ABSTRACT
Coastal wetlands appear to be both important sinks of global carbon and exporters of nutrients which help sustain the productivity of estuarine and other coastal ecosystems. This chapter discusses the major environmental settings of muddy coastlines, and then introduces the ecological and geomorphological characteristics of mudflats, marshes, mangroves and sabkhas. Muddy coastlines form in low-lying, relatively sheltered areas with abundant sediment supply, such as behind barrier islands, around estuaries and on deltaic coasts. Barrier islands and spits commonly have an associated back barrier zone with salt marshes, mangroves and lagoonal environments. In the upper tidal zone, landward of mud and sandflats, salt marshes often form. Found in a wide range of climatic conditions, salt marshes occur from the Arctic to the tropics, where they are mainly replaced by mangrove associations. Associations of mangrove trees growing in muddy coastal environments are often called mangrove forests or mangals. In the upper tidal zone, landward of mud and sandflats, salt marshes often form.
