D-2 

 DIURNAL 



1. Refers to an event, process, or specific 

 change that occurs every day; usually 

 associated with changes from day to night. 



2. Pertaining to those organisms that are 

 active during day time. (See Nocturnal ) 



DIVERSITY 



Pertaining to the variety of species within a 

 given association of organisms. Areas of high 

 diversity are characterized by a great variety 

 of species; usually relatively few individuals 

 represent any one species . Areas with low 

 diversity are characterized by a few species; 

 often relatively large numbers of individuals 

 represent each species. 



DOMINANT SPECIES 



Species of a community which by their activity, 

 behavior, or number, have considerable 

 influence or control upon the conditions of 

 existence of associated species; species 

 which "controls" its habitat and food web . 

 (See Predominant) 



DRIFT ORGANISMS 



Benthic organisms temporarily suspended in the 

 water and carried downstream by the current. 

 (See Incidental Drift , Periodic Drift , 

 Catastrophic Drift ) 



