Climate change will have dramatic effects on water regimes above and below the ground. Specialist organisms occur in groundwater and colonize spring systems which may harbour a mixture of regular and accidental subterranean species as well as above-ground dispersers (e.g. insects). Thus, spring communities can be seen as model metacommunities with limited dispersal between them. In addition, many springs have very specific abiotic conditions that may drive their community composition. For these reasons, communities in springs may be used as “biotic tracers” of hydrogeological patterns. We will investigate spring habitats to address the following research questions: 1) What are the determinants of community composition of springs? 2) Can organisms be used as natural tracers and help to determine catchment areas of springs? 3) How will communities change with rapid changes in water regimes in the future? In two model sites in the Alps, we will generate hydrogeological maps and conceptual flow models, measure physico-chemical field parameters, hydrochemical and isotope composition and discharge variations. Tracer tests will be carried out in karst areas, where appropriate and possible. The springs will be sampled for organisms including crustacean and aquatic insect species. Samples will be analysed for living organisms as well as eggs and resting stages to allow an assessment of potential dispersal of organisms through the aquifers.
