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Green marsh grass and a spot of sand and shells

Salt marsh seen from the boardwalk
in the Town of Port Royal

Photograph by Dennis Adams
(August 7, 2002)

Marshes of the

Dennis Adams
Information Services Coordinator

Marshes of the Lowcountry

Information about our Tidal Ecosystem

Marsh Gallery
Photographs of St. Helena Island
by Michael Broam

Marshes of the Lowcountry

South Carolina has an estimated 400,000 acres of coastal marshes and 100,000 acres of tidal swamps. Beaufort County (with 335.98 square miles of water area vs. 587.03 land area) and Charleston County (with 439.72 water vs. 917.42 land) have the greatest share of salt marshes in the state. Tidal rivers (the Santee, Stono, Ashley and Cooper) feed brackish marshes upstream, and there are many tidal fresh marshes and swamps along the drainage basins of coastal rivers (Combahee, Savannah, Edisto, Pee Dee, Waccamaw, Santee, Cooper and Ashepoo). Hunting Island State Park and Pinckney Island National Wildlife Refuge (near Savannah) preserved areas of coastal marshland, as are Cape Romain National Wildlife Refuge in Awendaw, Edisto Beach State Park, Huntington Island State Park in Murrells Inlet, and Charleston’s Folly Beach County Park.

Spartina grass species (cord grass, salt marsh cord grass, and marram) are by far the dominant plant life in salt water marshes (which are wetlands, like swamps; in swamps, trees and bushes are most common, however). There are just a few species of flora in the marsh. According to Peter Meyer, "marshes are some of the most productive land on earth. Using photosynthesis, marsh grasses convert vast amounts of solar energy into plant tissue; as the grasses die, large nutrient loads are released into adjacent estuarine waters." These organic nutrients (ten tons per year) go on to feed perhaps 95% of the fish, shrimp and shellfish harvested in our ocean sounds and high seas.  
A long stretch of tidal mud and green marsh grass between Port Royal  Island and Lady's Island
Marsh seen from "The Sands" boat landing
in the Town of Port Royal

Photograph by Dennis Adams
(August 7, 2002)

Among the types of fish nurtured in the "marine-estuarine ecosystem" are croaker, drum, flounders, kingfish, menhaden, mullet and spot. Marshes have even served as grazing land for horses and cattle. They improve water quality (by sifting sediments, nutrients and other materials from flooding waters) and protect shorelines (by slowing currents and reducing erosion from the flowing water).

Marsh mud itself is made when rain and river water bring in topsoil that has run off from dry land. The silt follows the slower currents into steep banks of the tidal stream. With time, the ooze slows the channel flow. The marsh grasses then colonize the sediment fields (and are covered to some extent at high tide). Mr. Meyer wrote, "Marsh sediments are stabilized by spartina as much as sand dunes are stabilized by Sea Oats and Beach Grass. Spartina grows taller near the water’s edge, smaller near higher land." These grasses seldom produce any fruit.

The movement of the waves sometimes forms "beach balls" (spheres of marsh mud containing bits of sea shells), and clumps of "rusty mud" appear when iron within the mud starts to oxidize. "Swash lines" composed of tidal debris intersect the marsh flats after the water has ebbed out.

A marsh at low tide exposes a lot of mud
Marsh at Pigeon Point (City of Beaufort)
at low tide

Photograph by Dennis Adams
(August 7, 2002)
At the same marsh scene at high tide, water has completely covered the mud
The same scene at high tide

Photograph by Dennis Adams
(August 7, 2002)

Lowcountry mudflats, wrote Todd Ballentine, are "a harsh habitat. Two to six feet of salty, silty tidal wash floods and ebbs." To keep safe from predators, the fiddler crabs, snails, worms and other tiny inhabitants must burrow into the "pluff mud" (dry at low tide), where surface temperatures can reach a broiling 140 degrees. The spartina grass excretes salt crystals in order to survive the high salinity of sea water. Alligators, marsh periwinkles, mussels, oysters, nutrias, muskrats and swamp rabbits are other denizens of the marshes. Certain shorebirds, wading birds and waterfowl, like wild ducks and geese, find shelter in marshes here during the winter or on migrations further south. More permanent marsh-dwelling birds are American and snowy egrets, blue herons, seaside sparrows, clapper rails, and marsh wrens.

Regarding the origin of the term, "pluff mud", the Myrtle Beach Convention Center’s webmaster offered this explanation: "‘Pluff’ is actually the sound you hear when your truck keys fall out of your shorts pocket, while you're climbing over the side to drag the boat out of the aforementioned pluff mud." The closest match of meaning for "pluff" in the Oxford English Dictionary is "to blow out (smoke or breath) with explosive action, to puff". The sound of the word echoes the noise it describes.

A broad view of green marsh and blue water from Downtown Beaufort
The City of Beaufort now preserves this marsh view
and several other tidal vistas on the historic "Point."
Photograph by Dennis Adams
(August 7, 2002)
  And then there’s that distinct "marsh smell". Though certainly an acquired taste, marsh smell has long been the first sign of homecoming for Lowcountry people returning from trips away from the mudflats (the cover of Pat Conroy’s novel, The Prince of Tides, depicted a salt marsh vista, after all). The smell is not sewage or pollution, as many newcomers suppose, though sulfur dioxide fumes from Savannah’s paper mills have reached Beaufort on southwesterly winds. Mr. Ballantine wrote, "the fine-packed (mud) sediments are oxygen poor. Here native anaerobic bacteria decay bottom matter and release hydrogen sulfide ... a poisonous gas smelling of rotten eggs."

An anaerobe is a microorganism that can live in the absence of free oxygen. Other elements in the "bouquet" of marsh air are saltwater (a mixture of simple table salt, magnesium, epsom, calcium, potassium, and lime), chlorophyll from the marsh grass, and decaying plants and animals.


  • Ballantine, Todd. Tideland Treasure: a Naturalist's Guide to the Beaches and Salt marshes of Hilton Head Island. Deerfield, 1983.
  • Meyer, Peter. Nature Guide to the Carolina Coast: Common Birds, Crabs, Shells, Fish and Other Entities of the Coastal Environment. Avian-Cetacian Press, 1991.
  • Oxford English Dictionary. Clarendon Press, 1961.
  • Radford, Albert E. et al. Manual of Vascular Flora of the Carolinas. University of North Carolina Press, 1968.
  • South Carolina State Budget and Control Board. Office of Reaearch and Statistics. South Carolina Statistical Abstract ’98. The Board, 1998.
  • Tiner, Ralph W. Field Guide to Coastal Wetland Plants of the Southeastern United States. The University of Massachusetts Press, 1993.

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