E— Continued 



epipelagic — The upper portion of the 

 oceanic province extending from the 

 surface to a depth of about 185 meters. 



estuary — In ecological usage: a semi- 

 enclosed coastal body of water which 

 has a free connection with the open sea. 

 The seawater is usually measurably 

 diluted with freshwater. 



eulittoral— That part of the littoral zone 

 less than 50 meters in depth. 



euphotic zone— The layer of water which 

 receives ample sunlight for photosyn- 

 thesis. It varies with the light extinction 

 coefficient. Usually no deeper than 

 about 60 meters. 



eury— A prefix referring to a wide range of 

 some parameter. Opposite of steno. 



eutrophic lake — A shallow lake that has 

 good primary productivity, usually abun- 

 dant littoral vegetation, and dense 

 plankton population. Blooms occur 



when nutrient and physical conditions 

 are right. The bottom water, during later 

 stages of eutrophication, tends to be- 

 come depleted of oxygen during the 

 summer. 



eutrophication— The process whereby a 

 body of water becomes highly produc- 

 tive due to the input of large quantities 

 of nutrients. It may have high dissolved 

 oxygen concentrations near the surface 

 during the day and low concentrations 

 during the night. The bottom waters 

 usually have low dissolved oxygen and 

 high organic concentrations at all times 

 of day. 



exoskeleton— A hard outer covering which 

 acts as a support structure for muscle 

 attachment. 



exotics— Nonendemics. Organisms which 

 are not native but introduced. 



exploitation— Usually the use of one species 

 by another. Usually only one species 

 benefits from this relationship. 



__F 



facultative anaerobe — An organism that 

 doesn't necessarily require lack of 

 oxygen for survival, but is able to live 

 either in the presence (usually at low 

 concentrations) or absence of oxygen. 

 See also anaerobe and obligate anaerobe. 



fauna— Animal hfe as opposed to flora 

 (plant hfe). Generally the entire group of 

 animals found in an area. 



fecundity— The amount of egg or sperm 

 production per individual or population. 



feral— An adjective describing formerly 

 domesticated animals gone wild. 



fidelity— The degree of restriction of a 

 species to a particular association. 



filter feeding— A feeding process employed 

 by many aquatic organisms in which 

 water currents are passed through a 

 filtering system and small organisms are 

 selectively strained out and eaten. 



flora— Plant life as opposed to fauna 

 (animal life). The entire group of plants 

 found in an area. 



