An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments. The word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. Here are some key characteristics of estuaries:
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Brackish water: Estuaries are bodies of water where freshwater from rivers and streams meets and mixes with saltwater from the ocean, resulting in brackish water that is somewhat salty, but not as salty as the ocean.
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Unique ecosystems: Estuaries are home to unique plant and animal communities that have adapted to brackish water. They are lined with marshes and sea grasses that filter water flowing to the ocean and act as a buffer protecting us from coastal storms.
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Tidal patterns: The tidal pattern in an estuary depends on its geographic location, the shape of the coastline and ocean floor, the depth of the water, local winds, and any restrictions to water flow. While strongly affected by tides and tidal cycles, many estuaries are protected from the full force of ocean waves, winds, and storms by reefs, barrier islands, or fingers of land, mud, or sand that surround them.
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Economic and environmental value: Estuaries provide ideal areas for migratory birds to rest and refuel during their long journeys, and many species of fish and wildlife rely on the sheltered waters of estuaries as protected spawning places, making estuaries often called the "nurseries of the sea". Estuaries also perform valuable environmental services, such as filtering out sediments and pollutants from water flowing through wetlands such as swamps and salt marshes, creating cleaner and clearer water that benefits both people and marine life.
