Multivariate Assessment of Environmental Preferences of Cyprinid Fishes of the Illinois River, Oklahoma

Abstract

Cyprinid fishes were collected from the Oklahoma drainage of the Illinois River in all seasons of 1978 and 1979. The Illinois River and its tributaries drain the Ozark Plateau and the Boston Mountains and support an Ozarkian fish fauna. Species included in this analysis were Campostoma anomalum, Nocomis asper, Notropis boops, N. nubilus, N. pilsbryi, N. rubellus, N. whipplei, Pimephales notatus, Phoxinus erythrogaster and Semotilus atromaculatus. Fishes were collected and 17 environmental variables measured from each of 15 localities sampled in every season. Species distributions were characterized in reference to each variable as follows: the value of a variable at each location was weighted by the number of individuals of a species present, and the mean of these weighted values was taken as that species' preferred state for that variable. Principal components analysis, with rotation of the component solution to simple structure, was used to elucidate the relationships among variables in terms of species distributions. In most seasons, components related to species preferences for upstream vs. downstream locations, different foods, and slowvs. fast-water habitats. For most species, differences in habitat preference between seasons were related to breeding (in the spring) and to preference for warmer locations during the rest of the year.