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Gulf Oysters: A National Treasure, Providing Natural Defenses
When people on the Gulf coast think of an oyster, what immediately comes to mind are the big, juicy blobs on the half-shell. But oysters are not just a delicious treat—they are also incredibly important for the health of the Gulf and its economy.
Unfortunately, it is estimated that oyster reefs have declined by as much as 90 percent globally for a multitude of reasons, including overharvesting, dredging, and changes in the quality, quantity and timing of fresh water flowing into coastal estuaries where oysters live. Today, the Gulf of Mexico is one of the few places in the world where there are enough wild oyster reefs to support a significant harvest. But even in the Gulf, oyster reef losses have been significant— more than 80 percent in parts of Mississippi and Alabama.
Here are some of the great things that oysters can do, and why NWF recommends restoring oyster reefs in the Gulf of Mexico—and elsewhere:
Oysters improve water quality
An adult oyster can filter as much as 50 gallons of water per day, both improving water quality and clarity. Two of the most common pollutants in U.S. waters today are nitrogen and phosphorus—largely the result of fertilizer runoff and wastewater. These nutrients cause phytoplankton to bloom rapidly and then die—using up oxygen in the water, and creating problems for many species of wildlife. Oyster reefs filter these problematic nutrients out of the water at high rates.
In places like Galveston Bay, it is estimated that a 130-acre oyster reef, containing 10 oysters per square meter, could filter about 260 million gallons of water per day—that’s more than all of the city of Houston’s 39 wastewater treatment plants put together in 2009!
In the Gulf, we support creating new oyster reefs in places like McKay Bay in the Tampa area, where stormwater and wastewater currently degrade water quality.
Oysters provide habitat for fish and wildlife
Hundreds of species of wildlife use oyster reefs, including fish, shellfish, and birds —which means these habitats rival salt marshes and seagrass beds in terms of their wildlife density and diversity. In fact, oyster reefs are so important, that building new reefs can actually increase the number of fish and crustaceans in an area. In one example, just 3.5 miles of newly-built oyster reefs resulted in nearly 7,000 pounds of additional fish and shellfish caught annually.
In places like Louisiana’s Biloxi Marsh, oyster restoration efforts are being designed that will protect nearby marshes from erosion—critical in an area with some of the high rates of wetlands loss in the world.
Oysters protect shorelines
Oysters reduce the energy from waves, boat wakes, and storm surge, creating calmer waters that protect other important habitats, such as marshes and seagrass beds. Oyster reefs have a unique benefit over traditional hard infrastructure such as seawalls, in that they can actually grow to keep up with, and in some cases outpace sea level rise.
In Mobile Bay, where more than 80 percent the bay’s oysters have been lost, the 100:1000: Restore Coastal Alabama partnership is rebuilding 100 miles of oyster reefs along the coast, which will in turn protect more than 1,000 acres of coastal marsh and seagrass.
Oyster reef restoration projects like those mentioned above will be necessary to reverse the downward trend in oysters across the Gulf of Mexico and to restore the health and resilience of the Gulf ecosystem.