S-2 



4. Polysaproblc Zone - That area of a 



grossly polluted stream which contains 

 the complex organic wastes that are 

 decomposing primarily by anaerobic 

 processes. 



SCAVENGER 



An organism that consumes decomposing organic 

 matter. 



SECONDARY 

 PRODUCTIVITY 



Total quantity of animal (and other 

 heterotrophic ) protoplasm produced per unit 

 of time in a specified habitat . (See Primary 

 Productivity , Productivity ) 



SEICHE 



Periodic oscillations in the water level of 

 a lake or other landlocked body of water due 

 to unequal atmospheric pressure, wind, or other 

 cause, which sets the surface in motion. These 

 oscillations take place when a temporary local 

 depression or elevation of the water level occurs. 



SENSITIVE ORGANISMS 

 (Intolerant 

 Organisms) 



Organisms that exhibit a rapid response to 

 environmental changes and are killed, driven 

 out of the area, or as a group are substantially 

 reduced in numbers when their environment is 

 fouled. (See Tolerant Association) 



SESSILE 



Pertaining to those organisms that are 

 attached to a substrate and not free to 

 move about; e.g., periphyton . (See Free- 

 Swimming ) 



