The freshwater and coastal ecosystems of the Everglades provide many socioeconomic benefits including important recreational and tourism opportunities, key fishery habitat, water quality improvements, flood and erosion mitigation, and mitigation of greenhouse gases through carbon storage and sequestration. Increasing pressures from sea-level rise (SLR) will influence the number, types, and value of ecosystem services expected in the future. These pressures combined with the geological history of Florida put the Everglades at the "forefront of transition." In the peat-based portions of the Everglades, where water depths can be altered either by changes in water elevation due to sea level and rainfall or by changes in elevation of the peat surface due to biophysical processes, slight changes in the depth and period of inundation can influence the presence and distributions of plant species and communities. As a flat, low-lying landscape, the conventional thinking is that Everglades coastal habitats will gradually migrate upslope with increases in sea level as a transgressive transition of saltwater into freshwater sawgrass marshes. Inland transgression of mangroves has been suggested as a means by which subtropical and tropical coastal landscapes will "adapt" to increasing sea-level rise (SLR). However, erosion of coastal peats, inundation ponding, and overstep (salt water encroachment too fast for all communities to retreat) has already been observed in the southeast saline Everglades. In several areas of coastal Everglades National Park, freshwater and oligohaline Everglades wetlands are expected to be exposed to increased duration and inundation of seawater, impacting processes that may lead to peat collapse. In some cases, the freshwater marsh has collapsed by some 0.5. m over a period of a few decades and has converted to an open water, mangrove-free environment. If coastal communities cannot adapt to the salinity changes associated with increasing sea levels, then significant coastal wetland loss may occur, dramatically altering and increasing the vulnerability of the south Florida coastline. Without restoration of freshwater flow to the Everglades, saltwater intrusion-induced peat collapse may be enhanced and landward migration of mangroves into freshwater peat soils stymied.
