BIOTIC STREAM RESPONSES TO STREAM REAERATION 41 



volumes are interpreted as a positive response to increased food and food 

 material supplies made available through stream recovery processes. 

 Further decreases downstream apparently result from the swiftness and 

 turbulence of the stream. 



While it would have been valuable to study the plankton for species 



miaa 



Graph 5. Total Oligochaeta, log. (no./sq. ft. x 100) 



that may be characteristic of waste sulphite liquor pollution, no attempt 

 could be made to do so. That information is lacking at the present time. 



Samples of the bottom deposits and their organisms were collected 

 with the Eckman or Peterson dredges or with the square-foot sampler with 

 downstream net. Samples were examined for physical quality of the sub- 

 stratum and determination of quality and populations of bottom organisms. 



Appreciable deposits of bark, chips or wood fiber were found as far as 

 6.1 miles downstream, and intermittent deposits of fiber 11 miles down- 

 stream. 



Bottom organisms, as referred to here, are those restricted in their 

 habitat to a position on the surface of, or imbedded in, the accumulated 

 deposits or natural bed of the stream. They obtain their food from the 

 supernatant medium in which they are bathed or feed as they burrow 

 through or creep over the beds of deposited substances. Inhabitants of 

 such substrata in pollutional areas must be able to tolerate low oxygen 

 supply and toxic products of anaerobic processes. Some of the larger 

 inhabitants are nematodes, flatworms, annelids, crustaceans, molluscs and 

 insect larvae. 



Since organisms vary in their powers of pollutional tolerance, it is 

 to be expected that some species will find suitable conditions for existence 



