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 ?
The salt marsh habitat of the Tuckerton Peninsula is rapidly decreasing in areal extent, and if this trend continues, it will be among the first along the central New Jersey coast to be eliminated by sea-level rise (Kennish et al.
Although there is a section in the book's first chapter about NZ's historical problems from human introductions of invasive species, there is scant mention of the weak biotic resistance because of NZ's depauperate indigenous fauna and flora in general and, in particular, its vulnerability to salt marsh colonization by an invasive mosquito because of the absence of a native culicid occupying that habitat.
Using chiefly historical evidence we have outlined how the salt marsh at Aust and Northwick warths in the Severn Estuary evolved during recent centuries over a frontage of about 4 km in a stepwise manner on a decadal-centennial time scale.
Anyone wishing to join the Coastal Rangers and Dee Wildfowlers, who help to manage to salt marsh and estuary lands, for lunch and a walk into the heart of the estuary should call the visitor centre at Wepre Park to book their place and find out details on meeting places.
For centuries the lower section of the River Team played host to a variety of industries and much of the salt marsh, an important feeding ground for birds and other wildlife like otters, was lost.
Once the students have acquired the background information, ask them to describe how different a salt marsh might look at high tide compared to low tide.
MA to replant salt marsh plants on barrier beaches; and Merrimack, NH to provide critical funding to remove an abandoned inland dam.
As they died, they were replaced by a salt marsh grass, Spartina patens.
PCR-positive pools were from birds sampled in estuarine, salt marsh, or standing water habitats (Table 2).
Of the sixty hatchlings tested, only one chose a seaward gate while fifty-three hatchlings chose a gate facing salt marsh.
If you wish to supply added covering, wait until between Thanksgiving and Christmas to spread a thin layer of salt marsh hay over the plants.