What is an Estuary?

Estuary Watercolor Illustrationestuary (n) - A coastal area where salt water from the ocean mixes with fresh water from rivers, rainfall, and upland runoff. Within the estuary, salt and fresh water proportions differ daily depending on the season, weather, and tides. Vital coastal ecosystems exist in these constantly changing conditions.

The mixing of salt and fresh water begins offshore, where water, sediment, and nutrients from the Mississippi River mix with the salt water of the Gulf of Mexico. Wind and tides drive this mixture, along with fish and shellfish, into the estuary. Changes on the coast affect water levels and habitats throughout the entire system.

This dynamic combination of physical and biological factors produces an ecosystem unrivaled in productivity and commerce. Such characteristics are often cited to describe estuaries as the "cradles of civilization." One of the most expansive and productive estuaries in the world is located in the United States at the interface of the Mississippi River and the Gulf of Mexico. The Barataria-Terrebonne National Estuary Program is chartered with the protection, development and study of this vital ecosystem.

Click here for more about the program charter.





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