Impoundment and diversion of watercourses for power production and water supply can have profound effects on the mayfly fauna. To explain such effects a species-specific approach is adopted on account of differing habitat requirements and life histories in the order and even within genera. Environmental conditions such as discharge and flow patterns, temperature, food availability, and predation may be changed. This leads to changes in the density and species composition of the mayfly community, especially when there is a hypolimnion drain from reservoirs. Temperature changes below such reservoirs may remove obligatory life cycle thresholds. Prolonged periods of low discharge lead to the dominance of genera, such as Paraleptophlebia, [...]
