A- 3 

 ANADROMOUS 



Pertaining to fishes that spend most of their 

 life in salt water but enter freshwater to 

 spawn ; e.g., salmon, shad, striped bass, etc. 

 (See Catadromous) 



ANAEROBIC 



Refers to life or processes occurring in the 

 absence of free oxygen; refers to conditions 

 characterized by the absence of free oxygen. 

 (See Aerobic) 



ANTAGONISM 



Reduction of the effect of one substance 

 because of the introduction or presence of 

 another substance; e.g., one substance may 

 hinder, or counteract, the toxic influence 

 of another. (See Synergism ) 



APHOTIC ZONE 



That portion of a body of water to which 

 light does not penetrate with sufficient 

 intensity to have any biological significance. 

 (See Euphotic Zone ) 



AQUATIC VASCULAR 

 PLANTS 



( Higher Aquatic Plants ) 



ARTIFICIAL 

 SUBSTRATE 



A device placed in the water (for a specified 

 period of time ) that provides living spaces 

 for a multiplicity of organisms; e.g., glass 

 slides, concrete blocks, multiplate samplers, 

 rock baskets, etc. The primary purpose of 

 artificial substrates is to allow the investi- 

 gator to collect organisms in areas where the 

 physical habitat is limiting or cannot be 

 adequately sampled using conventional methods. 



