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 mainland salt marshes of the Netherlands Wadden Sea are largely of anthropogenic origin, because their development has been promoted by ditching and construction of sedimentation fields, from at least the 17th century onwards (Verhoeven 1980, Esselink et al.
Salt marshes in New Jersey are particularly vulnerable to inundation.
Mangrove forests and salt marshes fill the same ecological niche in shallow coastal waters, both providing valuable services such as flood buffering, storing atmospheric carbon, and building soils.
It has long been known that many salt marshes associated with mudflats take the form of a sequence of terrace-like morphostratigraphic units with formerly eroding scarps between, which descend stair-like toward the sea (Luternauer et al.
Options for restoration and management of coastal salt marshes in Europe.
Experts estimate that we have lost over 50 percent of our salt marshes in the Gulf of Maine, and that pattern is repeated across the country.
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.
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).
Over the decades, the salt marshes along the shores of navigation channels have experienced some degradation and habitat loss due to a number of factors, including increased boat traffic and years of commercial construction and development along the shore.
When Pilgrims John and Priscilla Alden of Mayflower fame moved the few miles north from Plymouth in 1627, they found emerald green salt marshes and an upland clothed in maples, pine, and oak.