Table 4. Continued 



Emersed Hydrophytic Species Continued 



C. undiL?atim 

 Clematii U^iUiticl{\olia 

 SonahM) ixtlginoAui 

 Ptantago pataflonica 

 Ag fiopii^on sp. 

 AndAopoflon sp. 

 Ro6a woodiiU. 

 VlittLchlAJi AtfUcta 



Yellowstone 



Beaver Creek 



C 



c 



F 

 F 

 R 

 C 

 C 

 C 

 C 



C 

 C 



c 



F 



NF 



C 



c 

 c 

 c 



Damselflies and dragonflies are abundant in Beaver Creek. This group 

 is generally associated with sluggish waters in which they cling and climb 

 among the plant forms. TihnuAa sp. and EnaZlagma sp. appear to be 

 distributed throughout the creek. 



C/ictmia^op4 t/c/ie sp. is the most common caddisfly in the creek. This 

 genus seems to be tolerant of severe environmental conditions such as warm 

 temperatures, intennittence, low dissolved oxygen levels and shifting 

 substrates which limit other caddisflies. 



Hifci^ella azteca is found predominately in the upper reaches of the 

 stream. This amphipod is closely tied to sluggish water and a high density 

 of plant materials (Egqleton 1952). The downstream portions of the creek 

 are more lotic and contain fewer aquatic macrophytes which are preferred 

 by HijatzU.a. aztzca. 



Diptera is the most conmon group of invertebrates in Beaver Creek 

 (Figure 11). Their numbers increase steadily from the mouth up to a point 

 near Section 84 and then decrease. This may be due to intermittence in the 

 upper most sections which eliminates some forms. 



The chironomid fauna is typical of a warm, slow moving stream. The 

 subfamilies Tanypodinae and Chironominae are widely distributed while the 

 Orthocladiinae are rare. In South Dakota streams Hudson (1971) found 

 Tanypodinae and Chironominae most commonly in slow waters of warm climates. 

 These two groups are tolerant of low oxygen stress (Oliver 1971). The 

 Orthocladiinae are common under a wide range of conditions but in general 

 prefer cooler waters (Hudson 1971). They generally decrease in numbers as 

 water temperatures increase (Oliver 1971). 



-19- 



