Table 6. Percent abundance of major diatom species' and values 

 of selected diatom association metrics for periphyton 

 samples collected from Billman Creek near Livingston, 

 Montana on July 21, 2000. 



Species /Metric 

 (Pollution Tolerance Class) ^ 



Percent Abundance /Metric Values^ 



Mountain Criteria Plains Criteria" 

 Sta. 1 Sta. 2 Sta. 1 Sta. 2 



Fragilaria capucina (2) 

 Melosira varians (2) 

 Navicula capita toradiata 

 Navicula gregaria (2) 

 Navicula lanceolata (2) 

 Navicula tripunctata (3) 

 Nitzschia palea (1) 

 Nitzschia paleacea (2) 

 Surirella rninuta (2) 



Cells Counted 

 Total Species 

 Species Counted 

 Species Diversity 

 Percent Dominant Species 

 Disturbance Index 

 Pollution Index 

 Siltation Index 

 Percent Abnormal Cells 

 Percent Epithemiaceae 

 Similarity Index 



(2) 



37.56 



' 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; underlined and bold 

 values indicate poor biological integrity, severe impairment, 

 and non- support of aquatic life uses; all other values 

 indicate excellent biological integrity, no impairment, 

 and full support of aquatic life uses when compared to diatom 

 criteria for mountain and plains streams in Tables 3 and 4 . 



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

 1 = most tolerant of pollution. 



" Only metric values that exceed diatom biocriteria for plains 

 streams are shown. 



