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 ?
We have previously measured soil organic carbon storage in two restored salt marshes in Fluntington Beach, California (Keller et al.
In Atlantic Canada, salt marshes facilitate a high exchange productivity of nutrients.
2013) studied salt marshes along the US Atlantic coast and provide evidence that sediment starvation also promotes the initiation of salt marsh erosion.
A study by a Conservation International scientist revealed that plants in salt marshes, along with mangrove trees and seagrasses, are "extremely efficient" at locking carbon into the sediment beneath them, where it can remain for centuries.
Pannes are waterlogged, low-oxygen zones of salt marshes.
Vegetation succession in salt marshes is the result of the accumulation of nutrients in the soil leading to an increase in plant biomass and changes in species composition (Olff et al.
The Community's main salt marshes are located in Italy (25,000 tonnes), France (20,000 tonnes) and to a lesser extent Portugal, Spain and Slovenia.
This paper explores the potential for using coastal wetlands as an adaptive tool for dealing with climate change and sea-level rise, with particular focus on salt marshes in the Bay of Fundy in the Canadian Maritimes (Figure 1).
Main picture: when the crystals begin to form, the farmers use a special tool, known as an etelle, to create mounds of wet salt, which they leave to dry in the sun; Inset: wading birds flock to the warm, shallow waters of the salt marshes looking for shrimps and other invertebrates.
The three week earth-moving operation, which began yesterday, will allow the tides to flood the area, and create enlarged salt marshes, ponds and enriched habitats for birds and other wildlife.