Analysis of longitudinal zonation and the river continuum concept in the Oldman-South Saskatchewan River system.

Abstract

During summer-fall, the benthic macroinvertebrate communities of this system demonstrated a longitudinal zonation related to the subalpine forest, fescue prairie, and mixed prairie terrestrial ecosystems through which it flows. This zonation was primarily attributable to significant downstream increases in periphyton biomass, plant nutrients and water temperature. Zonation was reduced in late winter-spring, and absent in May during spring runoff. Longitudinal trends in macroinvertebrate functional feeding groups generally followed the predictions of the river continuum concept, with trophic composition apparently more strongly affected by autotrophic processes in summer, and heterotrophic processes in winter. By combining the river continuum concept with a watershed classification system biological comparisons of longitudinal zonation are enhanced.-from Authors