FAUNAL CHANGES, 1957 THROUGH 1959
The following species increased in abundance from 1957 to 1959 (Tables 10 and 11): long-nosed gar, short-nosed gar, river carpsucker, creek chub, gravel chub, sucker-mouthed minnow, mountain minnow, blunt-nosed minnow, parrot minnow, stoneroller, stonecat, Neosho madtom, green sunfish, slender-headed darter, and orange-throated darter.
These species can be separated into three groups, characteristic of different habitats but having in common a preference for permanent flow. One group, composed of long-nosed gar, short-nosed gar, river carpsucker, gravel chub, mountain minnow, parrot minnow, and Neosho madtom, prefers streams of moderate to large size.
A second group composed of creek chub, sucker-mouthed minnow, stoneroller, and orange-throated darter occurs most abundantly in small, permanent streams. The green sunfish may be included here on the basis of its abundance at the upper Neosho station; however, this is a pioneer species and does not require permanent flow.
The third group is characteristic of continuously flowing water, but in both upstream and downstream situations. The species in this group (blunt-nosed minnow, stonecat, and slender-headed darter), increased in response to a resumption of permanent flow, but did not respond as quickly as did channel catfish, flatheads and freshwater drum, which are discussed subsequently.
The fact that riffle-insects were abundant throughout my study convinces me that food was not a limiting factor in the re-establishment of the fish-fauna on riffles of the Neosho River.
The following species decreased in abundance during my study (Tables 10 and 11): gizzard shad, carp, rosy-faced shiner, blunt-faced shiner, red shiner, mimic shiner, black bullhead, yellow bullhead, channel catfish, flathead, slender madtom, tadpole madtom, freckled madtom, spotted bass, largemouth, black crappie, fan-tailed darter, and freshwater drum.
Among the species that decreased, three groups, characteristic of different habitats, can be distinguished. The first group occurs most commonly in ponded conditions or in slowly flowing streams. Species in this group are: shad, carp, black bullhead, tadpole madtom, largemouth, black crappie, and white crappie. Bullhead, bass and crappie commonly occur in farm ponds and lakes in Kansas and seem less well adapted to streams. It is therefore not surprising to find that these species decreased in abundance when flow was resumed.
A second group, composed of rosy-faced shiner, blunt-faced shiner, mimic shiner, slender madtom, freckled madtom, spotted bass, and fan-tailed darter, normally is characteristic of clear tributaries rather than the mainstream of rivers. These species probably used the mainstream as a refugium during drought; with the resumption of flow, conditions became unsuitable for these populations in the mainstream. At the same time, conditions probably became favorable to the re-establishment of these species in tributaries. Metcalf (1959:396) listed the rosy-faced shiner, blunt-faced shiner and mimic shiner as species that were characteristic of upland tributaries in the Flint Hills and Chautauqua Hills of Chautauqua, Cowley and Elk counties in Kansas. The slender madtom and fan-tailed darter are more common in clear streams of southeast Kansas than in other areas of the state (Cross, personal communication and data of the State Biological Survey of Kansas). Both species are recorded by Hall (1952:57-58) only in upland tributaries on the east side of Grand (Neosho) River in the Fort Gibson Reservoir area of Oklahoma. Neither species was taken in faunal studies of the Verdigris River in Oklahoma (Wallen, 1958), in the Verdigris and Fall rivers in Kansas (Schelske, 1957), or by Metcalf (1959).
The spotted bass is not so restricted in its distribution and its habitat-requirements as are other species in this group; but, in Kansas, spotted bass are most abundant in clear creeks in the southeast part of the state.
The freckled madtom was taken in most of the studies cited above and is most common in the smaller streams of the southeast one-fourth of Kansas and the northeast one-fourth of Oklahoma. Schelske (1957:47) reports that the freckled madtom was taken only in March, April, October and November in the Verdigris River, Kansas. My only record of this species was obtained in the Neosho River in April, 1958.
The third group is composed of channel catfish, flathead, and freshwater drum. This group represents that element of the population that responded most quickly to the resumption of continuous flow. The fact that adult channel catfish and flatheads live in pools and do not require flowing water to spawn gives these species a survival advantage as well as a reproductive advantage over obligatory riffle fishes (such as most darters) in the highly variable conditions found in Kansas streams. These factors resulted in unusually high reproductive success in 1957. Subsequent survival of fry was excellent; however, some mortality in the highly-dominant 1957 year-class became apparent in the 1958 and 1959 collections, accounting for a numerical decline in these species. The ability to respond immediately to increased flow is an adaptive feature that allows these species to maintain high levels of abundance in the highly fluctuating streams of Kansas.
The continuous flow that occurred in 1957 in the Neosho and Marais des Cygnes rivers, for the first time in four years, provided the necessary habitat for survival of young catfish hatched in that year. The nearly complete absence of other species on the riffles, and the abundant populations of riffle-insects that I observed in the summer of 1957, were undoubtedly factors contributing to the survival of young.
The decrease in abundance of the red shiner may be partially due to an increase in the numbers of other species that are well adapted to conditions of permanent flow. At the completion of my study, the red shiner was still the most abundant minnow in both rivers. In 1957 this species was common in many habitats, including swift riffles, that were later occupied by madtoms, darters, the gravel chub, mountain minnow and sucker-mouthed minnow.
The basic pattern of change was clearly an increase in the species that are characteristic of permanently flowing waters, and a decrease in the species that are characteristic of ponds or small, clear streams.