154 Ronald R. Cicerello and Robert S. Butler 



generally shared 50% or more of the fauna with sites 31-33 and exhi- 

 bited a gradual increase in similarity to these sites with each successively 

 closer site. The transitional nature of the fauna of sites 21-27 relative to 

 sites 1-14 and 31-33 is reflected by faunal resemblance values calculated 

 by pooling the fauna of each group of sites. Sites 21-27 had 72% and 

 79% shared fauna with 1-14 and 32-33, respectively. Sites 1-14 and 31-33 

 had 49% shared fauna. 



Analysis of the species characteristic of Units 1 and 2, based upon 

 the occurrence of a species in greater than 50% of the sites comprising 

 each unit, further illustrates the distinctions and similarities between the 

 two units (Table 4). Species characteristic of Unit 1 included Notropis 

 ardens, N. chrysocephalus, N. telescopus, Semotilus atromaculatus , 

 Fundulus catenatus, Etheostoma flabellare , and E. virgatum. These are 

 generally creek or small-stream fishes that migrate downstream in fall to 

 overwinter in larger and deeper waters (Pflieger 1975; Smith 1979; 

 Trautman 1981) such as that present in sites 21-27. Hybopsis amblops, 

 H. dissimilis, Notropis ariommus, N. atherinoides, N. photogenis, N. 

 rubellus, N. spilopterus, N. whipplei, Labidesthes sicculus, Etheostoma 

 camurum, E. maculatum, and Cottus carolinae were characteristic of 

 Unit 2 and typically inhabit moderate-to-large streams and small rivers 

 (Pflieger 1975; Etnier 1976; Smith 1979; Trautman 1981). Elsewhere in 

 Buck Creek these fishes were collected almost exclusively from the 

 downstream portion of Unit 1, sites 21-27. This indicates that sites 21-27 

 supported a mixture of small-stream, large-stream, and small-river 

 fishes and may be considered an area of transition between the faunas 

 of Units 1 and 2. Several species were excluded from this analysis 

 because they: (1) were collected from sites in all three units and were 

 considered ubiquitous (Campostoma oligolepis, Lepomis macrochirus , 

 L. megalotis, Micropterus dolomieui, and Percina caprodes), or (2) 

 occurred extensively throughout Units 1 and 2 and were thus not useful 

 in identifying differences between these units (N. galacturus, Pimephales 

 notatus, Hypentelium nigricans, Etheostoma blennioides, E. caeruleum, 

 and E. stigmaeum). 



The pattern of longitudinal distribution of fishes along the Buck 

 Creek mainstem was similar to that reported by Guillory (1982) for a 

 Louisiana stream, and involved: (1) the addition of species in the middle 

 section of Buck Creek (sites 21-33) to those widely distributed through- 

 out sites 1-27, and (2) replacement of upper- and middle-river species 

 with those typical of low-gradient, big-river habitat in the lower 

 impounded section of Buck Creek (Table 4). A general downstream 

 increase in the number of species was also noted (Table 4) and has been 

 reported for other streams (Kuehne 1962; Larimore and Smith 1963; 

 Sheldon 1968; Lotrich 1973; Guillory 1982). We believe that this pattern 



