Quite simply, the coast is defined as where the land meets the sea. How flora and fauna adapt to this region of abruptly different realms has fascinated naturalists for thousands of years. In order to study relationships in the natural world, scientists group plants and animals into ecosystems. Ecosystems can be as small as a drop of water or as large as the Northern Hemisphere. The Georgia coast is frequently divided into the following ecosystems: coastal marine, barrier island, estuaries and sounds, mainland upland, rivers, and swamps.
East of Georgia's shoreline is the continental shelf, which is 70 to 80 miles wide with a gentle slope of about 2 feet per mile, varying in depth from the shallows of the shoreline to 600 feet deep. It is covered by sediments deposited during low stands of the sea. Approximately 80 miles offshore, the continental shelf abrubtly increases in slope of descent known as the continental slope. Seaward of the continental shelf is the Blake Plateau, an intermediate plateau between the continental shelf and the ocean basin that averages 2,300 to 3,300 feet in depth.
Georgia's continental shelf consists primarily of two natural communities: sandy bottoms and live bottoms. Sandy bottoms are virtual aquatic deserts, with shifting sands preventing the establishment of large plant and animal communities. Live or "hard" bottoms, such as Gray's Reef National Marine Sanctuary, consist of limestone outcrops anchored on ancient shorelines that serve as reefs where flora and fauna can flourish. Smaller organisms are food for small fish, which in turn are eaten by larger fish such as Spanish and king mackerel, gag and scamp grouper, sea bass, cobia, wahoo, dolphin, and amberjack. The live bottoms are well documented and can be easily located with modern equipment, and saltwater fishermen make long boat trips to fish them, including Savannah Snapper Banks, Grand Banks, and Brunswick Snapper Banks. The Coastal Department of Natural Resources and saltwater fishing organizations, in an effort to increase habitat for fish, have created at least 13 artificial reefs by sinking bridges, barges, and Liberty ships. A series of eight offshore Navy towers are also popular fishing sites.
The sea serves as critical habitat for many migratory oceanic birds, sea turtles, and marine mammals, including the endangered right whale that calves in Georgia waters December through February. Only 300 of these tremendous creatures remain, and the future of the species is being determined off Georgia's shore. For more information on coastal marine environments, see Gray's Reef National Marine Sanctuary or the Georgia Department of Resources.
Because they are composed of unstable sand, barrier islands are fickle geologic entities that are constantly on the move from the action of tides, waves, winds, and storms. Relatively young and fragile, barrier islands are always losing and gaining sand, but in different places and at different rates. In the last 100 years, Tybee Island has lost 2,000 feet of beach, while Little St. Simons has gained at least that much. In essence, barrier islands are built-up sandbars with dunes where plants have gained a vulnerable foothold.
Off the Georgia coast, where the tidal range is high and wave energy is low, islands are relatively short. Along the Florida and North Carolina coasts, a low tidal range and high wave energy have produced long, narrow barrier islands.
Scientists divide barrier islands into several natural zones: sandbars, beach, dunes, interdune meadows, freshwater and brackish sloughs, and maritime forest.
Offshore toward inlets are extensive sandbars or shoals that play a role in the formation of islands as well as support marine life and shorebirds. Since the beginning of colonization, Georgia's inlets have been notorious among sailors for their tricky and ever-changing shoals that have trapped many an ancient and modern mariner.
Sandbars form from sands that have been transported from rivers, other barrier islands, or offshore areas. Currents and tides are continually moving and shaping complexes of sandbars that may be here today and gone tomorrow. Exposed at low tide, sandbar complexes are evidence of tidal influences and can be excellent areas to look for marine life such as sand dollars, worms, crabs, and other creatures. Be careful to not get stranded on them as the tide changes, as swimming back to shore against tidal currents can exhaust even good swimmers and result in drowning.
Shorebirds and seabirds use these sandbars for resting and feeding, and if sandbars build up to remain exposed during high tides, some birds may use them for nesting. A lack of established vegetation generally means an absence of mammalian predators that eat bird eggs. All of Georgia's barrier islands have sandbars to examine, but some of the easiest to see are on St. Simons and Tybee islands. On East Beach on St. Simons Island, one can examine sandbar formation and observe the many shorebirds that use the shoals of Gould's Inlet. The south end of Tybee Island is an excellent area to study shoals formed in a typical manner.
The Georgia beach is composed mainly of mineral sand eroded from the Piedmont and Appalachian highlands. Georgia's sand has less shell content and is finer than what is found on many higher energy beaches of the Atlantic. The majority is quartz sand with many other minerals present, including ilmenite, a heavier, black mineral. When winds blow across the beach, the lighter quartz gets pushed to the top, and the black sand rolls to the bottom, producing beautiful black and white patterns.
The beach is subdivided into two main areas: the intertidal beach and the upper beach. The intertidal area is defined as the portion submerged at high tide and exposed at low tide. In Georgia, this area is hard-packed and inhabited by a variety of life adapted to the pounding of the surf and an alternating wet and dry environment. Flourishing in these harsh conditions are burrowing filter-feeders, including echinoderms such as sand dollars (Mellita sp.) and brittle stars, polychaete worms, mole crabs, razor clams, and ghost shrimp (Callianassa sp.). Ghost shrimp live in pencil-size burrows identified by fecal pellets that look like chocolate sprinkles. These fecal pellets give the beach some of its color and add to the nutrient cycle of the beach. Straining beach sand will reveal small, whitish creatures known as amphipods that live between grains of sand. Hungry shorebirds are aware of these burrowing forms and are seen probing the sands with their sensitive beaks.
Newcomers to Georgia's beaches wonder why there aren't more shells. Shells are generally the skeletons of dead mollusks. Mollusks live far off the Georgia shoreline and with low surf energy, not as many are washed to the beach. The best time to find shells is after a storm at low tide, when one might come across cockles, letter olives, whelks, oyster drills (Urosalpinx cineraea), and Atlantic moon snails (Polinices duplicatus). A dramatic find on the beach is the horseshoe crab, a primitive form that can grow its helmet-looking shell to more than a foot long. The horseshoe crab feeds along muddy estuarine bottoms and comes ashore during spring tides to lay over 500 eggs. The shells found on the beach are frequently empty exoskeletons that have been shed by growing horseshoe crabs. The animal is related to scorpions, ticks, and sea spiders, and its larval form is very similar to 400-million-year-old trilobites. The tail is not a weapon but is used to flip the crab over. Horseshoes once were used for fertilizer and chicken feed in the northeast, and for eel bait in Georgia, but today are important in medicine. Their copper-rich, blue blood is used in cancer research and as an indicator of spinal meningitis.
Occasionally, beachcombers discover jellyfish stranded on the beach. The more common species are the moon jelly (Aurelia aurita), a translucent animal identified by a magenta sunburst and four U-shaped gonads, and cannonball jellyfish (Stomolophus meleagris), a thick, half-egg-shaped coelenterate with a reddish-purple band. Both of these are nonstinging and relatively safe to touch. Stinging forms to worry about include the sea wasp, which is found in coastal waters April to July and recognized by its tentacles that dangle from the four corners of its boxlike body; sea nettles (Chrysaora quiquecirrha), which are common in August as young hatch in 80-degree Fahrenheit waters; and Portuguese man-of-war (Physalia physalis), a severely stinging jellyfish identified by its sail-like, blue colored gas bag that floats above the surface of the water. These jellyfish can sting after they have washed up on the beach, so do not touch!
Sometimes the Georgia surf creates brown foam that is misidentified as water pollution. Actually, because Georgia waters are rich with plankton and detritus, the stirring of the surf produces bubbles because microscopic creatures act to coagulate the water, not unlike what happens when soap is added to dishwater to produce bubbles. Other misidentified but natural elements of the Georgia coast are greenish and yellowish smears seen on the beach. These are algae that live between grains of sand along with amphipods, diatoms, and worms, and are another sign of the living beach.
The upper beach is defined as the area above the high tide line. Here you find a great variety of insects, amphipods, sea wrack, and most conspicuously, ghost crabs. Ghost crabs live in burrows that are recognized by penny to half-dollar size holes. These fleet-footed arthropods are evolving from life in the water to life on land. While adults have lost their swimming legs and remain out of the sea, they periodically must wet their gill chambers with sea water to keep breathing, and females release their young into the ocean as plankton. Ghost crabs are great scavengers of the nighttime beach and are easily seen with a flashlight.
The upper beach is used as nesting grounds by a variety of birds, including oystercatchers, terns, and plovers, as well as loggerhead sea turtles, a signature animal of the Georgia coast. Loggerheads are the only marine turtle that regularly nests on Georgia beaches. Females, weighing between 150300 pounds, crawl ashore at night from late May to early August and bury an average of 120 eggs that look remarkably like ping-pong balls. Approximately two months later, the eggs hatch and the sand-dollar-size hatchlings race to the sea. Raccoons and feral hogs will come to the shore to feed on the eggs.
Those interested in Georgia's sea turtles should see Jekyll Island and Wassaw Island for volunteer opportunities.
During spring tides, beach wrack is deposited on the upper beach. Beach wrack is a mixture of cordgrass and other natural flotsam, which serves as an important mini-ecosystem for a wide variety of insects, amphipods, and microorganisms. The cordgrass traps blowing sand and as it decays, becomes a starter kit for new dunes on the beach.
Dunes are the front lines of island building. At some point, all barrier islands started as sand dunes that were colonized by hardy plants. For a plant to survive on a dune, it must adapt to many harsh conditions such as erosion from shifting sands, hot winds, salt spray, quick water drainage, and solar radiation. Plants are extremely important for dune formation. This is why beach lovers should always use boardwalks or paths instead of running over dune vegetation, which if killed results in the erosion of beach. Cumberland's feral horses, while popular with tourists, are unpopular with some environmentalists who worry about the damage caused by these animals that trample on the dunes as they graze on sand-trapping grasses.
The closer to the beach, the hardier the dune plants. These are called pioneer plants because they move in first. Typical species are seaside orache, croton, and spurge. Sea oats are the kings of dune building plants and are protected by law. Using excellent sand-trapping strategies, sea oats can live on the tops of dunes and stay ahead of migrating sands as other plants are buried.
As one moves away from the beach, species diversity increases. Dunes located behind the first set of dunes, called the secondary dunes, are older and have had a longer time to build up richer soils that support more kinds of plants. Between dune peaks in the swales are the greatest variety of plants because the conditions are more favorable: less wind, more water, and richer soil. Interdune meadows may support thorny plants such as yucca, sandspur, hercules club, and Russian thistle, as well as thick-leafed succulent species such as sea rocket, saltwort, seabeach sandwort, and prickly pear cactus. Farther back from the beach, woody species such as wax myrtle, and yaupon holly become more common. A variety of grasses flourishes from the primary dunes to the interdune meadows, including nutgrass, bitter panic grass, and common broomsedge, along with creeping vines such as beach pennywort, morning glory, and Smilax. Small mammals, including mice, rice rats, moles, and rabbits, are found in dune meadows, and they are preyed on by snakes, including the Eastern diamondback rattlesnake. Deer and feral hogs are common on Ossabaw, St. Catherines, and Cumberland islands.
Finding extensive interdune meadows is less and less easy on all coasts as beachfront developers gobble this property up. On the Georgia coast, however, interdune meadows can still be found, with the best examples on undeveloped islands.
An extremely important natural feature of Georgia's barrier islands is its fresh-water and brackish sloughs or ponds. These can be naturally formed or man-made, but either way, they add appreciably to an island's diversity. They serve as important freshwater sources and habitat for a variety of island life, including wading birds, reptiles, and amphibians. Migrating and wintering waterfowl use ponds as resting and feeding areas during winter. In the spring, many wading birds such as herons and egrets congregate around ponds to form rookeries where they build nests and raise their young. Frogs, fish, water snakes, crustaceans, and insects also use ponds for reproduction and become food for larger animals on the island. In early summer, alligators build nests of their own here.
Many of the freshwater sloughs appear in times of rainfall and disappear in dry periods. Opportunistic species have adapted to these fluctuations. Treefrogs will remain scattered about an island and go months without breeding until a torrential downpour creates temporary freshwater pools suitable for breeding. Then the frogs will gather at these pools in dense breeding congregations, which produce huge numbers of tadpoles that ensure the survival of their species. The temporary pools have naturally fewer predators than a year-round pond.
Wood storks (Mycteria americana) are so inefficient at catching fish that they depend on drier periods that shrink ponds and concentrate aquatic prey. Stork nesting cycles are timed with periods of falling water so sufficient food supplies are available for hatchlings.
Freshwater ponds can be observed on the northern ends of Blackbeard and Cumberland islands, as well as Little St. Simons and Wassaw islands. On the southern interior of Jekyll Island is a freshwater slough that's worth examining.
Maritime forests, the climax community of barrier islands, are an association of plants and shrubs that are well adapted to the harsh conditions of the island environment. Forming the forest canopy are Live Oaks, laurel oaks, Southern yellow pines, cabbage palms, red cedars, and magnolias that shelter the interior. Adding to the forest's beauty are the numerous vines, ferns, lichens, and mosses that grow on branches and trunks, including muscadine grape, Smilax, Spanish moss, and resurrection fern. A natural indicator of humidity, resurrection ferns are green and luxuriant after a rain and inconspicuous and brown during dry spells. Spanish moss (Tillandsia usneoides), a characteristic plant of the Georgia coast, is neither a parasite of trees nor a moss; it is a member of the pineapple family that survives by deriving its moisture and nutrients from rain and airborne dust. Seeing moss on dead branches, some people erroneously conclude that Spanish moss is harmful to trees. Actually, the Spanish moss thrives on dead branches because of a lack of competition from the tree's leaves.
In the understory are shrubs and smaller trees such as yaupon, wax myrtle, red bay, sparkleberry, and cherry laurel. Saw palmettos, a characteristic plant of a live oak maritime forest, grow along the ground and shoot up distinctive, fan-shaped fronds that give the forest a jungle appearance.
As trees grow higher than protective dunes and shrubs on the eastern side of an island, they adapt to the damaging salt-laden winds that blow in from the shoreline. Trees located near the shore form a gradual sloping shape in response to upward-angled winds. The trees here may be dwarfed and wind-sheared, an effect of salt pruning. Salt spray kills plants' terminal buds that extend beyond the protective canopy of the forest, resulting in thicker lateral growth below called the shrubbing effect. The end result is a protected, interior forest where little light reaches the forest floor.
The maritime forest provides a protected environment used by a wide variety of animals, including white-tailed deer, gray squirrels, and raccoons. Bird life is diverse, with warblers and songbirds flitting about in the canopy and wild turkeys strutting on the forest floor. Treefrogs and lizards can be found hiding on palmetto fronds.
Excellent extensive examples of maritime forest can be examined on Cumberland, Wassaw, Sapelo, Blackbeard, Jekyll islands.
Between the mainland and barrier islands are the sounds and estuaries where Georgia's rivers and the sea meet. Here one finds the salt marsh, the most prominent and characteristic feature of the Georgia coast, totaling approximately 378,000 acres in a band roughly 4 to 6 miles wide. Georgia has 10 sounds, each with its own unique attributes determined by tidal action, surrounding marshes, and the inputs of rivers of varying qualities. If the estuary is equated to the human body, the tides are the heartbeat, tidal waters are the blood stream, tidal creeks are the circulatory system, and salt marshes are the living tissue.
The brownish-green waters of southeastern coastal waters are not an indication of pollution but a sign of vitality. Tidal waters are rich with plankton, detritus, and sediments that support life processes on the Georgia coast. While many love the beautiful blue water of the Caribbean, this clear water is a virtual desert of microscopic life.
Plankton is a group consisting of plants (phytoplankton) and animals (zooplankton) that drift with the currents and tides. Plankton is the most abundant, basic, and important food in the ocean. Phytoplankton, such as one-celled diatoms, consists of fast-reproducing marine plants that make up 80 percent of the earth's vegetative population and are most responsible for producing the earth's oxygen. They give Georgia water its greenish hue. Zooplankton is a group of animals at the mercy of currents and tides, including larval forms of marine creatures, tiny crustaceans known as copepods, and jellyfish.
The brownish color comes from decaying plants and animals called detritus, a protein-rich mixture of 95 percent decaying Spartina and 5 percent algae, bacteria, fungi, and wastes.
Salt marshes in Georgia began as lagoons behind the barrier islands, which filled with rich alluvial sediments deposited by mainland rivers. After the lagoons have developed suitable soils and water salinities, emergent vegetation can survive and thrive in the estuarine zone. The dominant species in a particular area of the marsh is determined primarily by the elevation, which determines frequency, depth, and duration of salt water inundation and soil salinity.
Approximately 70 percent of the marsh is Spartina alterniflora, or smooth cordgrass. This plant has developed mechanisms that permit it to survive both the salinities and tidal fluctuations of the low tidal marsh. While Spartina grows even better in fresh water, it is unable to compete with more vigorous species, so it has claimed the salt marsh where it can thrive without much competition, growing to 10 feet tall in places. In higher areas with infrequent inundation and relatively low salinities, darker needlerush thrives in almost pure stands and makes up nearly 18 percent of the Georgia salt marsh. In these areas grow other salt-tolerant plans such as marsh elder, sea oxeye, and glassworts. Some areas in the marsh, called salt or sand pans, lack vegetation because of very high salinities that are too harsh for plants to survive.
Marshes produce biomass measuring nearly 20 tons to the acre, making them four times more productive than the most productive farmland. Georgia's salt marshes produce more food energy than any estuarine zone on the Eastern seaboard. Marsh plants and other tiny plants trap the sun's energy and covert it to food. As marsh plants die and decompose, they provide basic nutrients that benefit minute creatures in the estuary, which in turn are fed upon by larval forms of marine creatures such as crabs, oysters, and fish, which develop and support even larger marine animals. Coastal rivers add nutrients to the estuarine system where they are trapped by marsh. Tidal action plays an important role in this nursery by stirring nutrients and introducing planktonic plants and animals to the marsh. The rotten egg smell of the marsh is hydrogen sulfide (H2S), which is naturally released from the decaying action of anaerobic bacteria. Red streaks in marsh mud reveal the presence of oxidized iron, a common and important element in the marsh.
The marsh also provides shelter and food for a wide variety of coastal fauna. As coastal visitors soon learn, insects are very common residents of the marsh. While some are annoying to the tourist, insects are extremely important links in the food chain of the Georgia coast. Their larval and adult forms support a wide variety of fauna including fish, frogs, birds, and larger insects like damselflies. Some insects feed on vegetation and detritus, while others require the blood of mammals. Small insects and mites preying on man include no-see-ums (six species of midges), mosquitos, deerflies, horseflies, chiggers, and ticks.
No-see-ums are midges that are so small they can crawl through most screen mesh. They swirl around the face and inflict stabbing bites. They can breed in almost any damp area and are encountered everywhere on the coast. Another annoyance on the coast are chiggers, also known as red bugs. The larval form preys on humans. This mite, found in pine straw, leaves, and pine bark, crawls up human hosts to areas where body heat is high, then digs into the pores and sucks blood until a week later it's ready to drop off and mature into an adult. Ticks are also common on the coast. The adult forms hang off of grass stems and grab your clothing as you brush by. Then they climb to a soft spot on your body and shove their pronged beak into your skin. Ticks transmit potentially deadly diseases such as Rocky Mountain spotted fever and Lyme disease, so they should be carefully removed from your body once discovered. Apply alcohol to the tick then remove the anesthetized tick with a pair of tweezers, being careful to get the entire insect.
There are dozens of mosquito species on the coast. The females are the biters, as they quest for blood used in reproduction. The mosquito's anticoagulant saliva causes irritation of the skin. Mosquitoes also transmit diseases such as malaria and yellow fever. Deerflies and horseflies have the worst bites of the coastal insects and will swirl around your head and literally chase you down a barrier island path. All of these insects are most common from May to September, during which the visitor should be prepared to combat these nuisances by using insect repellant and wearing a floppy hat, long sleeves, and pants.
The marsh killifish (Fundulus confluentus) is one of the only fish species that spends its entire life in the salt marsh. It breeds and deposits eggs at the highest water levels in the salt marsh. When the waters recede, the eggs will remain stranded but will hatch in 15 minutes upon reflooding. A salt marsh mosquito (Aedes taeniorhynchus) also deposits its eggs, which hatch upon reflooding. The fish's behavior results in protection of its eggs from aquatic predators and provides its young with a food supply of mosquito larvae, which become available at the right time and the right place for killifish during reflooding.
Periwinkle (Littorina sp.) and saltmarsh (Melampus lineatus) snails are seen climbing marsh stalks and serve as easy prey for mammals and birds. Saltmarsh snails lack a protective covering for their foot opening, so are susceptible to dessication and must remain close to water. The snail moves up and down Spartina stalks with the tides. Its biological clock is timed to tidal movements and the snail begins its climb up the stalks before the tidal water arrives.
Armies of fiddler and square-backed crabs, perhaps the most common animals in the salt marsh, are observed scuttling across the muddy floor of the marsh. Crabs are fed on by raccoons, mink, rice rats, and birds, which make their homes on higher and drier ground in the marsh. Birds that live in the marsh include the clapper rail or marsh hen (Rallus longirostris), the long-billed marsh wren (Telmatodytes palustris), willets, and seaside sparrow. The clapper rail is a game animal and is approximately the size of a small chicken with a grayish color and a long, slightly down-curved bill. The long-billed marsh wren is a medium-sized bird with white stripes on a reddish-brown back, a white breast, and a prominent white line over the eyes.
Diamondback terrapins inhabit the marsh throughout the year. Alligators are occasionally observed in tidal creeks when they move between freshwater and brackish marshes. Feeding in the shallower areas of the marsh are wading birds including egrets, herons, ibis, and storks.
Freshwater marshes, such as the Savannah National Wildlife Refuge, support a greater diversity of aquatic plants than saltwater marshes, and are important nesting and resting habitat for migrating waterfowl. Except on Blackbeard Island, most coastal waterfowl management occurs in old rice field impoundments and newly diked marsh in brackish water areas. Alligators, frogs, turtles, and snakes are abundant residents of the freshwater marsh.
On the Georgia coast, you can study the salt marsh in many areas including Fort Pulaski National Monument, Earth Day Nature Trail, Harris Neck National Wildlife Refuge, and Jekyll Island State Park.
The sounds and tidal creeks, the subtidal zones of the estuary, are important natural areas that teem with life. The murky water is a veritable organic soup abounding with creatures, which support larger and larger animals. High tides flood the sounds and tidal creeks, stir up bottom nutrients, and introduce oceanic fish and plankton to the estuary. Low tides and currents pump nutrients and plankton outside the estuary into offshore areas where they support other marine animals.
It has been estimated that the salt marsh and surrounding waters serve as feeding and nursery grounds for 70 percent of all commercially important fish and crustaceans. In 1997, the commercial fisheries of fish, shrimp, and crab caught in Georgia sounds were worth $28 million. The most valuable commercial product was shrimp, with 4,543,631 pounds caught worth $22.2 million. Blue crab ranks a distant second, with 6,808,290 pounds caught worth $3.8 million.
Recreational fisheries are also dependent on the marshes and sounds, which serve as nurseries and feeding grounds for many inshore game fish, including red drum (also known as channel or spottail bass), spotted seatrout, flounder, croaker, black drum, sheepshead, and whiting. Tarpon (Tarpon atlanticus) is another popular game fish because of its fighting tendencies and size. Fish that are 6 feet in length and 100 pounds are common. Of all the game fish sought on the Georgia coast, the tarpon is the most primitive.
A prominent animal of tidal creeks and sounds is the Atlantic bottle-nosed dolphin, a beloved marine mammal known for its playfulness and intelligence. Manatees are also occasionally seen in subtidal areas during summer when the water is warmer.
Georgia's mainland upland may be the most significantly altered ecosystem on the Georgia coast. Much of the land is in cultivation for Southern yellow pine, the most commercially valuable agricultural product in Georgia.
Vegetative communities change over time in a natural process known as succession. Given enough time, a forest matures and changes until it reaches a stage where it becomes a stable, self-reproducing natural community. In Georgia, a cleared field eventually becomes a grassy meadow, which then becomes a pine forest. Pines are fast-growing and love sunlight. Below the pines, shade-tolerant hardwoods will start to grow, and eventually will shade out younger pines and dominate the forest. In this example, the hardwood forest is the climax community, which will exist indefinitely unless there is a major natural or man-made disaster that kills the hardwoods and starts the process over again.
Researchers believe the climax forest on the mainland upland of Georgia, before the arrival of the Europeans, was a diverse southern mixed hardwood forest, consisting of live oak, southern magnolia, American holly, American beech, white oak, pignut hickory, dogwood, saw palmetto, redbay, and pawpaw. Today, only a few examples of this forest remain. The southern mixed hardwood forest was not the only forest community found on the Coastal Plain. The Coastal Plain has a variety of natural communities, conditions, and soil types including sand ridges, bottomlands, and bluffs, which produce a great variety of forest types.
Also, fire was a natural influence on the Coastal Plain that kept large areas in perpetual youth, preventing them from reaching a climax form. Forest fires would kill hardwoods but spare fire-adapted pines. Much of the Coastal Plain was pine flatwoods consisting of longleaf and slash pine, with wiregrass growing in the understory. These pines were clear cut in the late 1800s to early 1900s, and today unspoiled examples of this forest community are very rare.
The Georgia coast would not be what it is today without its rivers. They deliver fresh water and nutrients that are vital to the estuarine system, and over the millennia, rivers have carried sediment loads that helped to create our barrier islands. Georgia's rivers are great places to observe a wide variety of wildlife, each with its preferred type of river habitat. In the river are many reptiles, including the alligators, snakes, and alligator snapping, mud, musk, and river turtles. A variety of fish also inhabit the waterways such as shad, crappie, bluegill, sunfish, catfish, and largemouth bass. River swamps are home to many species of amphibians, including the bird-voiced treefrog, green treefrog, and leopard and cricket frogs. Bird life is plentiful, and the quiet observer may see the rare swallow-tailed kite or bald eagle cruising the river. In tidal impoundments will be a wide variety of waterfowl such as wood ducks, pintails, mallards, geese, and wading birds such as herons, egrets, and ibis. Seen in the water and on the banks are shy otters, minks, and beavers, and more frequently heard are songbirds, woodpeckers, and owls hidden in the trees. In the bottomland forest may be white-tailed deer, raccoons, armadillos, bobcats, opossums, and wild turkeys. Near the Okefenokee Swamp one may catch sight of a Florida black bear.
Three distinctive types of rivers meet the Georgia coast: alluvial, blackwater, and tidewater. Alluvial rivers, such as the Savannah and Altamaha, originate in the Georgia mountains and Piedmont. Typically, alluvial rivers in Georgia carry a high sediment load and have a broad floodplain from 3 to 12 miles wide. In the 1700s and 1800s, rice plantations were established along these rivers in tidally influenced areas. Blackwater rivers originate in the Coastal Plain, carry low nutrients and low sediment loads, and have narrow floodplains. Blackwater rivers get their name from the tannin-stained color and reflective quality of their waters. The Satilla, St. Marys, and Suwannee rivers are blackwater rivers. The Ogeechee River is considered a mix of alluvial and blackwater characteristics. Tidewater rivers are located near the coastline and have short lengths and are greatly influenced by the tides. The Medway and Turtle rivers are examples of tidewater rivers.
Floodplains and river swamps should be considered part of the river and are extremely important to the health of the environment. During periods of high water, according to Dr. Charles Wharton, author of Southern River Swamp: A Multiple Use Environment, water overflows into these river swamps or floodplains, dissipating its energy over a wide area and depositing sediments and minerals that help the swamp ecosystem. Also, organic materials accumulated on the forest floor of the floodplain get swept up and carried into the river, helping to support detritus feeders in the river and eventually contributing nutrients to the coastal marine ecosystem. River swamps, sometimes called bottomland forests, also perform as highly efficient water treatment plants that naturally filter industrial, agricultural, and urban wastes at no cost, and help buffer downstream areas from flooding by holding and absorbing flood waters. The flood cycle is important to young fish, tadpoles, insects, and other organisms that mature and feed in freshwater sloughs and ponds, which serve as protected nursery areas. As development chews up natural areas across the state, it pushes wildlife into smaller patches of natural habitat. The river serves as a natural greenway that links wild areas such as river swamps together, providing natural travel corridors between havens for wildlife. A much greater abundance and diversity of wildlife is found in river swamps, compared with pine plantations found dominating much of Georgia's landscape.
During winter and early spring, rivers flow higher due to frequent rains. Flora and fauna of the river swamps and coastal estuaries have adapted and become dependent on these pulses of water and nutrients. In the estuaries, for example, oysters rely on the nutritional and freshwater inputs during spring for their development. If natural flows are interrupted (by dams), it can be disastrous to the survival of the species. Fresh water keeps the oyster predator, the saline dependent oysterdrill, out of the estuary when salinity is sufficiently lowered.
There are two types of river swamps: cypress-gum forests and bottomland hardwood forests. The cypress-gum swamp is more frequently inundated with water, and here you will find baldcypress, tupelo gum, and overcup oaks. In the less frequently inundated bottomland hardwood forest, indicator species are water hickory, diamond-leaf oak, cherrybark oak, and green ash.
Across Georgia, man has drained the bottomlands to harvest the trees and farm the rich soil. While this has produced timber and agricultural products, it has also destroyed many naturally occurring benefits of the river swamp, including the cycling of nutrients for swamp flora and fauna, flood buffering, and natural treatment of agricultural, industrial, and human wastes. It also has eliminated important wildlife habitat.
Man has tried to tame the river by channelizing and damming. Impoundments, built to provide a growing population with hydroelectric power and waterfront property, interrupt the natural pulses of water and sediment to downstream areas. Impoundments eliminate ecologically diverse whitewater areas upstream and replaced them with man-made lakes stocked with gamefish and surrounded by lake homes. Pollution, silt, and watercraft fill these impoundment lakes, where once existed a diversity of freshwater fish and mussels (the most endangered faunal group in the U.S.).
Man has built many channels, dikes, and levees to prevent the river from flooding. In some cases, it is believed floods are much worse because the river is not allowed into natural river swamps that would absorb the energy and waters of the flood.
Swamp, like the word wetland, is used to describe many types of wet areas. Here it refers to a depressed freshwater wetland (river swamps are discussed in the previous section). Across the Coastal Plain there are several types of swamps, ranging from 1-acre cypress ponds to the vast American treasure that is the Okefenokee Swamp. All forms of swamps are less and less common as massive agricultural operations drain and fill the depressions that make the swamps in order to grow Southern yellow pine.
The cypress-gum swamp is recognized by its arched form known as a cypress dome or head. Many of these are found in the depressed, former areas of marshes west of ancient shorelines. The ancient lagoons left behind clayey soils that resist draining, thus keeping water tables high, allowing cypress and blackgum to grow. These swamps serve as important water sources, as well as feeding and breeding grounds for a variety of amphibians, reptiles, birds, and mammals.
Another type is the bay swamp, a rare evergreen forest consisting of sweetbay, loblolly bay, swamp red bay, and myrtle. This natural type has a wet, peaty soil and is rarely flooded.
The Carolina bay is another wetland form that is common on the Coastal Plain, with approximately 1,000 identified in Georgia. Carolina bays are tear-drop shaped ponds that are typically inundated and circled by cypress and blackgum, with typical swamp vegetation in the interior. Scientists believe Carolina bays may have been scoured out by gale-force Pleistocene winds or a shower of nonmetallic meteors.
Two more types are savanna and herb bogs, which are wet grassland communities that depend on frequent fires. Fire keeps shrubs and hardwoods from invading the area. Wildflowers here are the most beautiful in coastal Georgia, including lilies, meadow beauty, hatpins, and a variety of orchids. Most fascinating about these bogs are the insectivorous plants that thrive in the low-nutrient acidic soils. These plants, such as the trumpet, hooded, and parrot pitchers, have adapted to poor conditions by developing various strategies for trapping and consuming insects.
Okefenokee is a vast mosaic of different vegetative communities, including bay swamp, herb bog, cypress-gum, and prairie. The swamp is profiled in detail in this book (see Okefenokee Swamp).
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