Estuaries

698 Words2 Pages

Estuaries

Estuaries are bodies of water along our coasts that are formed when fresh water from

rivers flows into and mixes with salt water from the ocean. In estuaries, the fresh river water is blocked from streaming into the open ocean by either surrounding mainland, peninsulas, barrier islands, or fringing salt marshes. This mixing of fresh and salt water creates a unique environment that brims with all kinds of life. The estuary gathers and holds an abundance of life-giving nutrients from the land and from the ocean.

They provide a unique habitat for over 75 percent of our nation's commercial fish. This along with commercial and recreational fishing, boating and tourism provides many jobs and lots of enjoyment for those who use the area.

Estuaries are important to our quality of life and our health for reasons other than jobs, healthy economies, and recreational opportunities. The local bay or sound often serves as the focal point for community life and traditions, hosting everything from harvest festivals to busy ports. They also protect water quality, are a center for research and education, and help stem the erosion of our shoreline communities.

Estuaries come in all shapes and sizes and go by many different names, often known as bays, lagoons, harbors, inlets, or sounds. Estuarine environments are among the most productive on earth, creating more organic matter each year than comparably-sized areas of forest, grassland, or agricultural land.

Among the cultural benefits of estuaries are recreation, scientific knowledge, education, and aesthetic values. Boating, fishing, swimming, surfing, and bird watching are just a few of the numerous recreational activities people enjoy in estuaries. These commercial...

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...ient as in a highly stratified estuary. The distinction is in the lack of saline water at the surface until it reasches the sea.

Estuarince Circulation

A feature of the stratified estuaries is that depth of the halocline (the thickness of the upper, low salinity layer) remains substantially constant from head to mouth of an estuary for a given runoff. If the estuary width does not change much, the constancy of depth of the upper layer means that the corss-sectional area of the upper layer outflow remains the same while its volume transport increases because of the entrainment of salt water from below. In consequence the speed of the ouflowing surface layer increases markedly along the estuary from head to mouth. The increase in volume and speed can be very considerable, the outflow at the mouth being as much as 10 to 20 times the volume flow of the river.

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