Ecological Attributes (Table 6) 



Several ecological attributes were selected from the diatom reports in the appendix and 

 modal categories of these attributes were extracted to characterize water quality tendencies at the 

 three sites (Table 6). All sites were dominated by alkaliphilous (high pH) diatoms, but this is the 

 only attribute that was common to all three sites. For four categories of ecological attributes, 

 most diatoms at the upper site were unclassified with regard to their ecological affinities. 



The site above the return from Deadman's Basin was different from the two sites below 

 the return in that it was dominated by highly motile, brackish-water diatoms. Most diatoms 

 below the return were non-motile and preferred fresher water. Modal categories were identical 

 for the lower two sites for all attributes except salinity. Most diatoms at the middle site prefer 

 fresh waters whereas most diatoms at the lower site prefer somewhat saltier (brackish-fresh) 

 water. 



The majority of diatoms at the two sites below the return were non-motile nitrogen 

 autotrophs that tolerate high levels of organics and exert a moderate demand for dissolved 

 oxygen. Nitrogen autotrophs require inorganic nitrogen (nitrates and ammonia) as nutrients. 

 The majority of diatoms at the two lower sites indicate elevated concentrations of inorganic 

 nutrients and a moderate amount of BOD loading. 



References 



APHA. 1998. Standard Methods for the Examination of Water and Wastewater. 20* Edition. American Public 

 Health Association. Washington, D.C. 



Bahls, L.L. 1979. Benthic diatom diversity as a measure of water quality. Proceedings of the Montana 

 Academy of Sciences 38:1-6. 



Bahls, L.L. 1993. Penph^-ton Bioassessment Methods for Montana Streams (revised). Montana Department of 

 Health and Environmental Sciences, Helena. 



Bahls, L.L. February 2000. Support of Aquatic Life Uses in Careless Creek, Lodgepole Creek, and the South Fork 

 of Lodgepole Creek Based on the Composition and Structure of the Benthic Algae Community. Prepared for the 

 Montana Department of Environmental Quality, Helena. 



