E-2 



EMERSED (Emergent) 

 AQUATIC PLANTS 



Plants that are rooted at the bottom of a body 

 of water, but project above the surface; e.g., 

 cattails, bulrushes, etc. (See Floating 

 Aquatic Plants , Submersed Aquatic Plants ) 



ENRICHMENT 



An increase in the quantity of nutrients 

 available to aquatic organisms for their 

 growth. (See Eutrophication ) 



ENRICHMENT FACTOR 



Number of times a substance is concentrated 

 in the tissue of an organism over the 

 concentration in its environment. (See 

 Biological Magnification ) 



ENVIRONMENT 



All external influences and conditions affecting 

 the life and development of an organism or 

 community . 



ENVIRONMENTAL 

 RESISTANCE 



Restriction imposed on the numerical increase 

 of a popula tion by environmental factors. 

 (See Biotic Potential) 



EPILIMNION 



The water mass extending from the surface to 

 the thermocline in a stratified body of water; 

 the epilimnion is less dense than the lower 

 waters and is wind-circulated and essentially 

 homothermous . (See Hypolimnion ) 



EQUILIBRIUM 



The condition in which a population or community 

 is maintained with only minor fluctuations in 

 composition over an extended period of time. 



