Estuary

Estuary is the diverse ecosystem lies between the seas and continents. It is the area at the mouth of the river where the river joins the sea or ocean. The upper limit of an estuary is called as its head and the lower limit as its mouth. Between the fresh water head and the saline water mouth of the estuary, lie several zones corresponding to the intermediate salinity ranges.

The organisms that live in estuary must have ability to survive the varying salinity level. The turbidity, limit the depth of the light penetration and thus limiting photosynthesis and primary production. Most of the estuarine species are detrivores. Some of the dwellers of the estuaries spawn in the fresh water and feed and grow at sea. Some of the species on the other way spawn at sea and feed and grow in fresh water. Other than permanent dwellers, estuaries are host for visitors like migratory birds and fishes.