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

 for periphyton samples collected from ttie 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, (continued) 



Species/Metric PINEC02 FOXC01 FOXC02 FSHTC01 FSHTC02 LMCHC01 LMCHC02 



Achnanthidium affine 



Ach. minutissimum 12.95 7.31 



A ulacoseira alpigena 12.13 8.71 



Cocconeis placentula 7.79 



Diatoma mesodon 



Encyonema silesiacum 



Epithemia sorex 



FraQJIaha capucina 13.11 



Fragilaria nitzschioides 



Fraqilaria vaucheriae 6.93 7.15 17.06 9.00 9.82 5.25 12.91 



Melosira varians 



Meridian circulare 



Navicula capitatoradiata 



Navicula minima 



Navicula reichardtiana 



Nitzsciiia arciiibaldii 



Nitzschia inconspicua 



Nitzschia linearis 



Nitzschia palea 



Planothidium spp. 6.61 6.38 



Pseudostaur. brevistriata 13.39 12.16 16.26 6.22 



Rhoicosphenia abbreviata 



Staurosira construens 11.97 18.20 9.12 9.48 9.66 8.69 



Staurosirella leptostauron 



Staurosirella pin n at a 1 .24 



Synedra ulna 6.53 10.43 12.91 



No. of Species Counted 65 48 58 65 71 81 90 



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 /Ya//cs ; 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. 



