this site. 



Sites at Breen's, Highway 89, Miller's, and Highway 221 all 

 supported green algae, diatoms, and cyanobacteria (Table 5) . The 

 number of genera of soft algae increased downstream from 4 at 

 Breen's, to 10 at Highway 89, to 11 at Miller's, to a Teton River 

 high of 13 at Highway 221. The small number of algal genera at 

 Breen's may be due in part to the extreme reduction in streamflow 

 recorded at this site (Figure 1) . 



The observed downstream increase in floristic richness from 

 Breen's to Highway 221 is probably due to an increase in habitat 

 complexity, coupled with floristic contributions from tributary 

 lakes and streams. Moderate increases in dissolved solids 

 (Figure 2) and nutrients (from the Choteau WWTP and Priest Butte 

 Lakes), a wider range of water temperatures, and an increase in 

 habitat diversity would all increase the number of niches 

 available for algae species. 



Zygnema, an unbranched filamentous green that prefer warmer 

 and slower moving waters, was the dominant soft alga at Breen's 

 (Table 5) . Zygnema was replaced as the dominant alga downstream 

 (at Highway 89, Miller's, and Highway 221) by Cladophora, another 

 filamentous green, but one that prefers cooler and faster moving 

 waters. All of the Cladophora collected from the upper Teton 

 River was senescent and covered with epiphytes, indicating that 

 the seasonal peak of growth for this alga had passed. 



Audouinella , a pollution-sensitive red alga, was very common 

 at Highway 89, Millers, and Highway 221. Euglena, an alga that 

 indicates organic loading, was present but rare at Highway 221. 

 Highway 221 was also the only site on the river at which Chara 

 (stonewort) was found. 



11 



