Policy Brief 4: Stronger need for maintaining environmental flow in streams in a changing climate

SciPol3Changes in bed and bank structure and modification of water flow are among the main threats to the ecological status of streams in Europe. Climate change impacts modify stream flow further. Experiments in REFRESH show that stream macroinvertebrates are vulnerable to spates 7 times greater than base flow and that ecosystems of natural streams are more resilient to multiple spates than those of semi-natural streams.  Aquatic macroinvertebrates sensitive to low flow disappear within days after the onset of stagnation and in eutrophic streams stagnation brings about oxygen depletion and an additional loss of macroinvertebrates with high oxygen requirements.  Pools remaining in temperate stream beds during droughts are not refugia for stream biota as is commonly believed. Storing water in the catchment is the principle measure to guarantee stable flow. Substrate variability can be managed by restoring stream morphology and creating retention basins.
Link: http://www.refresh.ucl.ac.uk/webfm_send/2261