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



of selected diatom association metrics for a periphyton 

 sample collected from the mouth of Bear Creek near 



Gardiner, Montana on July 13, 2000. 



Species/Metric Percent Abundance/Metric Value^ 

 (Pollution Tolerance Class) ^ 



Fragilaria vaucheriae (2) 15.69 



Gomphoneis winuta (3) 5.11 



Hannaea arcus (3) 50.85 



Synedra ulna (2) 5.4 7 



Cells Counted 411 



Total Species 32 



Species Counted 30 



Species Diversity 2 . 82 



Percent Dominant Species 50.85 



Disturbance Index 0.73 



Pollution Index 2.74 



Siltation Index 2.18 



Percent Abnormal Cells .24 



Percent Epithemiaceae 0.24 



^ 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 . 



^ Underlined values indicate good biological integrity, minor 

 impairment, and full support of aquatic life uses; bold values 

 indicate fair biological integrity, moderate impairment, and 

 partial support of aquatic life uses,- all other values 

 indicate excellent biological integrity, no impairment, and 

 full support of aquatic life uses. 



3 



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



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



species in this sample) . 



