Photo by VA Institute of Marine Science. CC BY-NC-ND 2.0
Latin Name: Crassostrea virginica
Species: Marine Invertebrate
Conservation Status: Not Evaluated
Eastern oysters grow a lumpy, irregular oval shell that narrows at one end. The inside is smooth, shiny, and white, sometimes with a purple hue. Some shells grow as large as 8 inches long, but 3-5 inch shells are more common. In intertidal areas, these oysters grow in large clusters known as oyster reefs, which can have hundreds or thousands of oysters.
Range & Habitat (map)
Eastern oysters grow in brackish and salty water all along the eastern coast of the U.S. including the Gulf of Mexico and extending into Canada. While the appearance of oysters can vary in different areas along the coast, they are all the same species.
Diet
Oysters are filter feeders, meaning they pump water through their gills and trap particles of food like algae, detritus, and other plankton.
Life History
Oysters reproduce through broadcast spawning in the spring through fall. Sperm and eggs are released directly into the water column, and once fertilized, they become free-swimming larvae. After approximately a month, the larvae settle on a hard surface (often old oyster shells) and begin to grow into adult oysters. Once attached, oysters are sessile and do not relocate.
Significance
Eastern oysters are incredibly important to salt marsh ecosystems in the Port Royal Sound and are considered a keystone species (a species that contributes more to its habitat than its size indicates). One oyster can filter up to 50 gallons of water a day and this filtration plays a significant role in keeping our water clean. Oyster reefs serve as a habitat for many aquatic animals, and are also a food source for many animals- including people. Oysters also protect our communities by preventing shoreline erosion.
Threats & How You Can Help
While oyster populations in South Carolina seem to be relatively stable, there are threats facing oysters locally and globally. Habitat destruction impacts oyster reefs, as does the spread of oyster diseases. Overharvesting of oyster shells without returning old shells to the water can limit the hard substrate on which larval oysters settle. SCDNR’s SCORE (South Carolina Oyster Restoration and Enhancement) Program recycles old oyster shells back into the environment to form new reefs. Properly recycling your oyster shells is an important way to support the protection of oysters.
Additional Resources
https://score.dnr.sc.gov/