BIOTIC STREAM RESPONSES TO STREAM REAERATION 



43 



Graph 7. All insect larvae minus Chironomidae, log. (no./sq. ft. x 100) 



The snail populations (Graph 8) consisted of 4 different species with 

 Campeloma integrum the dominant one. Three of them are pulmonates 

 which may breathe air by means of a lung and therefore are not dependent 

 upon dissolved oxygen values of the stream. For this reason, their distri- 

 bution is governed mainly by available food, suitable substratum and con- 



Graph 8. Total snails, log. (no./sq. ft. x 1(K)) 



