Table 4. Percent abundance of major diatom species^ and values 



of selected diatom association metrics for a periphyton 

 sample collected from Mol Heron Creek near Corwin 

 Springs, Montana on July 14, 2000. 



Species/Metric Percent Abundance/Metric Value^ 



(Pollution Tolerance Class) ^ 



Cymhella silesiaca (2) 21.48 



Diatoms vulgare (3) 2 0.75 



Hannaea arcus (3) 21.36 



Rhoicosphenia curvata (3) 5.7 



Cells Counted 412 



Total Species 41 



Species Counted 37 



Species Diversity 3.55 



Percent Dominant Species 21.48 



Disturbance Index 3.64 



Pollution Index 2.64 



Siltation Index 12.49 



Percent Abnormal Cells . 97 



Percent Epithemiaceae 0.00 



^ A major diatom species is here considered to be one that 



accounts for 5% or more of the cells in one or more samples of 

 a sample set . 



2 



Underlined values indicate good biological integrity, minor 

 impairment, and full support of aquatic life uses; all other 

 values indicate excellent biological integrity, no impairment, 

 and full support of aquatic life uses. 



3 = sensitive to pollution; 2 = tolerant of pollution; 

 1 = most tolerant of pollution (no class 1 diatoms were major 

 species in this sample) . 



