The project 'Adaptive strategies to mitigate the impacts of climate change on European freshwater ecosystems' (REFRESH) had three overarching goals. The first was to increase understanding of how freshwater ecosystems will respond to changes caused by climate, land use, water use and pollution over the next 50-60 years. Additional goals involved translating this knowledge into a form that can be used by water managers and ensuring the uptake of results by target stakeholders. Consortium members focused on three principal climate-related and interacting pressures: increasing temperature, changes in water levels and flow regimes, and excess nutrients. The work was conducted primarily in lowland rivers, lakes and wetlands as they often pose the greatest challenges in complying with the requirements of the Water Framework Directive (WFD) and Habitats Directive. Studies of streams provided a basis for applying knowledge on the effects of climate change and land-use change on the structure, functioning and biodiversity in rivers. They also provided insights into the effectiveness of adaption and mitigation methods to restore rivers. Scientists found that shading beside streams can help offset the impact of increased temperature and influence stream biodiversity. Increased winter flooding was found to have a longer-term effect on river vegetation. A new method was also devised for calculating net primary production from midday oxygen saturation. Stagnation and drought experiments provided insights into the role of low flow and drought in rivers and potential losses to the ecosystem. The experiments provided thresholds for low flow and drought in Atlantic lowland rivers. River flow and oxygen appeared vital for rivers and affect the functioning of the ecosystem. Good oxygen regimes and healthy flow conditions help ensure the objectives of the EU's WFD and Habitats Directive are met. Therefore, specific adaptive measures were evaluated and used to minimise the expected adverse effects of climate change on freshwater quantity, quality and biodiversity. The work carried out by REFRESH will improve understanding of freshwater ecosystems. This will enable them to be restored to good ecological health, support key species and mitigate the effects of climate variation. REFRESH will therefore help safeguard Europe's freshwater ecosystems from the impacts of climate change.
Freshwater ecosystems, climate change, land use, water use, pollution