Fast but transient recovery of aquatic and terrestrial communities after a large dam removal

Type Article
Date 2023-12
Language English
Author(s) Dézerald Olivier1, Roussel Jean-Marc1, Lanoë Elven1, Beauverger Thibaut2, 3, Bazin Alan2, 3, Rodríguez-Pérez Héctor4, 5, Dufour Simon6, Bernez Ivan1, Piscart Christophe4
Affiliation(s) 1 : DECOD (Ecosystem Dynamics and Sustainability), INRAE, Institut Agro, IFREMER, Rennes, France
2 : Pôle Gestion des Migrateurs Amphihalins dans leur Environnement, OFB, INRAE, Agrocampus Ouest, UPPA, Rennes, France
3 : U3E, Unité Expérimentale d’Ecologie et d’Ecotoxicologie Aquatique, INRAE, OFB, Rennes, France
4 : Univ. Rennes, CNRS, ECOBIO - UMR 6553, Rennes, France
5 : Pôle R&D ECLA, OFB, ECOAQUA, DRAS, Aix-en-Provence, France
6 : Université Rennes 2, CNRS, LETG UMR 6554, Rennes, France
Source Frontiers In Ecology And Evolution (2296-701X) (Frontiers Media SA), 2023-12 , Vol. 11 , P. 1254462 (13p.)
DOI 10.3389/fevo.2023.1254462
WOS© Times Cited 1
Keyword(s) ecological restoration, metacommunity, riparian vegetation, macroinvertebrate, habitat fragmentation and modification, river continuum

IntroductionEcological restoration through dam removals receives increasing attention from scientists, environmental managers and policy makers. However, most dam removal projects focus on small structures (< 10 m in height) and on few ecosystem compartments at a time (e.g. river morphology, reservoir sedimentation, aquatic invertebrates, terrestrial vegetation), but rarely aquatic and riparian ecosystems simultaneously. MethodsWe explored the joint taxonomic recovery (temporal patterns in α- and β-diversity) of three communities after the removal of the Vezins dam (36 m in height; Sélune River, France): aquatic benthic invertebrates, riparian invertebrates, and the riparian vegetation. These communities were monitored yearly, during three years after the dam removal, on sites located within (n = 3; restored sites) and outside (n = 3; two upstream and one downstream; non-impounded sites) the former reservoir. ResultsResults showed a fast recovery of the three ecological communities, as patterns in α-diversity between restored and non-impounded sites were not necessarily different from each other 1.5 years after complete reservoir dewatering. The mean number of species or morphospecies (± standard deviation) reached up to 28.2 ± 5.2, 17.0 ± 2.3 and 77.5 ± 11.2 for the aquatic invertebrates, and the riparian vegetation and invertebrates, respectively. Relative to the sampled area, the riparian invertebrates were the most diversified of all ecological communities with > 500 taxa (i.e., pooling all sites and years). In addition, in some restored sites, α-diversity kept increasing over time while species turnover (β-diversity) remained high after three years for all ecological communities suggesting a transient recovery (i.e., still facing temporal changes in species diversity and composition). This recovery was mediated by the identity of the ecological community as inter-annual changes in α- and β-diversity of the riparian vegetation were less pronounced compared to those of aquatic and terrestrial invertebrates. This recovery depended also on site-specific features as the most distant restored site from the former dam had more time for recovery following the slow reservoir dewatering and through increased sedimentation in the downstream site. DiscussionDifferential patterns of recovery in α- and β-diversity found in this study are discussed in light of species functional traits and ecosystem functioning.

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Dézerald Olivier, Roussel Jean-Marc, Lanoë Elven, Beauverger Thibaut, Bazin Alan, Rodríguez-Pérez Héctor, Dufour Simon, Bernez Ivan, Piscart Christophe (2023). Fast but transient recovery of aquatic and terrestrial communities after a large dam removal. Frontiers In Ecology And Evolution, 11, 1254462 (13p.). Publisher's official version : , Open Access version :