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Title

The interplay of flow processes shapes aquatic invertebrate successions in floodplain channels - A modelling applied to restoration scenarios

Authors
Riquier, Jérémie
Published in Science of the Total Environment. 2021, vol. 750, no. 142081
Abstract The high biotic diversity supported byfloodplains is ruled by the interplay of geomorphic and hydrological pro-cesses at various time scales, from dailyfluctuations to decennial successions. Because understanding such pro-cesses is a key question in river restoration, we attempted to model changes in taxonomic richness in anassemblage of 58 macroinvertebrate taxa (21 gastropoda and 37 ephemeroptera, plecoptera and trichoptera,EPT) along two successional sequences typical for former braided channels. Individual models relating the occur-rence of taxa to overflow and backflow durations were developed fromfield measurements in 19floodplainchannels of the Rhônefloodplain (France) monitored over 10 years. The models were combined to simulate di-versity changes along a progressive alluviation and disconnection sequence after the reconnection with the mainriver of a previously isolated channel. Two scenarios were considered: (i) an upstream + downstream reconnec-tion creating a lotic channel, (ii) a downstream reconnection creating a semi-lotic channel. Reconnection led to adirect increase in invertebrate richness (on average x2.5). However, taxonomical richness showed a constant de-crease asisolationprogressedand reachedanaverage of 2 for EPTand 7 for gastropodsatthe end of the scenarios.With more than 80% of the taxonomic models with an AUC equal or higher than 0.7 and slopes of linear relationsbetween observed and predicted richness of 0.75 (gastropods) and 1 (EPT), the Boosted Regression Trees (BRT)provided a goodbasis for prediction ofspeciesassemblages. These models canbeusedto quantify a priorithe sus-tainability and ecological efficiency of restoration actions and helpfloodplain restoration planning andmanagement.
Keywords FloodplainAlpha-diversityMachine learningLateral connectivityEcological successionInvertebrates
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Structures
Research groups Environmental Biogeochemistry and Ecotoxicology
Ecology and Aquatic Biology
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MARLE, Pierre et al. The interplay of flow processes shapes aquatic invertebrate successions in floodplain channels - A modelling applied to restoration scenarios. In: Science of the Total Environment, 2021, vol. 750, n° 142081. doi: 10.1016/j.scitotenv.2020.142081 https://archive-ouverte.unige.ch/unige:141781

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Deposited on : 2020-09-23

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