I. Estuaries are defined as the region between the most upstream extent of tidal influence and the lowermost extent of freshwater. When suspended sediment in river water is slowed when it reached the ocean, the sediment settles out of the water and forms deltas and mud flats that define nearshore habitats. In temperate regions Along the Atlantic coast down to about Florida, these mud flats communities are dominated by salt marshes , including salt-tolerant grasses, such as Spartina. In tropical regions, Mangrove swamps replace grasses as the dominant plant species. This photo was taken in the Fl keys and is typical of mangrove forests.
Mangroves grow on prop roots that elevate foliage above fluctuating water tables.
They are some of the most biologically diverse communities in the world, because these spaces offer hiding places for shrimp, fish, and other marine life from predation by crocodiles and birds. Many mangrove and other estuarine ecosystems are being destroyed by land use changes in coastal areas. For example, along the gulf coast of the US, Southeast Asia, and Latin America, the use of estuaries for managed shrimp aquaculture has all but destroyed the species diversity, and probably the functioning, of the native estuary. Check out the following article about the rise of shrimp farming and the loss of mangroves . Estuaries supply a significant amount of N and P to open waters.