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Actuellement, un consensus a été atteint pour protéger et restaurer les bras morts. Par conséquent, il est important de comprendre le fonctionnement de ces zones humides. Á notre connaissance, la distribution spatio-temporelle des diatomées, des macrophytes et des macroinvertébrés benthiques, en relation avec la géomorphologie n'a pas été étudiée de manière approfondie. Dans les zones amont et intermédiaire, la faible température de l'eau et les fortes concentrations ioniques ont révélé une connexion avec l'eau de nappe. De plus, le seuil géomorphologique, qui caractérise la zone intermédiaire, a créé les mêmes phénomènes de circulation de l'eau dans les sédiments que dans les rivières, avec un écotone « nappe phréatique/milieu hyporhéique/eau de surface » et produit des différences physico-chimiques entre l'amont et l'aval du bras mort et ainsi modifie la distribution des organismes. En aval, les apports d'eau du chenal principal de la rivière Allier ont permis le développement de taxons observés dans la rivière. Toutes ces connexions hydrologiques et la sédimentation ont modifié les caractéristiques physiques, chimiques et géomorphologiques, créant ainsi un gradient de qualité de l'eau, qui influence la répartition des communautés biologiques. Currently, a consensus has been reached to protect and restore cut-off meanders. Therefore, it is important to understand how these wetlands function. To our knowledge, the spatial and temporal distribution of both benthic diatoms and macroinvertebrates, associated with macrophytes communities, linked to the geomorphology, has not been studied extensively. In the upstream and intermediate zones, the low water temperature and the high conductivity revealed a connection with the groundwater. Moreover, the geomorphological riffle characterizing the intermediate zone created the same downwelling and upwelling processes as in running water, with a groundwater/hyporheic/surface water ecotone and produced physico-chemical differences between the upstream and the downstream zones and thereby modify the diatom, macroinvertebrate and macrophyte distribution. Downstream, water input from the main channel of the Allier River allowed the development of taxa observed in the River. All these hydrological connections and the sedimentation modified the physical, chemical and geomorphological characteristics, thereby, creating a gradient of water quality, influencing the distribution of the biotic communities. [ABSTRACT FROM AUTHOR]

Polar regions are very sensitive to climate variability. Glacial environments, such as Spitsbergen, respond drastically to climate warming by the disintegration of ice masses, release of huge amounts of free water and rapid evolution of terrestrial landforms. Paraglacial studies have shown that sediment yield decreases with time following a relaxation curve. The study examines the effects of scaling on rhythms of deglaciation and sediment fluxes in a small catchment. It appears that the paraglacial sequence, known as a morphogenic crisis, could be affected by internal small threshold events which are able to mobilize large quantities of sediment. It means that, at small scale, the curve profile is more irregular than suggested by large-scale models. [ABSTRACT FROM AUTHOR]