Salt marsh is vegetated almost completely by herbaceous plants, primarily grasses, sedges, and rushes. This community type occurs within the intertidal zone of coastal areas and may be infrequently (high marsh) to frequently (low marsh) inundated by salt or brackish water.
Salt marsh develops where wave energies are low and where mangroves are absent. Mangroves may extirpate shade-intolerant marsh species. The size of a salt marsh depends on the extent of the intertidal zone in which it occurs. Salt marshes of larger sizes are usually dissected by numerous tidal creeks. Areas that have low topographic relief and relatively high tidal ranges are likely to have larger salt marsh extents.
Within salt marsh, plant species are often distributed unevenly, especially in transitional areas. Species distributions are affected by biotic and abiotic variables such as elevation, substrate type, degree of slope, wave energy, competing species, and salinity. Smooth cordgrass typically occupies the lower elevations and is usually adjacent to tidal creeks and pools. Needlerush dominates the slightly less frequently inundated zone. Vegetation at the higher elevations forms transitional areas to uplands and may contain species such as marsh-hay, glassworts, saltwort, saltgrass, sea ox-eye daises, marsh-elder, and saltbush as well as many other species.
The salt marsh habitat is among the most productive communities in the world. Primary production is greatly affected by soil salinity and tidal frequency.
This conservation asset includes Salt Flat, Cordgrass, and Needlerush.
Saltwater marshes have considerable capacity to adjust to sea level rise under certain, more favorable conditions. Under more moderate rates of sea level rise, saltwater marshes should be able to keep pace and move inland. However, under more rapid rates of sea level rise there could be significant loss of saltwater marsh. Without inland migration, saltwater marsh is likely to have 95% of the current area inundated by 1 m of sea level rise and 99% inundated by 3 m of sea level rise. Additionally, mangrove migration and expansion could lead to loss of saltwater marsh as it is replaced by mangroves; saltwater marsh could be reduced by 60% in Florida with only a 2-4 °C increase in annual mean minimum temperature.
More information about general climate impacts to habitats in Florida.
Saltwater marsh species such as the black rail, salt marsh voles, and marsh wrens may lose habitat due to sea level rise, if there are barriers to saltmarsh inland migration or if saltwater marsh plants can't keep pace with the rate of sea level rise.
With increasing temperatures and fewer cold weather events, species may lose saltwater marsh habitat to mangrove habitat in the northern portions of their range due to mangrove range expansion.
Some species such as the Lower Keys marsh rabbit and silver rice rat, both found in the Florida Keys, are predicted to lose 100% of their habitat with 1m of sea level rise and don't have any options for migration.
Fluctuations in freshwater inputs due to changes in precipitation patterns can lead to decreased prey availability, decreased reproductive success, decreased recruitment, and increased mortality in fish and invertebrates species.
More information about general climate impacts to species in Florida.
This conservation asset was assessed as part of the Standardized Index of Vulnerability and Value Assessment - Natural Communities (SIVVA).
This conservation asset has a SIVVA vulnerability score greater than 70 but is not among the top 5 most vulnerable natural communities in any SIVVA vulnerability category.
Read more information about SIVVA natural communities.