Flooding and hydrologic connectivity modulate community assembly in a dynamic river-floodplain ecosystem - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue PLoS ONE Année : 2019

Flooding and hydrologic connectivity modulate community assembly in a dynamic river-floodplain ecosystem

Stefano Larsen
  • Fonction : Auteur
  • PersonId : 1049923
Ute Karaus
  • Fonction : Auteur
Ferdinand Sporka
  • Fonction : Auteur
Ladislav Hamerlík
  • Fonction : Auteur

Résumé

Braided river floodplains are highly dynamic ecosystems, where aquatic communities are strongly regulated by the hydrologic regime. So far, however, understanding of how flow variation influences assembly mechanisms remains limited. We collected benthic chironomids and oligochaetes over a year across a lateral connectivity gradient in the semi-natural Tagliamento River (Italy). Four bankfull flood events occurred during the study, allowing the assessment of how flooding and hydrologic connectivity mediate the balance between sto-chastic and deterministic community assembly. While invertebrate density and richness were positively correlated with connectivity, diversity patterns showed no significant correlation. Species turnover through time increased with decreasing connectivity. Contrary to expectations, hydrologic connectivity did not influence the response of community metrics (e.g. diversity, density) to floods. Invertebrate composition was weakly related to connectiv-ity, but changed predictably in response to floods. Multivariate ordinations showed that faunal composition diverged across the waterbodies during stable periods, reflecting differential species sorting across the lateral gradient, but converged again after floods. Stable hydrological periods allowed communities to assemble deterministically with prevalence of non-random beta-diversity and co-occurrence patterns and larger proportion of composi-tional variation explained by local abiotic features. These signals of deterministic processes declined after flooding events. This occurred despite no apparent evidence of flood-induced homogenisation of habitat conditions. This study is among the first to examine the annual dynamic of aquatic assemblages across a hydrologic connectivity gradient in a natural flood-plain. Results highlight how biodiversity can exhibit complex relations with hydrologic con-nectivity. However, appraisal of the assembly mechanisms through time indicated that flooding shifted the balance from deterministic species sorting across floodplain habitats, towards stochastic processes related to organisms redistribution and the likely resetting of assembly to earlier stages.
Fichier principal
Vignette du fichier
larsen et al 2019.pdf (2.15 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-02166735 , version 1 (27-06-2019)

Identifiants

Citer

Stefano Larsen, Ute Karaus, Cécile Claret, Ferdinand Sporka, Ladislav Hamerlík, et al.. Flooding and hydrologic connectivity modulate community assembly in a dynamic river-floodplain ecosystem. PLoS ONE, 2019, 14 (4), pp.e0213227. ⟨10.1371/journal.pone.0213227⟩. ⟨hal-02166735⟩
65 Consultations
72 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More