The Water Framework Directive (WFD), 2000/60/EC, requires an integrated approach to the monitoring and assessment of the quality of surface water bodies. The chemical status assessment is based on compliance with legally binding Environmental Quality Standards (EQSs) for selected chemical pollutants (priority substances) of EU-wide concern. In the context of the mandate for the period 2010 to 2012 of the subgroup Chemical Monitoring and Emerging Pollutants (CMEP) under the Common Implementation Strategy (CIS) for the WFD, a specific task was established for the elaboration of a technical report on aquatic effect-based monitoring tools. The activity was chaired by Sweden and co-chaired by Italy and progressively involved several Member States and stakeholders in an EU-wide drafting group. The main aim of this technical report was to identify potential effect-based tools (e.g. biomarkers and bioassays) that could be used in the context of the different monitoring programmes (surveillance, operational and investigative) linking chemical and ecological status assessment. The present paper summarizes the major technical contents and findings of the report.

This study is a consequence of a distinct fish decline in the Danube river since the beginning of the 1990s. In contrast to the decline of fish population, former studies have repeatedly documented that the water quality along the Danube river is improving. However, the conclusion of a pilot study in 2002 was that a high hazard potential is associated with local sediments. The present study documents that sediment samples from the Danube river showed comparatively high aryl hydrocarbon receptor mediated activity in biotests, using the cell lines GPC.2D.Luc, H4IIE (DR-CALUX) and RTL-W1. The combination of chemical analysis, fractionation techniques and different in vitro tests revealed that priority pollutants could not explain the main induction, even though the concentrations of priority polycyclic aromatic hydrocarbons (PAHs) were very high (maximum in the tributary Schwarzach, sum of 16 EPA PAHs 26 mug/g). In conclusion, this investigation shows that nonpriority pollutants mainly mediate the high induction rates. Nevertheless, owing to the effects of PAHs towards fish and the connection between dioxin-like activity and carcinogenicity, the link between contamination and the fish population decline cannot be ruled out.

As a consequence of climate change, flood events will increase in frequency and intensity at least in some regions such as Central Europe. Thus, it is crucial to identify the potential hazard of (re-)mobilized contaminants from reservoirs dislocated via floods and threatening especially aquatic organisms and cattle grazing in flood plains. Since other less persistent compounds seem to be more relevant to explain AhR-mediated activities in flood SPM, nonconventional PAHs and more polar compounds also need to be considered for risk assessment. Effect-directed analysis using broad-range fractionation methods taking into account compounds from polar to nonpolar should be applied for identification of pollutants causing biological effects, thus integrating biological and chemical parameters.

As a consequence of ubiquitous use of brominated organic chemicals, there is a concern for persistent or increasing environmental levels of polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and mixed polychlorinated and polybrominated dibenzo-p-dioxins/furans (PXDD/Fs). Hence, there is a need to broaden the toxicological and environmental knowledge about these compounds, as a basis for risk assessment. In the study presented here, the relative potencies (REPs) for 18 PBDD/F and PXDD/ F congeners were determined in four dioxin-specific bioassays from different species: dioxin receptor chemically activated luciferase expression assay (DR-CALUX, rat hepatoma cells), TV101L (human hepatoma cells), and GPC.2D (guinea pig adenoma cells), as well as ethoxyresorufin-O-deethylase induction in the fish cell line RTL-W1 (rainbow trout liver cells). The bioassay specific REP factors presented here enable the assessment of the contribution from PBDD/Fs and PXDD/Fs to total 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQs: toxic equivalents), using bioassay analysis. The PBDD/Fs were found to be equally potent as their chlorinated analogues in the three mammalian assays, whereas the PXDD/Fs showed relatively higher potencies. Of special concern were the 2,3,7,8-substituted penta- and tetrahalogenated congeners, for which mean REPs were > or =1. The 2-B-1,3,7,8-CDD (2-bromo-1,3,7,8-tetrachlorodibenzo-p-dioxin) was up to three times more potent than TCDD in individual experiments (on weight basis). The RTL-W1 was less sensitive to the tested compounds with overall 10-fold lower REPs than the mammalian cell lines. Although the REP factors exhibited species-specific differences, overall resembling rank orders of dioxin-like potency were obtained.

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In response to increasing concerns about the potential toxicological impacts of (extreme) flood events, scientists from several disciplines have joined to form the interdisciplinary research project named FLOODSEARCH. FLOODSEARCH is one of the recent Pathfinder Projects supported by the German Excellence Initiative via the Exploratory Research Space at RWTH Aachen (ERS). FLOODSEARCH aims to combine methodologies of hydraulic engineering and ecotoxicology in a new interdisciplinary approach to assess the risks associated with the remobilisation of particulate bound contaminants often observed after severe flood events. Impacts of extreme flood events and aspects of re-mobilisation of sedimentbound toxic compounds will be characterised and evaluated in controlled experiments fusing flood simulation technologies with biological effects assessment. The overall goal is to establish a novel and more realistic approach towards flood event testing that can be applied to a number of different questions and species. Specifically, model aquatic species such as rainbow trout (Onchorhynchus mykiss) will be exposed to particle-bound contaminants in flood-like conditions in a specifically designed annular flume that