This section describes the major features of Gray's Reef National Marine Sanctuary that were considered in preparing the management plan. It establishes the context within which sanctuary goals and objectives were formulated and management programs are to be implemented. A detailed description of the Sanctuary is presented in the Gray's Reef National Marine Sanctuary Final Environmental Impact Statement (OCRM, 1980). Pertinent information is summarized below.
- A. Sanctuary Location and Boundaries
- B. Geological Setting
- C. Oceanographic Setting
- D Living Marine Resources
- E. Cultural Resources
- F. Human Activities
A. Sanctuary Location and Boundaries
Gray's Reef National Marine Sanctuary encompasses 16.68 square nautical miles of intermittent live bottom habitat on the South Atlantic Continental Shelf in the Georgia Bight. The Sanctuary is located in high seas waters approximately 17.5 nautical miles off the coast of Sapelo Island, Georgia. The coordinates which mark the corners of the Sanctuary are: 3121.45'N, 8055.17'W; 3125.15'N, 8055.17'W; 3125.15'N, 8049.42'W; and 3121.45'N, 8049.42'W (Fig. II-l). The Sanctuary is marked by a fish haven buoy, "GRS" ("Gray's Reef Sanctuary"), which was formerly "SLB" "Sapelo Live Bottom," at 3124.5'N, 8052.6'W. The buoy is a foam-filled nun buoy with tower and radar reflector. It is located in 70 feet (22 meters) of water (USCG, 1982).
The coastal zone of Georgia is characterized by extensive coastal marshes and water ways, maritime forests and largely undeveloped sea islands. Offshore, the continental shelf is wide, flat, shallow and primarily covered by sand except for intermittent occurrences of emergent hardbottom, presumably reminiscent of old stands of sea level (Henry, 1981). Hard bottom and rock outcrops form ''reefs" that support rich invertebrate and fish communities. Reefs are less common nearshore due to weathering by river channels and deposition of sediments. Offshore, where less weathering and sediment deposition occur, reefs are more common and exhibit moderate to high relief and abundant marine life (Henry and Giles, 1979).
Although located nearshore, Gray's Reef is characteristic of live bottom reefs found further offshore in terms of relief and marine life (see Table II-l). The reason for this is uncertain. Relative to surrounding areas, Gray's Reef contains extensive but patchy and discontinuous hardbottom of moderate-relief (up to 2 meters) and moderate to abundant epibenthic and fish communities. Rock outcrops or "ledges" have formed in a northwest to southwest direction (Fig. II-2). Ledges are often separated by wide expanses of sand and are subject to weathering, shifting sands and slumping which create a complex habitat with caves, burrows, troughs and overhangs (Fig. II-3). Sandy areas between the ledges are coarse and shelly with varying amounts of "rock-like" litter (Henry and van Sant, 1982).
Geological records suggest that Gray's Reef was formed between 40,00 and 20,000 years ago in a shallow embayment experiencing fluctuations in sea level and wave energy. As opposed to reef substrate formed by living corals in the tropics, Gray's Reef was probably formed when heavily-ladened brines in the shallow, evaporating seas percolated through sediments changing the chemical composition and forming rock (Hunt, 1974). Fossil fragments of certain mollusks, bryozoa, echinoids and corals, along with their state of fragmentation, indicate that the rock was formed along a bar or a shoal.
Gray's Reef is located on the inner continental shelf where oceanographic conditions are more variable than those farther offshore where the Gulf Stream exerts its stabilizing influence. At Gray's Reef, wind and meteorological conditions are principal forcing mechanisms. Water temperatures follow seasonal trends and range from 14C (57F) in winter to 28C (82F) in summer. Vertical gradients are minimal.
Salinity of seawater fluctuates in response to local and seasonal events. Following spring rains, brackish waters from coastal tributaries are expelled onto the inner shelf and mix with ocean waters, which reduces salinity. Under certain wind and current conditions, and especially in summer, warm saline Gulf Stream waters meander landward causing locally increased salinities. Throughout the year, salinity at Gray's Reef ranges from 34 to 36 parts per thousand (Hunt, 1974).
Sea conditions at Gray's Reef are generally calm during late spring and throughout the summer, and except when northerners pass through the area, seas are less than 5 feet and winds are variable, less than 10 knots. During the late summer, fall and winter months, sea conditions are rougher because of more frequent storms.
Surface water circulation is generally to the south in fall and winter and to the north in spring and summer. Bottom currents show no consistent patterns but probably respond to indrafts of the northerly flowing Gulf Stream.
Live bottom reefs support unique assemblages of marine algae, invertebrates, reef fish, and sea turtles. The types of organisms found at a live bottom depends on the morphology of the habitat and its geographical location. Where hardbottom is covered by sand, only sparse marine life is found; however, where hardbottom is emergent, dense and diverse communities occur. Community structure is also controlled by hydrographic factors, such as water temperature, salinity and current patterns. In response to wide thermal variations and river runoff along the coast, live bottoms close to shore support more temperate species with a minor component of tropicals. Middle and outer shelf locations support more tropical biota in response to the influence of the Gulf Stream (Henry and van Sant, 1982).
Gray's Reef supports a mixture of temperate and tropical species. Many species are previously unreported for this area, some are "new" species and others represent extensions in previous geographical ranges.
A variety of seaweeds and invertebrates grow on exposed rock surfaces, Bryozoans, ascidians, sponges, barnacles, and hard-tubed worms form dense encrustations. Larger sessile invertebrates, such as sea whips and fans, hard corals, and large sponges, provide refuges for many smaller, more cryptic invertebrates. Other dominant invertebrates include starfish, brittlestars, crabs, lobsters, shrimps, bivalves, and snails.
Gray's Reef is a fish haven and year-round residence for many fishes. Important recreational target species include bottom-dwelling species of snapper, grouper, sea bass, porgy and sheepshead and seasonal migratory pelagic species of bluefish, jack, cobia, mackerel and little tunny. Small tropical reef fish, including cardinalfish, damsel fish, wrasses, blennies, gobies, and angelfish live in close association with benthic substrates and form an important component of the ecosystem. Their residence at Gray's Reef is believed to be only seasonal. Moray eels and other cryptic organisms hide in caves and burrows. Other commonly seen fishes include trigger, soap and goat fish, burrfish, tomtate, cubbyu and jackknife fish, lizard and toad fish and sea horses. Small schooling "bait" fishes, primarily scad and sardines, hover above the reef surface, and mid-water fishes (e.g., Atlantic spadefish, amberjack and barracuda) are found higher in the water column.
Sand bottom areas between rock outcrops are foraging grounds for some fishes and, whereas they may not contain the rich marine life associated with hardgrounds, apparently play a significant role in the structure and function of live bottom systems. The most obvious and common organisms in sand bottom areas are sea pens and sea pansies that do not require hard substrate for attachment (Continental Shelf Associates, 1979). Sea stars are common and sea cucumbers, sea biscuits and sea urchins are occasionally encountered (Henry and van Sant, 1982). Pearly razorfish pop in and out of burrows in the sand and several large schools of small planktivorous juvenile and adult fishes are often seen swimming over sand bottom areas (Henry and van Sant, 1982). These fishes include lizard and toadfish, sparids, porgies, and snappers (Nicholson, 1982, pers. comm.).
Loggerhead sea turtles are encountered at Gray's Reef throughout the year. It 1s speculated that they use live bottom areas for foraging and resting. Other marine turtles, including the kemps (Atlantic) ridley and the green, are known from the South Atlantic region but have not been encountered at Gray's Reef.
Little information exists concerning coastal or pelagic birds in the vicinity of Gray's Reef. Pelagic bird rookeries are found along the entire Georgia coast. Petrels, shearwaters, gannets, phalaropes, jaegers, and terns are seen at Gray's Reef as they pass from rookeries to offshore feeding grounds.
At some point during its geological history, Gray's Reef was a shallow coastal environment supporting oysters, clams and other estuarine organisms. Fossil bivalves and gastropods (Hunt, 1974) and a mastodon bone have been found at Gray's Reef (Bell and Smith, 1981, pers. comm.). It is possible that artifacts of human culture also may be uncovered at the reef.
The South Atlantic Continental Shelf also has the potential for containing many shipwrecks. Merchantmen, ships-of-war, blockade-runners and fishing vessels dating from the 18th Century to the present have been sunk, lost or run aground off the Carolinas and Georgia. The remains of many of these wrecks have not been found. It is possible that shipwrecks, armaments and other relics could be discovered in the vicinity of Gray's Reef following close examination of the area.
Gray's Reef attracts recreational fishermen and divers and serves as a natural laboratory for research and educational programs. There is currently little or no interest in the Gray's Reef area for commercial fishing, military activities, marine minerals development, ocean dumping, or dredge material disposal.
Although Gray's Reef is the closest natural reef offshore of Georgia, several factors limit its accessibility. Use of Gray's Reef is primarily limited to persons from coastal and inland Georgia who have seaworthy vessels, offshore experience and the electronic navigation equipment necessary for offshore travel.
There is no primary access point for the Sanctuary; rather, a variety of public and private boat launches and marinas from Savannah to Brunswick, Georgia, serve as staging points for sanctuary users. A boat trip to Gray's Reef takes from 1 to 3 hours depending on type of vessel, departure point and sea conditions.
Most offshore recreational vessels which operate at Gray's Reef are privately owned, 20 to 40 feet in length and gas or diesel powered. Research vessels and commercial fishing boats are generally larger and more seaworthy. Besides distance and travel time and variable weather and sea conditions, increasing fuel prices and limited availability of charter and party boats for recreational hire further limit public access to the Sanctuary.
1. Recreational FishingMarine recreational fishing in the southeast is relatively undeveloped. Offshore fishing opportunities are somewhat limited by the lack of suitable natural fish havens within a reasonable distance from shore. Except for Gray's Reef and several nearshore artificial reefs established by the Georgia Department of Natural Resources (Fig. II-4), the most desirable natural live bottom in terms of seasonal availability, size and abundance of target fishes is located 40 miles offshore. In 1979, Georgia attracted an estimated 103,000 participants and South Carolina, 360,000 (UGA, 1982).
Recreational fishing at Gray's Reef occurs nearly year-round but at different levels of intensity. Beginning in April and May, fishing steadily increases through the summer and then tapers off in autumn. This trend correlates with favorable weather conditions and the availability of favorite target species--king and Spanish mackerel. Fishermen troll, drift fish or live line for mackerel. Snapper, grouper, black sea bass and other bottom hook-and-line fisheries are generally available all year.
The Georgia Department of Natural Resources estimates that there are approximately 215 '"fishable'' days at Gray's Reef per year (i.e., days with less than 5-foot seas and winds variable, less than 10 knots). The best weather days occur from May through August with an average of 22 fishable days per month (Gordon, 1981, pers. comm.). Most fishing occurs on weekends.
2. Commercial Fishing
In the Southeast, commercial fishermen have been oriented traditionally to harvesting shrimp (UGA, 1982). With recent enactment of the Fisheries Conservation and Management Act and expansion of the territorial fishing limits to 200 miles, there have been increased efforts to encourage the development of offshore fin fisheries. Gear research and development programs, exploratory fishing activities, and training programs are being conducted by the University of Georgia's Marine Extension Service in Brunswick, Georgia, in an effort to foster year-round, profitable commercial fin fisheries (UGA, 1982). Three types of gear are proving successful for offshore bottom fisheries: handlines (manual or powered reels); wire fish traps; and, to a limited extent, roller-rigged trawls. Fishing for pelagic species is primarily by hook and line, although gill nets and seine nets are also used.
Gray's Reef supports very limited commercial fishing opportunities. Fish species composition and concentration at nearshore hardbottoms, such as Gray's Reef, are generally not sufficient enough to attract large-scale fishing operations involving fish traps or roller-rigged trawls. In the past, a few off-season shrimpers occasionally fished for black sea bass with wire fish traps at Gray's Reef; however, low market prices and declining yields limited the fishery. Sanctuary regulations now prohibit trap fishing and trawling to protect fish stocks and fishery habitats (see OCZM, 1980). Hook-and-line fishing is allowed and occasional commercial catches of Spanish and king mackerel, bluefish, and cobia are taken at Gray's Reef.
3. Recreational Diving
SCUBA diving by more hardy, experienced divers occurs year-round. Because of the variable and often hazardous sea conditions, open-ocean diver training is encouraged. Most diving occurs on weekends and often in conjunction with recreational fishing activities.
Spearfishing is allowed at Gray's Reef. At current low levels of harvest, there is no apparent adverse impact. Target fishes include snapper, grouper, black sea bass, flounder, triggerfish, porgy and sheepshead. Photography and underwater nature observing are also popular activities. Underwater collecting of marine life is prohibited in the Sanctuary, except on a limited basis under special permits for scientific and educational purposes.
4. Research and Education
Gray's Reef offers unique opportunities for research, yet it has received only moderate scientific attention. This is due primarily to its relatively recent discovery and, prior to sanctuary designation, lack of any coordinated effort to stimulate and promote research in this area.
Gray's Reef was discovered by scientists in 1961 while surveying the nearshore area off the University of Georgia's Marine Institute on Sapelo Island, Georgia (Gray, 1961). The first systematic collection from Gray's Reef--the Gray Collection--is housed at the University's Athens Campus and the Marine Resource Center on Skidaway Island, Georgia. In later years, Hunt (1974) studied its geology and origin, Harris (1978) reported on resident fish populations, the South Carolina Marine Resources Research Institute and Georgia Department of Natural Resources (1981) studied living marine resources for the United States Department of the Interior, Bureau of Lands Management, and Searles (1981) made limited seaweed collections. Since designation of Gray's Reef National Marine Sanctuary in January, 1981, funded research has been directed principally toward topics with management implications, including a reconnaissance hydrographic survey (Henry and van Sant, 1982), a study on the effect of roller-rigged trawls on benthic habitats (Georgia Department of Natural Resources and South Carolina Marine Resource Research Institute, 1982, in progress), an assessment of contemporary visual fish censusing techniques in live bottom areas (Georgia Department of Natural Resources, 1982, in prep.) and the preparation of a fieldguide to the fishes of Gray's Reef (Gilligan, 1982, in prep.). These studies are described in Appendix C. Future research needs are identified in Section V, Resource Studies Plan.
Several regional colleges, Universities, museums and private foundations have expressed interest in the use of Gray's Reef as a natural teaching laboratory, including the University of Georgia (Athens Campus, the Marine Resource Center on Skidaway Island and the Marine Extension Service in Brunswick), Georgia State University, Emory University, Savannah State College, Georgia Southern University, and Brunswick Junior College. Under the Marine Biology Program at Savannah State College, Gray's Reef is the site of student training in various fields of marine science (Gilligan, 1981). Programs proposed for the Sanctuary will further educational opportunities (see Section V, Resource Studies Plan and Section VI, Interpretation and Recreation Plan).
(back to top of page) 5. Tourism
Tourism in coastal Georgia is focused primarily in the Savannah and the Brunswick-Golden Isles areas. Main attractions at these locations are public beaches, historic sites and recreational activities such as golf, tennis and fishing. When compared with facilities present in Florida, however, coastal Georgia's tourism industry remains largely undeveloped. However, recent increases in visitor center use in Savannah and Brunswick, hotel and motel room rentals, and traffic flow on Interstate-95 (the main north-south corridor for tourist activities in coastal Georgia) have been noted.
The University of Georgia's Marine Resource Center trains docents to lead tourists and visiting groups on field trips, marsh and beach walks and other marine educational activities (UGA, 1982). The Georgia Department of Natural Resources' guided tours of the Sapelo Island National Estuarine Research Reserve attract many tourists. In addition, several local, regional and national publications (e.g., The Atlanta Journal, Brown's Guide, Outdoors in Georgia and Field and Stream) have run feature articles on recreational opportunities in coastal Georgia.
6. Military Operations
Gray's Reef lies within the western edge of U.S. Navy's Jacksonville Fleet Operating Area W-157 where operations related to national defense training and readiness are conducted (Fig. II-5). Although operational usage of Area W-157 can be heavy and can include surface and aerial gunnery, bombing, torpedo and missile firing, and air, surface ship and submarine maneuvering, few if any of these activities take place in the Sanctuary.
7. Marine Minerals Development
Explorations for oil and natural gas in the South Atlantic started in 1979. To date, no hydrocarbons have been found in the six exploratory wells that have been drilled. There are no oil and gas activities within the vicinity of the Sanctuary nor are there any natural gas or oil pipelines going through the area. The next South Atlantic Lease Sale (#78), scheduled for January 1984, covers an area of eighty-two million acres from Virginia to Florida, and extending from 3 miles offshore to as much as 230 miles out. Although some blocks lie on the continental shelf, most of them are in deep water on the continental slope or on the Blake Plateau (Fig. II-6). Gray's Reef is not in the area identified for Lease Sale #78 (DOI, 1982).
Sand is the only mineral currently mined commercially in Georgia's coastal region. Sand is mined along major tributaries for use as construction and fill material. Along the coast and immediately offshore, phosphate has a strong potential for economic development. Deposits are thought to be abundant, especially off Savannah (Georgia Department of Natural Resources, 1975). No investigations have been made in the Gray's Reef area.
8. Commercial Shipping
According to the U.S. Coast Guard, the Brunswick Pilots Association and recent sanctuary overflight surveys conducted by Georgia Department of Natural Resources (see Appendix C), there is little commercial shipping through or near the Sanctuary. As a general rule, most ship traffic servicing South Atlantic ports is found 8 to 33 miles east of Gray's Reef-. Those vessels traveling north "ride" the Gulf Stream while those traveling south remain shoreward of the current.
9. Ocean Dumping and Dredge Disposal
There are currently no active dumpsites in or around Gray's Reef, nor are any being contemplated for the near future.
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