Diversity measures indicating environmental change in alpine river ecosystems
Schütz Stefan, University of Innsbruck (AT)
Alpine rivers are among the most threatened ecosystems due to increasing human pressures and effects from climate/environmental change. These stressors strongly alter ecosystem structure and function, but cause-effect relationships have hardly been demonstrated in high alpine catchments. Within the framework of the project PROSECCO.ALPS (PROglacial Stream Ecology and Climate Change over the ALPS), this study wants to a) apply a comprehensive set of biological indices in order to b) find the most adequate ones for alpine lotic ecosystem condition and change. 18 sites in two alpine catchments (Sonnblick and Großglockner Group) were sampled three times from July until September 2011. All collected insect larvae from 159 samples were identified and included in the indicator analysis. More than 65 relevant indices were considered and grouped according to their expressiveness. The most adequate are applicable for the evaluation of: i) the species diversity (Q Statistic), ii) the dispersion (Smith & Wilson B), iii) the disparity of different sampling sites (Harrison 2), iv) assemblage changes along a stream (Epirhithral Biocenotic Region), v) the ecological function and vi) the nutrient content ((M)BMWP). The results show that selected sophisticated methodologies (here exemplified by a comprehensive set of indices) can be used to identify the ecosystem condition - although developed for the implementation in river systems at lower altitudes. However, by completing further species characteristics from alpine headwaters some indices (esp. functional) will even perform better.