title: The effect of temperature and a herbicide mixture on freshwater periphytic algae.
abstract: Temperature is a strong driver of biofilm formation and of the dynamics of microalgae in freshwater. Moreover, exposure to herbicides is a well-known stressor of periphytic communities in anthropized aquatic environments. We tested these two environmental factors on periphytic communities that had been sampled from the littoral zone of Lake Geneva and acclimatized in the lab for 3 weeks at 18, 21, 24 and 28 °C. After this acclimation period, differences in the composition of the diatom community and decreases in cell density were observed corresponding to the temperature gradient. These acclimated communities were then exposed to 23 and 140 nM of a mixture composed of equitoxic quantities of atrazine, terbutryn, diuron and isoproturon. The periphytic community was more sensitive to the herbicide mixture at 18 °C than at higher temperatures, suggesting that higher temperature reduced its toxicity. Small and pioneer diatom species known to be promoted by contamination also appeared to benefit from higher temperatures. Temperature therefore appears to condition the herbicide sensitivity of periphytic communities.
authors.affiliation: Institut National de la Recherche Agronomique, UMR 0042 Carrtel, Thonon, France. Electronic address: floriane.larras@thonon.inra.fr.
authors.forename: Floriane
authors.initials: F
authors.lastname: Larras
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Lambert
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pesce
authors.forename: Frédéric
authors.initials: F
authors.lastname: Rimet
authors.forename: Agnès
authors.initials: A
authors.lastname: Bouchez
authors.forename: Bernard
authors.initials: B
authors.lastname: Montuelle
mesh_terms: D001280:Atrazine / Q000633:toxicity; D018441:Biofilms; D017377:Diatoms / Q000187:drug effects*; D004237:Diuron / Q000633:toxicity; D005618:Fresh Water; D006540:Herbicides / Q000633:toxicity*; D010671:Phenylurea Compounds / Q000633:toxicity; D013696:Temperature; D014227:Triazines / Q000633:toxicity
chemical_list: D006540:Herbicides; D010671:Phenylurea Compounds; D014227:Triazines; C028904:isoproturon; D004237:Diuron; D001280:Atrazine; C010347:terbutryne
keywords: Herbicides; Mixture; Periphytic algae; Temperature