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Functional diversity in a large river floodplain: anticipating the response of native and alien macroinvertebrates to the restoration of hydrological connectivity

Dolédec, Sylvain
Mérigoux, Sylvie
Aldridge, David C.
Published in Journal of applied ecology. 2013, vol. 50, no. 1, p. 97-106
Abstract 1. Rivers and floodplains are among the most threatened ecosystems. Hydroelectric power plants and embankments have reduced the hydrological connectivity between rivers and their floodplain channels, leading to loss of freshwater habitats and biological communities. To prevent and reverse such loss, numerous restoration programmes have aimed at rejuvenating the lateral hydrological connectivity between rivers and floodplain channels. Despite considerable global attention, we know remarkably little about the ecological benefits of floodplain restoration programmes. 2. We analysed the functional diversity of different macroinvertebrate groups (natives and aliens) along a gradient of lateral hydrological connectivity on the Rhoˆ ne river in France. We used 36 sampling sites to describe the functional diversity (Rao's quadratic entropy) before and after the enhancement of the lateral hydrological connectivity by restoration. The effects of restoration on functional diversity were tested for each macroinvertebrate group and at multiple spatial levels (alpha and beta). 3. Before restoration, alpha functional diversity of the entire macroinvertebrate community peaked in sites with a high lateral connectivity. The contribution of the native groups to functional diversity was higher than that of the alien group. The latter was not constrained by high values of lateral hydrological connectivity and reached a maximum in highly connected sites. 4. After restoration, within-site functional diversity (alpha FD) declined linearly following the enhancement of lateral hydrological connectivity. The restoration operations increased the contribution of the aliens to functional diversity and reduced the contribution of a group of native taxa. In addition, among-sites functional diversity (beta FD) was successfully enlarged by restoration. 5. Synthesis and applications. The lateral hydrological connectivity (LHC) represents a key parameter for explaining the functional diversity (FD) of macroinvertebrates in a floodplain ecosystem. Our results demonstrate that restoration-induced changes to functional diversity can be predicted. Controversially, restoration-induced enhancement of lateral hydrological connectivity increased the functional diversity of the alien macroinvertebrates. However, these species contributed only to a small part of the total macroinvertebrate functional diversity. We recommend that restoration programmes diversify the levels of lateral hydrological connectivity among the channels to ensure an optimal functional diversity at the floodplain scale.
Keywords Assembly rulesFreshwaterLateral connectivityQuadratic entropyRestorationRhone riverBeta-diversity
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Article (Published version) (392 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Research groups Ecology and Aquatic Biology
ISE Biodiversité
ISE Pôle Sciences
Swiss National Science Foundation: PBGEP3 – 136309
Autre: Programme de Restauration Hydraulique et Ecologique du Rhône
(ISO format)
PAILLEX, Amael et al. Functional diversity in a large river floodplain: anticipating the response of native and alien macroinvertebrates to the restoration of hydrological connectivity. In: Journal of applied ecology, 2013, vol. 50, n° 1, p. 97-106. doi: 10.1111/1365-2664.12018 https://archive-ouverte.unige.ch/unige:26734

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Deposited on : 2013-03-12

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