A-4 



ASSIMILATION 



1. Removal of dissolved or suspended materials 

 from a water mass by biological, chemical 

 and physical processes; 



2. Conversion or incorporation of absorbed 

 nutrients into body substances. (See 

 Synthesis ) 



ASSOCIATION 



All organisms occupying a given habitat . 



ATOLL 



Large, thick, coral mass encircling a lagoon 

 in tropical oceans; cometimes portions of the 

 reef become built up with sand, silt, soil and 

 vegetation to become an island. (See Barrier 

 Reef , Fringing Reef ) 



AUFWUCHS 



( Periphyton ) 



AUTOCHTHONOUS 



Pertaining to those substances, materials, 

 or organisms originating within a particular 

 waterway and remaining in that waterway. 

 (See Allochthonous) 



AUTOTROPHIC 

 (Holophytic) 



Self nourishing; denoting those organisms that 

 do not require an external source of organic 

 material but can utilize light energy and 

 manufacture their own food from inorganic 

 materials; e.g., green plants, pigmented 

 flagellates. (See Heterotrophic) 



