NON- DIATOM ALGAE 



The Redwater River near Circle supported mostly a mix of 

 green algae, diatoms, and cyanobacteria (primitive algae of the 

 Phylum Cyanophyta, formerly called blue-green algae) (Table 4) . 

 Diatoms were the most abundant algae at all sites except above 

 the Fairgrounds (RW-1) . Each site supported from 10 to 12 genera 

 of non-diatom algae, which is about average for prairie streams 

 in Montana (Bahls 1993) . 



Cyanobacteria, which are capable of fixing atmospheric or 

 molecular nitrogen, dominated the sample collected above the 

 McCone Co. Fairgrounds, where they ranked first in biovolume 

 (Table 4) . Cyanobacteria ranked second in biovolume above the 

 Circle lagoons, but dropped to fourth below the lagoons. This 

 would indicate some nitrogen enrichment in the reach between RW-2 

 and RW-3. Diatoms and green algae have a growth advantage over 

 cyanobacteria when supplemental sources of nitrogen are provided. 

 Cyanobacteria resumed a rank of two below Horse Creek. 



An occasional cell of Euglena at RW-3 also indicates 

 moderate nutrient enrichment and organic loading below the Circle 

 lagoons. These cells may have originated within the lagoons, as 

 they are common in such habitats (Palmer 1977) . Euglena, a good 

 indicator of organic loading, was absent at the two upstream 

 sites and rare at the downstream site below Horse Creek (RW-5) . 



Anahaena was one of several nitrogen- fixing cyanobacteria in 

 the Redwater River. Under certain conditions, Anajbaena can 

 produce waterblooms that release neurotoxins into the water. 

 These toxins can be lethal to livestock, pets, and wildlife. 

 However, Anahaena was not abundant enough in the Redwater River 

 to pose a problem for livestock producers. 



