periphyton collections. The mathematical manipulations that are involved in 

 producing such indices are extensively described in Weber (1973). 



Periphyton Results 



Four soft-bodied algal genera (the blue-green Nostoc and Oscillatoria , 

 and the green algae Closterium and Ulothrix ) and a minimum of 82 species and 

 varieties of diatoms were identified through the three German Gulch samples. 

 A list of periphyton species and calculations of percent relative abundance 

 for the German Gulch study sites are included in Appendix C. A breakdown of 

 the taxa numbers by site and the diversity and equitability characteristics of 

 the stations are presented in Table 15. The number of different taxa that 

 were recognized in the scrapings from a site provides a general indication of 

 the stations' floral richness, while the diversity and equitability expres- 

 sions function to illustrate the overall structure of a periphyton community. 



Of the non-diatomaceous algae, Oscillatoria and Closterium were found to 

 be relatively rare through all three of the project sites, while Nostoc was 

 seen to be fairly abundant at the upper and middle locations on the gulch but 

 non-abundant in its lower reach. In opposition, Ulothrix was observed to be 

 quite common at the gulch's downstream station but rare at its upstream 

 locales. However, the low or high abundances of these particular soft-bodied 

 forms do not necessarily point to the existence of any distinct environmental 

 problems; rather, Nostoc , as one example, is oftentimes prevalent in waters 

 that can be described as having a largely pristine nature (Ingman et al 1979). 



Of the many diatom taxa, a significant proportion (82%) proved to be 

 relatively uncommon components of the gulch's periphytic associations with 

 mean PRA's across the stations at less than 2.0%. But the low abundances of 

 this particular group of diatoms are again not necessarily suggestive of 



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