Fishes of Buck Creek, Kentucky 155 



would have been more distinct if an additional collection site in the 

 intermittent headwaters of Buck Creek had been established, and through 

 further sampling of deepwater habitat in the downstream section of 

 Unit 2 and in Unit 3. 



The faunas of each unit are a product of the diverse conditions 

 found among the units. Numerous physicochemical factors that deter- 

 mine stream habitat diversity have been correlated with the longitudinal 

 succession of stream fishes. These factors include, but are not limited to, 

 depth (Sheldon 1968), drainage area (Larimore and Smith 1963), gra- 

 dient (Trautman 1942; Burton and Odum 1945), pool size (Minckley 

 1963), stream order (Kuehne 1962; Lotrich 1973), and stream width 

 (Burton and Odum 1945). Physicochemical factors excluded as primary 

 causes of observed faunal differences between the upper and middle sec- 

 tions of Buck Creek included water quality, which Harker et al. (1979, 

 1980) reported as similar between the two areas, and substrate, which 

 was characteristically cobble, slab boulder, and bedrock throughout the 

 stream. 



Observed faunal differences probably resulted from the interrela- 

 tionship of numerous physicochemical factors as postulated by Guillory 

 (1982). Since species characteristic of faunal Unit 1 of Buck Creek were 

 also an important component of the Unit 2 fauna, the habitat require- 

 ments of additional species characteristic of Unit 2 may explain faunal 

 differences (Table 4). These species (e.g., N. atherinoides, N. photogenis, 

 H. dissimilis, E. camurum, E. maculatum) typically inhabit moderate-to- 

 large streams and rivers and are thus adapted to relatively stable envir- 

 onments. We speculate that factors such as discharge and permanence 

 of flow are important determinants of faunal differences observed 

 between Units 1 and 2. These factors, which are more constant in the 

 large-stream or small-river habitat of Unit 2 than Unit 1, are closely 

 interrelated with several of the previously cited physicochemical factors, 

 and are important to the maintenance of a stable environment. 



The fauna of the lower impounded river was also related to the 

 type of habitat present. Within this part of Buck Creek gradient is low 

 and the stream is deep (10-25 m), providing habitat suitable for large- 

 river and lentic species (Table 4). 



ACKNOWLEDGMENTS.— We thank E. F. Crowell, C. F. Gor- 

 ham, and B. T. Kinman of the Kentucky Department of Fish and Wild- 

 life Resources, and J. M. Clayton and S. L. Steele, for field assistance. 

 For generously sharing collection information, confirming identifica- 

 tions, and other courtesies we are grateful to: B. A. Branson and J. C. 

 Williams, Eastern Kentucky University; B. M. Burr, Southern Illinois 



