while the equivalent measurement at Laurel (676) indicates gross 

 nutrient enrichment. Diatom species indicators and diversity in- 

 dexes (Bahls, unpublished data) lend support to Stadnyk's findings. 

 Stigeoclonium , a polluted water cohort of Cladophora preferring 

 even more enriched situations, is also a common resident of the 

 upper and middle river (Table 3). Phosphate and nitrate have been 

 shown by Thurston et al_. (13) to be maximum in the upper river. 



There is no evidence, however, that C^, glomerata is or ever 

 was a nuisance in the Yellowstone River. "Dominance" as reported 

 in this paper is totally relative--relative to the other algae in 

 the sample. It says nothing of total biomass or standing crop, 

 measurements of which must await research more sophisticated than 

 that reported here. Even if it does approach nuisance levels, as 

 it does elsewhere in Montana, it is not clear whether on a whole 

 this would be detrimental or beneficial. 



Two examples will illustrate this point. Several miles below 

 the Bozeman sewage effluent the East Gallatin River supports a 

 luxuriant bed of Cladophora . A similar situation holds below Yellow- 

 tail Dam on the Bighorn River. Both waters are culturally enriched; 

 both waters support bank to bank beds of Cladophora ; and both waters 

 have an enormously productive fishery. The relationship between the 

 enriched, stabilized flows and the Cladophora is straightforward, 

 however it is not obvious whether the fish are there because of the 

 Cladophora or whether they occur coincidental ly with it without being 



-21- 



