Salt marsh

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Salt marsh

A maritime habitat characterized by grasses, sedges, and other plants that have adapted to continual, periodic flooding. Salt marshes are found primarily throughout the temperate and subarctic regions.

The tide is the dominating characteristic of a salt marsh. The salinity of the tide defines the plants and animals that can survive in the marsh area. The vertical range of the tide determines flooding depths and thus the height of the vegetation, and the tidal cycle controls how often and how long vegetation is submerged. Two areas are delineated by the tide: the low marsh and the high marsh. The low marsh generally floods and drains twice daily with the rise and fall of the tide; the high marsh, which is at a slightly higher elevation, floods less frequently. See Mangrove

Salt marshes usually are developed on a sinking coastline, originating as mud flats in the shallow water of sheltered bays, lagoons, and estuaries, or behind sandbars. They are formed where salinity is high, ranging from 20 to 30 parts per thousand of sodium chloride. Proceeding up the estuary, there is a transitional zone where salinity ranges from 20 to less than 5 ppt. In the upper estuary, where river input dominates, the water has only a trace of salt. This varying salinity produces changes in the marsh—in the kinds of species and also in their number. Typically, the fewest species are found in the salt marsh and the greatest number in the fresh-water tidal marsh.

The salt marsh is one of the most productive ecosystems in nature. In addition to the solar energy that drives the photosynthetic process of higher rooted plants and the algae growing on the surface muds, tidal energy repeatedly spreads nutrient-enriched waters over the marsh surface. Some of this enormous supply of live plant material may be consumed by marsh animals, but the most significant values are realized when the vegetation dies and is decomposed by microorganisms to form detritus. Dissolved organic materials are released, providing an essential energy source for bacteria that mediate wetland biogeochemical cycles (carbon, nitrogen, and sulfur cycles). See Biological productivity

The salt marsh serves as a sediment sink, a nursery habitat for fishes and crustaceans, a feeding and nesting site for waterfowl and shorebirds, a habitat for numerous unique plants and animals, a nutrient source, a reservoir for storm water, an erosion control mechanism, and a site for esthetic pleasures. Appreciation for the importance of salt marshes has led to federal and state legislation aimed at their protection.

References in periodicals archive ?
What factors other than autocyclicity could explain the sequential episodes of tidal salt-marsh destruction and reformation we have recorded?
There is some local salt-marsh cyclicity (Greensmith and Tucker 1965; Harmsworth and Long 1986), but the general trend since Roman times has been unsteady marsh-edge retreat and/or creek-widening.
Evolution of salt-marsh cliffs in muddy and sandy systems: a qualitative comparison of British west-coast estuaries.
Sites breached as part of managed realignment schemes were sampled in June 2005 giving several examples of salt-marsh development on former agricultural land.
In this study, the target species were halophilic species, defined by their preference or exclusive presence in salt-marsh habitats, and rare species belonging to the Red Data Book and/or the Review of Nationally Notable Spiders of Great Britain (both statuses from Harvey et al.
For example, among the six species only found at natural sites, the presence of at least two lycosid species can directly be related to the presence of a dense vegetation cover: Pardosa nigriceps, living on low vegetation (Roberts 1987), and the rare Arctosa fulvolineata that inhabits the heterogeneous litter of some salt-marsh habitats (Petillon et al.
As well as our local Dyfi estuary lambs, which according to Will are usually Welsh crossed Lln breeds for hardiness with a little Suffolk or Texel for conformation (shape to you and me!), salt-marsh lamb is produced on the Lln peninsula (Wales' largest production area) and in the West, around the Taf/Tywi estuaries.
Although people wax lyrical about spring lamb, for me most lamb is better for a few more months grazing in order to acquire more flavour from the herbage on which it has been raised, and this is never more true than with salt-marsh lamb.
During the third and fourth instars, salt-marsh mosquito larvae have the unique ability to cluster together, sometimes forming huge rafts 20 or more feet in width.
Effects of five years of grazing on a salt-marsh vegetation.
Dispersal, germination and early establishment of halophytes and glycophytes on a grazed and abandoned salt-marsh gradient.
The move is necessary because ecologically important coastal habitats such as salt-marshes are eroding at an alarming rate.