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

 for periptiyton samples collected from the Big Hole River TMDL Planning Area in 2003. Underlined values 

 indicate minor stress; bold values indicate moderate stress; underlined and bold values indicate severe 

 stress; all other values indicate no stress and full support of aquatic life uses when compared to biocriteria 

 (thresholds) in Table 2. Observed stress may be natural or anthropogenic, (concluded) 



Species/Metric' LOSTC01 LOSTC02 SWLGC01 SWLGC02 CAMPC01 CAMPC02 CAMPC03 



Achnanthidium affine 36.57 



Ach. minutlssimum 21.46 12.73 



Aulacoseira alpigena 



Cocconeis placentula 24.84 6.33 20 79 



Diatoma mesodon 



Encyonema silesiacum 9.26 14.90 



Epithemia sorex 

 Fraqilaria capucina 

 Fragilaria nitzschioides 



Fraqilaria vaucheriae 7.54 



Melosira varians 

 Meridian circulare 



Navicula capitatoradiata 10.52 



Navicula minima 19.40 



Navicula reichardtiana 10.05 



Nitzschia archibaldii 

 Nitzschia inconspicua 30.37 



Nitzschia linearis 11.38 6.61 



Nitzschia palea 



Planothidium spp. 15.06 12.87 18.61 7.24 



Pseudostaur. brevistriata 



Rhoicosphenia abbreviata 10.09 



Staurosira construens 9.03 



Staurosirella leptostauron 

 Staurosirella pinnata 

 Synedra ulna 6.34 



No. of Species Counted 39 34 67 75 60 71 79 



Species Diversity 



Pollution Index 



Siltation Index 



Disturbance Index 



% Dominant Species 



% Abnormal Cells 



Similarity Index^ 



A major diatom species accounts for 9.0% or more of the cells at one or more stations in a sample set. 

 Values for major species are shown only where they equal or exceed 5.0% of the cells in that sample. 

 ^Species that are sensitive to organic pollution are in italics; species that are somewhat tolerant of organic 



pollution are underlined ; species that are very tolerant to organic pollution are in bold face type. 

 Percent Community Similarity (Whittaker 1952) when compared to the diatom assemblage at the 

 adjacent station on the same stream. 



