Explanation:

Estuary is a place where the fresh water of river or stream meets with ocean water. This place provides the conducive conditions for development of different species.Estuaries are vital habitats for thousands of marine species. Estuaries have been called the "nurseries of the sea" because the protected environment and abundant food provide an ideal location for fish and shellfish to reproduce.Besides fish, many species of birds depend on estuaries for food and nesting areasAn unparalleled example of a salt wedge estuary is the Mississippi River.The Mississippi River is a particularly good example of a salt wedge estuary, since its size allows the detailed observation of the current field even in the narrow interface between the salt wedge and the freshwater layer.