title: Copper-induced modifications of the trophic relations in riverine algal-bacterial biofilms.
abstract: The effects of copper (Cu) on photosynthetic riverine biofilms were studied in artificial stream channels. Direct effects on the composition and functioning of the biofilms were investigated using plant pigments, community-level physiological profiles (CLPP), and pulse-amplitude-modulated (PAM) fluorescence. Copper caused a significant reduction of microalgal biomass and induced a shift in the population from diatoms to cyanobacteria. However, a decrease in biomass indicated that the replacement of species was not totally effective to counteract the toxic effects of Cu. A direct effect of Cu could also be shown in the bacterial community, and, furthermore, changes in the CLPP could be related to the Cu treatment. Copper-exposed biofilms lost the capacity to use between 11 and 15% of the substrates, but many of the remaining capacities became more robust, indicating an increased Cu tolerance due to the exposure. The change in the biofilm microbial composition points to the indirect effects of Cu on biofilms due to the close interdependence between biofilm autotrophic and heterotrophic compartments. Grazing by snails, which appeared to be an important factor structuring biofilms without any Cu addition, had a very minor effect on Cu-exposed biofilms. Although grazing changed the bacterial composition, its effects were not detected either on the algal community or on the biofilm community tolerance to Cu.
authors.affiliation: Department of Aquatic Ecology and Ecotoxicology, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands. barranguet@science.uva.nl
authors.forename: Christiane
authors.initials: C
authors.lastname: Barranguet
authors.forename: Frank P
authors.initials: FP
authors.lastname: van den Ende
authors.forename: Michiel
authors.initials: M
authors.lastname: Rutgers
authors.forename: Anton M
authors.initials: AM
authors.lastname: Breure
authors.forename: Marianne
authors.initials: M
authors.lastname: Greijdanus
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Sinke
authors.forename: Wim
authors.initials: W
authors.lastname: Admiraal
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D018441:Biofilms / Q000187:drug effects*; D018533:Biomass; D015169:Colony Count, Microbial; D003300:Copper / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D003627:Data Interpretation, Statistical; D056890:Eukaryota / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D005453:Fluorescence; D005618:Fresh Water / Q000382:microbiology*; D008828:Microbiological Techniques / Q000379:methods; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology; D010860:Pigments, Biological / Q000032:analysis / Q000737:chemistry; D014871:Water Microbiology
chemical_list: D010860:Pigments, Biological; D003300:Copper