D-/ 



DECOMPOSERS 



( Reducers) 



DELTA 

 (Alluvial Fan) 



A fan-shaped deposition of silt, sand, gravel 

 or other fine materials from a stream. These 

 occur when the hydraulic gradient lessens 

 abruptly, as in the discharge of a stream 

 into a lake, or a river into an ocean. 

 (See Alluvial) 



DENSITY 

 (Population 

 Species) 



The number of individuals in relation to the 

 space in which they occur; refers to the 

 closeness of individuals to one another 

 at a given time. 



DENSITY 

 STRATIFICATION 



(Stratification) 



DEPOSITING 

 SUBSTRATES 



Bottom areas where solids are being actively 

 deposited because of slackening movement of 

 the transporting agent. These often occur 

 in the vicinity of effluent discharges. 

 (See Sludge Deposits ) 



DETRITUS 



Fragments of detached or broken down material. 



DIRECT TOXICITY 



Toxicity that has an effect on organisms 

 themselves instead of having an effect by 

 alteration of their habitat or interference 

 with their food supply. (See Acute Toxicity , 

 Chronic Toxicity , Indirect Toxicity) 



