Diversity and distribution of Amphipods in Switzerland
The present thesis investigated the diversity and distribution of amphipods (Crustacea, Amphipoda) in Switzerland, based on an extensive collection and analysis of faunistic and ecological data. The thesis aimed to provide an updated and substantiated foundation for future ecological, faunistic and taxonomic research on these important crustaceans, with a particular focus on Switzerland. The thesis was conducted as integral part of the project Amphipod.CH that was initiated to intensify the study of amphipods in Switzerland.
Amphipods are an order of crustaceans that represent keystone species in a wide variety of both marine and freshwater ecosystems. As such they contribute considerably to the biodiversity and functioning of these ecosystems, for example by linking different trophic levels or as major decomposers. In many temperate freshwater ecosystems (including groundwater, caves, lakes and stream ecosystems), amphipods are among the most abundant macroinvertebrates. However, their communities are also rapidly changing due to their high sensitivity to environmental change and pollution as well as a high proportion of non-native amphipod species reaching new habitats, particularly in Europe and Switzerland. It is therefore crucial to understand their ecology and systematics in order to detect and understand such changes and take appropriate conservation measures.
In my thesis I focused on improving the knowledge and data on amphipods in Switzerland. Before the onset of the project, only limited information on amphipods had been available for the European Alps and Switzerland in particular. With several major European drainage areas originating in Switzerland, the region represents a biogeographically interesting area . In a first step, I reviewed for the thesis all previously published literature on amphipods and summarized this ecological and faunistic information for a general introduction to amphipods of Switzerland. This includes publications from the 19th century up to the most recent findings from 2017. I then described several new species for Switzerland or even new to science based on molecular methods and morphological features, some of these species are even endemic to Switzerland. Based on this work, I developed a fully illustrated species identification key. It covers all 44 species of amphipods known from Switzerland, is fully compliant with recent systematics and covers all drainage areas of Switzerland. Thereby, it is the first ever key to all amphipods of Switzerland. Finally, I analyzed amphipod communities using diversity analyses covering a large spatial extent to get a deeper insight into the importance of dispersal and habitat connectivity for community formation and biological invasions in dendritic networks. Overall, my thesis improves and synthesizes the knowledge on amphipods of Switzerland and will hopefully ease all future work on this important taxonomic group of freshwater macroinvertebrates.