Beach Ecology
The intertidal beaches of Georgia can extend as much as a quarter of a mile out to sea.
Beaches generally have high levels of wind and irregular water currents, making beach sand a difficult habitat for plants and shore life. The sand on the beach is at some point mixed with sand that is offshore, such as sand bars, submerged beaches, and inlet shoals.
Because Georgia has such extreme tidal ranges and a gentle sloped shore, Georgia’s beaches are described as having vast intertidal zones with narrow or nonexistent berms. The intertidal zone is the area that is above water at low tide and under water at high tide, whereas the berm is the area of land that makes up the active shoreline. Georgia’s beaches are also made up of sand dunes, hills that have been built with dry beach sand blown inland and trapped by vegetation. As the sand accumulates the dunes become higher and wider.
Intertidal Zone
The intertidal zone is the area that is above water at low tide and under water at high tide.The size of the zone is dependent on the tidal range and the slope of the beach. The intertidal beaches of Georgia can extend as much as a quarter of a mile out to sea.
The intertidal zone has little diversity of marine sea life. The waves and daily flooding of seawater make the area a difficult place to reside. The majority of sea life are either found in burrows or scattered about in the wet sand. During low tide, the burrows of some creatures are exposed, such as the ghost shrimp. Filterfeeders like coquina clams position themselves just beneath the surface of the sand after the backwash of the surf passes over them. Terrestrial animals may visit for meals and aquatic animals float in with the tide to feed or escape predators.
Berm
The area of land that makes up the active shoreline is known as the berm. It is the dry sandy section between the intertidal zone and the dune systems. Although the berm usually stays above water, the area is still influenced by waves. During storms or high tidal ranges, the berm is often flooded. During low tide, the wind pushes sand and rebuilds the zone. The berm does not permit the growth of vegetation.
Dune Systems
Dunes are an important part of the beach ecosystem. They act as buffers against wave damage during storms and protect the plant communities from salt water, sea spray and strong winds. The dunes also replenish and maintain the beach at times of erosion.
Salt spray, rapid water drainage, shifting sand and constant sun exposure make the primary dunes a harsh habitat. Many of the plants that inhabit the dune system have developed adaptations similar to desert plants. Some plants have a deep, single taproot that reaches the water table while others have far-reaching and widespread fibrous root systems that catch rainfall.
Sea oats eventually become an established species along Georgia’s coast. Their long leaves and tall heads trap windblown sand that helps the dunes grow. The sand could bury sea oats and other plant life as it grows, but the sea oats work to grow new leaves and roots before the sand builds up over the plant.
The other plants in this type of community suffocate, degrade and ultimately provide organic matter known as humus. The humus helps the sea oats grow and get taller. The State of Georgia prohibits the picking of sea oats because of the vital role they play in building and stabilizing dunes.