| 14h00 - 15h00 |
Volker Grimm, Helmholtz Center for Environmental Research, Leipzig Mechanistic effect models for ecological risk assessment of chemicals: CREAM and the documentation framework TRACE More information on the Volker Grimm website |
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| 15h00 - 15h30 | Pause café |
| 15h30 - 16h30 |
Christelle Lopes, CEMAGREF
Emilie Lacaze, ENTPE LSE et CEMAGREF |
| 16h30 - 17h00 | Discussion générale |
Volker Grimm, Helmholtz Center for Environmental Research, Leipzig
Mechanistic effect models for ecological risk assessment of chemicals: CREAM and the documentation framework TRACE
Population-level effects of chemicals, for example pesticides, depend not only on exposure and toxicity but also on ecological factors. It is impossible to fully address these factors empirically. Mechanistic effect models, for example ecological models, can solve this problem. They can be used to extrapolate results from single species tests and higher tier tests to the population level and larger scales. Currently, however, there is no common framework that would allow developing such models and assessing their quality in a coherent way. The EU-funded project CREAM ("Mechanistic Effect Models for Ecological Risk Assessments of Chemicals") aims at developing and establishing such a framework. CREAM will not only focus on what Good Modelling Practice is but also on how it can be developed and established. CREAM's central approach will be to use a common framework for documenting the modelling process, dubbed TRACE (Transparent Comprehensive Modelling) documentation1. TRACE provides a common structure for organizing and, at the same time, documenting the modelling process on a day-to-day basis. I will demonstrate the use of TRACE using example models. Finally, I will discuss a main further challeng of ecological modelling for chemical risk assessment: the agreement on practical but meaningful population-level endpoints.
Christelle Lopes, CEMAGREF
Transfer of PCB from sediment to biota in the Rhône river : development of a bioaccumulation model in a risk assessment perspective
Many chemical, physiological and trophic factors are known to be important in the bioaccumulation processes and trophic transfer of PCB in the biota. Understanding the primary factors influencing PCB contamination of fishes is critical for predicting and assessing risks to upper-trophic levels consumers including humans. We proposed here to (1) identify PCB contamination pathways that could explain between and within species variability in fish concentration levels; and (2) describe PCB transfer along fish food chain. Three freshwater river fishes (Barbel, Bream and Chub) were sampled in three sites along the Rhone river (France), where fish consumption is prohibited because of many exceeding of the European sanitary level. No relation was underlined between trophic position and fish PCB concentrations, while diet habitat exploitation appeared as an essential factor, the sediment compartment playing a central role in the contamination process. We showed that fish length, PCB concentration in the sediment and foraging habitat (exploitation of detrital carbon) explained around 80% of the within- and between species variability observed in PCB concentrations, saying that what fishes eat is less important in the contamination pathway than the place where they feed on. A bioaccumulation food-web model was thus developed in order to describe PCB transfer along the food chain of these fish species and to help determining sediment management guidelines.
Emilie Lacaze, ENTPE LSE et CEMAGREF
Aquatic ecosystems : tools for contaminant exposure and effect diagnosis in ecotoxicological survey -The example of a genotoxicity biomarker
The European Water Directive (2000/60/CE) aims to assess marine and freshwater quality in order to promote sustainable water use and improve the status of aquatic ecosystems. To this end, biomarkers and bioindicators have been developed and validated, in addition to conventional chemical analyses. Theoretically, these warning tools allow assessing the health of organisms and populations in aquatic ecosystems. However, several bottlenecks must be removed (large spatial and long-term time scales) to provide relevant tools for ecosystems biomonitoring (Flammarion et al.,2002; Forbes et al., 2006). Among these markers of particular interest is the development of genotoxicity biomarker because genotoxic agents can alter the structural integrity of the DNA and may produce a cascade of adverse changes from the cellular to the individual levels. We exposed here our scientific approach to develop a relevant biomarker of exposure and effect in an ecologically key species (Gammarus fossarum) and the intrinsic difficulties we met. In the perspective of a biomonitoring application for assessing genotoxicity of freshwater ecosystems, it is thus essential to (i) develop a procedure for which the lowest biomarker variability related to methodological and intrinsic biotic factors is obtained, (ii) define reference values of biomarker basal response taking into account its spatio-temporal changes and (iii) link the sub-individual response to higher level of biological organisation.
This session is sponsored by le cluster Environnement
