Copying Nature:  Biomimicry in Oyster Reef Restoration

Posted 15 June 2016 by Carol Brighton

Nature has evolved a finely tuned system with solutions to most of society’s environmental problems.  Oyster reefs represent one of nature’s answers to a multitude of coastal concerns. In addition to protective and cleansing services, the reefs create an environment that supports fisheries, wildlife and carbon storing assets. Unfortunately, due to overharvesting and disease, natural reefs have been decimated and along with them, hugely valuable ecosystem services.

Nonprofit and government agencies led by the Army Corps of Engineers have mobilized oyster restoration efforts. There’s just one problem. There is a shortage of natural shell to rebuild reefs. According to Jim Wesson of the Virginia Marine Resources Commission, “the price of shell has tripled over the last five years.” With high demand for shell for oyster aquaculture and limited supply available, the VMRC recommends the use of artificial substrate for sanctuary reefs which are not harvested.  A new and unique reef material developed by an award winning Virginia architect and entrepreneur, looks to be a promising product to help fill the void.

Artificial Reef Emulates the Real Thing

Grow Oyster Reefs based in Charlottesville, VA is producing a substrate that mimics a natural reef in design and composition. As Evelyn Tickle founder of the company explains,  “I wanted to recreate the environment in nature that was so successful.” Through research and trials, she developed a shell-less, calcium enriched concrete mix that closely matches the composition of actual oyster shell.  With a surprisingly small amount of cement and no admixtures, she asserts her product is very clean and will biodegrade in about 20 years. Perhaps just as important, the mix is cast in a form that simulates the intricate and complex infrastructure of a natural reef. The square foot tiles interlock horizontally in mats and vertically in towers. In the company's only trial so far in the Chesapeake Bay, the product performed well, successfully colonizing oyster larvae through natural spawn (see image below).  Tickle has not nailed down a price for the engineered material, but she did indicate that it compared competitively with natural oyster shell. She is eager to partner with school programs and hopes to see her forms put to work close to home in the Bay watershed as well as further afield. Within a couple of years she envisions the deployment of mobile fabrication units to cast substrate on location at restoration sites along the country's coasts.

Grow Oyster Reefs' patent pending portfolio also includes a disk that can be incorporated into existing rock sills, jetties and armored shoreline. And the mix can be applied to existing seawalls and other marine structures to foster oyster colonization. With many urban waterways already armored by 50% and more, the ability to create oyster habitat in the developed marine environment offers real hope to restoring impaired waters. Tickle is working on stronger load bearing blends that could be incorporated into new infrastructure like bridge or other marine foundations.

TNC Summer Tile Tests

The product has caught the attention of a scientist at the Nature Conservancy. TNC is a pioneer in the land and marine conservation arena and a global leader in the field of oyster reef restoration. Jeremy Bell, Aquatic Habitat Restoration Manager for the TNC Maine office plans to test the tiles this summer. Bell is interested in the bivalve for its role in a “mosaic” of ecosystem services. According to Bell, “the Gulf of Maine is warming 99% faster than the global ocean.”  He's concerned that along with warming waters, the ocean is becoming more acidic while population pressure along the coast is contributing to other water quality issues. As a result, eel grasses are declining and fisheries are suffering. In particular, the clam industry has been hard hit. Not only are more acidic waters weakening shells, the warming has been accompanied by an invasion of green crabs that are devastating soft shell clams. And with the crash of this fishery, the second most valuable in Maine, there are major economic impacts. Oyster culture offers the potential to offset some of these effects.

Bell initially planned to install 64 of the square foot tiles but has doubled the order. The objective of the installation is to evaluate set and cultivation methodologies for the cold Maine waters and identify successful products for more substantial endeavors in the future. The tiles will be deployed near Phippsburg along with other artificial reef substrate covering a total of 1000 sq. feet. Bell notes that the project represents the first man-made oyster restoration project in the state. No natural shell is being tested this summer as acquired product must cure to remove disease before it can be reintroduced in a reef. Next summer Bell plans to introduce some natural shell to see how it performs compared to the artificial substrate.

As demonstrated elsewhere, oyster reefs not only provide a potentially viable economic product, they support forage and commercially sought species while improving water quality and buffering waves and acidity. The living structures can also grow along with rising sea levels and protect shorelines from erosion while supporting “blue carbon” assets:  The huge amount of carbon locked away in seagrass beds and salt marshes.

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Read more about blue carbon and ecological services in these TidewaterCurrent.com posts:

The Climate Cure

Nature at Work: Building Ecological Infrastructure

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