Landscape Ecotoxicology and Spatially Explicit Risk Assessment
Andreas Focks, Alterra and Wageningen University, Paul van den Brink, Alterra and Wageningen University, Melissa Reed, UK Health and Safety Executive, Mikhail Beketov, Helmholtz Centre for Environmental Research,UFZ
Natural ecosystems are often characterized by a high spatial and temporal variability (e.g., patch dynamics) that strongly influences ecological processes and can modify the exposure and effects of toxicants on organisms. While the spatial dimension has gained increasing attention in the exposure assessments in recent years, the effects assessment still largely ignores these aspects despite its relevance for realistic prediction and assessment of effects.
The session “Landscape Ecotoxicology and Spatially Explicit Risk Assessment” held during the SETAC Europe 23rd Annual Meeting, May 2012 in Glasgow, UK, aimed at advancing the inclusion of the spatial and temporal heterogeneity of natural systems within the field of ecotoxicology. It brought together researchers investigating the spatial and temporal dynamics of exposure to and effects of toxicants using field studies and modelling as well as a range of methods including genetics, biomonitoring and multivariate statistics.
When aiming for more ecological realism, the challenge for ecological risk assessment of chemicals is to integrate different aspects of exposure and effects: spatial scales of emissions, chemical exposure patterns in space and time, population growth dynamics and dispersal behaviour in landscapes. These aspects are not considered in the current scheme for risk assessment, but risk assessors and managers express increasing interest in understanding more about the occurrence and the effects of chemicals on the landscape level.
Presentations in this session gave insights into current research in this area. Field monitoring studies showed considerable concentrations of the already banned pesticides lindane and atrazine in the grey partridge (Perdix perdix) in France, hence indicating either illegal use of these compounds or long-term residues in the environment. In a more general study, Mikhail Beketov related pesticide occurrence in waters to measures of regional biodiversity in Europe and Australia. The exciting results showed a clear relation between the pesticide concentration levels in aquatic systems and the regional taxonomic pools of freshwater invertebrates. The results of this study challenge the performance of current risk assessment procedures to protect biodiversity on a regional level. Jes Rasmussen showed an increased toxicity of a pyrethroid insecticide in the presence of suspended organic matter in water, which is of considerable relevance for risk assessment. Mechteld ter Horst explained, based on a simulation study, how water network structures in landscapes influence the concentration dynamics of an insecticide, hence pinpointing the importance of a spatially explicit view on the exposure to pesticides. Jaqueline Augusiak came up with the suggestion to use the term “evaludation” in relation to the validation of mathematical and simulation models, something that is in particular needed for incorporation of chemical fate and effect models on a landscape or regional scale. Chris Topping showed that the outcome of larger-scale risk assessment is strongly influenced by the choice of the spatial scale for the analysis. Paul van den Brink showed results from a simulation study that indicate that the effects of multiple pesticides on aquatic invertebrates add up, but population recovery times are not higher for combinations of toxicants as compared to single compounds.
In general, there is a clear awareness of the need for research in the field of spatially explicit risk assessment and landscape ecotoxicology and of the urge to make headway in this sector to meet challenges such as the threatening loss of biodiversity. The current level of research is still on a basic level. Field monitoring studies and spatially explicit landscape-scale fate models are available, but often are not linked with each other. Landscape-scaled and spatially realistic effect models are “in development.” A clear direction and common objectives and hence the power of synergistic interdisciplinary research is, however, missing. Thus, the upcoming challenge appears to be linking individual research initiatives to provide more evidence and understanding of the processes that govern fate and effects of chemicals on a regional scale.
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