Table 4. Percent abundance of major diatom species^ and values of selected diatom association metrics for 

 penphyton samples collected from Beaver Creek in 2002. Underlined values indicate minor stress; 

 bold values indicate moderate stress: underlined and bold values indicate severe stress; all 

 other values indicate no stress and full support of aquatic life uses when compared to criteria for 

 mountain streams in Table 2. Stress may be natural or anthropogenic (see text) 



:? 



Species/Metric 



Achnanthidium minutissimum 

 Encyonema sileslacum 

 Fragilaria vaucheriae 

 Hannaea arcus 

 Reimeria sinuata 

 Staurosira construens 



Number of Species Counted 

 Shannon Species Diversity 

 Pollution Index 

 Siltation Index 

 Disturbance Index 

 Percent Dominant Species 

 Percent Abnormal Cells 

 Similarity Index'^ 



68.00 



# 



A major diatom species accounts for 3.0% or more of the cells at one or more stations in a sample set. 

 ^(Organic) Pollution Tolerance Class (Lange-Bertalot 1979): 1 = most tolerant; 2 = tolerant; 3 = sensitive. 

 ■^Percent Community Similarity (Whittaker 1952) when compared to the diatom assemblage at the adjacent 



upstream station 



