Sapelo Island National Estuarine Research Reserve, Georgia

Source: NOAA


Located midway on the Georgia coastline on the eastern fringe of McIntosh County, Sapelo Island is defined by the Sapelo River to the north, the waters of Doboy Sound to the south, the Atlantic Ocean to the east, and the Duplin River to the west. The 16,500-acre island is the 4th largest barrier island in the State of Georgia.

The Sapelo Island National Estuarine Research Reserve (SINERR), located on the western perimeter of Sapelo, is dedicated to research, education, stewardship, and sound management of coastal resources in Georgia. Specifically, we focus on the natural, cultural, and historical resources of Sapelo Island and the Duplin River estuary.

SINERR, one of 27 in the National Estuarine Research Reserve System (NERRS), is administered by the National Oceanic and Atmospheric Administration (NOAA) and managed by Georgia Department of Natural Resources, Wildlife Resources Division.

Site Description

caption Sapelo Island estuary map. (Source: NERRS)

The Sapelo Island Reserve habitats include a sand-sharing system comprised of shoreface, foreshore, backshore and dune components; an extensive band of salt marsh (comprising two-thirds of the reserve) and some 2,300 acres of upland forest, dominated by stands of oak hardwoods and pines.


Estuaries are those areas where fresh water from rivers and streams meets salt water from the ocean. These areas are extremely important, as they are some of the most biologically productive systems in the world. Estuaries serve several vital functions including providing food, nesting, and nursery ground habitat for aquatic animals as well as a variety of birds, mammals, and reptiles. Furthermore, these salt marsh systems offer filter, buffer, and "sponge-like" capabilities unlike any other ecosystem on Earth.

Georgia's coastline, though only about 100 miles in length, is unique as its marshes account for nearly one-third of the total salt marsh on the east coast of the United States. Sapelo Island, Georgia's fourth largest barrier island, is located midway on the Georgia coastline and is separated from the mainland by 5 miles of marsh and tidal waterways. A total of 16,500 acres make up Sapelo Island, of which, nearly 5,600 acres are tidal salt marsh. The Sapelo Island National Estuarine Research Reserve occupies just over one-third of Sapelo and is comprised of 2,100 upland acres and 4,000 acres of tidal salt marsh. The Reserve lies in the midst of an estuary where the currents of Doboy Sound and the Duplin River converge. The Reserve encompasses ecologies typical of the Carolinian biogeographic region which spans the south Atlantic coastline of the United States from North Carolina to Northern Florida. This region is characterized by vast expanses of tidal salt marshes protected by a buffer of barrier islands.

Here in coastal Georgia, nearly 90% of the marsh is covered by one species of plant, smooth cordgrass, known as Spartina alterniflora. To survive in estuarine areas, marsh plants are uniquely designed to tolerate the salt water that floods the marshes twice daily at high tide. Likewise, aquatic animals that frequent the marshes are accustomed to fluctuating salinity and oxygen levels, temperature, and food availability.


The upland maritime forest on the Sapelo Reserve is comprised of a mix of native hardwoods, such as live oak, red bay and southern magnolia timber stands of slash and loblolly pine. Much of the Sapelo Reserve's pine forest grows on areas once under cultivation in Sea Island cotton, sugar cane and other crops associated with the island's agricultural operations during the 1800s and the early 1900s. This secondary growth pine forest is comprised primarily of slash, longleaf and loblolly pine. The island's dunes are dominated by sea oats, which play a primary role in stabilizing the dune. Other dune plants include bayberry, dogfennel, bitter panic grass, broomsedge, wax myrtle and Spanish bayonet (Yucca).

About 90 percent of the reserve's marshland is covered by smooth cordgrass (Spartina alterniflora). Glasswort, saltwort, salt grasses and oxeye are other salt-tolerant plants that exist in and around the marsh. In low-salinity areas of the marsh, black needlerush grass becomes dominant. Other plants found commonly within the reserve include Spanish moss, resurrection fern, prickly pear, saw palmetto, sabal palmetto, yaupon holly, red cedar, smilax and sweet grass.


The most conspicuous animals of the salt marsh are the graceful egrets and herons along the tidal creeks and marshes at high tide. Fiddler crabs, raccoon, mink and otter are other easily recognizable reserve inhabitants. However, many other less visible creatures live within the reserve, including mollusks (clams, mussels, whelks, etc.), marsh periwinkles, oysters, shrimp, fishes (menhaden, shad, red drum), worms and insects. Mice, moles and marsh rabbits live in the dunes. Hawks and snakes, their predators, live in the back dunes. Here, in the back dunes, large rattlesnakes are often found.

Endangered Species

Endangered and threatened species of Sapelo Island include the Southern bald eagle, peregrine falcons, ospreys, brown pelicans, woodstorks, Wilson's plovers, American Alligators, loggerhead sea turtles, the northern right whale and manatees.

Tidal Range

Sapelo Island sits in the middle of the Southern Atlantic Bight, an inward curvature of the coastline from Cape Fear, N.C. to, Cape Canaveral, Fla. Sapelo's position puts it at the height of a tidal gradient created by the bight. Average daily tides are in the range of 7.5 feet mean high tide. The tides can be significantly enhanced or retarded depending upon the direction and intensity of the winds. Northeasters blow in off the Atlantic Ocean amplifying the high tides and sometimes cause coastal flooding.

Soil Types

Georgia's barrier islands are composed of sands brought to the coastal area by rivers, such as the Savannah and the Altamaha, whose headwaters arise in the Georgia piedmont and mountains. The salt marshes are dominated by slightly alkaline clays topped by a thin sandy layer at higher elevations. Upland soils are predominantly Ona and Rutledge sands that are very poorly drained and often highly acidic.


Like other barrier islands along the Atlantic coast, Sapelo Island was formed as sediment gradually built up into a ridge along Georgia's shore through the actions of wind and waves. The formation of the estuarine marsh occurred during the Holocene period (15,000 years ago) when continental glaciers melted and increased the ocean's volume of water substantially. The ridge that had formed along the shore was then isolated from the land by this flooding, leaving the mainland and the ridge island as two separate land entities. Subsequent submergence and emergence further shaped the island. Today, the island continues to be molded by the powerful actions of wind and waves.

Sapelo Island: A Historical Overview

caption Barn at Chocolate built by Charles Rogers in the 1830s and restored by Howard Coffin in 1927. (Source: Georgia Dept. of Archives and History)

The human history of Sapelo dates back about 4,500 years. Archaeological investigations on the island have determined an extensive Native American presence on Sapelo during the Archaic Period of pre-history (2,000-500 B.C.). The name Sapelo itself is of Indian origin, called Zapala by Spanish missionaries who established themselves on the island from ca. 1573 to 1686. The Franciscan mission of San Josef was situated on the north end of the island at or near the Native American Shell Ring, a pre-historic ceremonial mound which represents one of the most unique archaeological features on the Georgia coast.

English colonization of Georgia beginning in 1733 led to an agreement with the Creeks by which the colony acquired the land between the Savannah and Altamaha rivers, with the Indians reserving hunting lands on several barrier islands, including Sapelo. In 1757, another treaty with the Creeks resulted in the cession of Sapelo, Ossabaw and St. Catherines islands to the royal colony.

The first private owner of the island was Patrick Mackay, who grew crops there before the Revolution. The estate of Mackay sold Sapelo to John McQueen, then, in 1789, Sapelo was acquired by a consortium of Frenchmen who wished to cultivate Sea Island cotton, cut live oak timber for sale to naval shipbuilders, stock the island with slaves and raise cattle. French involvement on Sapelo was characterized by mystery, intrigue and mayhem. Disagreements and mistrust over use of land and money led to the breakup of the six-man French partnership in 1795. One partner, Chappedelaine, was killed in a duel on the island by one of the other partners while another, Dumoussay, died of yellow fever soon after.

In the first decade of the nineteenth century, Sapelo was acquired through purchase or inheritance by three men, Thomas Spalding (south end), Edward Swarbreck (Chocolate), and John Montalet (High Point), the latter having married the daughter of one of the departed Frenchmen. By 1843, Spalding had acquired virtually the entire island, except a 600-acre tract at Raccoon Bluff. It was Spalding (1774-1851) who left the most important legacy to Sapelo. He was one of the leading planters on the tidewater, an agricultural innovator, amateur architect, astute businessman and leading citizen of McIntosh County. Spalding introduced the cultivation of sugar cane and the manufacture of sugar to Georgia. He built his own sugar mill, reintroduced the use of tabby as a primary building material on the coast, contributed important techniques for the culture of Sea Island cotton and gradually developed Sapelo into an antebellum plantation empire. Spalding and his children owned 385 slaves on Sapelo in the 1850s.

caption View of the lighthouse group from Doboy Sound in 1932. (Early Days on the Georgia Tidewater, (c) 2002)

The Civil War ended the plantation economy and Sapelo became the home to a large African-American community during the Reconstruction and postbellum periods. The William Hillery Company, a partnership of freedmen, bought land at Raccoon Bluff as early as 1871. Over time, many of the former slaves purchased land on Sapelo and established permanent settlements, including Hog Hammock, Raccoon Bluff, Shell Hammock, Belle Marsh and Lumber Landing. The First African Baptist Church was organized in 1866 at Hanging Bull, eventually moving to Raccoon Bluff, which was also the site of a black school. Sapelo's blacks engaged in subsistence agriculture, timbering and oyster harvesting in the Duplin River estuary.

Most of Sapelo was sold by Spalding descendants after the Civil War. In 1912, Detroit automotive engineer Howard E. Coffin (1873-1937) consolidated the various holdings on Sapelo and bought the entire island, except for the black communities, for $150,000. Coffin owned Sapelo for twenty-two years. He rebuilt the south end mansion into one of the most palatial homes on the coast from 1922-25, this being a tabby-stucco structure originally built by Spalding in 1810. Coffin engaged in large-scale agriculture, sawmilling and seafood harvesting. He also built roads, drilled artesian wells and added other improvements to the island. Many distinguished visitors were guests of the Coffins on Sapelo, including two presidents, Calvin Coolidge (1928) and Herbert Hoover (1932), and the aviator Charles A. Lindbergh (1929). During this period Coffin and his young cousin, Alfred W. Jones, established the Cloister resort on nearby Sea Island.

In 1934, due to financial reversals brought on by the Depression, Coffin sold Sapelo to North Carolina tobacco heir Richard J. Reynolds, Jr. (1906-1964). Reynolds utilized the island as a part-time residence for thirty years. Reynolds' most important contribution was his establishing the Sapelo Island Research Foundation and providing the facilities and other support for the University of Georgia Marine Institute, begun in 1953. Reynolds' widow, Annemarie Schmidt Reynolds, sold Sapelo to the state of Georgia in two separate transactions in 1969 and 1976, the later sale resulting in the creation of Sapelo Island National Estuarine Research Reserve, a state-federal partnership between the Georgia Department of Natural Resources and the National Oceanic and Atmospheric Administration.


caption (Source: NERRS)

Sapelo Island NERR research and monitoring programs aim to promote and provide support for coastal environment, specifically estuarine, research efforts within the NERR System and the SINERR. Representatives of University of Georgia Marine Institute, University of Georgia School of Marine Programs, Skidaway Institute of Oceanography, University of Georgia Marine Extension Program, Georgia Tech, and Georgia Southern University are among those pursuing research on the Reserve.

NERR System initiatives include the System Wide Monitoring Program (SWMP) for water quality and meteorological monitoring within each reserve's watershed. The data collected provides a national baseline for assessment of short-term variability and long-term trends in our nation's estuaries.

Other SINERR projects include habitat restoration, oyster reef ecological studies, and invasive species monitoring. SINERR also participates in the Georgia Coastal Ecosystems Long Term Ecological Research (GCE LTER) program and is involved with the development of International Ocean Observing Systems (IOOS) efforts in the NERR system and on the Georgia coast.


Water quality, nutrient, and weather monitoring

The System-wide Monitoring Program measures changes in estuarine water quality to track the health of our nation's National Estuarine Research Reserves and coastal areas. It provides valuable long-term data on water quality and weather at high frequency time intervals to researchers, natural resource managers, and other coastal decision makers.

In order to understand changes in water quality, reserve staff use automated dataloggers to collect data on water depth, temperature, salinity, dissolved oxygen, turbidity (cloudiness or clarity) and pH. These data are critical indicators of environmental conditions for numerous estuarine species. The measurements are taken at 30-minute intervals at four stations within each of the 26 reserves.

Each reserve also has a weather monitoring station. Weather patterns have a major impact on estuarine habitats. Storms increase runoff into an estuary and can influence its temperature, salinity, dissolved oxygen, turbidity, and pH.

The System-wide Monitoring Program has already provided some coastal managers with a tool to make informed decisions on local and regional issues, such as “no discharge zones” for boats, agricultural practices, and urban runoff pollution. As the program expands, the ability to correlate specific land use practices with the health of our estuaries will increase on a national level. It also will increase our understanding of how estuaries function and change naturally over time.

Monitoring data for each reserve are available from the reserve system's Centralized Data Management Office.

Water quality data is also available for the monitoring site at Hudson Creek near the Sapelo Island Visitor Center in Meridian.


SINERR operates a National Atmospheric Deposition Program (NADP) site on Sapelo Island. This site is one of a network of sites nationwide that monitor precipitation. Samples are collected weekly and are tested to monitor the amount of chemicals present in rainfall.

Partners and Supporters

Sapelo Island Reserve is managed in partnership by the National Oceanic and Atmospheric Administration and the Georgia Department of Natural Resources, Wildlife Resources Division. An advisory committee was established in 1989 to facilitate effective coordination and cooperation among Sapelo Island Reserve interest groups.

Further Reading

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the National Oceanic and Atmospheric Administration. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the National Oceanic and Atmospheric Administration should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.



(2008). Sapelo Island National Estuarine Research Reserve, Georgia. Retrieved from


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