REFRESH Policy Briefs

SciPol1

Policy Brief 1: Zooplankton-an integrative Biological Quality Element for assessing the Ecological Status of lakes

The EU Water Framework Directive environmental objectives are established on the basis of ecological status assessment, focused on five species groups (macroinvertebrates, fish, phytoplankton, macrophytes and phytobenthos). The assessments do not considering zooplankton. REFRESH has demonstrated that zooplankton is an important, integrative and cost-efficient indicator of the ecological quality of lakes and of recovery after restoration. We recommend that zooplankton metrics be included among mandatory biological quality elements for lakes as this will improve our capacity for lake management under future climate and land use changes.

SciPol2Policy Brief 2: Riparian Forest can help mitigate climate warming effects in lowland temperate streams

Stream water temperature is predicted to increase with climate change, and will affect stream biotic assemblages and ecosystem functioning, threatening the implementation of the EU Water Framework Directive and Biodiversity Strategy 2020. Results from the REFRESH project conducted in five lowland temperate streams show that the presence of riparian forest has a cooling effect ranging from 1°C to 3°C, depending on the reach length and canopy cover. River restoration by planting riparian trees, combined with open reaches allowing the presence of aquatic plants, can be a useful adaptation measure to combat the negative effects of future warmer temperatures on freshwater life.

SciPol3Policy Brief 3: Stricter nutrient loading limits help lake ecosystems to withstand climate change pressures

Despite improvements in some regions, nutrient loading from agriculture remains a major pressure on Europe's freshwaters, resulting in widespread eutrophication. The main consequences of nutrient enrichment include excess phytoplankton growth, increased frequency of cyanobacteria blooms, and depletion of dissolved oxygen, all leading to a decline in water quality and biodiversity. REFRESH provides new evidence for climate change impacts on lakes, showing that increased lake temperatures generally have a eutrophication-like effect. As the impact of eutrophication and climate change follow the same pathways affecting nutrient availability and cascading effects in the food web, and given the high variability of both pressures, it is unlikely that their impacts can be disentangled in each particular case.
A review of more than 450 climate change adaptation measures related to water carried out by the REFRESH concludes that all measures leading to reduced nutrient losses from agriculture can be considered win-win measures as they meet environmental objectives set by the Water Framework Directive and will enhance the resilience of lake ecosystems under future climate change.

SciPol4Policy Brief 4: Stronger need for maintaining environmental flow in streams in a changing climate

Changes 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.

SciPol5Policy Brief 5: Advocating riparian restoration

Successful restoration measures need to integrate conservation and management programmes at the catchment scale. One key message from the symposium was the need to further reduce nutrient loading in the future considering expected climate change, with clear implications for the catchment land use. Given the evidence of the multiple benefits provided by riparian areas, their restoration should be promoted within the River Basin Management Plans. This would offer win-win solutions by enhancing ecological quality and ecosystem services (e.g. natural water retention measures for climate change adaptation), but also would encourage synergies with other sectorial policies such as greening of the CAP (e.g. the identification of ecological focus areas). Considering that time lags of 10-20 years are expected to observe a recovery of freshwaters from the impact of multiple stressors, riparian restoration should be recognized as a priority for management actions.