North Inlet-Winyah Bay National Estuarine Research Reserve, South Carolina
Created in 1972, the National Estuarine Research Reserve System (NERRS) is dedicated to conservation, research, education, and stewardship activities in America’s estuaries—coastal areas where the rivers meet the sea. The North Inlet-Winyah Bay Reserve was established in 1992 and is one of 27 sites around the coastal United States. Each reserve receives funding from the National Oceanic and Atmospheric Administration (NOAA) and matched resources from the host state agency. The North Inlet-Winyah Bay Reserve is hosted by the University of South Carolina, Belle W. Baruch Institute for Marine and Coastal Sciences.
The Reserve encompasses 12,327 acres of tidal marshes and wetlands. North Inlet-Winyah Bay NERR features high quality, ocean-dominated waters and salt marshes in North Inlet, contrasting with the brackish waters and marshes of Winyah Bay. The bay's estuary is dominated by riverine discharges from a watershed impacted by agricultural, municipal and industrial development. Former rice fields and canals provide another system for study within the Reserve.
The entire Winyah Bay system has an extremely diverse plant community arising from the broad range of salinities in the estuary. Low marsh, in the more saline reaches of the bay, is dominated by smooth cordgrass (Spartina alterniflora). Black needlerush, sea ox-eye, salt grass, salt marsh fimbristylis, glassworts, marsh elder and sea lavender are common in the high marsh. Brackish marsh species include giant cordgrass (Spartina cynosuroides), salt marsh bulrush, common three-square, soft-stem bulrush, broadleaf cattail, arrowhead, spider-lily, salt reedgrass, reed and arrow arum.
Giant cutgrass is a common plant in freshwater marshes, along with pickerel weed, sawgrass, jewelweed, water parsnip and smartweeds. The intertidal marsh in North Inlet is dominated by smooth cordgrass (Spartina alterniflora), while the high marsh community contains a mix of species, including smooth cordgrass, black needlerush, sea oxeye, salt grass, salt hay, salt marsh fimbristylis, glassworts, marsh elder and others.
The North Inlet-Winyah Bay area is home to hundreds of species of animals in a variety of habitats including upland and maritime forests, salt marshes, tidal creeks, and the fresh and brackish (a mix of fresh and salt) waters of abandoned rice fields and the Winyah Bay estuary. A long-term monitoring program provides regular information on the abundance, biomass, and sizes of hundreds of species of fish, crabs, and shrimp and includes sampling of the various life stages of many of these animals.
Some of the common resident species in the creeks throughout the year include smaller fish like mummichogs, killifish, sheepshead minnows, blennies, gobies, and silversides. Transient species that move in and out of the estuary include spot, pinfish, menhaden, flounder, white and striped mullet, and red drum (the official mascot of the North Inlet-Winyah Bay Reserve). Other researchers are also studying the area’s larger aquatic species such as the bottlenose dolphin and several kinds of sharks, but much smaller animals in the waters and sediments of the estuary are sampled and studied as well. Larval stages of invertebrates including oysters, clams, crabs, and shrimp, and larval fishes make up a large percentage of the zooplankton samples, especially in the summer.
More common animals of the salt marsh include birds such as the great blue heron, osprey, brown pelican, clapper rail, oystercatchers, and white ibis. The diamondbacked terrapin and Federally endangered loggerhead sea turtle are frequently seen during warmer months. Crabs abound here too and include fiddler crabs, hermit crabs, blue crabs, mud crabs, and square-backed crabs. Common marsh snails such as periwinkles, coffee bean snails, and mud snails feed on detritus and are a food source for the larger animals in the marsh. Oysters and clams are conspicuous filter feeders that also reside in the tidal creeks. The abundance of marsh plants and the expanses of Spartina (salt marsh cordgrass) provide a habitat for hundreds of insects as well.
The Winyah Bay fauna differs somewhat from the North Inlet fauna. A gradual change in salinity from the ocean to the rivers provides a greater diversity of habitats than can be found in the high salinity North Inlet system. Primary differences are seen in the upper reaches of Winyah Bay where brackish conditions support dozens of species that do not occur in the lower portions of the bay. Longnose gar, striped bass, several catfishes and various sunfishes occur only in the tidal freshwater and brackish areas. Seasonal changes in the abundance and biodiversity of the assemblages are large, but both North Inlet and Winyah Bay are very active biologically all year.
While the Reserve’s research focuses primarily on the estuary, the uplands and forests near the Reserve provide a home to many terrestrial species including numerous mammals, birds, reptiles, and insects. Some of the mammals include bobcat, white-tailed deer, wild (feral) pig, gray and red foxes, raccoon, opossum, rabbits, beaver, river otter, gray fox, and flying squirrels. Birds are almost too numerous to mention, but include threatened and endangered species such as the bald eagle and the red cockaded woodpecker, as well as wild turkeys, ducks, and several species of owls and hawks. Frogs, toads, salamanders, venomous and non-venomous snakes, and alligators also reside in freshwater creeks, swamps, and other low-lying swampy areas on the property.
The Winyah Bay watershed is approximately 18,000 square miles. Four major rivers drain into the system. More than 16,000 square miles of this drainage area is associated with the Pee Dee-Yadkin river system which originates in the Blue Ridge Mountains area of North Carolina. Water from this area flows across the Piedmont region of both North and South Carolina, and into Winyah Bay through the Pee Dee River. The Waccamaw River also receives water from the Pee Dee as the poorly defined, shallow, wide, swampy waterways merge. The Black and Sampit rivers drain much smaller watersheds.
Tidal Range and River Flow
The Reserve experiences a regular semi-diurnal tidal pattern. Mean tidal amplitude is on the order of 1.4 meters at the ocean end of Winyah Bay and North Inlet, and 1 meter at the Sampit River (1.6 m and 1.2, respectively on the spring tide.) Maximum amplitude near the ocean is about 2.2 meters. Due to its shallow character, North Inlet is thoroughly flushed by the tides, with about 50% of its water ebbing into the ocean twice per day.
In Winyah Bay, a salt wedge effect occurs as heavier salt water moves up-estuary along the bottom with the flooding tide, even though the overlying fresh water may be flowing toward the ocean. During periods of low freshwater inflow, flooding tides move salt water more then fifteen miles upstream of the Highway 17 bridges, but under average river flow, the penetration is usually within a mile of the bridges. Differences between surface and bottom salinities during these periods may be more than 20 parts per trillion (ppt).
Freshwater input into Winyah Bay estuary ranges from 2,000 to about one million cubic feet per second (cfs), and the mean runoff is approximately 15,000 cfs. Riverine influence is strong enough to limit ocean water penetration to the lower bay, especially during winter and spring.
Most of the salt marsh soils in North Inlet and Winyah Bay are classified as "Bohicket silty clay loam". These poorly drained soils have a high sulfur content and are flooded twice daily by the tides. Former rice field marshes along Winyah Bay are edged with "Levy silty clay loam" soils. Marsh islands in Winyah Bay created by dredging activity include Bohicket silty clay loam soils and areas of "Udorthents, loamy" in places where fossilized shell material has piled up.
North Inlet waters drain a very large marsh located between Debidue Island, North Island and the mainland. The mainland consists of Pleistocene Storm Beach Terrain with ridges oriented in a northeasterly-southwesterly direction. These ridges intersect the Atlantic Ocean at the north end of Debidue Island. These superficial mainland features are underlain by a complex sequence of older coastal plain sediments, a sequence which is poorly understood in the immediate area at the present time.
Debidue and North Island represent part of the Holocene Barrier Beach System. This system has migrated southwest in recent times, with principal evidence here being the major spit along the northern entrance to Winyah Bay, and the smaller spit migration land forms along the northern border of North Inlet.
North Inlet drains numerous tidal creeks, and two of these extend back though the marsh to lie in close proximity to the Pleistocene mainland. The creeks are very shallow in depth, never exceeding thirty feet below sea level, commonly showing floors which are occupied by sand bars. The marsh areas are underlain by silts and clays which extend to an unknown depth below the surface. Relief is generally flat; the western third of the peninsula has the most relief with bluffs adjacent to Winyah Bay as high as fifteen meters. Geologically, Winyah Bay represents a drowned river basin and receives water from an extensive drainage basin. North Inlet is a bar-built/barrier beach estuary, while Winyah Bay is a salt wedge estuary.
A comprehensive research program, ranging from studies of molecular processes to ecological landscapes has evolved at the Reserve. The primary focus of the research program is the NERR system-wide monitoring program. The NIWB NERR has four monitoring sites: Clambank Creek, Debidue Creek, Oyster Landing, and Thousand Acre.
Clambank Creek (CB) - (latitude 33°20'02" longitude 79°11'34") The Clambank Creek monitoring site is located roughly in the center of the reserve boundary. This site is surrounded by a Spartina marsh and drains associated forested uplands. Salinity ranges from 0.4 to full strength seawater (based on data from August-December 2001). The bottom is mostly comprised of oyster shell hash and some fine sediment. This site is considered a pristine site and is influenced by its close proximity to North Inlet.
Debidue Creek (DC) - (latitude 33°21'37" longitude 79°10'05") The Debidue Creek monitoring site is considered to be an impacted site, located approximately 1 km south of the DeBordieu Colony. The Colony is a large residential development built around wetlands and human-made canals that directly drain into the northern portion of Debidue Creek. The DC site is located in an ocean-dominated Spartina marsh that was formerly surrounded by pine uplands. Salinity can range from 0 to full strength seawater and the average tidal flux is approximately 2 meters. The approximate depth and width at mean high water (MHW) is 2.2m and 70m respectively. The bottom is mostly comprised of oyster shell hash with some fine sediment and detritus.
Oyster Landing (OL) - (latitude 33°20'58" longitude 79°11'34") The OL meteorological and water quality monitoring site, located at the end of the pier, is considered a fairly pristine and undisturbed area. The pier stretches into the upper reaches of Crabhaul Creek in the mid-western portion of North Inlet. The sampling site is located approximately 2.8km from the headwaters of Crabhaul Creek. The creek directly drains pine forested uplands and wetlands. Salinity can range from 0-32 ppt and average tidal flux is approximately 1.4m.
The creek has an average depth of ~2m MHW and an average width of ~150m at MHW. The bottom is comprised mostly of oyster shell hash with some fine sediment and detritus.
Thousand Acre (TA) - (latitude 33°17'57" longitude 79°15'36") The present site is about 15 meters from the mouth of the creek. At the sampling site, creek depth is approximately 2m MHW and creek width is approximately 10m. The creek empties into the northeastern side of the mid portion of Winyah Bay and directly drains pine forested upland and wetlands. Salinity ranges from 0 to 15 ppt and tidal flux is approximately 1m. The bottom is mostly composed of fine sediments and detritus. Georgetown, 5km upstream from the Thousand Acre site and on the southern side of Winyah Bay, is the home to a number of heavy industries including a steel plant, paper mill, chemical plant, and a coal-fired power plant. A public sewage treatment plant, which discharges into the bay, is also located in Georgetown.
NERR System-Wide Monitoring Program (SWMP)
The System-Wide Monitoring Program (SWMP) was designed at the national level of the Reserve system to fulfill two major overall goals:
- to support state-specific non-point source pollution control programs by establishing local networks of continuous water quality monitoring stations in representative protected estuarine ecosystems; and
- to develop a nation-wide database on baseline environmental conditions in the NERR system of estuaries.
The specific goal of the SWMP is "to identify and track short-term variability and long-term changes in the integrity and biodiversity of representative estuarine ecosystems and coastal watersheds for the purpose of contributing to effective national, regional, and site specific coastal zone management."
The principal objective of the long-term meteorological monitoring program for the NIWB NERR is to observe any environmental changes or trends over time. The weather station is located at the end of Oyster Landing (OL) pier. A wind sensor, temperature and humidity sensor, barometric pressure sensor, Eppley Pyranometer, Tipping Bucket Rain Gauge, and a LiCor Sensor all are located on an aluminum tower at a height of approximately 3.5 meters. Sensors are wired into a Campbell Scientific CR10X data logger. Samples are taken every 5 seconds continuously throughout the year, producing an average of 15 minute, hourly, daily data. The data is used to compliment other biological, chemical, or physical research conducted throughout the reserve, including YSI water quality data.
The principal objective of the long-term water quality monitoring program for the NIWB NERR is to observe any physical changes or trends in water quality over time. Four sites were chosen; two to represent the relatively pristine conditions in North Inlet, and the other two to represent impacted sites within the reserve boundary. Measurements are recorded every 30 minutes with a YSI 6600 EDS data logger. The parameters measured are specific conductivity, salinity, dissolved oxygen, water temperature, pH, turbidity, and water level. These parameters are important indicators of habitat quality for numerous estuarine species and to determine health criteria and human uses. Biofouling of the individual probes and expected battery life necessitate a two-week sampling interval.
The NIWB NERR 20 day water chemistry database was initiated in June of 1993 to monitor nutrients in the North Inlet Estuary system. This monitoring program combines the water chemistry, chlorophyll a, and suspended sediment monitoring data with other existing ecological data to provide ecosystem-level information and understanding.
Monthly grab samples were initiated across the NERRS platform on February 1, 2001 as a method of providing baseline information on inorganic nutrient and chlorophyll a water quality status within the Reserve system. The NIWB NERR began collecting monthly grab samples on April 17, 2002. Samples for the 20-day program and the monthly grabs are collected at each of the four NERR water-quality monitoring stations.
There is some evidence that Spanish explorers visited the area in the early 1500s. By the 17th century, English influence had spread from Virginia, and in 1718, the King of England granted the Hobcaw Barony to Lord Carteret. This area become well-known for rice culture and the general region of Georgetown County was one of the richest areas in the colonies. On the Barony are located remnants of a Civil War fort, a rice mill, three slave villages and cemeteries. Artifacts of early Indian settlements are found throughout the area.
The King's highway, which was the coastal road from Wilmington, N.C. to Charleston, S.C., crosses the property. George Washington used this road in 1791. In more recent time, Mr. Bernard Baruch, a famous financier and advisor to presidents, purchased land in 1905 and 1907 which comprises the 17,500-acre tract known as Hobcaw Barony. During Mr. Baruch's ownership, many famous world leaders visited the Barony, including President Franklin Delano Roosevelt and Winston Churchill. The property was later acquired by Mr. Baruch's daughter, Belle W. Baruch, who treasured the natural resources of Hobcaw.
Belle W. Baruch died in 1964 and specified in her will that the property be used "... for the purposes of teaching and/or research in forestry, marine biology and the care and propagation of flora and fauna in South Carolina..." The Belle W. Baruch Foundation was established to carry out Miss Baruch's wishes. Both Clemson University and the University of South Carolina have research and education programs at the site that are contributing to a better understanding of coastal forests, marshes and estuaries.
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