This glossary is provided as a tool for studying
this chapter. Keep it handy while you read, in order to find definitions
of unfamiliar words, or of familiar words that may have an unfamiliar meaning
in the context of this chapter.
If
you do not find the term you are looking for on this page, try the complete
glossary.
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Anadromous fish: Fish that breed in fresh water but spend most of
their adult lives in salt water. Examples are salmon and striped bass.
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Anoxic: Water without dissolved oxygen.
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Catadromous fish: Fish that breed in salt water but live most of
their adult lives in fresh water. The American eel is an example.
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Clean Water Act: The name given to a series of water-quality improvement
laws and their amendments passed in the United States beginning in 1964.
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Concentration: In the context of air or water quality, the amount
of a substance per unit (weight or volume) of air or water.
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Continental shelf: Area of the seafloor averaging less than 650
ft (200 m) deep, which generally was exposed at times of lower sea level
in the past.
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Deep ocean: Ocean areas seaward of the continental shelf.
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Deforestation: Any process of replacement of forest vegetation with
other types.
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Dissolved oxygen: Oxygen found in dissolved form in water.
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El Niño/La Niña: A transient, periodic warming of
the equatorial eastern Pacific Ocean, associated with fisheries depletion
and large-scale climatic fluctuations.
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Ecosystem: The collection of all living organisms in a geographic
area together with all living and nonliving things they interact with.
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Estuary: A semi_enclosed water body, open to the sea, in which seawater
is significantly diluted by fresh water from the land.
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Euphotic zone: The upper portion of the sea, in which sunlight is
intense enough to allow plant growth.
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Eutrophication: The process by which lakes become increasingly nutrient-rich
and shallow. It is a natural process that is accelerated by water pollution.
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Exclusive economic zone: A zone of the oceans over which a particular
nation has claims or exclusive control of certain economic activities,
such as fishing.
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Gyres: A circular flow pattern in the ocean.
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Halocline: A marked change in salinity at a particular depth in
the ocean or an estuary; it signals the boundary between two layers of
water.
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High seas: Areas of the oceans beyond the legal control of any nation.
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Internal waters: Waters under the exclusive control of a coastal
nation, including bays, estuaries, and rivers.
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International Whaling Commission (IWC): An organization set up under
the International Convention for the Regulation of Whaling in 1946, to
regulate the whaling industry.
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Law of the Sea Treaty: A treaty establishing jurisdiction over marine
resources in coastal and deep-sea areas.
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Nonpoint source: A pollution source that is diffuse, such as urban
runoff.
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Salinity: The concentration of mineral salts in water. The average
salinity of the oceans is about 35 parts per thousand.
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Stratified estuary: An arm of the sea in which fresh water from
the land overlies denser salt water.
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Territorial sea: A band of open ocean adjacent to the coast, over
which the coastal nation has control. It is generally either 3 or 12 nautical
miles (5.6 or 22 km) wide.
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Thermocline: A zone in a water body in which temperature declines
rapidly with increasing depth. Vertical water circulation is limited by
the presence of a thermocline.
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Upwelling: An upward movement of seawater that usually occurs near
the margins of oceans.
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