A GLOSSARY OF ECOLOGICAL TERMS FOR COASTAL ENGINEERS 



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adaptive radiation — An evolutionary proc- 

 ess whereby a species goes through 

 evolutionary divergence from a single 

 phyletic line (a single species) into a 

 series of different niches or adaptive 

 zones usually as the result of intraspe- 

 cific competition. 



aerobe— An organism that can live and grow 

 only in the presence of oxygen. 



aggregation— (1) The clumping or nonran- 

 dom distribution of individuals. (2) A 

 situation where certain dominant species 

 or genera are always found in certain 

 niches and have similar communities or 

 associations. 



algaculture— The growing, or farming, of 

 algae, usually as a food source for higher 

 organisms. See also aquaculture and 

 mariculture. 



anabolism— The metabolic process of build- 

 ing products from less complex substan- 

 ces (e.g., proteins from amino acids)— as 

 opposed to catabohsm. See also metabo- 

 lism. 



anadromous— A life cycle in which matu- 

 rity is attained in the ocean and the 

 adults ascend rivers and streams to 

 spawn in freshwater (e.g., salmon). 



anaerobic— An oxygen-independent type of 

 respiration. 



anaerobic sediment— A highly organic sedi- 

 ment with no free oxygen present. 

 Usually rich in hydrogen sulfide. 



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anaerobic zone— A zone where oxygen is 

 lacking. Substances are reduced, not 

 oxidized. 



alkaline— The excess of hydroxyl ions over 

 hydrogen ions. Seawater is usually 

 alkaline. 



alkalinity— The capacity of a water to 

 accept protons, i.e., hydrogen ions. It is 

 usually expressed as milliequivalents per 

 liter. 



allochthonous— Usually refers to material 

 resources whicli originated outside the 

 division of an ecosystem under consid- 

 eration. 



allogenic succession — Succession induced 

 by geochemical processes acting from 

 outside the local community. 



anaerobe— An organism living under no or 

 little oxygen concentrations. See also 

 facultative anaerobe and obligate anaer- 

 obe. 



annuals— Plants that go through an entire 

 life cycle of seed to adult to seed in one 

 year. 



antagonism— A relationship between species 

 in which at least one species is harmed. 



antibiosis— The relationship between spe- 

 cies in which certain substances pro- 

 duced or excreted by one species are 

 generally harmful to others (e.g., fish 

 kills caused by red tide toxins). 



amensalism— The interaction of two species 

 resulting in one species being inhibited 

 and the other not affected. 



aphotic zone— An aquatic zone of no light 

 penetration, therefore, no primary pro- 

 ductivity takes place in this zone. 



