Arkansas River Fauna
This fauna contained Notropis girardi, Notropis blennius, Hybopsis aestivalis tetranemus, and Fundulus kansae which, in this area, did not seem to wander far from the sandy main stream of the Arkansas. Minnows abounded; Notropis lutrensis and N. deliciosus missuriensis predominated; and Notropis girardi, N. percobromus, and Hybognathus placita were common. In quiet backwaters, coves, and shallow pools Gambusia affinis occurred in great numbers. Lepisosteus osseus seemed to be the most important predator.
Lower Walnut River Fauna
The Walnut River in Cowley County supported large populations of deep-bodied suckers, carp, and gar. Notropis lutrensis and N. percobromus were characteristic minnows. Lepomis humilis abounded at some stations. The fauna of the main stream of the Walnut River was somewhat intermediate between that of the Arkansas River and that of the three streams considered below. Fifteen of the species common to the Big Caney, Elk, and Grouse systems were also taken in the Walnut River main stream. Thirteen species were common to the Walnut and Arkansas rivers. Seven species were common to all these streams.
Caney-Elk-Grouse Main Stream Fauna
This fauna includes fishes living not only in the main streams but also in the lower parts of the larger tributaries of these streams. The fauna was comparatively rich: in the main stream of Big Caney River 39 species were taken, in Grouse Creek 35 species, in the Walnut River main stream 21 species, and in the Arkansas River 19 species. It has been pointed out that large rivers such as the Walnut and Arkansas have been subjected to greater direct and indirect modification by man, possibly resulting in a less diverse fauna than would otherwise occur in these streams. At present, there is a paucity of ecological niches in the upland tributaries and large rivers, as compared with streams of intermediate size. Fishes typical of the Caney-Elk-Grouse association were Notropis umbratilis, Lepomis megalotis, Lepomis humilis, Labidesthes sicculus, Fundulus notatus, and the two species of Micropterus (Micropterus punctulatus was not taken in Grouse Creek).
Upland Tributary Fauna
Tributary faunas were divisible into two categories: (1) Those of the Walnut River and Grouse Creek (intermittency was severe, species were few, with Ictalurus melas and Lepomis cyanellus predominating); (2) those of Big Caney River (stream-flow was more stable, and eastern fishes, some of which have Ozarkian affinities, occurred in greater abundance than in any other part of the area surveyed). In the latter streams Campostoma anomalum and Etheostoma spectabile usually were dominant. Pimephales notatus, Notropis volucellus, N. camurus, N. boops, and N. rubellus characteristically occurred. Notropis lutrensis was sparsely represented in flowing tributaries. Notropis umbratilis, which seems to prefer habitats intermediate between those of Notropis lutrensis and Ozarkian shiners, was usually represented. Deep-bodied suckers and carp were not taken in upland tributaries but Moxostoma erythrurum was common and Minytrema melanops was taken.
The kinds and numbers of shiners (Notropis) taken at different points along Grouse Creek seem significant. N. lutrensis and N. umbratilis occurred throughout the stream but were rare in sluggish areas where populations of Gambusia affinis, Fundulus notatus, and Labidesthes sicculus flourished. At the lowermost station Notropis percobromus and N. buchanani were taken; these were not present in other collections. In the uppermost stations where water remained plentiful, N. boops and N. volucellus were taken, and N. rubellus has been recorded.
In the broader distributional sense those fishes that seemed most tolerant of intermittency (Lepomis cyanellus, Lepomis humilis, Ictalurus melas, Notropis lutrensis) are widely distributed in the Arkansas River Basin, and are common in the western part of the Arkansas River Basin. Species less tolerant of intermittency are Notropis boops, Notropis camurus, Notropis rubellus, Notropis volucellus, and Pimephales tenellus; they have not been taken far west of the area studied, and become more common east of it.