B-2 

 BENTHOS 



Organisms growing on or associated principally 

 with the bottom of waterways. These include: 



(1) sessile animals such as sponges, barnacles, 

 mussels, oysters, worms, and attached algae; 



(2) creeping forms such as snails, worms and 

 insects; (3) burrowing forms, which include 

 clams, worms, and some insects; and (4) fish 

 whose habits are more closely associated with 

 the benthic region than other zones; e.g., 

 flounders. 



BIOASSAY 



A determination of the biological effect of 

 some substance, factor or condition employing 

 living organisms or cells as the indicator. 



BIOCOENOSIS 



The plants and animals comprising a community . 



BIOLOGICAL 

 CONTROL 



1. Use of natural predators , parasites or 

 viruses to reduce or eliminate pest 

 organisms; e.g., use of gambusia to 

 feed on mosquito larvae; 



2. Control of organisms by interference 

 with their physiological processes; 

 e.g., sterilization of male flies. 



BIOLOGICAL 

 MAGNIFICATION 



The ability of certain organisms to remove 

 from the environment and store in their tissues 

 substances present at nontoxic levels in the 

 surrounding water. The concentration of these 

 substances becomes greater each higher step 

 in the food chain. (See Enrichment Factor) 



