Georgia Natural Wonder #26 - Gray's Reef National Marine Sanctuary. 831

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Georgia Natural Wonder #26 - Gray's Reef National Marine Sanctuary

Gray's Reef National Marine Sanctuary is Georgia's amazing underwater park. The natural live-bottom reef is teeming with marine life and is part of the endangered North Atlantic right whale's calving ground. Loggerhead turtles rest at the reef, where scientists have identified more than 200 fish species.



Gray's Reef is the only protected natural reef area on the continental shelf off the Georgia coast. The 22 square miles of Gray's Reef protects an area that is recognized nationally and internationally. The mission of Gray's Reef National Marine Sanctuary is to identify, protect, conserve, and enhance the natural and cultural resources, values and qualities of the sanctuary for current and future generations.

History

Gray's Reef National Marine Sanctuary was named in recognition of Milton "Sam" Gray, who studied the area in the 1960's as a biological collector and curator at the University of Georgia Marine Institute on Sapelo Island, GA. The near-shore hard-bottom reef off the coast of Sapelo Island was recognized by Sam Gray in 1961 in connection with his extensive biological surveys of the ocean floor off the Georgia coast. Collections made during the surveys are under the protective supervision of the University of Georgia Natural History Museum and maintained as the "Gray's Reef Collection".



In 1974, Jesse Hunt, a graduate student working under Dr. V. J. Henry was the first scientist to study the reef. He proposed the name "Gray's Reef" for this live-bottom habitat to commemorate Sam's valuable contribution to the understanding of offshore habitats and marine organisms, especially those of the near-shore continental shelf of Georgia. The Georgia Department of Natural Resources submitted a nomination to the Secretary of Commerce in June 1978 recommending the designation of Gray's Reef as a marine sanctuary. Gray's Reef was made an Active Candidate for Sanctuary Designation in in1979. Final designation as a National Marine Sanctuary came January 16, 1981.



"Live bottom" is a term used to refer to hard or rocky seafloor that typically supports high numbers of large invertebrates such as sponges, corals and sea squirts. These spineless creatures thrive in rocky areas, as many are able to attach themselves more firmly to the hard substrate, as compared to sandy or muddy "soft" bottom habitats. Within the Gray's Reef National Marine Sanctuary there are rocky ledges with sponge and coral live bottom communities, as well as sandy bottom areas that are more typical of the seafloor off the southeastern U.S. coast.



A Different Kind of Reef

Gray's Reef is not considered a coral reef such as those found in the tropics, as its foundation was not built by living hard corals. Instead, it was formed by the cementing and consolidation of marine and terrestrial sediments (shell fragments, sand and mud) which were originally deposited as a blanket of loose grains between six and two million years ago. Some of these sediments were brought to the coast by rivers and others were probably transported to the region by ocean currents. The "cement" that glued the grains together more than 2 million years ago was briny calcium-carbonate seawater. The resulting rock that is the foundation of Gray's Reef is a carbonate-cemented sandstone.



During the Pleistocene Epoch (~2 million to 10,000 years ago, and after Gray's Reef had formed) the climate oscillated between glacial ice ages and interglacial warmer periods. As a result, sea level fluctuated dramatically as glacial ice expanded (sea level fell) and melted (sea level rose). At one time, Gray's Reef was dry land! The sanctuary was periodically exposed above sea level when the shoreline was as much as 80 miles east of today's location. The fossils of large Pleistocene terrestrial animals such as mammoths have been found at the reef, indicating that either these beasts lived in the area when sea level was low, or their remains were washed down old river channels and deposited at what is now the sanctuary. Learn more about gearcharological and paleontological research at Gray's and J-Y Reefs from studies conducted by Dr. Ervan G. Garrison, a professor in the Geology and Anthropology Departments of the University of Georgia.

 

An ever growing number of scientists have been working on the 36,000 year old gray whale mandible (jawbone) found by the University of Georgia's Dr. Scott Noakes at JY Reef near Gray's Reef. Prior to this discovery, no known evidence of gray whales had ever been documented offshore Georgia. After two years and numerous dives, the mandible was recovered from the seafloor in sections totaling approximately 1.5 m in length. The mandible was sent to Emory University's Carlos Museum in Atlanta, Georgia for reassembly and conservation. During this time, several Emory and UGA student interns gained valuable hands on experience in conservation practices. Due to the importance of the find and the desire to display and generate interest in the Atlantic Ocean's whales, the Smithsonian National Museum of Natural History offered to make multiple quality casts of the mandible.


From the Red and Black. Amy painting.

The casts will be displayed on the UGA campus; UGA Marine Extension on Skidaway Island, Savannah, GA; and the Georgia Aquarium in Atlanta. The SNMNH will retain one cast for their research efforts on the now extinct Atlantic gray whales. The original mandible is currently being used as a model for students in UGA's Scientific Illustration department in the Lamar Dodd School of Art to prepare the casts for display.



Habitat of the Reef

Today, the rocky ledges can be as tall as six feet but lie under 60 to 70 feet of ocean water. The rocky ledges are complex - they have nooks and crannies, and caves and bumps that provide plenty of places for invertebrates (animals without backbones) to latch on to or hide in. Those invertebrates provide food for many fishes that also shelter in the cracks and crevices, or that hover above the reef. The rocky places provide a firm base for a variety of invertebrates that live their lives permanently attached to the rock. These animals include bryozoans (moss animals), ascidians or tunicates (sea squirts), sponges, barnacles, and hard-tubed worms. These animals form a dense carpet of living creatures that in places completely hides the rock. That gives the habitat of Gray's Reef its name - "live bottom".


Live but potentially deadly. Nurse Shark.

Gray's Reef is one of the most popular spots off the Georgia coast for recreational diving. The sanctuary is only accessible by private boat. Some independent operators run dive trips to the Sanctuary. Below is an alphabetical listing of charter operators and dive clubs in the area. We also recommend checking the yellow pages and online for updates.



Grays' Reef National Marine Sanctuary does not endorse or promote individual businesses or clubs, but to our knowledge the following are currently the only businesses that may offer dive charters to Gray's Reef NMS:

South Georgia Dive Charters

Island Dive Center


Jane Yarn and boat named after her.

The reefs of the sanctuary are located at a crossroads of convergent currents which, depending on the season, bathe the area with a varying supply of marine larvae. Gulf Stream filaments bring sub-tropical species to our waters from farther south and some species find their way via the colder Western Boundary Undercurrent from farther north. The larvae which ultimately settle onto the carbonate-cemented sandstone reefs and sand expanses will endure challenging environmental conditions throughout their lifetimes; survival of the organisms is largely dependent on their physical tolerance of ocean temperatures which range from 55-86 degrees Fahrenheit and violent undersea "sandstorms" associated with high wind and seas which scour the ledges every winter. These constantly changing conditions contribute to an incredible diversity of marine life which can be found nowhere else than the reefs of the South Atlantic Bight.



Sport fishing occurs year-round but at different levels of intensity. Fishing for pelagic species such as king mackerel is one of the most popular activities; sport fishing tournaments sponsored by private fishing clubs and marinas take place in the spring and Gray's Reef is a popular destination for participants.



When the new regulations became effective on February 16, 2007, only specific types of fishing gear are allowed (i.e. rod and reed, handline, and spearfishing gear without powerheads) at Gray's Reef. It is also against regulations to drop an anchor in Gray's Reef except during an emergency. They will drop the hammer on you.

 
Anchor damage.

Gray's Reef is an open ocean environment; divers encounter strong currents and occasionally low visibility. Temperatures vary by season and range from 50° F (10°C) to 80°F (26°C.).



Pelagic bird watching at Gray's Reef is growing in popularity. Some of the species seen in the Sanctuary include true pelagic birds - birds like shearwaters, petrels and bridled terns that spend their entire lives at sea except when they nest or are blown inshore during heavy storms-- as well as seabirds like gulls and royal terns that forage at sea but return regularly to land.


Blue Footed Boobies.

Stormy Petrels of Oglethorpe University! The only Georgia team beside Georgia Tech, to defeat UGA in football (1929) just before we beat Yale first game at Sanford Stadium.

 

If you are interested in science conducted in Gray's Reef National Marine Sanctuary, you are encouraged to learn more about the researchers who have worked here and the publications that have been produced. Because of the volume of work resulting from science conducted in and around the sanctuary.

 
Sam Gray and RV named after him.

Gray's Reef has been dubbed the "most intensively studied patch of "live bottom" reef anywhere in the South Atlantic Bight" (the area between Cape Lookout, NC and Cape Canaveral, FL) yet many mysteries remain. Since the flora and fauna of this area were first described in the early 1960's by the sanctuary's namesake, Milton "Sam" Gray, researchers have been attracted to this unique and diverse environment.



Back to the mountains tomorrow to a highway named after our great Senator from Winder. Scuba GNW Gal for today.