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An assessment of five cut-off channels of the Rhône River with adult and benthic caddisfly assemblages

Defense Maîtrise : Univ. Genève, 2015
Abstract A large-scale river restoration programme was launched on the French Rhône in 1998. Among other objectives, it seeks to enhance the lateral connectivity between the river and its floodplain and the diversity of secondary-channels. Caddisflies are recognized as valuable indicators to assess aquatic ecosystems in general but only few studies concerned adult caddisflies in the Rhône River. The aim of the study was to carry out a comparative assessment of five floodplain channels in one sector of the Upper-Rhône, on the basis of their caddisfly assemblages. Caddisflies were sampled in 2015 in the larval and adult stages via benthic samples and light-traps, respectively. Previous data were also available for both stages. The analyses were based on the species list and few habitat variables. They used diversity indices (specific richness, diversity, evenness, rarity), abundance distribution models and biological traits. Abundance classes combining larval and adult data were set up to better describe their distribution along the lateral connectivity gradient. Our results examplified how side-channels contribute to the maintenance of sector-scale aquatic biodiversity; especially through the lateral coexistence of species and assemblages otherwise typical for contrasted level of the longitudinal typology. The study also suggested i) that the interaction between lateral connectivity and year-to-year hydrological variations may be crucial in explaining changes in caddisfly abundances and ii) that the study of rank-abundance models along connectivity gradients may be of general interest in the study of floodplain diversity patterns.
Keywords CaddisflyRiverFloodplainCut-off channelsLateral connectivityBiodiversitylight-trapBenthic samplingRhône RiverRiver restorationTypologyAbundanceSpecies assemblages
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Research group Ecology and Aquatic Biology
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MARLE, Pierre. An assessment of five cut-off channels of the Rhône River with adult and benthic caddisfly assemblages. Université de Genève. Maîtrise, 2015. https://archive-ouverte.unige.ch/unige:88877

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Deposited on : 2016-11-14

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