title: Functional and structural impact of linuron on a freshwater community of primary producers: the use of immobilized algae.
abstract: An approach in determining ecosystem integrity and stress on ecosystem level is to assess processes within ecosystems. The aim of the present study was to evaluate the potential use of an in situ assay with immobilized Chlorella vulgaris as an indicator of effects on ecosystem functioning with regard to primary production. The herbicide linuron, applied in concentrations of 20, 60, and 180 microg linuron/L, was used to induce direct effects on primary producers. Direct and indirect changes in structure and function within outdoor model ecosystems of 3 m3 were monitored. The intermediate and highest concentration of linuron caused a decline in growth of the macrophyte Elodea sp., resulting in a significant increase of concentrations of nutrients. The increase in concentrations of nutrients caused an indirectly stimulated growth of immobilized C. vulgaris at the intermediate concentration, whereas similar concentrations of nutrients, at the highest treatment, did not stimulate Chlorella growth. It appeared that the direct effect of linuron on C. vulgaris growth was masked by nutrient availability at the intermediate but not at the highest linuron concentration. The observed immobilized algal growth was an accumulated effect of toxic and trophic pressures within the ecosystem, resulting in an integrative endpoint to detect actual impairment of ecosystem function.
authors.affiliation: TNO-Netherlands Organization for Applied Scientific Research, POB 57, 1780 AB, Den Helder, The Netherlands. d.slijkerman@mep.tno.nl
authors.forename: Diana M E
authors.initials: DM
authors.lastname: Slijkerman
authors.forename: Matilde
authors.initials: M
authors.lastname: Moreira-Santos
authors.forename: Robbert G
authors.initials: RG
authors.lastname: Jak
authors.forename: Rui
authors.initials: R
authors.lastname: Ribeiro
authors.forename: Amadeu M V M
authors.initials: AM
authors.lastname: Soares
authors.forename: Nico M
authors.initials: NM
authors.lastname: Van Straalen
mesh_terms: D001682:Biological Availability; D048408:Chlorella vulgaris / Q000187:drug effects / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D017753:Ecosystem; D020387:Food Chain; D006540:Herbicides / Q000633:toxicity*; D008044:Linuron / Q000633:toxicity*; D018977:Micronutrients / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship; D018675:Toxicity Tests / Q000379:methods
chemical_list: D006540:Herbicides; D018977:Micronutrients; D008044:Linuron