Sample Notes 



Little Dry Creek at Cohagen. The sample from this site was anoxic and black with 

 H2S, but it was cleared with H2O2 and was usable. Fine particulate organic matter and fine to 

 coarse inorganic sediment were very abundant in the sample. 



Little Dry Creek near mouth of Uall Creek. The sample from this site was also anoxic 

 and black with H2S, but it was also cleared with H2O2 and usable. Fine particulate organic 

 matter and fine inorganic sediment were abundant in the sample. 



Little Dry Creek near Van Norman School. The sample from this site was anoxic, 

 putrid, and opaque black with H2S. Algal features were obscured but clear enough for positive 

 identification. Fine particulate organic matter was very abundant. 



Non-Diatom Algae (Table 3) 



All three sites had similar non-diatom assemblages dominated by the filamentous green 

 alga Rhizodonhim. Rhizoclonium and Cladophora are mat-forming green algae that often cause 

 problems in standing waters in the western United States (Wehr and Sheath 2003). Algae 

 interfere with water uses — e.g., fishing, swimming, boating, irrigation — only when standing 

 crops are excessive. Mat-forming filamentous algae are normal components of many aquatic 

 ecosystems, including prairie streams, and there is no evidence from this study that standing 

 crops of these algae in Little Dry Creek are excessive. Also, criteria have not been established 

 for determining when algal growth in prairie streams is excessive. 



The filamentous and nitrogen-fixing cyanobacterium Tolypothrix was abundant and 

 ranked second in biovolume in Little Dry Creek at Cohagen. Tolypothrix requires cooler waters 

 than most other cyanobacteria. This site also supported two other genera of filamentous green 

 algae besides Rhizoclonium (Table 3). The co-occurrence of Tolypothrix with filamentous green 

 algae is not unusual. Diatoms were abundant and ranked third in biovolume at all three sites. 



