title: Functional redundancy and food web functioning in linuron-exposed ecosystems.
abstract: An extensive data set describing effects of the herbicide linuron on macrophyte-dominated microcosms was analysed with a food web model to assess effects on ecosystem functioning. We showed that sensitive phytoplankton and periphyton groups in the diets of heterotrophs were gradually replaced by more tolerant phytoplankton species as linuron concentrations increased. This diet shift--showing redundancy among phytoplankton species--allowed heterotrophs to maintain their functions in the contaminated microcosms. On an ecosystem level, total gross primary production was up to hundred times lower in the treated microcosms but the uptake of dissolved organic carbon by bacteria and mixotrophs was less sensitive. Food web efficiency was not consistently lower in the treated microcosms. We conclude that linuron predominantly affected the macrophytes but did not alter the overall functioning of the surrounding planktonic food web. Therefore, a risk assessment that protects macrophyte growth also protects the functioning of macrophyte-dominated microcosms.
authors.affiliation: Laboratory of Environmental Toxicity and Aquatic Ecology, Ghent University, Plateaustraat 22, 9000 Ghent, Belgium. frederik.delaender@ugent.be
authors.forename: F
authors.initials: F
authors.lastname: De Laender
authors.forename: P J
authors.initials: PJ
authors.lastname: Van den Brink
authors.forename: C R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D017753:Ecosystem; D004784:Environmental Monitoring; D020387:Food Chain; D006540:Herbicides / Q000633:toxicity*; D008044:Linuron / Q000633:toxicity*; D010839:Phytoplankton / Q000187:drug effects / Q000502:physiology; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D008044:Linuron