B— Continued 



biotic factors — Factors of a biological 

 nature such as availability of food, 

 competition between species, preditor- 

 prey relationship etc., which besides the 

 purely physical and chemical factors, 

 also affect the distribution and abun- 

 dance of species. 



biotic potential— (1) The maximum repro- 

 duction power or ability. The inherent 

 property of an organism to reproduce 

 and survive in greater numbers. (2) The 

 ability of an organism to reproduce in an 

 optimum, unrestricted, noncompetitive 

 environment. 



biotic succession— The natural replacement 

 of one or more groups of organisms 

 occupying a specific habitat by new 

 groups. The preceding groups in some 

 ways prepare or favorably modify the 

 habitat for succeeding groups. 



biotope— Habitat, a rather specific kind of 

 living space. See also ecotope. 



biotype— In plants or animals, a phenom- 

 enon where the genotypes are similar, 

 but the phenotypes are different due to 

 local conditions. 



birthrate— Number of births in a given time 

 period. Usually expressed as births per 

 1,000 population per year or per 

 generation. 



bloom— See plankton bloom. 



B.O.D.— See Biochemical Oxygen Demand. 



brine— Water containing a concentration of 

 dissolved salts higher than that of 

 ordinary seawater. 



budding— An asexual means of reproduc- 

 tion in lower organisms where a small 

 replica of the adult grows from the 

 parent. 



--C-- 



carnivore— A flesh eater. The highest tropic 

 level(s) at the top of most food chains. 



carrying capacity— The maximum number 

 of a species that any particular area can 

 support over an extended period of time. 



casts— Deposits of fecal material with 

 attendant undigested sediment. Fre- 

 quently found as pellets or strands. 



catabolism— The metabolic process break- 

 ing compounds (e.g., sugar) into simpler 

 substances to release energy— as opposed 

 to anabolism. See also metabolism. 



catadromous— A life cycle in which matu- 

 rity is reached in freshwater and 

 spawning takes place at sea (e.g., the 

 American eel). 



chemotrophic nutrition — A process by 

 which an organism manufactures its food 

 by using the energy derived by oxidizing 

 inorganic matter. 



chitin— A nitrogenous polysaccharide form- 

 ing the basic part of the arthropod 

 exoskeleton. 



chlorophyll— The green pigment used in 

 photosynthesis, found primarily in 

 plants. 



circadian rhythm— The most common man- 

 ifestation of the biological clock, being 

 the ability to repeat certain functions 

 daily without external clues, such as 

 light-dark cycles. See also diel perio- 

 dicity. 



