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Toxic stress in multiply stressed ecosystems

Toxic stress in multiply stressed ecosystems. Helmut Segner, Daniel Bontje, Pavel Jurajda, Bob Kooi, Isabel Munoz, Peter von der Ohe, Marketa Ondrakova, Stefanie Rotter, Sergi Sabater, Mechthild Schmitt-Jansen, Michael Wenger, Dick de Zwart.

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Toxic stress in multiply stressed ecosystems

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  1. Toxic stress in multiply stressed ecosystems Helmut Segner, Daniel Bontje, Pavel Jurajda, Bob Kooi, Isabel Munoz, Peter von der Ohe, Marketa Ondrakova, Stefanie Rotter, Sergi Sabater, Mechthild Schmitt-Jansen, Michael Wenger, Dick de Zwart

  2. Motivation: understanding the relation between chemical and ecological status of aquatic resources Chemical status relates to ecological status Chemical status does not relatesto ecological status Cf. presentationm Jos van Gils

  3. Why are there mismatches between chemical and ecological status ? • Effects of unknown chemicals (cf. presentation Werner Brack) • Flaws in predicting of ecological responses to complex chemical mixtures on the basis of single compound, single chemical laboratory tests • Impacts of multiple stressors, chemical and non-chemical ones (hydromorphology, pathogens, climate change,...)

  4. Case study of MODELKEY: disaggregating multiple stressors in the Bilina river, Czech Republic Toxic chemical impact expressed as „toxic units“ Linear downstream increase of toxic impact Wenger et al., in press

  5. Case study of MODELKEY: disaggregating multiple stressors in the Bilina river, Czech Republic Fish ecological status does not relate to chemical status U shape Only fish species left; chub  hypoxia trolerant Wenger et al., in press

  6. Case study of MODELKEY: multiple stressors in the Bilina river, Czech Republic Fish ecological status relates to water oxygen levels U-shape Wenger et al., in press

  7. The WFD expresses the need to consider non-chemical together with chemical stressors • The WFD requires „the identification of significant anthropogenic pressures and the assessment of their impacts on water bodies„ (Annex II, WFD). • In European river basins we are frequently confronted with multiple stressor situations, with the role of non-chemical stressors increasing at decreasing toxic stress. • In order to decide on priority actions for improving the ecological status, water managers must be able to define a hierarchy amongst the various stressors and to understand combined impacts of multiple stressors.  But how to tackle this practically ?

  8. Correlational approaches to diagnose the importance of toxic chemicals in relation to other stressors A3A 1.0 Ibuprofen Pharmaceuticals and temperature explain 71 % of the species variance in the Llobregat river (MODELKEY case study; redundancy analysis) Temperature LL4C LL4A LL3A LL2C LL1A LL1C LL3C LL2A A2C LL2B Propranolol A3B A3C LL3B A1A A1C A1B Indomethacine LL1B A2A LL4B -0.6 A2B -0.4 1.2 Muñoz et al.; Env.Tox.Chem., 28 (12): 2706-2714 (2009)

  9. Correlational approaches to diagnose the importance of toxic chemicals in comparison to other stressors Effect-and-possible-cause pies (EPCs) Dick de Zwart et al. 2009

  10. A major challenge is to assess stressor interactions: for instance, combination effects Dose metrics to measure the interaction between water ion concentrations and prometryn toxicvity on biofilm communities Synergism ? Rotter et al. 2009

  11. A major challenge is to assess stressor interactions: for instance, non-linear effects Organism altered repro-duction Estrogen-active compounds Molecular and physiological effects Molecular and physiological effects reduced survival pathogen

  12. A major challenge is to assess stressor interactions: for instance, non-linear effects altered repro-duction Estrogen-active compounds Molecular and physiological effects Molecular and physiological effects Synergistic effect on survival pathogen

  13. Worldwide decline of amphibians: consequence of interactions between toxicants and pathogens ? PNAS, 2002

  14. Additional complication in assessing combined stressor impact: biological scaling e.g., prediction to population level: Example: Critical prometryn concentrations for flagellate population in combination with varying nitrogen levels More: : Presentation Leo Posthuma e.g., species traits and sensitivities

  15. Conclusions • To identify causes of ecological impairment in a multiple stressor situation, water managers need tools, approaches and models • for setting hierarchies on the relative importance of stressors: e.g., tools to quantify various stressors and stressor-related responses; • for evidencing cause-effect relationships: e.g., toxico-genomics to identify unexpected interactions, bioenergetic models, dose metrics to determine thresholds of combined effects, species vulnerability models, • for extrapolating multiple stressor effects across biological, spatial and temporal scales: e.g. epidemiological tools, ecology-based models • Recent years have seen much progress in approaches to assess ecological impact of toxic chemicals and chemical mixtures, we are now ready to close the existing gaps in multiple stressor assessment.

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