estuary

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estuary

(ĕs`cho͝oĕr'ē), partially enclosed coastal body of water, having an open connection with the ocean, where freshwater from inland is mixed with saltwater from the sea. One type of estuary, called a drowned river valley, can be caused by crustal subsidence or a rise in sea level. Chesapeake Bay is one of the largest estuaries of this type in the United States and was formed during the melting of the Pleistocene ice sheets (see Pleistocene epochPleistocene epoch
, 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, table). According to a classification that considered its deposits to have been formed by the biblical great flood, the epoch was originally called the Quaternary.
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). Fjordsfjord
or fiord
, steep-sided inlet of the sea characteristic of glaciated regions. Fjords probably resulted from the scouring by glaciers of valleys formed by any of several processes, including faulting and erosion by running water.
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, or drowned glacial troughs, form similar types of estuaries, particularly in Norway, Alaska, New Zealand, and other glaciated, mountainous coastal regions. Salt marshes and lagoons found behind barrier beaches, such as along the south shore of Long Island, and down faulted sections of the earth's crust, such as San Francisco Bay, are additional types of estuaries. The shape of an estuary affects the height of the tide; some estuaries (such as the Severn and the Bay of Fundy) are characterized by a wavelike tidal borebore,
inrush of water that advances upstream with a wavelike front, caused by the progress of incoming tide from a wide-mouthed bay into its narrower portion. The tidal movement tends to be retarded by friction as it reaches the shallower water and meets the river current; it
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. Estuaries represent one of the most sensitive and ecologically important habitats on earth. They provide sanctuary for many species of waterfowl, store nutrients for larval and juvenile marine life, and serve as breeding grounds for many desirable species of ocean fish. Since estuaries commonly provide excellent harbors, most of the large ports in the United States (New York, Philadelphia, Baltimore, Mobile, Galveston, Seattle, and San Francisco) are located in estuaries. However, the development of high-density population centers causes deleterious effects that can destroy the very properties of the estuary that made development of the region possible. Human impact on estuaries includes reclamation of tidal land by filling; pollution from sewage, solid waste, industrial effluent, and hot water; increased sedimentation filling the estuary; and alteration of the salinity of estuarine waters by withdrawal or increased influx of freshwater. Increasingly, federal and state governments are passing legislation to protect estuarine environments.

Estuary

 

a single-channel, funnel-shaped seaward end of a river that widens toward the sea. Estuaries form in cases where the sediment carried by the river is removed by sea currents or tidal movements and the adjacent part of the sea is very deep. In such cases no sediment is deposited at the mouth, even if the sediment load is large. The Enisei and the Thames are two of the many rivers that have estuaries.

estuary

[′es·chə ‚wer·ē]
(geography)
A semienclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water. Also known as branching bay; drowned river mouth; firth.

estuary

1. the widening channel of a river where it nears the sea, with a mixing of fresh water and salt (tidal) water
2. an inlet of the sea
References in periodicals archive ?
Mehgan is featured in a new video discussing National Estuaries Week and the actions that individuals can take to make a positive impact on estuaries.
This link between tidal dynamics, fluvial input and sediment distribution could be a good example to compare with other similar estuaries.
Most studies examining the relationship between abiotic gradients and biotic interactions in tidal environments have been conducted in regular estuaries in the medium and high latitudes of the Northern Hemisphere (Costa et al.
Although oyster populations in larger northern Florida estuaries like Apalachicola Bay are well documented, descriptions of oysters in many of the southern estuaries, where hydrological cycles vary greatly, are limited in duration and spatial extent (Wilson et al.
2) Estuaries provide protection from ocean waves, storms, and heavy winds.
Further, most studies have focused on large natal estuaries such as the Hudson River (Secor and Piccoli, 1996), Chesapeake Bay (Mansueti, 1961; Kohlenstein, 1981; Secor, 2007), and to some extent the Delaware River (Waldman and Wirgin, 1994; Able et al.
Earlier, Davies (1964) approached estuaries as groupings within a climatic and geographical association, describing estuariee form related to glacial processes at one climatic extreme and to corallineprocesses at the other extreme, creating a primary classification very much like the more recent effort by Kennish.
The National Estuarine Research Reserve System-Wide Monitoring Program (SWMP): a scientific framework and plan for detection of short-term variability and long-term change in estuaries and coastal habitats of the United States.
Ministers have written to the European Commission applying for SAC status for the three estuaries under the EU habitats directive.
While the 98-page handbook focuses on estuaries, its principles and examples are relevant to any organization involved in watershed management, and it describes innovative approaches developed and conducted by the 28 National Estuary Programs, which are community-based watershed-management organizations that restore and protect coastal watersheds.
Estuaries are the borderlands between salt- and freshwater environments, and they are incredibly diverse both biologically and physically.
Estuaries are dynamic coastal waterways where salt and fresh water mix in highly productive ecosystems.