title: Effects of the fungicide metiram in outdoor freshwater microcosms: responses of invertebrates, primary producers and microbes.
abstract: The ecological impact of the dithiocarbamate fungicide metiram was studied in outdoor freshwater microcosms, consisting of 14 enclosures placed in an experimental ditch. The microcosms were treated three times (interval 7 days) with the formulated product BAS 222 28F (Polyram®). Intended metiram concentrations in the overlying water were 0, 4, 12, 36, 108 and 324 μg a.i./L. Responses of zooplankton, macroinvertebrates, phytoplankton, macrophytes, microbes and community metabolism endpoints were investigated. Dissipation half-life (DT₅₀) of metiram was approximately 1-6 h in the water column of the microcosm test system and the metabolites formed were not persistent. Multivariate analysis indicated treatment-related effects on the zooplankton (NOEC(community) = 36 μg a.i./L). Consistent treatment-related effects on the phytoplankton and macroinvertebrate communities and on the sediment microbial community could not be demonstrated or were minor. There was no evidence that metiram affected the biomass, abundance or functioning of aquatic hyphomycetes on decomposing alder leaves. The most sensitive populations in the microcosms comprised representatives of Rotifera with a NOEC of 12 μg a.i./L on isolated sampling days and a NOEC of 36 μg a.i./L on consecutive samplings. At the highest treatment-level populations of Copepoda (zooplankton) and the blue-green alga Anabaena (phytoplankton) also showed a short-term decline on consecutive sampling days (NOEC = 108 μg a.i./L). Indirect effects in the form of short-term increases in the abundance of a few macroinvertebrate and several phytoplankton taxa were also observed. The overall community and population level no-observed-effect concentration (NOEC(microcosm)) was 12-36 μg a.i./L. At higher treatment levels, including the test systems that received the highest dose, ecological recovery of affected measurement endpoints was fast (effect period < 8 weeks).
authors.affiliation: Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Lin
authors.forename: Laura
authors.initials: L
authors.lastname: Buijse
authors.forename: Mauricio R
authors.initials: MR
authors.lastname: Dimitrov
authors.forename: Peter
authors.initials: P
authors.lastname: Dohmen
authors.forename: Sujitra
authors.initials: S
authors.lastname: Kosol
authors.forename: Lorraine
authors.initials: L
authors.lastname: Maltby
authors.forename: Ivo
authors.initials: I
authors.lastname: Roessink
authors.forename: Jos A
authors.initials: JA
authors.lastname: Sinkeldam
authors.forename: Hauke
authors.initials: H
authors.lastname: Smidt
authors.forename: René P A
authors.initials: RP
authors.lastname: Van Wijngaarden
authors.forename: Theo C M
authors.initials: TC
authors.lastname: Brock
mesh_terms: D000818:Animals; D000458:Cyanobacteria / Q000187:drug effects / Q000378:metabolism; D004050:Ditiocarb / Q000032:analysis / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D017753:Ecosystem; D023381:Endpoint Determination; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000032:analysis / Q000633:toxicity*; D006207:Half-Life; D015999:Multivariate Analysis; D010573:Pesticide Residues / Q000032:analysis / Q000633:toxicity*; D010839:Phytoplankton / Q000187:drug effects / Q000378:metabolism; D018570:Risk Assessment; D012403:Rotifera / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D015048:Zooplankton / Q000187:drug effects / Q000378:metabolism
chemical_list: D005659:Fungicides, Industrial; D010573:Pesticide Residues; D014874:Water Pollutants, Chemical; C008971:polymarcine; D004050:Ditiocarb