Switzerland’s drainage systems are divided into three major European river basins, i.e. the Po, the Rhône, and the Rhine basins. Until recently 32 species of freshwater mussel species (i.e. belonging to the genera Anodonta and Unio ) were recognized for the country, albeit their identity and number remain uncertain especially, given the recent recognition of Unio mancus Lamarck, 1819 from the Rhône in France, and Unio elongatulus C. Pfeiffer, 1825 and Anodonta exulcerata Porro, 1838 from the Po basin in Italy. In this study, we molecularly assess Swiss populations of freshwater mussels to understand the identity and number of species as well as to characterize their distributions within this geologically differentiated Alpine country. We collected 125 specimens in 42 lakes and rivers representing the three major basins and performed a phylogenetic investigation of the collected specimens using two mitochondrial markers (COI & 16S) and one nuclear marker (28S). COI Haplotype networks are then presented for the identified species. Our new findings show that Unio elongatulus inhabits water bodies north of the main Alpine arc. No living populations of Unio mancus could be detected in Switzerland. Anodonta exulcerata is recorded from two localities north of Lake Maggiore and in the Swiss part of Lake Lugano. Anodonta anatina (Linnaeus, 1758) shows genetic differences between southern alpine and northern alpine populations. Our genetic data from Swiss populations of unionid species provides new records and knowledge concerning freshwater mussels from Central Europe and specifically from the Alpine region.

In 2014 and 2015 the macrozoobenthos and the water temperature of 61 alpine springs of the Central Swiss Alps between 1720 and 2515 m a.s.l. were investigated and gave evidence of 99 EPT species (Ephemeroptera, Plecoptera, Trichoptera). A CCA showed, that 27 Plecoptera and Trichoptera species were associated with springs of high altitudes and especially cold water. Preference of high elevation, headwaters and spring habitats, endemism and short emergence period were the ecological traits used to develop a value indicating the vulnerability for each species. A new climate change vulnerability index (CCVI) revealed 53 of the 61 investigated spring habitats as being vulnerable to climate change.

Temperature monitoring in 41 springs in different parts of the Swiss Central Alps revealed individual patterns, which seem to be determined by different factors. Geology plays an important role since karst springs in limestone rock often show temperatures below 3°C during winter. They are paralleled to the formation of ice and/or a strong decrease in discharge. In karst springs with permanent flow, temperature did not differ from springs of other geological formations. The water temperature of springs depends on thermal exchanges with the rock during the recharge process. Therefore, elevation, exposure, and permafrost location in the catchment area are expected to be the key factors governing water temperatures in alpine springs. The temperature showed a significant decrease of 0.37°C per 100 m of elevation. The water in springs facing north and west was significantly colder than in south-exposed springs. The temperature significantly increased with the distance to regions of permafrost in the catchment. Understanding the factors governing the thermal patterns will help predict the implication of climate change on springs.

Amphipods are key organisms in many freshwater systems and contribute substantially to the diversity and functioning of macroinvertebrate communities. Furthermore, they are commonly used as bioindicators and for ecotoxicological tests. For many areas, however, diversity and distribution of amphipods is inadequately known, which limits their use in ecological and ecotoxicological studies and handicaps conservation initiatives. We studied the diversity and distribution of amphipods in Switzerland (Central Europe), covering four major drainage basins, an altitudinal gradient of>2,500 m, and various habitats (rivers, streams, lakes and groundwater). We provide the first provisional checklist and detailed information on the distribution and diversity of all amphipod species from Switzerland. In total, we found 29 amphipod species. This includes 16 native and 13 non-native species, one of the latter (Orchestia cavimana) reported here for the first time for Switzerland. The diversity is compared to neighboring countries. We specifically discuss species of the genus Niphargus, which are often receiving less attention. We also found evidence of an even higher level of hidden diversity, and the potential occurrence of further cryptic species. This diversity reflects the biogeographic past of Switzerland, and suggests that amphipods are ideally suited to address questions on endemism and adaptive radiations, post-glaciation re-colonization and invasion dynamics as well as biodiversity-ecosystem functioning relationships in aquatic systems.