Habitat associations of Plecoptera larvae: Environmental parameters in Ozark streams

Ozark streams provide habitat for a diverse array of stonefly (Plecoptera) taxa. These insects are generally regarded as environmentally sensitive and are used in various metrics to assess water quality. Although several habitat variables have been used to predict the presence of particular stonefly species, how these species use physical resources to partition habitat has not been quantified. In this study, Missouri Department of Conservation collections, housed in the Enns Entomology Museum, University of Missouri, were used to determine which environmental variables best characterized distributions and densities for six Ozark stonefly species within four families with differing life cycles, diets, and habitat requirements. Collections were taken over a 30-year period and consisted of quantitative benthic samples with corresponding habitat parameters from Ozark streams. All samples collected from the 1970s were used in multiple stepwise regression analyses to determine the individual contribution of each significant habitat variable to predict the density of each species independently. In addition, Discriminant Function Analysis was used to evaluate the degree to which physical habitat space differed among species. Species density was significantly correlated with stream order and proportion of gravel. Further, habitat distinctions reflected taxonomic differences among species. Moreover, interspecific differences in habitat association were less apparent among congeners than between genera or higher taxa. An understanding of environmental attributes of stonefly habitats may aid in assigning protective status to streams with these attributes and to streams that harbor species with limited distributions.