The eastern oyster is one of the most recognizable species in the Chesapeake Bay. Since the late 19th century, the oyster industry—including the catch, sale, shucking, packing and shipping of oysters—has contributed millions of dollars to the region’s economy and built a rich cultural heritage in the region. European settlers once reported that huge oyster reefs thrusting up from the Bay’s bottom posed navigational hazards to their ships. But the interaction of over-harvesting, disease, sedimentation and poor water quality has caused a severe decline in oysters throughout the Bay.
Because oysters contribute to clean water and healthy habitat, restoring the bivalves will be critical to restoring the Bay. Oysters are filter feeders; this means they feed by pumping water through their gills and removing plankton and other particles. As they do so, oysters also remove nutrients, suspended sediments and chemical contaminants, helping to keep the water clear and clean. One oyster can filter more than 50 gallons of water per day.
Oysters also provide underwater habitat in the form of aquatic reefs. With their many nooks and crannies, oyster reefs can create 50 times the hard surface area of an equally sized flat mud bottom. Hundreds of Bay creatures, including sponges, sea squirts, small crabs and many species of fish, need hard surfaces like those found on aquatic reefs to survive. In addition to providing habitat, oysters are a source of food for a host of animals.
In the late 19th century, the native oyster population could filter a volume of water equal to that of the entire Bay every three to four days; today’s depleted population takes nearly a year to filter the same volume. In 2010, the Chesapeake Bay Program adopted a tributary-based restoration strategy that will build, seed and monitor reefs in several Maryland and Virginia waterways.
It is important to note that the Bay’s poor health is not due solely to a diminished oyster population and, therefore, cannot be corrected by restoring oysters alone. Other pressures on the Bay—such as polluted runoff from farms, cities, suburbs and construction sites—must be addressed for restoration efforts to be successful.