title: How to characterize chemical exposure to predict ecologic effects on aquatic communities?
abstract: Reliable characterization of exposure is indispensable for ecological risk assessment of chemicals. To deal with mixtures, several approaches have been developed, but their relevance for predicting ecological effects on communities in the field has not been elucidated. In the present study, we compared nine metrics designed for estimating the total toxicity of mixtures regarding their relationship with an effect metric for stream macroinvertebrates. This was done using monitoring data of biota and organic chemicals, mainly pesticides, from five studies comprising 102 streams in several regions of Europe and South-East Australia. Mixtures of less than 10 pesticides per water sample were most common for concurrent exposure. Exposure metrics based on the 5% fraction of a species sensitivity distribution performed best, closely followed by metrics based on the most sensitive species and Daphnia magna as benchmark. Considering only the compound with the highest toxicity and ignoring mixture toxicity was sufficient to estimate toxicity in predominantly agricultural regions with pesticide exposure. The multisubstance Potentially Affected Fraction (msPAF) that combines concentration and response addition was advantageous in the study where further organic toxicants occurred. We give recommendations on exposure metric selection depending on data availability and the involved compounds.
authors.affiliation: Quantitative Landscape Ecology, Institute for Environmental Science, University of Koblenz-Landau, Fortstraße 7, D-76829 Landau, Germany. schaefer-ralf@uni-landau.de
authors.forename: Ralf B
authors.initials: RB
authors.lastname: Schäfer
authors.forename: Nadine
authors.initials: N
authors.lastname: Gerner
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Kefford
authors.forename: Jes J
authors.initials: JJ
authors.lastname: Rasmussen
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Beketov
authors.forename: Dick
authors.initials: D
authors.lastname: de Zwart
authors.forename: Matthias
authors.initials: M
authors.lastname: Liess
authors.forename: Peter C
authors.initials: PC
authors.lastname: von der Ohe
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical