MODELKEY. Models for assessing and forecasting the impact of environmental key pollutants on freshwater and marine ecosystems and biodiversity

BACKGROUND

Triggered by the requirement of Water Framework Directive for a good ecological status for European river systems till 2015 and by still existing lacks in tools for cause identification of insufficient ecological status MODELKEY (http:// www.modelkey.org), an Integrated Project with 26 partners from 14 European countries, was started in 2005. MODELKEY is the acronym for 'Models for assessing and forecasting the impact of environmental key pollutants on freshwater and marine ecosystems and biodiversity'. The project is funded by the European Commission within the Sixth Framework Programme.

OBJECTIVES

MODELKEY comprises a multidisciplinary approach aiming at developing interlinked tools for an enhanced understanding of cause-effect-relationships between insufficient ecological status and environmental pollution as causative factor and for the assessment and forecasting of the risks of key pollutants on fresh water and marine ecosystems at a river basin and adjacent marine environment scale. New modelling tools for risk assessment including generic exposure assessment models, mechanistic models of toxic effects in simplified food chains, integrated diagnostic effect models based on community patterns, predictive component effect models applying artificial neural networks and GIS-based analysis of integrated risk indexes will be developed and linked to a user-friendly decision support system for the prioritisation of risks, contamination sources and contaminated sites.

APPROACH

Modelling will be closely interlinked with extensive laboratory and field investigations. Early warning strategies on the basis of sub-lethal effects in vitro and in vivo are provided and combined with fractionation and analytical tools for effect-directed analysis of key toxicants. Integrated assessment of exposure and effects on biofilms, invertebrate and fish communities linking chemical analysis in water, sediment and biota with in vitro, in vivo and community level effect analysis is designed to provide data and conceptual understanding for risk arising from key toxicants in aquatic ecosystems and will be used for verification of various modelling approaches.

CONCLUSION AND PERSPECTIVE

The developed tools will be verified in case studies representing European key areas including Mediterranean, Western and Central European river basins. An end-user-directed decision support system will be provided for cost-effective tool selection and appropriate risk and site prioritisation.

A population physiologically based pharmacokinetic/pharmacodynamic model for the inhibition of 11-beta-hydroxysteroid dehydrogenase activity by glycyrrhetic acid

Glycyrrhizic acid is widely applied as a sweetener in food products and chewing tobacco. Habitual consumption of this compound may lead to hypertension and electrolyte disturbances due to inhibition of 11-beta-hydroxysteroid dehydrogenase by the metabolite glycyrrhetic acid. The effect of 130 mg glycyrrhetic acid/day for 5 days on 11-beta-hydroxysteroid dehydrogenase activity was studied by measuring the cortisol-cortisone ratio in 24-h urine. A twofold increase in this ratio was observed. It took 4 days for the elevated urinary cortisol-cortisone ratio to return to the baseline ratio after cessation of the treatment. The pharmacokinetics of glycyrrhetic acid were studied after the first and last dose. Using data from a previously performed single-dose study and present multiple-dose treatment, a physiologically based pharmacokinetic model for glycyrrhetic acid was developed. The variability of the pharmacokinetics of glycyrrhetic acid in the population studied could be explained for a considerable part by interindividual differences in gastrointestinal transit of glycyrrhetic acid metabolites. The relationship between glycyrrhetic acid exposure and changes in urinary cortisol-cortisone ratio was described by a pharmacodynamic model, using nonlinear mixed-effect modeling. Literature data on the inhibitory effect of glycyrrhetic acid on 11-beta-hydroxysteroid dehydrogenase activity under various exposure scenarios could be adequately described by the model. Due to the relationship between the pharmacokinetics of glycyrrhetic acid and its inhibitory effect on 11-beta-hydroxysteroid dehydrogenase activity, reflected by a change in the urinary cortisol-cortisone ratio, this ratio might serve as a noninvasive marker to identify individuals at risk for glycyrrhizic acid over-consumption.

Hard work impinges on fitness: an experimental study with zebra finches

In experiments in which brood size is manipulated, it is impossible to disentangle the effects of changes in intensity and duration of parental care on parental fitness from those of changes in the parental energy budget. To determine whether a change in parental energy budget affects the costs of reproduction, we assessed the effects of increased levels of hopping activity, independent of parental care, on later reproductive decisions in zebra finches, Taeniopygia guttata. We imposed two levels of workload on individual, nonbreeding birds. After the workload periods, the birds were allowed to breed in ad libitum conditions. Each bird went through three alternating periods of working followed by breeding. The birds were more active, but weighed less and ate less, during the high workload than during the low workload periods. Clutch sizes and brood sizes did not vary with the previous work level. However, after a period on the high workload, reproduction, on average, was started 6 days later than after a low workload period. Females gained weight just before egg laying, but this might have been a result of egg production. If so, the delay in reproduction did not simply reflect extra time needed to restore body mass after a period of increased activity. We conclude that the level of daily activity itself, or the resulting energy budget during the workload periods, delayed reproduction. We suggest that these observations on the effects of increased activity demonstrate a causal mechanism for reduced residual fitness of parents. Copyright 1999 The Association for the Study of Animal Behaviour.