Slideshow: Half Moon Reef
See how this innovative oyster reef is being constructed
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 futures are intertwined with the Gulf: Texas, Louisiana, Mississippi, Alabama and Florida. That’s why The Nature Conservancy has restored Half Moon Reef, an underwater oyster colony in the heart of Texas’ Matagorda Bay.
The 54-acre Half Moon Reef is the first reef the Conservancy has constructed from the ground up and one of the largest restoration projects around the country, said Boze Hancock, research scientist for the Conservancy’s Global Marine Team.
It is also sub-tidal (fully submerged underwater) and designed to maximize structural complexity. A more diverse structural habitat leads to differently sized niches, which attract not only oysters, but also a variety of fish, shellfish, small invertebrates and sea turtles; that, in turn, ensures a healthy, thriving Gulf ecosystem. “We are not [just] restoring oysters, we are restoring habitat,” Hancock said.
Early results have shown this complex design is working. According to Mark Dumesnil, associate director of coastal restoration in Texas, Half Moon Reef is showing “phenomenal colonization and marketable-sized oysters.” Scientific monitoring crews have also noted a high level of biodiversity in and around the reef.
“It has not only met our expectations, it has exceeded them,” Dumesnil said of the restoration project.
Jumpstarting Coastal Resilience
In the 19th century, there were extensive oyster reefs throughout the various bays along the Texas Gulf Coast, including Trinity, East and West bays, near Galveston. Soon enough, oyster shells became a popular construction material and people began to harvest them 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 dredging, 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 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—communities must learn to adapt as a changing climate brings rising sea levels and more intense storms. 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. Those breakwaters keep critical habitat for plants and animals intact.
Moreover, oysters are one of nature’s most efficient filtration systems. 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. With 40,000 gallons of water flows into Matagorda Bay every second, healthy oyster reefs are critical to keeping the Gulf ecosystem balanced.
The Conservancy completed the multi-phase project with grant funding from the Coastal Impact Assistance Program and guidance from the U.S. Army Corps of Engineers, which restored a 12-acre expanse of Half Moon Reef. KBR, Shell Oil and the Meadows Foundation contributed matching funds to help finance the project, which will provide a blueprint for upcoming restoration work in Galveston and Copano bays. Taken together, these projects promise to create fully functional marine habitats that will help restore the health and heritage of the entire region.