Intensifying hydrologic alteration and the resultant degradation of river ecosystems worldwide have catalyzed a growing body of ecohydrological research into the relationships between flow regime attributes, physical habitat dynamics and biotic response, particularly for determining environmental flows. While invertebrate response to floods has received most attention, in this thesis the aim was to identify and characterize low flows that constituted various degrees of physical disturbance to benthic macroinvertebrate assemblages of perennial rivers