摘要：The Arkansas darter, Etheostoma cragini, has an extremely limited distribution in Arkansas and is designated as a andidate for listing under the Endangered Species Act. It was first discovered in the state in 1979 in Wilson Spring near Fayetteville and has since been found in4 additional headwater streams in Benton and Washington counties prior to this study. A study in 1997 (bund the species in3 of the 5 historic streams, but one stream yielded only a single individual. This study sought to reassess the status of the 5 historically known populations and sample additional spring-run habitats in the Arkansas River basin in these 2 counties. Spring branch habitats were identified using USGS topographic maps and available GIS coverages. Surveys targeting E. cragini were conducted at 75 sites providing abroad coverage of the basin and including intense searches in the vicinity of historic sites. E. cragini were encountered in15 stream segments, concentrated in4 areas within the Illinois River basin. All segments supported numerous E. cragini and fell within a 2 km radius of historic sites. Each segment was broadly surveyed to delineate the extent of occupied stream length, which ranged from 10 to 1,645 m. Based on this survey the total occupied stream length for E. cragini in Arkansas was determined to be 5,676 m. These segments include three historic locations and 5 disjunct stream reaches. While the presence of E. cragini in Arkansas is persisting, rapid urban development in northwest Arkansas raises concern for some populations.
