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Reed bed management is one of the main wetland related issues in Europe and among the diverse approaches developed for that purpose, some restoration methods are considered rather intrusive. There is nonetheless a lack of research investigating how invertebrate communities react to such restoration methods. In this study, we assessed the suitability of reed bed soil strippings, also called bed lowerings, as habitats for aquatic beetles by sampling a total of 101 sites along the southern shore of Lake Neuchâtel, Switzerland. We compared water beetle species richness and taxonomic structure between reed bed soil strippings and other habitats found in the surrounding wetland. Additionally, we evaluated the promotion of new species through strippings and investigated the evolution of water beetle communities along the temporal gradient of reed bed soil strippings. No difference in species composition was found between the sampled habitats, suggesting a well-connected landscape mosaic within the study area. Managed sites did not increase species diversity at the landscape level. We identified a gradual diminution in species richness with age of restored site, as well as a shift in taxonomic assemblages. In conclusion, we advise reed bed soil strippings to be phased temporally and spatially, thus providing managed wetlands open water bodies of different successional stages.

Currently, the distribution of diving beetles in Switzerland is poorly known making it difficult to determine conservation priorities for species with small and/or declining populations. In order to establish conservation priorities, in 2018, we surveyed diving beetles of the genusGraphoderusin the Grande Cariçaie reserves with special consideration for the Red ListedG.bilineatus. WhileG.bilineatusandG.cinereusshowed high habitat niche overlap, the distribution ofG.bilineatuswas limited to mainly one of the eight reserves. When comparing our results to available historical data, the habitat ofG.bilineatushas likely diminished during the last 40 years. Our study provides the first comprehensive documentation of the distribution ofGraphoderusspecies in the Grande Cariçaie. We further highlight the importance for improving the knowledge ofG.bilineatusdistribution in Switzerland to develop policy for conservation of this globally threatened species.