Effects of Spates and Drying on Macroinvertebrate Assemblages of an Intermittent and a Perennial Prairie Stream

Abstract

We compared macroinvertebrate population and assemblage responses to seasonal spates and dewatering in an intermittent and a perennial prairie stream in southern Oklahoma. Total densities, population densities, and indices of assemblage structure were examined as response variables. A 90% reduction of total invertebrate densities at both sites suggested that assemblages had low resistance to spring and fall spates. Caenis, Leptophlebia, and Baetis mayflies were more resistant to spates than other common taxa. Recovery of total densities was slower after the fall spate relative to spring. This delay may reflect a reduced availability of colonists and low population growth rates due to lower temperatures. Invertebrate assemblage structure in both streams remained stable during the spring spate, either through resistance (intermittent stream) or resilience (perennial stream). Beyond a few weeks, the effects of the spring spate on assemblage structure was not evident in either stream. Long term assemblage sta...