title: Combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition.
abstract: Loss of biodiversity and altered ecosystem functioning are driven by the cumulative effects of multiple natural and anthropogenic stressors affecting both quantity and quality of water resources. Here we performed a 40-day laboratory microcosm experiment to assess the individual and combined effects of drought and the model fungicide tebuconazole (TBZ) on leaf litter decomposition (LLD), a fundamental biogeochemical process in freshwater ecosystems. Starting out from a worst-case scenario perspective, leaf-associated microbial communities were exposed to severe drought conditions (four 5-day drought periods alternated with 4-day immersion periods) and/or a chronic exposure to TBZ (nominal concentration of 20μgL(-1)). We assessed the direct effects of drought and fungicide on the structure (biomass, diversity) and activity (extracellular enzymatic potential) of fungal and bacterial assemblages colonizing leaves. We also investigated indirect effects on the feeding rates of the amphipod Gammarus fossarum on leaves previously exposed to drought and/or TBZ contamination. Results indicate a stronger effect of drought stress than fungicide contamination under the experimental conditions applied. Indeed, the drought stress strongly impacted microbial community structure and activities, inhibiting the LLD process and leading to cascading effects on macroinvertebrate feeding. However, despite the lack of significant effect of TBZ applied alone, the effects of drought on microbial functions (i.e., decrease in LLD and in enzymatic activities) and on Gammarus feeding rates were more pronounced when drought and TBZ stresses were applied together. In a perspective of ecological risk assessment and ecosystem management for sustainability, these findings stress the need for deeper insight into how multiple stressors can affect the functioning of aquatic ecosystems and associated services.
authors: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 Rue de la Doua, CS70077, 69626 Villeurbanne Cedex, France. Electronic address: stephane.pesce@irstea.fr.
authors: Stéphane
authors: S
authors: Pesce
authors: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 Rue de la Doua, CS70077, 69626 Villeurbanne Cedex, France. Electronic address: olfa.zg@gmail.com.
authors: Olfa
authors: O
authors: Zoghlami
authors: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 Rue de la Doua, CS70077, 69626 Villeurbanne Cedex, France. Electronic address: christelle.margoum@irstea.fr.
authors: Christelle
authors: C
authors: Margoum
authors: Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université Blaise Pascal, Clermont-Ferrand, France; CNRS, UMR 6023, LMGE, Aubiere, France. Electronic address: Joan.ARTIGAS_ALEJO@univ-bpclermont.fr.
authors: Joan
authors: J
authors: Artigas
authors: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 Rue de la Doua, CS70077, 69626 Villeurbanne Cedex, France. Electronic address: arnaud.chaumot@irstea.fr.
authors: Arnaud
authors: A
authors: Chaumot
authors: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 Rue de la Doua, CS70077, 69626 Villeurbanne Cedex, France; Laboratoire d'Écologie Alpine, UMR 5553CNRS, Université Grenoble Alpes, BP 53, 38041 Grenoble Cedex 9, France. Electronic address: arnaud.foulquier@ujf-grenoble.fr.
authors: Arnaud
authors: A
authors: Foulquier
mesh_terms: D033304:Amphipoda / Q000187:drug effects / Q000502:physiology; D000818:Animals; D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D055864:Droughts; D017753:Ecosystem; D004783:Environmental Microbiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D005618:Fresh Water / Q000737:chemistry; D005658:Fungi / Q000187:drug effects; D005659:Fungicides, Industrial / Q000494:pharmacology; D064307:Microbiota / Q000187:drug effects / Q000502:physiology; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology*; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology; D014230:Triazoles / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000494:pharmacology
chemical_list: D005659:Fungicides, Industrial; D014230:Triazoles; D014874:Water Pollutants, Chemical; C087114:tebuconazole
keywords: Aquatic food web; Biodiversity-ecosystem function relationship; Microbial communities; Microbial ecotoxicology; Multistress; Shredders