title: Environmental effects of realistic pesticide mixtures on natural biofilm communities with different exposure histories.
abstract: This study deals with the use of Polar Organic Chemical Integrative Sampler (POCIS) extracts to assess the impact of low-dose pesticide mixtures on natural biofilm communities originating from either a chronically contaminated or a reference field site. To investigate how natural biofilm communities, pre-exposed to pesticides in situ or not might respond to environmentally realistic changes in pesticide pressure, they were exposed to either clean water or to POCIS extracts (PE) in order to represent toxic pressure with a realistic pesticide mixture directly isolated from the field. The impacts of PE were assessed on structure, physiology and growth of biofilms. Initial levels of tolerance of phototrophic communities to PE were also estimated at day 0. PE exposure led to negative effects on diatom growth kinetics independently of in-field biofilm exposure history. In contrast, the impacts observed on dry weight, ash-free dry mass and algal fluorescence-related parameters followed different trends depending on biofilm origin. Exposure to PE induced changes in diatom assemblages for the biofilm originating from the reference field site with higher relative abundance of Eolimna minima and Nitzschia palea with PE exposure. Initial tolerance of phototrophic communities to PE was 8-fold higher for the biofilm originating from the chronically contaminated site compared to the reference field site. The use of POCIS extracts allowed us to highlight both chronic impacts of low doses of a mixture of pesticides on natural communities with regard to biofilm exposure history as well as initial levels of tolerance of phototrophic communities.
authors.affiliation: Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France; University of Bordeaux, EPOC, UMR 5805, F-33120 Arcachon, France. Electronic address: sandra.kimtiam@gmail.com.
authors.forename: Sandra
authors.initials: S
authors.lastname: Kim Tiam
authors.affiliation: Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France.
authors.forename: Soizic
authors.initials: S
authors.lastname: Morin
authors.affiliation: Irstea, UR MALY, 5 rue de la Doua, CS 70077, F-69626 Villeurbanne cedex, France.
authors.forename: Stephane
authors.initials: S
authors.lastname: Pesce
authors.affiliation: University of Bordeaux, EPOC, UMR 5805, F-33120 Arcachon, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Feurtet-Mazel
authors.affiliation: Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Moreira
authors.affiliation: University of Bordeaux, EPOC, UMR 5805, F-33120 Arcachon, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Gonzalez
authors.affiliation: Irstea, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex, France. Electronic address: nicolas.mazzella@irstea.fr.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mazzella
mesh_terms: D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D010575:Pesticides / Q000633:toxicity*; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Diatom assemblages; Low-dose exposure; Mixture effects; Passive samplers; Periphyton; Pesticides