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

 of selected diatom association metrics for periphyton 

 samples collected from Big Dry Creek and Little Dry 

 Creek near Jordan, Montana. 



Species /Metric 

 {Pollution Tolerance Class) ^ 



Percent Abundance/Metric Values^ 



Big Dry Creek 

 (8/23/00) 



Little Dry Creek 

 (5/27/99) 



Achnanthes minutissima (3) 

 CyjTijbella af finis (3) 

 Diploneis puella (2) 

 Entowoneis paludosa (2) 

 Gomphonewa parvulum (!) 

 Navicula duerrenbergiana (1 

 Navicula recens (2) 

 Nitzschia frustulum (2) 

 Nitzschia palea (1) 



Cells Counted 

 Total Species 

 Species Counted 

 Species Diversity 

 Percent Dominant Species 

 Disturbance Index 

 Pollution Index 

 Siltation Index 

 Percent Abnormal Cells 

 Percent Epithemiaceae 

 Similarity Index 



16. 



1. 



6. 

 21. 

 11 . 



5. 



9. 



99 

 33 

 19 

 72 

 89 

 83 

 22 



412 



48 



45 

 3 .90 



21.72 

 0.00 

 1.56 



69.66 

 0.00 

 1.09 



36.86 



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 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. 



A "p" indicates that the taxon was recorded as present during 

 a preliminary floristic scan of the diatom slide, but it was 

 not encountered during the diatom proportional count. 



