enjoys a worldwide uniformity. The rheophile habitat is marked by steep 

 gradient, swift current velocity, boulder-rubble-cobble substrates, cold 

 thermal regime and a periphyton-detritus production base. Examples of rheo- 

 philous organisms collected in German Gulch Creek included: Cinygmula , Epeorus 

 spp., I), doddsi , D^. spinif era , C_. hystrix , R.. robusta, Amphinemura , Zapada , 

 P_. expansa , Parapsyche , Rhyacophila , Glossosoma , Apatania , Heterlimnius 

 Diamesa , Stempel line 11a , C_. nostocicola , etc. The fauna observed at the Upper 

 and Lower Sites was generally limited to rheophile forms; however, the fauna 

 of the Lower Site included facultative forms collected only at that station. 

 Such facultative forms are common inhabitants of larger rivers and lowland 

 streams of the region and are tolerant of a wider range of substrate type, 

 current velocity, dissolved oxygen and water temperature than the rheophile 

 community. Facultative forms collected only at the Lower Site included: 

 Pseudocloeon sp., P_. badia , Hydropsyche sp., Narpus sp., Brillia sp., Cardio- 

 cladius sp., Cricotopus (Cricotopus) sp., Eiseniella sp. and Haplotaxis sp. 



Macroinvertebrate Abundance 



A total of 3,847 aquatic macroinvertebrates were collected in the German 

 Gulch samples of which 30% were collected from the Upper Site, 52% from the 

 Middle Site and 18% from the Lower Site. Summer samples from the Upper and 

 Lower Sites exhibited marked increases in abundance over the spring samples 

 (Table 17); however, spring and summer abundance was equal at the Middle Site. 



Mean numbers of macroinvertebrates per square foot are presented by 



sample site and by sample site and season in Table 17. Macroinvertebrate 



2 

 abundance was lowest at the Lower Site (115/ft ), intermediate at the Upper 



Site (191 /ft 2 ) and highest at the Middle Site (335/ft 2 ). The Middle Site 



represented a relatively productive habitat characterized by a dense growth of 



•26- 



