Deliverable D5.2-5: Report on effects of global change on reference conditions and ecological status of lakes

WISER aims to support the implementation of the Water Framework Directive (WFD) by developing tools for the assessment of the ecological status of European surface waters. With many European lakes unlikely to achieve ‘good’ ecological status without restorative measures, the assessment systems used in the WFD are required to consider recovery in order to judge restoration success. Most previous projects dealing with assessment systems have focused on the effects of deterioration. WISER also deals with recovery. The report summarizes the progress made within the WISER project in the following areas: Reviewing the current understanding of the impacts of climate change on lakes and how this can be utilised to develop and improve our understanding of lake restoration. Investigating the pathways of degradation in lakes where eutrophication has been the primary stressor and examining how these pathways react during lake recovery following remedial action. Two further studies are presented which use lake sediment records and long-term monitoring data sets to assess the relative importance of climate versus eutrophication. The role of cladocerans in tracking long-term changes in shallow lakes is explored; a study which highlights the sensitivity of this biological group and presents it as a strong candidate as the single best indicator for assessing trophic change in lakes. Finally Baysian network models are presented as an effective tool for unravelling the complex interaction between the impacts of lake restoration and climate change on the ecological status of lakes. In addition to providing an assessment of the various tools available for tracking environmental change in lakes, this report highlights the complexities of ecosystem recovery under changing global conditions. A reduction of environmental stressors (e.g. eutrophication) will undoubtedly result in ecosystem improvement, but it is unlikely to simply be the reversal of deterioration and some examples show that recovery may lead to conditions very different from the original undisturbed stage. These studies contribute towards the scientific basis for underpinning the management of freshwaters in order that it is strengthened and targeted appropriately The main achievement of societal relevance is the increased understand of how strategies for the sustainable management of freshwaters, for example, as required by the WFD, may need to be modified to take account of global, especially climate change

The response of Cladocerans to recent environmental forcing in an Alpine Lake on the SE Tibetan Plateau

The final publication is available at Springer via http://dx.doi.org/10.1007/s10750-016-2868-6Global environmental change has affected aquatic ecosystems of the southeast Tibetan Plateau during the past 200 years, altering the composition and biomass of primary producers (e.g. algae). However, the response of primary consumers (e.g. cladocerans) to this recent environmental forcing is not well documented. Samples of cladoceran remains from sediment traps (1-year deployment), surface sediments covering a range of water depths and a short 22.5-cm sediment core were analysed in a small, remote alpine lake (Moon Lake) in Sichuan Province (SW China). Littoral forms, notably Chydorus sphaericus and Acroperus harpae, together with Daphniapulex dominated the cladoceran community. Remains of these cladocerans were well represented in the sediment core assemblages as indicated by their relative abundance in the surface sample. There was a marked increase in the abundance of D. pulex and total cladoceran fluxes in the sediment core from ca. 1880 AD, coinciding with the changes in diatom assemblages and pigments. Analysis of the multi-proxy data (cladocerans, diatom, pigment, total organic carbon, C/N ratio, air temperature and atmospheric NO3− records) suggests that both direct and indirect climatic forcing, coupled with enhanced nutrient supply (e.g. NO3− deposition) effects on primary producers have changed cladoceran community dynamics in Moon Lake over the last ~200 years