Department Environmental Toxicology

ERAfresh – Environmental risk assessment in freshwaters

A major challenge in environmental risk assessment of micropollutants (MPs) entering fresh waters via effluents of wastewater treatment plants (WWTPs) is the establishment of a causal relationship between field exposure and observed effects on biotas. To establish this relationship, we combined in the ERAfresh project, time-integrative passive sampling technologies with the assessment of the extract toxicity on in-situ periphyton communities sampled downstream and upstream of WWTPs. Sensitivity of communities to passive sampler extracts was determined according to the pollution-induced community tolerance (PICT) concept by measuring the response of various functional endpoints, which target phototrophic and heterotrophic components of the periphyton. PICT predicts increased tolerance to MPs that have induced changes in the structure of the communities. The project is being carried out in various streams at sites of interest within the Ecoimpact project ( We have recently shown that despite low concentrations of MPs detected downstream of the effluents in four WWTPs in Switzerland, phototrophic and heterotrophic components of the sampled periphyton displayed increased tolerance towards these MPs. Moreover, long-term exposure of periphyton to WWTP effluents induced changes in the structure of the microbial communities, reflecting a selection pressure exerted by the MPs on the diversity of microbial communities leading to higher tolerance towards these MPs.


Tlili, A.; Hollender, J.; Kienle, C.; Behra, R. (2017) Micropollutant-induced tolerance of in situ periphyton: establishing causality in wastewater-impacted streams, Water Research, 111, 185-194, doi:10.1016/j.watres.2017.01.016, Institutional Repository
Tlili, A.; Berard, A.; Blanck, H.; Bouchez, A.; Cássio, F.; Eriksson, K. M.; Morin, S.; Montuelle, B.; Navarro, E.; Pascoal, C.; Pesce, S.; Schmitt-Jansen, M.; Behra, R. (2016) Pollution-induced community tolerance (PICT): towards an ecologically relevant risk assessment of chemicals in aquatic systems, Freshwater Biology, 61(12), 2141-2151, doi:10.1111/fwb.12558, Institutional Repository