While oysters are one of the most delicious bivalves around, they are, more importantly, the unsung heroes of the Gulf of Mexico. They play a vital role in protecting our shorelines and the health of our oceans, and contribute tremendously to the economic vitality of the five states whose future is intertwined with that of the Gulf: Texas, Louisiana, Mississippi, Alabama and Florida. That’s why The Nature Conservancy is working to restore Half Moon Reef, an underwater oyster colony in the heart of Matagorda Bay, which is one of the most productive fisheries for blue crabs, oysters and shrimp in Texas. Once massive, Half Moon Reef today has little to no cultch—or fossilized oyster shell—material left.
While we’ve previously constructed new oyster beds and restored existing reefs along the upper and lower Texas coast, the 45-acre Half Moon Reef will be the Conservancy’s first reef constructed from the ground up. It’s also one of the largest restoration projects around the country, said Boze Hancock, research scientist for the Conservancy’s Global Marine Team.
The reef will be sub-tidal (fully submerged underwater) and designed to maximize structural complexity —a more diverse structural habitat leads to differently sized niches, which not only attract oysters, but a variety of fish, shellfish, small invertebrates and sea turtles. That variety ensures a healthy, thriving Gulf ecosystem. “We are not [just] restoring oysters, we are restoring habitat,” Hancock said. Once complete, Half Moon Reef will mimic an underwater karst system, characterized by niches, caves and passageways.
This type of restoration work offers the Gulf Coast a jumpstart of sorts: an individual oyster can filter around 50 gallons of water each day; a healthy one-acre reef filters approximately 24 million gallons of water daily. In other words, these reefs play a major role in building and maintaining coastal resiliency and enhancing and improving water quality. And with 207 estuaries and 30 major rivers draining into the Gulf—approximately 40,000 gallons of water flows into Matagorda Bay every second—oysters’ natural water filtration process becomes incredibly important in keeping the ecosystem healthy and balanced.
One thing is certain: Keeping the Gulf healthy is paramount for both nature and people. The Lone Star State has more than 3,000 shoreline miles of Gulf Coast bays, lagoons and estuaries, and nearly one-quarter of Texas’ population lives along the Gulf Coast. Literally millions of people across the state and around the country rely on the Gulf of Mexico. Consider this:
Moreover, the Texas coast provides critical stopover and nesting sites for threatened and endangered birds, sand dunes where endangered sea turtles nest and some of the most important fish and shellfish nursery habitat in the Gulf.
In the 19th century, there were extensive oyster reefs throughout the region’s various bays. Soon enough, oyster shells became a popular construction material and people began to harvest on a large scale. By the first half of the 20th century, oyster shells were a hot commodity and dredging intensified; in the process, millions of cubic yards of oyster shell were removed from reefs hugging the Texas coast.
After decades of commercial fishing and overfishing, the global oyster population was decimated. Roughly 85 percent of the world’s oyster reefs have disappeared since the late 19th century, with many once-bountiful reefs rendered functionally extinct due to overharvesting and other causes. Three-quarters of the remaining reefs are in just five locations in North America; of those regions, the Gulf of Mexico—which has lost about 50 percent of its reefs—is considered the last, best hope for full restoration of healthy oyster reefs.
“There aren’t many other projects, within [The Nature Conservancy] or otherwise, that are at the scale of Half Moon Reef. This is a really exciting trajectory in oyster reef restoration,” Hancock said.
Events such as 2008’s Hurricane Ike and the 2010 Deepwater Horizon oil spill crystallized the need for large-scale restoration. Coastal resiliency is vital—as our coastlines move and change over time and as climate change brings higher seas and more intense storms, communities need to continuously adapt. Oyster reefs are an integral part of that adaptation process. They serve as natural buffers against rising sea tides and hurricanes by forming breakwaters that protect shorelines and wetlands from erosion due to storm surge. Those breakwaters keep critical habitat for plants and animals intact.
The restoration of Half Moon Reef is financed in part by a grant from the Coastal Impact Assistance Program and matching funds from KBR, Shell Oil and the Meadows Foundation. Once complete, it will not only provide suitable habitat for oysters but a fully functional marine habitat, creating a micro-ecosystem that will help reclaim the health and heritage of the entire region.
November 20, 2013