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Salt marshes are both complex and fragile. They are also some of the most threatened environments on the planet as they occupy coastal locations that are attractive for industrial, commercial and recreational use. These uses create pressures for development and contribute to pollution and other damage to the marshes. The marshes are also vulnerable to environmental change. This includes global climate change which is leading to rising sea levels. A salt marsh is a type of Marsh found in the Intertidal transition between land and ocean. They are dominated by Halophytic Herbaceous plants. They are also called '''tidal marshes'''. The water is Saline , and both the water table level and salinity are dependent on tides. They develop on stretches of coast with gentle tidal action where erosion is light enough to allow vegetation to take hold. They are common on Low-energy Coast s such as Estuaries , enclosed bays, and the land sides of Barrier Islands and strips. The Sediment in salt marshes is delivered not constantly, as in other types of marshes, but cyclically due to the tides. As would be expected at the coast, the sediment is high in sand, shells, and organic material from the ocean. Plant species diversity is low, since the flora must be tolerant of salt, complete Submersion , and anoxic mud substrate. The most common salt marsh plants are Glasswort s (''Salicornia'' spp.) and the Cord Grasses (''Spartina'' spp.), which have worldwide distribution. They are often the first plants to take hold in a Mudflat and begin its Ecological Succession into a salt marsh. Their roots spread into the substrate and stabilize the sticky mud so that other plants can establish themselves as well. Plants such as Sea Lavender s (''Limonium'' spp.), Plantains (''Plantago'' spp.), and varied Sedges and Rushes grow once the mud has been vegetated by the Pioneer Species . The flora of a salt marsh is differentiated into levels according to the plants' individual tolerance of salinity and water table levels. Vegetation found at the water must be able to survive high salt concentrations, periodical submersion, and a certain amount of water movement, while plants further inland in the marsh can sometimes experience dry, low-nutrient conditions. Salt marshes are quite photosynthetically active and are extremely productive habitats. They serve as depositories for a large amount of organic matter, and are full of decomposition, which feeds a broad food chain of organisms from bacteria to mammals. In wintertime the saltmarsh looks more sparce than in summer. More space is seen between reeds as snow falls between them. The water partly freezes, which makes it look rather spectacular. EXTERNAL LINKS
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