Oysters: Guardians of the Coast


Live oyster bed, Broad Creek. Photo: Marianne Ballantine

MEET THE OYSTER—the humble, craggy Eastern Oyster. It’s the lowliest of the creatures that live in the shoals of Lowcountry salt marshes, tidal streams, and wide waters like Port Royal Sound, Calibogue Sound and May River. Submerged at high tide, exposed to the elements at low, oysters are among the most ancient species on earth. For 120 million years, of years, oysters have created valuable habitat for wildlife, from dolphins and migratory birds to the tiniest blobs and gobs of the marine world. And now, in this era of climate change, oysters are even more valuable to humans.



Oysters cluster together in dense colonies, also called “reefs,” “rakes,” or beds.” Here the oysters cement themselves to one another, forming craggy walls of shells between the high and low tides.  The millions upon millions of oysters feed on plankton (microscopic plants) filtered from the tidal stream. Oysters reproduce by shedding up to 500 million eggs per oyster in one season. Juvenile oysters, or “spat” settle on the reef and enlarge the colony. It soon becomes a living Mecca of life snails, crabs, starfishes, birds, fishes, and of course, more oysters.

Oyster reefs have been equally valuable to humans. Since the Archaic Indians migrated to the Atlantic Coast 5,000-8,000 years ago, people have consumed oysters. Early Native Americans built shell rings and mounds for ceremonial purposes. African Gullah slaves added oyster shells to the sandy coastal soil, providing lime needed for growing valuable Sea Island Cottonbefore the Civil War. In recent years, oysters have been the main course in Lowcountry seafood fests, and the bedding in many landscaping features. But now, our sturdy oyster reefs have an even more important job.

Sea Island Cotton. Photo: Marianne Ballantine









            Since the end of the last Ice Age about 20,000 years ago, global glacial ice sheets have melted and the sea level has risen over 400 feet along the South Carolina-Georgia coast. Scientists predict that due to climate change, the sea level will rise as much as 4 feet more by 2100. Forty-eight inches higher is a big deal in the flat-as-a-table Lowcountry. This event would significantly affect coastal development and people’s lives in the Hilton Head region. Yet, higher seas would really put pressure on our productive salt marshes—the cradle of all seafood. Sea level rise will slowly, but surely, alter tides, currents, and coastal erosion in inshore waters. Salt marshes thrive in a few inches of water, but would vanish when inundated by deeper water, more often, and for hours every day.

Could oysters save our great salt marshes? The answer is: Yes, there is still hope.

Oyster reefs withstand waves and flooding. Oyster reefs accumulate tons of sand and are the best defense for fragile wetlands. And oysters go with the flow—settling upstream according to the changing level of salt water.

Hilton Head Island and other Lowcountry communities can shore up their future by building new oyster reefs. It has been in South Carolina’s ACE Basin and the great Chesapeake Bay in Maryland and Virginia. Why not here? Hilton Head Island, Bluffton and our neighbor communities should build new living reefs in local waters to save the oysters, the ancient Guardians of the Coast.