The fifteen common German Gulch diatoms accounted for about 72% of the 

 study's total frustule counts, and the remaining tabulations were thinly 

 spread among the 67 remaining, less common forms. Such a dominance by a 

 disproportionately small assortment of species is in agreement with the 

 community structures that can be recognized in most of the natural biological 

 systems. In the case of extensively polluted streams, this dominance would be 

 more thickly spread across a much smaller set of periphytic organisms with a 

 much reduced level of floral richness, i.e., with a much narrower selection of 

 the rarer diatom species, and such pollutive restrictions do not appear to be 

 evident in the German Gulch collections. 



The environmental status of German Gulch was additionally judged by 

 reviewing the Shannon-Wiener diversity numbers of the three periphyton 

 samples. To set the stage for making such evaluations, the refined data of 

 this kind that are now on hand for numerous Montana streams as available in 

 Tngman et al (1979), Bahls et al (1979), and Bahls et al (1981) were first 

 assessed for comparative purposes. As revealed by these reports, a statewide 

 average of 42.7 diatom taxa was secured for the summer season with an average 

 Shannon-Wiener diversity value for this same period of 3.99. These mean 

 values can then be used as a reference point for judging the biological 

 aspects and the structures of the German Gulch periphyton scrapings. 



In conjunction with such statewide means, Montana's streams also produced 

 a typically high taxa count of 63.6 species with a maximum of 67, and 12% of 

 the collections produced taxa numbers in excess of 60 species. The streams 

 further produced a typically high diversity of A. 87 with a maximum of 5.00, 

 and 12% of the samples provided diversities in excess of 4.77 units. 

 Contrariwise, these same Montana waters produced typically low taxa numbers 

 and diversity levels of 25.1 and 2.85 respectively with minimums of 22 and 



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