Georgia's Salt Marshes
Georgia's salt marshes play a unique role in maintaining the delicate balance of nature so vital along our coastal estuaries.
Created as a result of glacial processes during the ice ages, the origin of Georgia's marshlands can be traced back to the melting of the continental glaciers resulting in higher sea levels. One theory suggests that sediment, sand, and soil brought down by the rivers, blown by the wind, and washed ashore by the waves gradually built up into ridges and dunes on the landward side of the shoreline. Water from the melting glaciers resulted in rising sea levels, which flooded the coast and mainland, and the ridges were given prominence as barrier islands. Ocean waters behind these islands formed lagoons, and later the marshlands. This process took place several times; thereby creating additional marshes between more barrier islands, and finally the salt marshes as we know them today.
Developed from the lagoons that filled with sediments and deposits from rivers and streams flowing to the ocean, the marshlands of Georgia gradually began to assume their status as a vital part of some of the world's greatest estuaries.
The most common of the salt marsh plants in Georgia is a tall cane-like grass called smooth cord-grass, Spartina alterniflora, which virtually covers the coastal marsh area. The environment in which the salt marsh flourishes is neither all terrestrial nor all marine, but rather a combination of both.
Many salt marsh plants actually do better in a fresh water environment but are not often found there because of the competition from other species. But in the zone where land meets a salt water bay, very few plants can survive. Most plants die when flooded by salt water at high tide, but salt marsh plants have the ability to remove most of the salt from the water it uses. This is accomplished by keeping high concentrations of dissolved solids in the root structure and extracting salt through highly specialized salt glands on the leaves.
These plants are hardy and have extensive underground structures. The plants root system grows horizontally, giving rise to new plants. This allows the marsh grass to spread rapidly. That's important, because these structures hold the marsh together and slow erosion. An added benefit of the plants root structure is that the plant is protected from hazards such as freezing or fire. This salt marsh grass is responsible for the continuation and survival of the balance of nature within the estuarine ecology. Georgia's coastal marshlands encompass approximately 378,000 acres in a four to six mile wide band behind the barrier islands. Thriving in the waters of the estuaries, these marshes have been identified as one of the most extensive and productive marshland systems in the United States. It is production almost beyond comprehension, producing nearly twenty tons to the acre; it is four times more productive than the most carefully cultivated corn. Georgia's salt marshes produce more food energy than any estuarine zone on the eastern seaboard.
The tide is truly the life blood of the marsh bringing its contribution with each coming and going. The incoming tide nourishes and feeds the grasses of the marsh and the outgoing tide transports food and nutrients produced by the salt marsh to the sea. In general, the higher the tidal range the greater the production potential. Georgia tides average approximately 6 1/2 feet but exceed 10 feet during the highest spring tides.
As the salt marsh grasses die and decompose, nutrient by-products are produced and taken by the outgoing tides and begin to feed an ever-growing number of organisms until all forms of marine life in the estuary have benefited. These minute, decaying grass particles feed small fish, plankton, oysters, shrimp, clams, and crabs. The marsh serves as a nursery ground for young fish, shellfish, and crustaceans, which in turn support larger fish and the cycle goes on and on. In addition, the stems and grass provide refuge for many adult animals in estuaries where the salt and fresh water mixes.
The salt marsh serves as a primary nursery ground for many economically important fish and shellfish. Were it not for the marsh, juvenile populations of crabs, shrimp, and fish would be greatly reduced.
The commercial catches of many popular offshore food fish show a direct relationship to the ratio of marsh versus open water inshore. In other words, in regions where the inshore areas contain abundant salt marshes, the offshore regions are more productive yielding more fish and other important food species. Catches of many species of shrimp are greatly increased by the amount of salt marsh inshore of the commercial fishing area.
Additionally, our salt marshes act as buffers against offshore storms. Without their dissipating effect, hurricanes and northeasters on the Atlantic coast would do much more damage. The destructive fury of large storm waves and tides is greatly reduced by their passage across the marsh. The grass absorbs most of the wave and current energy, which lessens the damage that can be done.
The Coastal Marshlands Protection Act
In 1970, the State of Georgia established the Coastal Marshlands Protection Act (CMPA) to protect the marsh and estuarine areas, and to regulate the activities within these public trust lands that is held for the citizens of Georgia. Through the Georgia Department of Natural Resources, Coastal Resources Division (GADNR-CRD), the CMPA is enacted to protect the estuarine area so that residents and visitors of Georgia alike can fish, boat, use, and enjoy all our salt marsh and tidal waters have to offer. Activities and structures in the coastal marshlands are regulated to ensure that the values and functions of the coastal marshlands are not impaired and to fulfill the responsibilities of each generation. As public trustees of the coastal marshlands for succeeding generations, GADNR-CRD allows for the sustainable use of the estuarine area through permits and other methods of authorization that will preserve the condition of the marsh while still allowing for its enjoyment.
The Coastal Marshlands Protection Act (CMPA) regulates activities and water dependent structures in jurisdictional marshlands. Projects that require a CMPA permit include marinas, community docks, bridges, dredging, bank stabilizations longer than 500’, modifications to any such structure, and any construction not exempted from the Act, such as single-family private recreational docks. If you are planning any construction or activity in or near salt marsh in the State of Georgia, you must contact our office for a jurisdictional determination and to find out if you need a CMPA permit for your project. Click here for more information