BEACH EROSION - The carrying away of heach materials by wave action, tidal 

 currents, littoral currents, or wind. 



BENTHIC - Pertaining to the subaquatic bottom. 



BENTHOS - A collective term describing: (11 Bottom organisms attached or 

 resting on or in the bottom sediments. (.21 Community of animals living 

 in or on the bottom. 



BIOASSAY - The use of living organisms as an index to determine environ- 

 mental conditions. 



BIOCHEMICAL OXYGEN DEMAND (BOD) - The amount of oxygen required by the 

 biological population of a water sample to oxidize the organic matter in 

 that water. It is usually determined over a 5-day period under stan- 

 dardized laboratory conditions and hence may not represent actual field 

 conditions. 



BIOLOGICAL RESISTANCE - Ability to resist degradation due to microorganisms. 



BIOMASS - The amount of living material in a unit area for a unit time. 

 Also standing crop, standing stock, live-weight. 



BIOTA - The living part of a system (flora and fauna) . 



BOULDER - A rounded rock more than 10 inches in diameter; larger than a 

 cobblestone. See SOIL CLASSIFICATION. 



BOTTOM - The ground or bed under any body of water; the bottom of the sea. 



BREAKER - A wave breaking on a shore, over a reef, or other feature. 



BREAKWATER - A structure protecting a shore area, harbor, anchorage, or 

 basin from waves. 



BULKHEAD - A structure or partition to retain or prevent sliding of the 

 land. A secondary purpose is to protect the upland against damage from 

 wave action. 



BUOY - A float; especially a floating object moored to the bottom, to 

 mark a channel, anchor, shoal, rock, etc. 



BUOYANCY - The resultant of upward forces, exerted by the water on a 

 submerged or floating body, equal to the weight of the water displaced 

 by this body. 



BURST STRENGTH - The resistance of a fabric to rupture due to pressure 

 applied at right angles to the plane of the fabric under specified con- 

 ditions, usually expressed as the pressure causing failure. Burst is due 

 to tensile failure of the fabric. 



CATHODE - The negative pole or electrode of an electrolytic cell. 



CAUSEWAY - A raised road, across wet or marshy ground, or across water. 



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