Modelkey is a 5 years Integrated Project (IP) funded by the European Sixth Framework Program, started on 1st February 2005 and involving 25 partners in the European countries. Its main objective was to develop interlinked and verified diagnostic and predictive modelling tools as well as state of-the-art effect-assessment and analytical methods generally applicable to European freshwater and marine ecosystems. In order to address this objective it was structured in the following 7 subprojects:

• KEYTOX (tool development and application for effect-directed identification of site- and basin-specific key toxicants),
• BASIN (database development),
• EXPO (establishment of easy-to-use exposure models for the prediction of risks of toxic pollution in river basins and adjacent coastal areas),
• EFFECT (development of deterministic and stochastic models for understanding, diagnosis and prediction of effects on populations, communities and ecosystems and their biodiversity),
• SITE (to deliver and apply site-directed experimental and field tools),
• DECIS (development of integrated risk indexes and decision support systems),
• DIS/TRAIN (dissemination of results and organization of training programmes for MODELKEY participants, external scientists and end-users).

In particular, Venice Research Consortium (CVR) was in charge of the coordination of the subproject DECIS that included three workpackages:

1. DECIS 1 (Development of Conceptual Framework and hot spots prioritisation module) aimed at providing a common framework to integrate project deliverables and at formulating DSS structure. Moreover, it developed the hot spots prioritisation module, in particular the socio-economic and economic analysis.
2. DECIS 2 (Integrated Risk Index) aimed at developing and applying a Weight of Evidence (WoE) based Integrated Risk Index (IRI), which provides the integrated estimation of ecological impacts of identified contaminants on biodiversity.
3. DECIS 3 (Development and evaluation of DECIS DSS) concerned the Decision Support System computer development and its evaluation through the application to the MODELKEY case-studies: Elbe, Scheldt and Llobregat.

The developed MODELKEY DSS prototype is a tool supporting the Water Framework Directive (WFD) implementation (e.g. by assessing chemical and ecological status and prioritizing hot-spots according to environmental and socio-economic perspectives). It is currently downloadable from the project website after registration.