2 R. M. Anderson, J. B. Layzer, and M. E. Gordon 



length of unimpounded river and quantitative data for three sites in the 

 lower 22.8 km of river, which is designated a Kentucky Wild River. The 

 two most common species in their quantitative samples were the 

 Cumberlandian endemics Ptychobranchus subtentum (Say, 1825) and 

 Pegias fabula. Alhstedt (1986), who examined several sites in LSF in 

 1984 and 1985, found numerous fresh-dead and relic unionid shells but 

 few living specimens. He observed deposits of silt at one riffle in the 

 lower section of the river, but the source and effects of this siltation 

 apparently were not investigated. Our study was made to determine the 

 present distribution of mussels within LSF, with particular reference to 

 the status of the two endangered species. 



MATERIALS AND METHODS 



In 1987, we repeated qualitative surveys at the 16 sites (Fig. 1) 

 studied by Starnes and Bogan (1982). At each site we searched for 

 mussels with glass-bottom buckets and by snorkeling. Relic shells (shells 

 showing chalkiness or algal growth on the nacre) and fresh-dead shells 

 were retained; live mussels were identified and returned to the river. 

 Three sites (8, 13, and 16 in Fig. 1) were sampled quantitatively. Ten 

 samples (0.092 m 2 ) were taken along each of three transects at each site. 

 The samples were collected by removing the substrate from the stream 

 bottom to a depth of about 1 1 cm and placing the material into the net 

 of a Surber sampler. On shore, the collected substrate was separated 

 with a 4-mm sieve. This procedure differed from the procedure used by 

 Starnes and Bogan (1982) only in that they used a mask and snorkel to 

 search the substrate within the 0. 1 m 2 frame in situ. Thus, our method 

 may have been more efficient in recovering small unionids and 

 Corbicula. 



RESULTS 



A total of 21 unionid species and the Asian clam, Corbicula 

 fluminea (M tiller, 1774), were collected (Table 1). The overall species 

 composition determined from shells and live specimens was similar in 

 our study to that reported by Starnes and Bogan (1982). Although we 

 did not collect four species reported by Starnes and Bogan (1982), 

 namely, Cyclonaias tuberculata (Rafinesque, 1820), Anodonta grandis 

 Say, 1829, Anodonta imbecillis Say, 1829, and Actinonaias ligamentina 

 (Lamarck, 1819), we collected Villosa lienosa (Conrad, 1834), a species 

 not previously reported from LSF. Further, we found more species than 

 did Starnes and Bogan at sites 4, 5, and 7 (Table 1). In contrast, when 

 only live mussels are considered, the results of our sampling differed 

 substantially from those of Starnes and Bogan (1982). We collected 

 more species alive upstream from site 8 than they had, but found 

 substantially fewer species alive at all downstream sites. In fact, most 



