Mangrove coasts are those where mangrove plants have rooted in the shallow water of bays, and sediments around their roots have built up to sea level, thus extending the coast. Mangroves include several species of low trees and shrubs that thrive in the warm, shallow, saltwater environments of the lower latitudes.
Mangroves have the ability to form unique intertidal forests that are characterized by dense entangled networks of arched roots, called prop roots, that facilitate trapping of fine sediments, thereby promoting accretion and the development of marshlands. The prop roots and upright exposed roots called pneumatophores also allow the plants to withstand occasional wave action and allow oxygen to reach the roots in anaerobic soils.
The most extensive mangrove coast in the United States is the southwest shore of Florida in the Everglades National Park and the region of Florida Bay. Mangrove islands and marshes continue at intervals along the western coast of Florida. Barriers replace the mangrove coast along the Florida Panhandle and Alabama coast, but farther west mangrove coastal areas and swamps redevelop in the Mississippi River delta region.