and preserve all of Southern California's water bodies and restore them to healthy, fully functioning systems that would protect recreational uses and aquatic life.
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