Trans-European Fresh Water Experiments: Adaptive strategies to mitigate the impact of climate change on European Freshwater Ecosystems
Climate is changing rapidly, beyond the range of previous natural variability. Natural ecosystems, already under stress from land-use change and pollution, now face additional pressures from climate change. These pressures pose serious threats to human society as the availability and quality of freshwater determines the functioning of every ecosystem. In addition to furthering understanding of the way aquatic ecosystems respond to direct and indirect climate change impacts, the output of earlier research was used for the development of policies and implementation strategies needed to protect aquatic and riparian wetland ecosystems. The foundation for REFRESH was laid in the EU Framework 6 project Euro-limpacs: Integrated Project to Evaluate the Impacts of Global Change on European Freshwater Ecosystems, which was concerned with the direct and indirect impacts of climate change on both the physical and ecological characteristics of European freshwater ecosystems.
The key objective of REFRESH is to develop a framework that will enable water managers to design cost-effective restoration programs for freshwater ecosystems. This will account for the expected future impacts of climate change and land-use change in the context of the Water Framework and Habitats Directives.
Large-scale field experiments spread along gradients over Europe are set up to develop this framework. Experiments of this size on this issue have never been attempted before. The ‘trans-Europe’ approach is also new: every participating country is carrying out exact the same experiments and records exact the same data. The experiments focus on three of the main factors in climate change that affect water: changes in water temperature, water level and flow and nutrients. As part of the stream experiments, in 2011 and 2012 by-passes will be constructed to allow sections of streams to stagnate and dry up. This is designed to measure the effects of summer droughts as predicted to occur in Europe in the next decades.
The experiments on stream temperatures started in 2010. The first reports are scheduled for late 2011. In the Figure the stream water temperature (left vertical axis) and the amount of shading (leaf area index in the right vertical axis) is plotted along a gradient from a shaded stream section (horizontal axis left to middle) towards an open stream section (horizontal axis middle to right). It is clear that the leaf area index drops at point 0 (the boundary between shaded and open) and that the water temperature rises.