Notes on the Distribution of the Arkansas Darter, Etheostoma cragini Gilbert, with a New Record from Bluff Creek, Clark County, Kansas

Abstract

The distribution of the Arkansas darter, Etheotomv cragini Gilbert ts limited to isolated populations (Cross, 1967; Metcalf, 1959) of the Arkansas River Basin in eastern Colorado (Ellis and Jaffa, 1918), southern Kansas (Cross, 1967), northeastern Oklahoma (Moore and Cross, 1950; Blair, 1959), and southwestern Missouri (Branson, Triplett, and HartmanS 196g). This localization of populations is due to the paucity of the optimum habitat for this species in the Arkansas River basin, which is a spring or spring-run filled with water cress (Blair and Windle, 1961). Because E. cragini is distributed in isolated populations, it is subject to extirpation during periods of drought. Cross (1967) suspected that much local extinction has occurred in the last century, and Blair (1959) stated that E. cragini might become extinct in northeastern Oklahoma because three of the Sve streams from which he collected E. craginz dried up in the summer of 1955 and another was reduced to poioles. This situation could desrelop in southwestern Kansas and eastern Colorado where the climate is typically arid and the streams are small. In view of the current distribution of E. cragini} I believe it should be considered an endangered species. Thus7 new records regarding the distribution and habits of E. cragini may be important in keeping it from becoming extinct. It is interesting to note that E. cragini is the only darter existing in southwestern Kansas west of 99° 30' west longitude. This indicates that E. cragini can tolerate the fluctuating water levels and sluggish currents of the streams in a dry climate. However, because iis species is usually found in a spring or spring-run which would tend to have clearer water ian the rest of a stream, I believe it cannot tolerate much turbidity. In the past century man has gradually cultivated more and more land in ie Arkansas River basin. This has caused more surface runoff to enter the streams than iat which would occur under natural conditions, thus the turbidit has increased in many of the streams in the Arkansas River basin. This in turn has caused E. crdgini to seek the clearer springs which are rare