The dam constitutes obstacles for longitudinal exchanges along river systems and as such result in the fragmentation (reduced connectivity) of ecosystems. It not only alters the pattern of downstream flow (intensity, timing and frequency) it also change sediment and nutrient regimes and alter water temperature and chemistry. The dam may be viewed as anthropogenic alterations that disrupt dynamic processes and so impact on the ecological integrity of natural systems. The dam disrupts the river continuum and cause upstream and downstream shifts in abiotic and biotic parameters and processes. They have a significant impact on transport rates and retention within the river system.
Dam modifications had significant effects on both abiotic and biotic variables, and macroinvertebrate assemblages exhibited significant longitudinal differences. | 
