the upper fringe of soft sediment shores is often dominated by salt marsh vegetation comprising woody perennials,succulent annuals and grasses. Saltmarshes are usually associated with temperate climates but occur throughout the world, from sub-polar regions to the tropics. On tropical shores, sailmarshes are often associated whit mangroves, occupying the upper and lower intertidal zone respectively. Species composition is determined to a large extent by salinity. For example, in low salinity or brackish waters found in the upper reaches of estuaries, marsh vegetation gives way to reed beds. Plant detritus carried away from marshes also contributes to food webs in estuaries and near shore waters. Many saltmarshes have been attributed special conservation status under the Ramsar Convention on Wetland of International Importance, due to their importance as habitats for birds, especially migratory species.