Table 5. Percent abundance of major diatom species^ and values 

 of selected diatom association metrics for periphyton 

 samples collected from Cottonwood Creek and Rock Creek 

 near Clyde Park, Montana in the summer of 2000. 



• 



Species/Metric 

 [Pollution Tolerance Class) ^ 



Achnanthes minutissima (3) 

 Cymbella af finis (3) 

 Cymhella minuta (2) 

 Cymbella silesiaca (2) 

 Gomphonewa angustatwn (2) 

 Gomphonema minuti forme (3) 

 Nitzschia palea (1) 

 Reimeria sinuata (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* 



Percent Abundance/Metric Values^ 

 Cottonwood Creek Rock Creek 

 Station 2 



29.25 



11.13 



16.88 



9.25 



0.50 



5.25 

 0.50 



400 

 40 

 39 



3 .58 

 29.25 

 29.25 



2.48 

 21.27 



0.13 



0.13 



36.93 



52.64 



^ 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 

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

 values indicate excellent biological integrity, no impairment, 

 and full support of aquatic life uses when compared to 

 criteria for mountain streams in Table 3 . 



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

 1 = most tolerant of pollution. 



■* The percent community similarity between Cottonwood Creek 

 Station 2 and Rock Creek Station 2 was 53.88%. 



