Coastal wetlands are found along the Atlantic, Pacific, Alaskan, and Gulf coasts and include estuaries. Mangrove swamps, dominated by halophytic shrubs or trees, are common in warm climates, for example, in southern Florida, Puerto Rico, and Louisiana.
Tidal freshwater wetlands form in upstream coastal wetlands where the influence of salt water ends.
This system is appropriate for an ecologically based understanding of wetland definition. The entire Classification of Wetlands and Deepwater Habitats of the United States , including tables and figures of the hierarchical structure, is available online. The following is a brief description of the major classes of wetlands under the Cowardian system. Salinities exceed 30 parts per thousand. Ocean-derived salinities are always less than .5 parts per thousand.