A river of grass swaying in the breeze where the land meets the water, salt marshes are among the most productive habitats found. Because they exist in areas which man has steadily developed or altered over many years, they are also among the most threatened habitats.

Salt marshes are coastal wetlands which develop along low-energy estuary shores. There is usually a pronounced tidal fluctuation within a salt marsh and the vegetation which occurs here exhibits various degrees of salt water tolerance. The zonation of the various grass species which form the basis of the salt marsh community is highly dependent on each species' tolerance to inundation (partial submergence) by salt water.

Salt marshes are among the most productive ecosystems on earth. Live marsh grass is not used as a source of food, but the dead plants are a source of nourishment for bottom-dwelling scavengers such as worms, fishes, shrimps, marsh snails, and crabs. Insects are also abundant in the salt marsh. Most of these insects consume living plants, and are preyed upon by the birds and fish that inhabit the salt marsh. Fishes, crabs, and shrimps live in salt marshes where stems, leaves, and roots provide food and shelter from predators. The abundance of food and protection given by marsh plants allows the young of salt marsh inhabitants to survive to adulthood.

Many fish that inhabit the marshes move with the tide. Some marsh-dwelling fishes and shrimps, remain on the marsh surface after the tide recedes. They live in potholes and standing pools of water. Very few reptiles live in salt marsh habitats.

Many birds depend on the abundant food supply found in the salt marsh. Birds such as herons and egrets feed on fishes, shrimps, and fiddler crabs.