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Drying and fragmentation drive the dynamics of resources, consumers and ecosystem functions across aquatic-terrestrial habitats in a river network.
  • +8
  • Romain Sarremejane,
  • Teresa Silverthorn,
  • Angélique Arbaretaz,
  • Amélie Truchy,
  • Nans Barthélémy,
  • Naiara Lopez-Rojo,
  • Arnaud Foulquier,
  • Laurent Simon,
  • Hervé Pella,
  • Gabriel Singer,
  • Thibault Datry
Romain Sarremejane
INRAE Centre Lyon-Grenoble Auvergne-Rhône-Alpes

Corresponding Author:romain.sarremejane@inrae.fr

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Teresa Silverthorn
INRAE Centre Lyon-Grenoble Auvergne-Rhône-Alpes
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Angélique Arbaretaz
INRAE Centre Lyon-Grenoble Auvergne-Rhône-Alpes
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Amélie Truchy
Swedish University of Agricultural Sciences
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Nans Barthélémy
INRAE Centre Lyon-Grenoble Auvergne-Rhône-Alpes
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Naiara Lopez-Rojo
Universite Grenoble Alpes
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Arnaud Foulquier
Laboratoire d'Ecologie Alpine
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Laurent Simon
University Claude Bernard Lyon 1
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Hervé Pella
INRAE Centre Lyon-Grenoble Auvergne-Rhône-Alpes
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Gabriel Singer
University of Innsbruck
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Thibault Datry
INRAE
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Abstract

Disturbance and connectivity control biodiversity, ecosystem functioning and their interactions across connected aquatic and terrestrial ecosystems, that form a meta-ecosystem. In rivers, detrital organic matter (OM) is transported across terrestrial-aquatic boundaries and along the river network and decomposed on the way by diverse communities of organisms, including microorganisms and invertebrates. Drying naturally fragments most river networks and thereby modify organism dispersal and OM transfers across ecosystems. This may prevent organisms from reaching and consuming OM, generating mismatches between community composition and decomposition. However, little evidence of the effects of drying on river network-scale OM cycling exists. Here, we aim to examine the effects of fragmentation by drying on the structure of consumer communities and ecosystem functioning within interacting aquatic-terrestrial river ecosystems. We monitored leaf resource stocks, invertebrate communities and decomposition rates in the instream and riparian habitats of 20 sites in a river network naturally fragmented by drying. Although instream resource quantity and quality increased with drying severity, decomposition decreased due to changes in invertebrate communities and particularly leaf-decomposer abundance. Invertebrate-driven decomposition peaked at intermediate levels of upstream connectivity, suggesting that intermediate levels of fragmentation can promote the functioning of downstream ecosystems. We found that the variability in community composition was unrelated to variability in decomposition at sites with low connectivity and high drying severity, suggesting that such conditions can promote mismatches between community composition and decomposition. Decomposition instream was correlated to decomposition in the riparian area, revealing one of the first network-scale evidence of the links between ecosystem functions across terrestrial-aquatic boundaries. Our river network-scale study thus demonstrates the paramount effect of drying on the dynamics of resources, communities and ecosystem functioning in river networks, with crucial implications for the adaptive management of river networks and preservation of their functional integrity.
31 Mar 2023Submitted to Oikos
03 Apr 2023Submission Checks Completed
03 Apr 2023Assigned to Editor
03 Apr 2023Review(s) Completed, Editorial Evaluation Pending
14 Apr 2023Reviewer(s) Assigned
05 Jun 2023Editorial Decision: Revise Major
13 Sep 20231st Revision Received
13 Sep 2023Submission Checks Completed
13 Sep 2023Assigned to Editor
13 Sep 2023Review(s) Completed, Editorial Evaluation Pending
24 Sep 2023Reviewer(s) Assigned
15 Nov 2023Editorial Decision: Revise Minor