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SFS Annual Meeting

Abstract Details

5/23/2019  |   11:30 - 11:45   |  151 G

SPATIAL HOMOGENIZATION OF MAYFLY, STONEFLY AND CADDISFLY ASSEMBLAGES IN SWISS RUNNING WATERS IN THE FACE OF GLOBAL WARMING Several studies assessed stream macroinvertebrates in the Swiss Alps but few focused on lower regions and none on beta-diversity at the countrywide scale. Our main goals were to predict the pattern of mayfly, stonefly and caddisfly (EPT) diversity across Switzerland and to assess the impact of warming temperatures on compositional heterogeneity. We used Generalized Dissimilarity Modeling to analyze the spatial turnover of EPT assemblages from samples covering the entire country. Climatic, topographic, geologic and land use variables were used as predictors. Contrasted climate change scenarios were used for future predictions. Results showed the largest amount of EPT turnover occurred along the air temperature and slope gradients. These variables represented good proxies for water temperature and hydrologic constraints, usually regarded as main drivers of aquatic macroinvertebrate diversity. We predicted a biotic homogenization with increasing temperatures due to the upstream expansion of assemblages from the sub-montane level. This study allowed the first countrywide prediction of EPT composition patterns and provided insights into the vulnerability to warming temperatures of assemblages occurring at high elevations. Our results support the urgency of immediate and significant reductions of greenhouse gases to limit compositional homogenization in the long term.

Pablo Timoner (Primary Presenter/Author), University of Geneva,;