A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
Abyssal zone: the deepest zone of the open ocean, begins at about 1500 meters and continues to the ocean floor.
Accelerated erosion: exceeds the rate of soil profile maintenance and is thus destructive.
Acid deposition: the falling of acids from the atmosphere to the earth's surface.
Anthropocentric: human-centered worldview.
Aquaculture: the commercial raising of fish and shellfish for food.
Aquifer: a porous, water-saturated layer of sand, gravel, or bedrock through which groundwater flows.
Bathyal zone: the middle zone of the open ocean.
Benthic zone: the very bottom of the lake.
Biocentric: life-centered worldview.
Biological extinction: the complete disappearance of a species from the planet.
Biological oxygen demand: the amount of oxygen required for the decomposition of organic compounds by microorganisms in a given amount of water.
Breakwaters: structures that are placed offshore to deflect strong currents and protect a beach from the energy of incoming waves in order to reduce beach erosion.
Buoyancy: the upward force that water exerts.
Bycatch: species caught accidently during fishing that have little commercial value and are often endangered or at a risk of becoming so (dolphins, seals, sea turtles).
Coastal zone: the area of the ocean close to land.
Commercial extinction: the point at which it is no longer profitable for fishers to harvest an aquatic species.
Confined aquifer: one that is bounded above and below by beds of rock.
Continental shelf: the shallow seabed surrounding a continent, or the part of the continent land mass that is under water.
Contouring: the planting of crops in rows along hills to prevent erosion.
Demersal: the term for species of fish that dwell near the bottom of a body of water (cod, flatfish).
Density: the mass of an object per unit of volume.
Desalinization: using distillation or reverse osmosis in order to remove the salt from saltwater and turn it into usable freshwater.
Discharge areas: bodies of water that collect groundwater as it flows out of an aquifer (lakes, geysers, streams, oceans).
Distillation: heating salt water until it evaporates and condenses as fresh water, leaving behind salt in its solid form.
Drift-net fishing: a fishing method that uses nets made of invisible filament mesh in order to catch and hold fish by their gills.
Ecocentric: Earth-centered worldview.
Epilimnion: is the upper layer of warm water in a lake.
Erosion: the breaking down and wearing away of any part of Earth's surface by water, wind, ice, or gravity.
Estuary: partially enclosed area of coastal water where sea water mixes with fresh water and nutrients from rivers, streams, and runoff.
Euphotic zone: the uppermost zone of the open ocean, extending from the surface to about 200 meters below.
Eutrophic lake: has a large, excessive supply of nutrients (mostly nitrates and phosphates) and a high primary productivity.
Fisheries: regions of water where the levels of particular aquatic species are suitable for commercial harvesting.
Fish farming: using a controlled environment, usually a pond or tank, to breed and raise fish until they reach the desired size for harvesting.
Fish ranching: holding fish in captivity for the first few years of their lives, releasing them, and then harvesting the adults when they return to breed.
Floodplain zone: the area where streams merge into wider, deeper rivers that flow slowly across broad, flat valleys.
Groundwater: results from precipitation that infiltrates the ground and seeps downward through fractures, pores, and other spaces in soil and rock.
Heat capacity: the capability of water to absorb heat without undergoing an increase in temperature.
Hypolimnion: the lower layer of colder, denser water in a lake.
Intertidal zone: a sub-category of the coastal zone, the part of the coast that is submerged during high tide but uncovered during low tide.
Limnetic zone: the sunlit part at the top of the lake, similar to the littoral zone.
Lentic: standing bodies of water (lakes, ponds, and inland wetlands).
Littoral zone: the area near the shore at the top of the lake that receives sunlight, extending down to the depth where rooted plants stop growing.
Long-lining: a fishing method in which long fishing lines, some up to eighty miles long, are sent out from a ship hung with thousands of bated hooks.
Lotic: flowing systems (streams and rivers).
Mesotrophic lake: somewhere between the two extremes of oligrotrophic and eutrophic.
Nonpoint pollution: pollution that enters the environment from a large or dispersed land area (cropfields, streets).
Normal erosion: land surfaces are worn away gradually under normal environmental conditions.
Oligotrophic lake: a newly-formed lake with a small supply of plant nutrients, deep and steep banks, and low primary productivity.
Overfishing: occurs when the harvest of a species exceeds that species' sustainable yield.
Pelagic: the term for species of fish that dwell near the surface of water (salmon, tuna, mackerels).
pH: a measurement of the concentration of hydrogen ions (protons) in a solution, and an indication of the relative acidity of the solution.
Point pollution: pollution that enters the environment from one specific location (chimneys, cars).
Profundal zone: is the deep open water of a lake, where it is too dark for photosynthesis.
Purse-seine fishing: using a draw-string net to catch large surface-dwelling species of fish such as tuna.
Recharge areas: areas of land through which groundwater passes downward into the aquifer.
Reforestation: the intentional growth of plants in order to improve the soil and reduce erosion.
Reverse Osmosis: pumping salt water at high pressure through a membrane that allows water molecules to pass through, but not dissolved salts.
Runoff: surface water that ends up flowing into a stream.
Sheet erosion: a specific case of accelerated erosion, occurs when a layer of soil over an entire area is washed away.
Source zone: the area where the stream begins.
Surface water: precipitation that does not sink into the ground or evaporate.
Sustainable yield: the largest amount of organisms that can be continually harvested from a population without causing the population to crash.
Thermocline: the area in between in which water temperature decreases rapidly with depth in a lake.
Transition zone: the area where mountain streams merge to form wider, deeper streams that flow down more gradually and with fewer obstacles.
Trawlers: fishing boats that drag large nets across the ocean floor.
Unconfined aquifer: lies underneath a water table.
Watershed: the land area that contributes runoff sediment and dissolved substances to a stream.
Wetlands: areas on land that can be covered with water.
Zone of aeration: a layer of earth in an aquifer in which rock and soil may be moist but are not saturated with water.
Zone of saturation: the layer of soil in an aquifer that directly above bedrock and is completely filled with water.
Thinkquest Team "Fish," March 2005, Disclaimer and copyright information