benefited by its presence. Trout do not eat Cladophora but they do 

 eat invertebrates this alga is known to harbor. 



Cladophora is favored by low turbidity, high nutrient levels and 

 stabilized flows. These conditions prevail below a bottom-withdrawal 

 impoundment. Consequently, it is almost certain that Cladophora 

 production would increase below such an impoundment regardless of where 

 it was placed on the Yellowstone. On the other hand, uncoordinated 

 major withdrawals without flow stabilization would result in more 

 divergence in discharge and temperature extremes. These conditions 

 are inimical to Cladophora and production would decrease below the zone 

 of greatest diversion. To reduce Cladophora to the theoretically minor 

 status it held prior to civilization may require elimination of all 

 point sources and a major share of the non-point source pollution in 

 the drainage. It is suspected, however that naturally high background 

 nutrient levels have always sustained Cladophora as a dominant taxon 

 in the river and that no amount of pollution control would ever reduce 

 it to a minor role. 



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