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Add To Calendar 25/02/2016 15:30:0025/02/2016 15:50:00America/ChicagoAquaculture 2016Coastal Bioengineered Reefs and Engineered Cage Culture to grow Eastern Oysters Crassostrea virginica for Food and Coastal Protection restoration   Versailles 3The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY

Coastal Bioengineered Reefs and Engineered Cage Culture to grow Eastern Oysters Crassostrea virginica for Food and Coastal Protection restoration  

Steven G. Hall*, Jeanne Steyer, Melody Thomas
 
Biological and Agricultural Engineering
Louisiana State University, Baton Rouge, LA 70803
 Shall5@lsu.edu

Oysters such as Crassostrea virginica are estuarine species, growing in reefs which may reduce wave energy.  Engineered reef structures and systems encourage growth of desired species, while reducing coastal erosion. A main cause of coastal wetland loss is relative sea level rise, which includes subsidence.  Structures which are emplaced to protect the coast tend to sink and degrade over time. An alternative design, bioengineered oyster reefs, use substrates which allow organisms to attach and grow. These oyster reefs then aid in coastal restoration by dissipating wave energy.

Examples of oyster reefs which were placed in the Gulf of Mexico off the coast of Louisiana include two reefs consisting of approximately 560 rings; 40 rings across, 7 rows, and 2 layers. These rings were 5 feet in diameter and 9 inches thick. During high tide the western reef is completely submerged, promoting the growth of oysters on the rings closer to the shore. The eastern reef's back rings remain out of the water the majority of the time, which allows for a more complete dissipation of the wave energy, however preventing oysters from overrunning the structure. Over time, oysters have grown on the rings, increasing the strength and size of the barrier. This phenomenon can help influence future structures to be more sustainable while providing substrate and breeding stock for nearby oyster culture. Data on oyster growth and strength shows enhanced growth and strength, and vertical accretion of the reefs.  

An alternative concept is to use longline culture to reduce wave energy.  Preliminary design analyses show that these systems can, when emplaced at 10 meter widths, parallel to the coast, reduce wave energy 10-20%. Each of these concepts combines the goals of maintaining habitat and protecting coastal wetlands while providing enhanced growth for oyster culture, resulting in enhanced coastal sustainability.



Figure 1. Two engineered reefs in western Louisiana grow oysters, protect and accrete land and allow plant growth. Reefs total about 200 meters end to end.
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