organisms carried along by the current. Scraper or grazing organisms are 

 found throughout the river, and silt-tolerant organisms become abundant 

 in the low-gradient portions. 



Faunal zones, both for fish and bottom-dwelling organisms, are broad and 

 not distinctly defined. Throughout the upper half of the river, the salmonid 

 community gradually decreases, as does the Plecoptera fauna. Ephemeroptera, 

 however, exhibit a gradual shift in species composition from one community 

 to another with the exception of several adaptable species that are present 

 throughout the entire river. 



101 



