title: Comparative sensitivity to the fungicide tebuconazole of biofilm and plankton microbial communities in freshwater ecosystems.
abstract: Stream and lake ecosystems in agricultural watersheds are exposed to fungicide inputs that can threaten the structure and functioning of aquatic microbial communities. This research analyzes the impact of the triazole fungicide tebuconazole (TBZ) on natural biofilm and plankton microbial communities from sites presenting different degrees of agricultural contamination. Biofilm and plankton communities from less-polluted (LP) and polluted (P) sites were exposed to nominal concentrations of 0 (control), 2 and 20 μg TBZ L(-1) in 3-week microcosm experiments. Descriptors of microbial community structure (bacterial density and chlorophyll-a concentration) and function (bacterial respiration and production and photosynthesis) were analyzed to chart the effects of TBZ and the kinetics of TBZ attenuation in water during the experiments. The results showed TBZ-induced effects on biofilm function (inhibition of substrate-induced respiration and photosynthetic activity), especially in LP-site communities, whereas plankton communities experienced a transitory stimulation of bacterial densities in communities from both LP and P sites. TBZ attenuation was stronger in biofilm (60-75%) than plankton (15-18%) experiments, probably due to greater adsorption on biofilms. The differences between biofilm and plankton responses to TBZ were likely explained by differences in community structure (presence of extracellular polymeric substances (EPS) matrix) and microbial composition. Biofilm communities also exhibited different sensitivity levels according to their in-field pre-exposure to fungicide, with P-site communities demonstrating adaptation capacities to TBZ. This study indicates that TBZ toxicity to non-targeted aquatic microbial communities essentially composed by microalgae and bacteria was moderate, and that its effects varied between stream and lake microbial communities.
authors.affiliation: Irstea, UR MALY, 3 bis quai Chauveau, CP 220, 69336 Lyon, France; Clermont Université, Université Blaise Pascal, Laboratoire "Microorganismes: Génome et Environnement", BP 10448, 63000 Clermont-Ferrand, France; CNRS, UMR 6023, LMGE, 63177 Aubière, France. Electronic address: joan.artigas_alejo@univ-bpclermont.fr.
authors.forename: J
authors.initials: J
authors.lastname: Artigas
authors.forename: N
authors.initials: N
authors.lastname: Pascault
authors.forename: A
authors.initials: A
authors.lastname: Bouchez
authors.forename: J
authors.initials: J
authors.lastname: Chastain
authors.forename: D
authors.initials: D
authors.lastname: Debroas
authors.forename: J F
authors.initials: JF
authors.lastname: Humbert
authors.forename: J
authors.initials: J
authors.lastname: Leloup
authors.forename: R D
authors.initials: RD
authors.lastname: Tadonleke
authors.forename: A
authors.initials: A
authors.lastname: ter Halle
authors.forename: S
authors.initials: S
authors.lastname: Pesce
mesh_terms: D000704:Analysis of Variance; D018441:Biofilms / Q000187:drug effects*; D058448:Biota / Q000187:drug effects*; D002853:Chromatography, Liquid; D004305:Dose-Response Relationship, Drug; D005602:France; D005618:Fresh Water / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000737:chemistry / Q000633:toxicity*; D007211:Indoles; D007700:Kinetics; D010933:Plankton / Q000187:drug effects*; D011156:Population Density; D013045:Species Specificity; D053719:Tandem Mass Spectrometry; D014230:Triazoles / Q000737:chemistry / Q000633:toxicity*
chemical_list: D005659:Fungicides, Industrial; D007211:Indoles; D014230:Triazoles; C087114:tebuconazole; C007293:DAPI
keywords: Adaptation; Algae; Bacteria; Fungicide; Photosynthetic efficiency; Substrate-induced respiration