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1535 Cards in this Set

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absolute dating
Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
absorption
Conversion of sound or light energy into heat.
abyssal clay
lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
abyssal hill
Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
abyssal plain
Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
abyssal storm
Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
abyssal zone
The ocean between 13,120 and 19,680 feet deep.
abyssopelagic
Oceanic zone from 4000m to the deepest depth.
accessory pigment
One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
accretion
An increase in the mass of a body by accumulation or a clumping of smaller particles.
acid
A substance that releases a hydrogen ion (H+) in solution.
acid rain
Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
acoelomate
Without a secondary body cavity (coelom).
acoustic profiling
The use of seismic energy to measure sediment thickness and layering on the sea floor.
acoustic thermometry of ocean climate
ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
acoustical tomography
A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
action plan for the human environment
In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
active margin
Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
active sonar
A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
active transport
The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
adaptation
An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
adhesion
Attachment of water molecules to other substances of hydrogen bonds. Wetting.
adiabatic
Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
adsorption
Attraction of ions to a solid surface.
advection
Horizontal or vertical transport of seawater, as by a current.
agar
Substance produced by red algae; the gelatin-like product of these algae.
Agnatha
The class of jawless fishes: hagfishes and lampreys.
ahermatypic
Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
air mass
A large mass of air with nearly uniform temperature, humidity, and density throughout.
Alaska gyre
A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
algae
Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
algin
A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
Algulhas Current
A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
alkaline
Basic. See also base.
alluvial plain
A flat deposit of terrestrial sediment eroded by water from higher elevations.
alternation of generations
A reproductive cycle in which a plant alternates between sexual and asexual stages.
alveoli
A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
amnesic shellfish poisoning
Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
amphidromic point
A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
anaerobic
Living or functioning in the absence of oxygen.
andesite
A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
angiosperm
A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
angle of incidence
In meteorology, the angle of the sun above the horizon.
animal
A multicellular organism unable to synthesize its own food and often capable of movement.
Animalia
The kingdom to which multicellular heterotrophs belong.
Annelida
The phylum of animals to which segmented worms belong.
anoxic
Deficient in oxygen.
Antarctic Bottom Water
The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
Antarctic Circle
The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
Antarctic Circumpolar Current
The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Antarctic Convergence
Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
Antarctic Ocean
An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
antinode
Portion of a standing wave with maximum vertical motion.
aphelion
The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
aphotic zone
The part of the ocean where no surface light can penetrate.
apogean tide
A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
apogee
The point in the orbit of a satellite farthest from the main body; opposite of perigee.
aquaculture
The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
Arctic Circle
The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
Arctic Convergence
Convergence zone between Arctic Water and Subarctic Surface Water.
Arctic Ocean
An ice-covered ocean north of the continents of North America and Eurasia.
armored beach
A beach that is protected from wave and water erosion by coarse-size lag deposits.
Arthropoda
The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
artificial system of classification
A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
ascidian
The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
aseimic ridge
see transverse ridge
Asteroidea
The class of the phylum Echinodermata to which sea stars belong.
asthenosphere
The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
astrolabe
An early navigation instrument that was the forerunner of the sextant.
atmospheric circulation cell
Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
atmospheric pressure
Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
atoll
A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
atom
The smallest particle of an element that exhibits the characteristics of that element.
ATP
Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
attenuation
Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
authogenic sediment
Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
autotroph
An organism that makes its own food by photosynthesis or chemosynthesis.
auxospore
A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
Aves
The class of birds.
backshore
That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
backshore
Sand on the shoreward side of the berm crest, sloping away from the ocean.
backwash
The water retreating down the shore after an incoming wave.
backwash
Water returning to the ocean from waves washing onto a beach.
bacteria
Single-celled prokaryotes, organisms lacking membrane-bound organelles.
Baguio
The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
Balearic Sea
One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
baleen
The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
Bali Sea
A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
Baltic Sea
A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
bank
An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
bar
Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
Barents Sea
One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
baroclinic
Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
barotropic
Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
barrier island
A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
barrier layer
the layer between the thermocline and the halocline
barrier reef
One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
barrier reef
A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
barycenter
Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
basalt
The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
base
A substance that combines with a hydrogen ion (H+) in solution.
basin
An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
bathyal zone
The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
bathyal zone
The ocean between about 200 and 4,000 meters deep.
bathybius
Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
bathymetry
the measurement and charting of the spatial variation of the ocean depths.
bathymetry
The discovery and study of submerged contours.
bathypelagic zone
The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
bathyscaphe
Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
bathythermograph
A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
bay
A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
bay mouth bar
An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
Bay of Bengal
The northeastern arm of the Indian Ocean, located between India and Burma.
Bay of Nice
Located in the north western Mediterranean basin.
beach
The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
beach
A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
beach berm
The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
beach face
The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
beach scarp
Vertical wall of variable height marking the landward limit of the most recent high tides.
Beaufort scale
Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
Beaufort Sea
The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
benthic
Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
benthic zone
The seabed.
benthic zone
The zone of the ocean bottom. See also pelagic zone.
benthos
Organisms living on or in the ocean bottom.
Bering Sea
A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
berm
A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
berm
A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
berm crest
The seaward limit of a beach berm.
berm crest
The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
beta refraction
An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
bias
The amount by which the average of a set of values departs from a reference value.
big bang
The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
bilateral symmetry
Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
biodegradable
Able to be broken by natural processes into simpler compounds.
biodiversity
The variety of different species within a habitat.
biogenic
One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
biogenous sediment
Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
biogeochemical sediment
Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
biological amplification
Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
biological factor
A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
biological pump
Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
biological resource
A living animal or plant collected for human use. Also called a living resource.
bioluminescence
The generation of light by living organisms using the enzyme luciferase.
bioluminescence
Biologically produced light.
biomass
The mass of living material in a given area or volume of habitat.
biosynthesis
The initial formation of life on Earth.
bioturbation
The stirring of sediment by animal life.
bioturbation
Reworking of sediments by organisms that burrow into them and ingest them.
Bivalvia
The class of phylum Mollusca that includes clams, oysters, and mussels.
Bjerknes, Vilhelm
(1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
Black Sea
A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
Blade
Algal equivalent of a vascular plant's leaf. Also called a frond.
bloom
The sudden increase in phytoplankton number, usually associated with season changes.
bloom
High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
Bohol Sea
A small sea centered in the Philippines at about 124°E and 9°S.
bond
An energy relationship that holds two atoms together as a result of changes in their electron distribution.
borderland
undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
Bowen ration
The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
brackish
Describing water intermediate in salinity between seawater and freshwater.
Bransfield Strait
A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
brash ice
A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
Brazil Basin
An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
breaker
Sea surface water wave that has become too steep to be stable and collapses.
breaker zone
The portion of the nearshore zone where waves arriving from offshore become unstable and break
breakwater
Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
breakwater
An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
bucket temperature
The surface temperature of the ocean as measured by a bucket thermometer.
bucket thermometer
A thermometer with an insulated container around the bulb.
buffer
A group of substances that tends to resist change in the pH of a solution by combining with free ions.
buffer factor
Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
buffer sublayer
That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
bulkhead
Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
buoy
Floating object to float due to the support of the fluid the body is in or on.
buoyancy
The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
by-catch
See incidental catch.
bykill
Animals unintentionally killed when desirable organisms are collected.
caballing
Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
cabbeling
A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
calcareous
Of or containing calcium carbonate or another, usually insoluble, calcium salt.
absolute dating
Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
absorption
Conversion of sound or light energy into heat.
abyssal clay
lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
abyssal hill
Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
abyssal plain
Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
abyssal storm
Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
abyssal zone
The ocean between 13,120 and 19,680 feet deep.
abyssopelagic
Oceanic zone from 4000m to the deepest depth.
accessory pigment
One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
accretion
An increase in the mass of a body by accumulation or a clumping of smaller particles.
acid
A substance that releases a hydrogen ion (H+) in solution.
acid rain
Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
acoelomate
Without a secondary body cavity (coelom).
acoustic profiling
The use of seismic energy to measure sediment thickness and layering on the sea floor.
acoustic thermometry of ocean climate
ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
acoustical tomography
A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
action plan for the human environment
In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
active margin
Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
active sonar
A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
active transport
The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
adaptation
An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
adhesion
Attachment of water molecules to other substances of hydrogen bonds. Wetting.
adiabatic
Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
adsorption
Attraction of ions to a solid surface.
advection
Horizontal or vertical transport of seawater, as by a current.
agar
Substance produced by red algae; the gelatin-like product of these algae.
Agnatha
The class of jawless fishes: hagfishes and lampreys.
ahermatypic
Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
air mass
A large mass of air with nearly uniform temperature, humidity, and density throughout.
Alaska gyre
A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
algae
Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
algin
A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
Algulhas Current
A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
alkaline
Basic. See also base.
alluvial plain
A flat deposit of terrestrial sediment eroded by water from higher elevations.
alternation of generations
A reproductive cycle in which a plant alternates between sexual and asexual stages.
alveoli
A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
amnesic shellfish poisoning
Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
amphidromic point
A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
anaerobic
Living or functioning in the absence of oxygen.
andesite
A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
angiosperm
A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
angle of incidence
In meteorology, the angle of the sun above the horizon.
animal
A multicellular organism unable to synthesize its own food and often capable of movement.
Animalia
The kingdom to which multicellular heterotrophs belong.
Annelida
The phylum of animals to which segmented worms belong.
anoxic
Deficient in oxygen.
Antarctic Bottom Water
The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
Antarctic Circle
The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
Antarctic Circumpolar Current
The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Antarctic Convergence
Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
Antarctic Ocean
An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
antinode
Portion of a standing wave with maximum vertical motion.
aphelion
The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
aphotic zone
The part of the ocean where no surface light can penetrate.
apogean tide
A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
apogee
The point in the orbit of a satellite farthest from the main body; opposite of perigee.
aquaculture
The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
Arctic Circle
The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
Arctic Convergence
Convergence zone between Arctic Water and Subarctic Surface Water.
Arctic Ocean
An ice-covered ocean north of the continents of North America and Eurasia.
armored beach
A beach that is protected from wave and water erosion by coarse-size lag deposits.
Arthropoda
The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
artificial system of classification
A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
ascidian
The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
aseimic ridge
see transverse ridge
Asteroidea
The class of the phylum Echinodermata to which sea stars belong.
asthenosphere
The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
astrolabe
An early navigation instrument that was the forerunner of the sextant.
atmospheric circulation cell
Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
atmospheric pressure
Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
atoll
A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
atom
The smallest particle of an element that exhibits the characteristics of that element.
ATP
Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
attenuation
Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
authogenic sediment
Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
autotroph
An organism that makes its own food by photosynthesis or chemosynthesis.
auxospore
A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
Aves
The class of birds.
backshore
That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
backshore
Sand on the shoreward side of the berm crest, sloping away from the ocean.
backwash
The water retreating down the shore after an incoming wave.
backwash
Water returning to the ocean from waves washing onto a beach.
bacteria
Single-celled prokaryotes, organisms lacking membrane-bound organelles.
Baguio
The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
Balearic Sea
One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
baleen
The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
Bali Sea
A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
Baltic Sea
A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
bank
An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
bar
Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
Barents Sea
One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
baroclinic
Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
barotropic
Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
barrier island
A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
barrier layer
the layer between the thermocline and the halocline
barrier reef
One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
barrier reef
A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
barycenter
Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
basalt
The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
base
A substance that combines with a hydrogen ion (H+) in solution.
basin
An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
bathyal zone
The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
bathyal zone
The ocean between about 200 and 4,000 meters deep.
bathybius
Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
bathymetry
the measurement and charting of the spatial variation of the ocean depths.
bathymetry
The discovery and study of submerged contours.
bathypelagic zone
The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
bathyscaphe
Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
bathythermograph
A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
bay
A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
bay mouth bar
An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
Bay of Bengal
The northeastern arm of the Indian Ocean, located between India and Burma.
Bay of Nice
Located in the north western Mediterranean basin.
beach
The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
beach
A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
beach berm
The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
beach face
The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
beach scarp
Vertical wall of variable height marking the landward limit of the most recent high tides.
Beaufort scale
Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
Beaufort Sea
The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
benthic
Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
benthic zone
The seabed.
benthic zone
The zone of the ocean bottom. See also pelagic zone.
benthos
Organisms living on or in the ocean bottom.
Bering Sea
A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
berm
A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
berm
A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
berm crest
The seaward limit of a beach berm.
berm crest
The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
beta refraction
An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
bias
The amount by which the average of a set of values departs from a reference value.
big bang
The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
bilateral symmetry
Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
biodegradable
Able to be broken by natural processes into simpler compounds.
biodiversity
The variety of different species within a habitat.
biogenic
One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
biogenous sediment
Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
biogeochemical sediment
Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
biological amplification
Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
biological factor
A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
biological pump
Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
biological resource
A living animal or plant collected for human use. Also called a living resource.
bioluminescence
The generation of light by living organisms using the enzyme luciferase.
bioluminescence
Biologically produced light.
biomass
The mass of living material in a given area or volume of habitat.
biosynthesis
The initial formation of life on Earth.
bioturbation
The stirring of sediment by animal life.
bioturbation
Reworking of sediments by organisms that burrow into them and ingest them.
Bivalvia
The class of phylum Mollusca that includes clams, oysters, and mussels.
Bjerknes, Vilhelm
(1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
Black Sea
A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
Blade
Algal equivalent of a vascular plant's leaf. Also called a frond.
bloom
The sudden increase in phytoplankton number, usually associated with season changes.
bloom
High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
Bohol Sea
A small sea centered in the Philippines at about 124°E and 9°S.
bond
An energy relationship that holds two atoms together as a result of changes in their electron distribution.
borderland
undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
Bowen ration
The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
brackish
Describing water intermediate in salinity between seawater and freshwater.
Bransfield Strait
A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
brash ice
A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
Brazil Basin
An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
breaker
Sea surface water wave that has become too steep to be stable and collapses.
breaker zone
The portion of the nearshore zone where waves arriving from offshore become unstable and break
breakwater
Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
breakwater
An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
bucket temperature
The surface temperature of the ocean as measured by a bucket thermometer.
bucket thermometer
A thermometer with an insulated container around the bulb.
buffer
A group of substances that tends to resist change in the pH of a solution by combining with free ions.
buffer factor
Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
buffer sublayer
That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
bulkhead
Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
buoy
Floating object to float due to the support of the fluid the body is in or on.
buoyancy
The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
by-catch
See incidental catch.
bykill
Animals unintentionally killed when desirable organisms are collected.
caballing
Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
cabbeling
A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
calcareous
Of or containing calcium carbonate or another, usually insoluble, calcium salt.
calcareous ooze
Partially composed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water; a fine-grained, deep-sea deposit of pelagic origin containing more than 30% calcium carbonate derived from the skeletal material of various plankton. It is the most extensive deposit on the ocean floor but restricted to depths less than about 3500 m due to the carbon compensation depth.
calcareous ooze
Ooze composed mostly of the hard remains of organisms containing calcium carbonate.
calcium carbonate compensation depth
The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments. Below this depth, sediment contains little or no calcium carbonate.
caldera
undersea feature; a collapsed or partially-collapsed seamount, commonly of annular shape.
calorie
The amount of heat needed to raise the temperatures of 1 gram (0.035 ounce) of pure water by 1°C (1.8°F).
calving
Breaking away of a mass of ice from its parent glacier, iceberg, or sea ice formation.
Camotes Sea
A small sea within the Visayan Islands that comprise the middle portion of the Philippines.
Canary Basin
An ocean basin located to the west of the Canary Islands in the eastern North Atlantic Ocean.
canyon
Undersea feature; a relatively narrow, deep depression with steep sides, the bottom of which generally deepends continuously, developed characteristically on some continental slopes.
Cape Basin
An ocean basin located to the west of South Africa at about 35°S in the South Atlantic Ocean.
Cape Verde Basin
An ocean basin located at about 15°N off the west coast of Africa in the North Atlantic Ocean.
capillary wave
A wave on a fluid interface for which the restoring force is surface tension.
capillary wave
A tiny wave with a wavelength of less than 1.73 centimeters (0.68 inch), whose restoring force is surface tension; the first type of wave to form when the wind blows.
carbon cycle
The cycling of carbon in the form of carbon dioxide, carbonates, organic compounds, etc. between various reservoirs, e.g. the atmosphere, the oceans, land and marine biota and, on geological time scales, sediments, and rocks.
carbon dioxide
The most important of the greenhouse gases with an atmospheric concentration of 353 ppm.
carbon-14 dating
A radioisotope dating method wherein a radioactive isotope of carbon, also called radiocarbon, is used to date materials containing carbon.
carbonate compensation depth
(CCD) Also known as the calcite compensation depth, is the depth at which the amount of calcium carbonate preserved falls below 20% of the total sediment. This is also commonly defined as the depth at which the amount of calcium carbonate produced by organisms skeletal material in the overlying water column is equal to the rate at which it is dissolved in the water. No calcium carbonate will be deposited below this depth.
Cariaco Basin
A 1400 m deep depression within the continental shelf of Venezuela.
Caribbean Sea
The largest marginal sea of the Atlantic Ocean, with a surface area twice that of the Mediterranean Sea.
Carnivora
The order of mammals that includes seals, sea lions, walruses, and sea otters.
carrageenan
Substance produced by certain algae that acts as a thickening agent.
carrying capacity
The size at which a particular population in a particular environment will stabilize when its supply of resources--including nutrients, energy and living space -- remains constant.
cartilage
A tough, elastic tissue that stiffens or supports.
cartographer
A person who makes maps and charts.
Catalan Sea
See Balearic Sea
catastrophism
The theory that the Earth's surface features are formed by catastrophic forces such as the biblical flood. Catastrophists believe in a young Earth and a literal interpretation of the biblical account of Creation.
cat's-paw
Patch of ripples on the water's surface, related to a discrete gust of wind.
Celebes Sea
Alternate name for the Sulawesi Sea.
celestial navigation
The technique of finding one's position on Earth by reference to the apparent position of stars, planets, the moon, and the sun.
cell
The basic organizational unit of life on this planet.
Celtic Sea
A shallow embayment of the eastern North Atlantic bounded by Southern Ireland. Separated from the Irish Sea by a line drawn from Ramsey Island to Carnsore Point and from the English Channel by a line drawn from Ushant to Lands End.
Cenderawasih Bay
A bay on the northern coast of Irian Jaya centered at approximately 135°E and 2.5°S at the southwestern edge of the Pacific Ocean.
centers of action
Large semi permanent belts of high or low sea level pressure distributed around the Earth that largely control the general circulation of the atmosphere and the concomitant long-term weather patterns.
central water
A term used to identify thermocline water masses in all three oceans. The water arrives at a thermocline via a process known as subduction.
centrifugal force
Outward-directed force acting on a body moving along a curved path or rotating about an axis; an inertial force.
cephalopod
An advanced group of mollusks that includes the squids, octopuses, and cuttlefishes.
Cephalopoda
The class of the phylum Mollusca that includes squid, octopuses, and nautiluses.
cetacea
The order of mammals that includes porpoises, dolphins and whales.
cetaceans
The whales and dolphins.
CFCs
A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
chaetognaths
Free-swimming, carnivorous, pelagic, wormlike, planktonic animals; arrowworms.
Challenger Expedition
The first wholly scientific oceanographic expedition, 1872-76. Named for the steam corvette used in the voyage.
channel
A body of water that connects two larger bodies of water. A channel is also part of a river or harbor that is deep enough to let ships sail through.
chart
A map that depicts mostly water and the adjoining land areas.
chemical bond
An energy relationship that holds two atoms together as a result of changes in their electron distribution.
chemical equilibrium
In seawater, the condition in which the proportion and amounts of dissolved salts per unit volume of ocean are nearly consistent.
chemosynthesis
The synthesis of organic compounds from inorganic compounds using energy stored in inorganic substances such as sulfur, ammonia, and hydrogen. Energy is released when these substances are oxidized by certain organisms.
chitin
A complex nitrogen-rich carbohydrate from which parts of arthropod exoskeletons are constructed.
chiton
A polyplasophoran mollusk.
chlorinated hydrocarbons
The most abundant and dangerous class of halogenated hydrocarbons, synthetic organic chemicals hazardous to the marine environment.
chlorine titration
The method developed by Knudsen in 1902 to determine the chlorinity and therefore salinity of a sea water sample.
chlorinity
A measure of the amount of chlorine or other halides in water (especially seawater).
chlorinity
A measure of the content of chloride, bromine, and iodide ions in seawater. We may derive salinity from chlorinity by multiplying by 1.80655.
chlorofluorocarbons
A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
chlorophyll
A pigment responsible for trapping sunlight and transferring its energy to electrons, thus initiating photosynthesis.
Chlorophyta
Green algae.
Chondrichthyes
The class of fishes with cartilagenous skeletons: the sharks, skates, rays, and chimaeras.
Chordata
The phylum of animals to which tunicates, Amphioxus, fishes, amphibians, reptiles, birds, and mammals belong.
chromatophore
A pigmented skin cell that expands or contracts to affect color change.
chronometer
A watch or clock able to maintain its accuracy on long sea voyages.
chronometer
A very consistent clock. It doesn't need to tell accurate time, but its rate of gain or loss must be constant and known exactly so that accurate time may be calculated.
ciguatera
Toxin found in fish of tropical regions; produced by dinoflagellates.
cilia
Microscopic, hairlike projections of living cells that beat in coordinated fashion and produce movement.
clamshell sampler
Sampling device used to take shallow samples of the ocean bottom.
classification
A way of grouping objects according to some stated criteria.
clay
Sediment particle smaller than 0.004mm in diameter; the smallest sediment size category.
climate
The long-term average of weather in an area.
climax community
A stable, long-established community of self-perpetuating organisms that tends not to change with time.
clockwise
Rotation around a point in the direction that clock hands move.
clumped distribution
Distribution of organisms within a community in small, patchy aggregations, or clumps; the most common distribution pattern.
Cnidaria
The phylum of animals to which corals, jellyfish, and sea anemones belong.
cnidoblast
Type of cell found in members of the phylum Cnidaria that contains a stinging capsule. The threads that evert from the capsules assist in capturing prey and repelling aggressors.
coast
The zone extending from the ocean inland as far as the environment is immediately affected by marine processes.
coastal cell
The natural sector of a coastline in which sand input and sand outflow are balanced.
coastal upwelling
Upwelling adjacent to a coast, usually induced by wind.
coccolithophore
A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediments.
cohesion
Attachment of water molecules to each other by hydrogen bonds.
cold seep
Cold seawater, rich in methane, hydrogen sulfide, and hydrocarbons issuing from the seafloor.
colligative properties
Those characteristics of a solution that differ from those of pure water because of material held in solution.
Columbus, Christopher
1451-1506. Italian explorer in the service of Spain who discovered islands in the Caribbean in 1492. Although traditionally credited as the discoverer of America, he never actually sighted the North American continent.
commensalism
A symbiotic interaction between two species in which only one species benefits and neither is harmed.
commercial extinction
Depletion of a resource species to a point where it is no longer profitable to harvest the species.
community
The populations of all species that occupy a particular habitat and interact within that habitat.
compass
An instrument for showing direction by means of a magnetic needle swinging freely on a pivot and pointing to magnetic north.
compensation depth
The depth in the water column at which the production of carbohydrates and oxygen by photosynthesis exactly equals the consumption of carbohydrates and oxygen by respiration. The break-even point for autotrophs. Generally a function of light level.
compound
A substance composed of two or more elements in a fixed proportion.
condensation theory
Premise that stars and planets accumulate from contracting, accreting clouds of galactic gas, dust, and debris.
conduction
The transfer of heat through matter by the collision of one atom with another.
conservative constituent
An element that occurs in constant proportion in seawater. For example, chlorine, sodium, and magnesium.
constructive interference
The addition of wave energy as waves interact producing larger waves.
consumer
A heterotrophic organism.
continental crust
Solid, outer layers of earth, including the rocks of the continents
continental crust
The solid masses of the continents, composed primarily of granite.
continental drift
The theory that the continents move slowly across the surface of the earth.
continental margin
The submerged outer edge of a continent, made of granitic crust. Includes the continental shelf and continental slope. Compare ocean basin.
continental rise
Gently sloping base of the continental slope.
continental rise
The wedge of sediment forming the gentle transition from the outer (lower) edge of the continental slope to the abyssal plain. Usually associated with passive margins.
continental shelf
the shallow, gently sloping edge of a continental landmass where it meets the sea.
continental shelf
Gradually sloping submerged extension of a continent composed of granitic rock overlain by sediments. Has features similar to the edge of the nearby continent.
continental shelf break
Zone along which there is a marked increase of slope at the outer margin of a continental shelf.
continental slope
The steeply inclined edge of a continental plate below the continental shelf.
continental slope
The sloping transition between the granite of the continent and the basalt of the seabed. The true edge of a continent.
contour current
A bottom current made up of dense water that flows around (rather than over) seabed projections.
convection cell
Circulation in a fluid, or fluidlike material, caused by heating from below. Heating the base of a fluid lowers its density, causing it to rise. The rising fluid cools, becomes denser, and sinks, creating circulation.
convection cell
Movement within a fluid resulting from differential heating and cooling of the fluid. Convection produces mass transport or mixing of the fluid.
convection current
A single closed-flow circuit of rising warm material and falling cool material.
convergence zone
The line along which waters of different density converge. Convergence zones form the boundaries of tropical, sub-tropical, temperate, and polar regions.
convergent evolution
The evolution of similar characteristics in organisms of different ancestry; the body shape of a porpoise and a shark, for instance.
convergent plate boundary
A region where plates are pushing together and where a mountain range, island arc, and/or trench will eventually form. Often a site of much seismic and volcanic activity.
Cook, James
(1728-1779) Officer in the British Royal Navy who led the first European voyages of scientific discovery.
copepod
Small, shrimplike member of the zooplankton; in the class Crustacea.
coral
Any of over 6,000 species of small cnidarians, many of which are capable of generating hard calcareous (aragonite CaCO3) skeletons.
coral reef
A linear mass of calcium carbonate (aragonite and calcite) assembled from coral organisms, algae, mollusks, worms, and so on. Coral may contribute to less than half of the reef material.
corange lines
In a rotary tide, lines of equal tidal range about the amphidromic point.
core
The innermost layer of the Earth, composed primarily of iron, with nickel and heavy elements. The inner core is thought to be a solid 6,000°C (11,000°F) sphere, the outer core a 5,000°C (9,000°F) liquid mass. The average density of the outer core is about 11.8 g/cm3, and that of the inner core is about 16 g/cm3.
corer
Device that plunges a hollow tube into bottom sediments to extract a vertical sample.
Coriolis effect
The apparent deflection of a moving object from its initial course when its speed and direction are measured in reference to the surface of the rotating Earth. The object is deflected to the right of its anticipated course in the Northern hemisphere and to the left in the Southern Hemisphere. The deflection occurs for any horizontal movement of objects and has no effect at the equator.
Coriolis, Gaspard Gustave de
(1792-1843) The French scientist who in 1835 worked out the mathematics of the motion of bodies on a rotating surface. Refer to Coriolis effect.
cosmogenous sediment
Sediment of extraterrestrial origin.
counterclockwise
Rotation around a point in the direction opposite to that in which clock hands move. Also called anticlockwise.
countercurrent
A surface current flowing in the opposite direction from an adjacent surface current.
covalent bond
A chemical bond formed between two atoms by electron sharing.
crest
Highest part of a progressive wave above average water level.
crust
The outermost solid layer of Earth, composed mostly of granite and basalt; the top layer of the lithosphere. The crust has a density of 2.7-2.9 g/cm3 and accounts for 0.4% of Earth's mass.
Crustacea
The class of phylum Arthropoda to which lobsters, shrimp, barnacles, crabs, and copepods belong.
crustaceans
Invertebrates with jointed limbs and hard chalky shells, such as lobsters, crabs, and shrimp.
crustal plate
A segment of Earth's surface. Continental plates are about 25 miles thick and oceanic plates 3.1 miles thick.
cryptic coloration
Camouflage. May be active (under control of the animal) or passive (an unalterable color or shape).
current
A flow of water in the sea, generated by wind, tidal movements, or thermohaline circulation.
current
Mass flow of water. (The term is usually reserved for horizontal movement.)
cyclone
A weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Not to be confused with a tornado, a much smaller weather phenomenon associated with sever thunderstorms. Se also extratropical cyclone; tropical cyclone.
Darwin, Charles
(1809-1882) English biologist. Co-discoverer (with Alfred Russell Wallace) of evolution by natural selection.
deadweight ton
(DWT) Capacity of a vessel in tons of cargo, fuel, stores, and so on; determined by the weight of the water displace.
declinational tide
See diurnal tide
deep scattering layer (DSL)
A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
deep zone
The zone of the ocean below the pycnocline, in which there is little additional change of density with increasing depth. Contains about 80% of the world's water.
deep-water wave
A wave in water deeper than one-half its wavelength.
degree
An arbitrary measure of temperature. One degree Celsius (°C) equals 1.8 degrees Fahrenheit (°F).
delta
The deposit of sediments found at a river mouth, sometimes triangular in shape (hence the name after the Greek letter).
demersal fish
Fish living near and on the bottom.
density
The mass per unit volume of a substance, usually expressed in grams per cubic centimeter (g/cm3); the mass of a substance for a given volume.
density curve
A graph showing the relationship between a fluid's temperature or salinity and its density.
absolute dating
Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
absorption
Conversion of sound or light energy into heat.
abyssal clay
lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
abyssal hill
Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
abyssal plain
Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
abyssal storm
Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
abyssal zone
The ocean between 13,120 and 19,680 feet deep.
abyssopelagic
Oceanic zone from 4000m to the deepest depth.
accessory pigment
One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
accretion
An increase in the mass of a body by accumulation or a clumping of smaller particles.
acid
A substance that releases a hydrogen ion (H+) in solution.
acid rain
Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
acoelomate
Without a secondary body cavity (coelom).
acoustic profiling
The use of seismic energy to measure sediment thickness and layering on the sea floor.
acoustic thermometry of ocean climate
ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
acoustical tomography
A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
action plan for the human environment
In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
active margin
Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
active sonar
A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
active transport
The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
adaptation
An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
adhesion
Attachment of water molecules to other substances of hydrogen bonds. Wetting.
adiabatic
Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
adsorption
Attraction of ions to a solid surface.
advection
Horizontal or vertical transport of seawater, as by a current.
agar
Substance produced by red algae; the gelatin-like product of these algae.
Agnatha
The class of jawless fishes: hagfishes and lampreys.
ahermatypic
Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
air mass
A large mass of air with nearly uniform temperature, humidity, and density throughout.
Alaska gyre
A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
algae
Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
algin
A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
Algulhas Current
A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
alkaline
Basic. See also base.
alluvial plain
A flat deposit of terrestrial sediment eroded by water from higher elevations.
alternation of generations
A reproductive cycle in which a plant alternates between sexual and asexual stages.
alveoli
A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
amnesic shellfish poisoning
Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
amphidromic point
A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
anaerobic
Living or functioning in the absence of oxygen.
andesite
A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
angiosperm
A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
angle of incidence
In meteorology, the angle of the sun above the horizon.
animal
A multicellular organism unable to synthesize its own food and often capable of movement.
Animalia
The kingdom to which multicellular heterotrophs belong.
Annelida
The phylum of animals to which segmented worms belong.
anoxic
Deficient in oxygen.
Antarctic Bottom Water
The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
Antarctic Circle
The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
Antarctic Circumpolar Current
The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Antarctic Convergence
Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
Antarctic Ocean
An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
antinode
Portion of a standing wave with maximum vertical motion.
aphelion
The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
aphotic zone
The part of the ocean where no surface light can penetrate.
apogean tide
A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
apogee
The point in the orbit of a satellite farthest from the main body; opposite of perigee.
aquaculture
The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
Arctic Circle
The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
Arctic Convergence
Convergence zone between Arctic Water and Subarctic Surface Water.
Arctic Ocean
An ice-covered ocean north of the continents of North America and Eurasia.
armored beach
A beach that is protected from wave and water erosion by coarse-size lag deposits.
Arthropoda
The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
artificial system of classification
A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
ascidian
The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
aseimic ridge
see transverse ridge
Asteroidea
The class of the phylum Echinodermata to which sea stars belong.
asthenosphere
The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
astrolabe
An early navigation instrument that was the forerunner of the sextant.
atmospheric circulation cell
Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
atmospheric pressure
Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
atoll
A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
atom
The smallest particle of an element that exhibits the characteristics of that element.
ATP
Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
attenuation
Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
authogenic sediment
Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
autotroph
An organism that makes its own food by photosynthesis or chemosynthesis.
auxospore
A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
Aves
The class of birds.
backshore
That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
backshore
Sand on the shoreward side of the berm crest, sloping away from the ocean.
backwash
The water retreating down the shore after an incoming wave.
backwash
Water returning to the ocean from waves washing onto a beach.
bacteria
Single-celled prokaryotes, organisms lacking membrane-bound organelles.
Baguio
The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
Balearic Sea
One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
baleen
The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
Bali Sea
A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
Baltic Sea
A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
bank
An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
bar
Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
Barents Sea
One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
baroclinic
Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
barotropic
Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
barrier island
A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
barrier layer
the layer between the thermocline and the halocline
barrier reef
One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
barrier reef
A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
barycenter
Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
basalt
The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
base
A substance that combines with a hydrogen ion (H+) in solution.
basin
An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
bathyal zone
The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
bathyal zone
The ocean between about 200 and 4,000 meters deep.
bathybius
Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
bathymetry
the measurement and charting of the spatial variation of the ocean depths.
bathymetry
The discovery and study of submerged contours.
bathypelagic zone
The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
bathyscaphe
Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
bathythermograph
A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
bay
A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
bay mouth bar
An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
Bay of Bengal
The northeastern arm of the Indian Ocean, located between India and Burma.
Bay of Nice
Located in the north western Mediterranean basin.
beach
The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
beach
A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
beach berm
The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
beach face
The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
beach scarp
Vertical wall of variable height marking the landward limit of the most recent high tides.
Beaufort scale
Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
Beaufort Sea
The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
benthic
Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
benthic zone
The seabed.
benthic zone
The zone of the ocean bottom. See also pelagic zone.
benthos
Organisms living on or in the ocean bottom.
Bering Sea
A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
berm
A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
berm
A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
berm crest
The seaward limit of a beach berm.
berm crest
The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
beta refraction
An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
bias
The amount by which the average of a set of values departs from a reference value.
big bang
The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
bilateral symmetry
Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
biodegradable
Able to be broken by natural processes into simpler compounds.
biodiversity
The variety of different species within a habitat.
biogenic
One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
biogenous sediment
Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
biogeochemical sediment
Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
biological amplification
Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
biological factor
A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
biological pump
Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
biological resource
A living animal or plant collected for human use. Also called a living resource.
bioluminescence
The generation of light by living organisms using the enzyme luciferase.
bioluminescence
Biologically produced light.
biomass
The mass of living material in a given area or volume of habitat.
biosynthesis
The initial formation of life on Earth.
bioturbation
The stirring of sediment by animal life.
bioturbation
Reworking of sediments by organisms that burrow into them and ingest them.
Bivalvia
The class of phylum Mollusca that includes clams, oysters, and mussels.
Bjerknes, Vilhelm
(1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
Black Sea
A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
Blade
Algal equivalent of a vascular plant's leaf. Also called a frond.
bloom
The sudden increase in phytoplankton number, usually associated with season changes.
bloom
High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
Bohol Sea
A small sea centered in the Philippines at about 124°E and 9°S.
bond
An energy relationship that holds two atoms together as a result of changes in their electron distribution.
borderland
undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
Bowen ration
The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
brackish
Describing water intermediate in salinity between seawater and freshwater.
Bransfield Strait
A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
brash ice
A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
Brazil Basin
An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
breaker
Sea surface water wave that has become too steep to be stable and collapses.
breaker zone
The portion of the nearshore zone where waves arriving from offshore become unstable and break
breakwater
Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
breakwater
An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
bucket temperature
The surface temperature of the ocean as measured by a bucket thermometer.
bucket thermometer
A thermometer with an insulated container around the bulb.
buffer
A group of substances that tends to resist change in the pH of a solution by combining with free ions.
buffer factor
Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
buffer sublayer
That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
bulkhead
Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
buoy
Floating object to float due to the support of the fluid the body is in or on.
buoyancy
The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
by-catch
See incidental catch.
bykill
Animals unintentionally killed when desirable organisms are collected.
caballing
Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
cabbeling
A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
calcareous
Of or containing calcium carbonate or another, usually insoluble, calcium salt.
calcareous ooze
Partially composed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water; a fine-grained, deep-sea deposit of pelagic origin containing more than 30% calcium carbonate derived from the skeletal material of various plankton. It is the most extensive deposit on the ocean floor but restricted to depths less than about 3500 m due to the carbon compensation depth.
calcareous ooze
Ooze composed mostly of the hard remains of organisms containing calcium carbonate.
calcium carbonate compensation depth
The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments. Below this depth, sediment contains little or no calcium carbonate.
caldera
undersea feature; a collapsed or partially-collapsed seamount, commonly of annular shape.
calorie
The amount of heat needed to raise the temperatures of 1 gram (0.035 ounce) of pure water by 1°C (1.8°F).
calving
Breaking away of a mass of ice from its parent glacier, iceberg, or sea ice formation.
Camotes Sea
A small sea within the Visayan Islands that comprise the middle portion of the Philippines.
Canary Basin
An ocean basin located to the west of the Canary Islands in the eastern North Atlantic Ocean.
canyon
Undersea feature; a relatively narrow, deep depression with steep sides, the bottom of which generally deepends continuously, developed characteristically on some continental slopes.
Cape Basin
An ocean basin located to the west of South Africa at about 35°S in the South Atlantic Ocean.
Cape Verde Basin
An ocean basin located at about 15°N off the west coast of Africa in the North Atlantic Ocean.
capillary wave
A wave on a fluid interface for which the restoring force is surface tension.
capillary wave
A tiny wave with a wavelength of less than 1.73 centimeters (0.68 inch), whose restoring force is surface tension; the first type of wave to form when the wind blows.
carbon cycle
The cycling of carbon in the form of carbon dioxide, carbonates, organic compounds, etc. between various reservoirs, e.g. the atmosphere, the oceans, land and marine biota and, on geological time scales, sediments, and rocks.
carbon dioxide
The most important of the greenhouse gases with an atmospheric concentration of 353 ppm.
carbon-14 dating
A radioisotope dating method wherein a radioactive isotope of carbon, also called radiocarbon, is used to date materials containing carbon.
carbonate compensation depth
(CCD) Also known as the calcite compensation depth, is the depth at which the amount of calcium carbonate preserved falls below 20% of the total sediment. This is also commonly defined as the depth at which the amount of calcium carbonate produced by organisms skeletal material in the overlying water column is equal to the rate at which it is dissolved in the water. No calcium carbonate will be deposited below this depth.
Cariaco Basin
A 1400 m deep depression within the continental shelf of Venezuela.
Caribbean Sea
The largest marginal sea of the Atlantic Ocean, with a surface area twice that of the Mediterranean Sea.
Carnivora
The order of mammals that includes seals, sea lions, walruses, and sea otters.
carrageenan
Substance produced by certain algae that acts as a thickening agent.
carrying capacity
The size at which a particular population in a particular environment will stabilize when its supply of resources--including nutrients, energy and living space -- remains constant.
cartilage
A tough, elastic tissue that stiffens or supports.
cartographer
A person who makes maps and charts.
Catalan Sea
See Balearic Sea
catastrophism
The theory that the Earth's surface features are formed by catastrophic forces such as the biblical flood. Catastrophists believe in a young Earth and a literal interpretation of the biblical account of Creation.
cat's-paw
Patch of ripples on the water's surface, related to a discrete gust of wind.
Celebes Sea
Alternate name for the Sulawesi Sea.
celestial navigation
The technique of finding one's position on Earth by reference to the apparent position of stars, planets, the moon, and the sun.
cell
The basic organizational unit of life on this planet.
Celtic Sea
A shallow embayment of the eastern North Atlantic bounded by Southern Ireland. Separated from the Irish Sea by a line drawn from Ramsey Island to Carnsore Point and from the English Channel by a line drawn from Ushant to Lands End.
Cenderawasih Bay
A bay on the northern coast of Irian Jaya centered at approximately 135°E and 2.5°S at the southwestern edge of the Pacific Ocean.
centers of action
Large semi permanent belts of high or low sea level pressure distributed around the Earth that largely control the general circulation of the atmosphere and the concomitant long-term weather patterns.
central water
A term used to identify thermocline water masses in all three oceans. The water arrives at a thermocline via a process known as subduction.
centrifugal force
Outward-directed force acting on a body moving along a curved path or rotating about an axis; an inertial force.
cephalopod
An advanced group of mollusks that includes the squids, octopuses, and cuttlefishes.
Cephalopoda
The class of the phylum Mollusca that includes squid, octopuses, and nautiluses.
cetacea
The order of mammals that includes porpoises, dolphins and whales.
cetaceans
The whales and dolphins.
CFCs
A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
chaetognaths
Free-swimming, carnivorous, pelagic, wormlike, planktonic animals; arrowworms.
Challenger Expedition
The first wholly scientific oceanographic expedition, 1872-76. Named for the steam corvette used in the voyage.
channel
A body of water that connects two larger bodies of water. A channel is also part of a river or harbor that is deep enough to let ships sail through.
chart
A map that depicts mostly water and the adjoining land areas.
chemical bond
An energy relationship that holds two atoms together as a result of changes in their electron distribution.
chemical equilibrium
In seawater, the condition in which the proportion and amounts of dissolved salts per unit volume of ocean are nearly consistent.
chemosynthesis
The synthesis of organic compounds from inorganic compounds using energy stored in inorganic substances such as sulfur, ammonia, and hydrogen. Energy is released when these substances are oxidized by certain organisms.
chitin
A complex nitrogen-rich carbohydrate from which parts of arthropod exoskeletons are constructed.
chiton
A polyplasophoran mollusk.
chlorinated hydrocarbons
The most abundant and dangerous class of halogenated hydrocarbons, synthetic organic chemicals hazardous to the marine environment.
chlorine titration
The method developed by Knudsen in 1902 to determine the chlorinity and therefore salinity of a sea water sample.
chlorinity
A measure of the amount of chlorine or other halides in water (especially seawater).
chlorinity
A measure of the content of chloride, bromine, and iodide ions in seawater. We may derive salinity from chlorinity by multiplying by 1.80655.
chlorofluorocarbons
A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
chlorophyll
A pigment responsible for trapping sunlight and transferring its energy to electrons, thus initiating photosynthesis.
Chlorophyta
Green algae.
Chondrichthyes
The class of fishes with cartilagenous skeletons: the sharks, skates, rays, and chimaeras.
Chordata
The phylum of animals to which tunicates, Amphioxus, fishes, amphibians, reptiles, birds, and mammals belong.
chromatophore
A pigmented skin cell that expands or contracts to affect color change.
chronometer
A watch or clock able to maintain its accuracy on long sea voyages.
chronometer
A very consistent clock. It doesn't need to tell accurate time, but its rate of gain or loss must be constant and known exactly so that accurate time may be calculated.
ciguatera
Toxin found in fish of tropical regions; produced by dinoflagellates.
cilia
Microscopic, hairlike projections of living cells that beat in coordinated fashion and produce movement.
clamshell sampler
Sampling device used to take shallow samples of the ocean bottom.
classification
A way of grouping objects according to some stated criteria.
clay
Sediment particle smaller than 0.004mm in diameter; the smallest sediment size category.
climate
The long-term average of weather in an area.
climax community
A stable, long-established community of self-perpetuating organisms that tends not to change with time.
clockwise
Rotation around a point in the direction that clock hands move.
clumped distribution
Distribution of organisms within a community in small, patchy aggregations, or clumps; the most common distribution pattern.
Cnidaria
The phylum of animals to which corals, jellyfish, and sea anemones belong.
cnidoblast
Type of cell found in members of the phylum Cnidaria that contains a stinging capsule. The threads that evert from the capsules assist in capturing prey and repelling aggressors.
coast
The zone extending from the ocean inland as far as the environment is immediately affected by marine processes.
coastal cell
The natural sector of a coastline in which sand input and sand outflow are balanced.
coastal upwelling
Upwelling adjacent to a coast, usually induced by wind.
coccolithophore
A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediments.
cohesion
Attachment of water molecules to each other by hydrogen bonds.
cold seep
Cold seawater, rich in methane, hydrogen sulfide, and hydrocarbons issuing from the seafloor.
colligative properties
Those characteristics of a solution that differ from those of pure water because of material held in solution.
Columbus, Christopher
1451-1506. Italian explorer in the service of Spain who discovered islands in the Caribbean in 1492. Although traditionally credited as the discoverer of America, he never actually sighted the North American continent.
commensalism
A symbiotic interaction between two species in which only one species benefits and neither is harmed.
commercial extinction
Depletion of a resource species to a point where it is no longer profitable to harvest the species.
community
The populations of all species that occupy a particular habitat and interact within that habitat.
compass
An instrument for showing direction by means of a magnetic needle swinging freely on a pivot and pointing to magnetic north.
compensation depth
The depth in the water column at which the production of carbohydrates and oxygen by photosynthesis exactly equals the consumption of carbohydrates and oxygen by respiration. The break-even point for autotrophs. Generally a function of light level.
compound
A substance composed of two or more elements in a fixed proportion.
condensation theory
Premise that stars and planets accumulate from contracting, accreting clouds of galactic gas, dust, and debris.
conduction
The transfer of heat through matter by the collision of one atom with another.
conservative constituent
An element that occurs in constant proportion in seawater. For example, chlorine, sodium, and magnesium.
constructive interference
The addition of wave energy as waves interact producing larger waves.
consumer
A heterotrophic organism.
continental crust
Solid, outer layers of earth, including the rocks of the continents
continental crust
The solid masses of the continents, composed primarily of granite.
continental drift
The theory that the continents move slowly across the surface of the earth.
continental margin
The submerged outer edge of a continent, made of granitic crust. Includes the continental shelf and continental slope. Compare ocean basin.
continental rise
Gently sloping base of the continental slope.
continental rise
The wedge of sediment forming the gentle transition from the outer (lower) edge of the continental slope to the abyssal plain. Usually associated with passive margins.
continental shelf
the shallow, gently sloping edge of a continental landmass where it meets the sea.
continental shelf
Gradually sloping submerged extension of a continent composed of granitic rock overlain by sediments. Has features similar to the edge of the nearby continent.
continental shelf break
Zone along which there is a marked increase of slope at the outer margin of a continental shelf.
continental slope
The steeply inclined edge of a continental plate below the continental shelf.
continental slope
The sloping transition between the granite of the continent and the basalt of the seabed. The true edge of a continent.
contour current
A bottom current made up of dense water that flows around (rather than over) seabed projections.
convection cell
Circulation in a fluid, or fluidlike material, caused by heating from below. Heating the base of a fluid lowers its density, causing it to rise. The rising fluid cools, becomes denser, and sinks, creating circulation.
convection cell
Movement within a fluid resulting from differential heating and cooling of the fluid. Convection produces mass transport or mixing of the fluid.
convection current
A single closed-flow circuit of rising warm material and falling cool material.
convergence zone
The line along which waters of different density converge. Convergence zones form the boundaries of tropical, sub-tropical, temperate, and polar regions.
convergent evolution
The evolution of similar characteristics in organisms of different ancestry; the body shape of a porpoise and a shark, for instance.
convergent plate boundary
A region where plates are pushing together and where a mountain range, island arc, and/or trench will eventually form. Often a site of much seismic and volcanic activity.
Cook, James
(1728-1779) Officer in the British Royal Navy who led the first European voyages of scientific discovery.
copepod
Small, shrimplike member of the zooplankton; in the class Crustacea.
coral
Any of over 6,000 species of small cnidarians, many of which are capable of generating hard calcareous (aragonite CaCO3) skeletons.
coral reef
A linear mass of calcium carbonate (aragonite and calcite) assembled from coral organisms, algae, mollusks, worms, and so on. Coral may contribute to less than half of the reef material.
corange lines
In a rotary tide, lines of equal tidal range about the amphidromic point.
core
The innermost layer of the Earth, composed primarily of iron, with nickel and heavy elements. The inner core is thought to be a solid 6,000°C (11,000°F) sphere, the outer core a 5,000°C (9,000°F) liquid mass. The average density of the outer core is about 11.8 g/cm3, and that of the inner core is about 16 g/cm3.
corer
Device that plunges a hollow tube into bottom sediments to extract a vertical sample.
Coriolis effect
The apparent deflection of a moving object from its initial course when its speed and direction are measured in reference to the surface of the rotating Earth. The object is deflected to the right of its anticipated course in the Northern hemisphere and to the left in the Southern Hemisphere. The deflection occurs for any horizontal movement of objects and has no effect at the equator.
Coriolis, Gaspard Gustave de
(1792-1843) The French scientist who in 1835 worked out the mathematics of the motion of bodies on a rotating surface. Refer to Coriolis effect.
cosmogenous sediment
Sediment of extraterrestrial origin.
counterclockwise
Rotation around a point in the direction opposite to that in which clock hands move. Also called anticlockwise.
countercurrent
A surface current flowing in the opposite direction from an adjacent surface current.
covalent bond
A chemical bond formed between two atoms by electron sharing.
crest
Highest part of a progressive wave above average water level.
crust
The outermost solid layer of Earth, composed mostly of granite and basalt; the top layer of the lithosphere. The crust has a density of 2.7-2.9 g/cm3 and accounts for 0.4% of Earth's mass.
Crustacea
The class of phylum Arthropoda to which lobsters, shrimp, barnacles, crabs, and copepods belong.
crustaceans
Invertebrates with jointed limbs and hard chalky shells, such as lobsters, crabs, and shrimp.
crustal plate
A segment of Earth's surface. Continental plates are about 25 miles thick and oceanic plates 3.1 miles thick.
cryptic coloration
Camouflage. May be active (under control of the animal) or passive (an unalterable color or shape).
current
A flow of water in the sea, generated by wind, tidal movements, or thermohaline circulation.
current
Mass flow of water. (The term is usually reserved for horizontal movement.)
cyclone
A weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Not to be confused with a tornado, a much smaller weather phenomenon associated with sever thunderstorms. Se also extratropical cyclone; tropical cyclone.
Darwin, Charles
(1809-1882) English biologist. Co-discoverer (with Alfred Russell Wallace) of evolution by natural selection.
deadweight ton
(DWT) Capacity of a vessel in tons of cargo, fuel, stores, and so on; determined by the weight of the water displace.
declinational tide
See diurnal tide
deep scattering layer (DSL)
A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
deep zone
The zone of the ocean below the pycnocline, in which there is little additional change of density with increasing depth. Contains about 80% of the world's water.
deep-water wave
A wave in water deeper than one-half its wavelength.
degree
An arbitrary measure of temperature. One degree Celsius (°C) equals 1.8 degrees Fahrenheit (°F).
delta
The deposit of sediments found at a river mouth, sometimes triangular in shape (hence the name after the Greek letter).
demersal fish
Fish living near and on the bottom.
density
The mass per unit volume of a substance, usually expressed in grams per cubic centimeter (g/cm3); the mass of a substance for a given volume.
density curve
A graph showing the relationship between a fluid's temperature or salinity and its density.
density stratification
The formation of layers in a material, with each deeper layer being denser (weighing more per unit of volume) than the layer above.
dependency
A feeding relationship in which an organism is limited to feeding on one species or, in extreme cases, on one size phase of one species.
deposition
Accumulation, usually of sediments.
depositional coast
A coast in which processes that deposit sediment exceed erosive processes.
desalination
The process of removing salt from seawater or brackish water.
desiccation
Drying.
destructive interference
The subtraction of wave energy as waves interact, producing smaller waves.
detritus
Any loose material, especially decomposed, broken, and dead organic materials.
diatom
Earth's most abundant, successful, and efficient single-celled phytoplankton. Diatoms possess two interlocking valves made primarily of silica. The valves contribute to biogenous sediments.
diatomaceous ooze
Sediment made up of more than 30% skeletal remains of diatoms.
diffusion
The movement--driven by heat-- of molecules from a region of high concentration to a region of low concentration.
dinoflagellate
One of a class of microscopic single-celled flagellates, not all of which are autotrophic. The outer covering is often of stiff cellulose. Planktonic dinoflagellates are responsible for "red tides".
dispersion
Separation of wind waves by wavelength (and therefore wave speed) as they move away from the fetch (the place of their formation). Dispersion occurs because waves with long wavelengths move more rapidly than waves with short wavelengths.
disphotic zone
The lower part of the photic zone, where there is insufficient light for photosynthesis.
dissolution
The dissolving by water of minerals in the rocks.
disthermal zone
The zone of stable temperature below the thermocline.
disturbing force
The energy that causes a wave to form.
diurnal
Applies to a location that normally experiences one high water and one low water during a tidal day of 24 hours.
diurnal inequality
Difference in height between two high waters or two low waters of each tidal day; the difference in speed between the two flood currents or two ebb currents of each tidal day.
diurnal tide
A tidal cycle of one high tide and one low tide per day.
divergent evolution
Evolutionary radiation of different species from a common ancestor.
divergent plate boundary
A region where plates are moving apart and where new ocean or rift valley will eventually form. A spreading center forms the junction.
dobson unit
Ozone unit, defined as 0.01 mm thickness of ozone at Standard Temperature and Pressure. If all the ozone over a certain area is compressed to 1 atm pressure at 0°C, it forms a slab of a thickness corresponding to a number of Dobson units.
doldrums
The zone of rising air near the equator known for sultry air and variable breezes. See also intertropical convergence zone (ITCZ).
downwelling
Circulation pattern in which surface water moves vertically downward.
drag
The resistance to movement of an organism induced by the fluid through which it swims.
dredge
Cyllindric or boxlike sampling device made of metal, net, or both, that is dragged across the bottom to obtain biological or geological samples.
drift bottle
Bottle released into the sea for use in studying currents; contains a card identifying date and place of release and requesting the finder to return it with date and place of recovery.
drift net
Fine, vertically suspended net that may be 7 meters (25 feet) high and 80 kilometers (50 miles) long.
drift sector
See coastal circulation cell.
drumlin
A streamlined hill formed by a glacier.
DSL
Deep Scattering Layer: A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
dugong
See sea cow.
dune
An accumulation of wind-blown sand often found above the high-tide mark on sand shores. Also, a great book by Frank Herbert!
dynamic equilibrium
State in which the sums of all changes are balanced and there is no net charge.
dynamic theory of tides
Model of tides that takes into account the effects of finite ocean depth, basin resonances, and the interference of continents on tide waves.
earth sphere depth
Uniform depth of earth below the present mean sea level, if the solid earth surface were smoothed off evenly (2440 m).
earthquake
A sudden motion of Earth's crust resulting from waves in Earth caused by faulting of the rocks or by volcanic activity.
eastern boundary current
Weak, cold, diffuse, slow-moving current at the eastern boundary of an ocean (off the west coast of a continent). Examples include the Canary Current and the Humboldt Current.
ebb current
Water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches.
ebb tide
tide period between high and low water; falling tide; the period of the tide between high water and the next low water.
Echinodermata
The phylum of exclusively marine animals to which sea stars, brittle stars, sea urchins, and sea cucumbers belong.
Echinoidea
The class of the phylum Echinodermata to which sea urchins and sand dollars belong.