![]() NPS Photo/Audrey Bohl ![]() NPS Photo The Cumberland Island salt marshes are found on the western side of the island, protected from the force of the waves by the main island. It is bordered by the maritime forest. A small transition zone separates the forest from the marsh. This is referred to as the marsh border. During large storms and very high tides the marsh border gets flooded by salt water, so the plants are salt tolerant. Cedars, palms, palmettos and groundsel tree are commonly seen in this area. The tide plays a vital role in the salt marsh. It brings in nutrients, oxygen, and water, as well as animals. Few animals actually live in the marsh. Most are visitors looking for food or shelter. Many enter the marsh as plankton (microscopic drifters) and leave as adults. Crabs and shrimp are good examples of this. Other organisms enter to stay, like periwinkle snails and oysters. Each has adaptations to help them survive in this changing environment. ![]() NPS Photo The low marsh is flooded with salt water for 6-8 hours per day. There is only one kind of plant that has adapted to survive this - Spartina alternaflora (smooth cordgrass), making it a true, natural monoculture. This grass has several adaptations that allow it to live in the salt marsh. As it absorbs water through its roots, a membrane filters out most of the salt, allowing mostly fresh water to enter the plant. Extra salt is collected by a gland in the leaves and then excreted through special pores. You can sometimes see the salt crystals on the stem and leaves of the Spartina grass. The soil is dark and squishy in the low marsh. Bacteria are hard at work decomposing dead plant matter and turning it into nutrients for plants and planktonic creatures. Sometimes this muck can produce a distinctive, musky smell due to the decomposing plant matter. Tidal creeks wind through the sea of grass in the salt marsh. The tidal creek is the life blood of the marsh. It brings nutrients, oxygen and water into the marsh and then carries wastes away, just like the blood vessels of the human body. Bordering the tidal creeks is a raised area called a levee. It is formed from tidal deposits as the waters flow over the bank. Friction causes the water to slow and drop the sediment load which is how the levee is built. The salt marsh is one of the most productive ecosystems in the world. Much of the seafood that we eat start it’s life in the protection of the salt marsh. By preventing flooding, cleaning water and providing habitat for animals the salt marsh provides vital ecosystem functions that make it important to preserve. |
Last updated: December 14, 2018