Stress-ecology, the need of an integrative approach
The aim of stress-ecology is to gain basic knowledge on how stressors impact the fitness of populations,the structure and dynamics of communities and the functioning of ecosystems. The ultimate goal of ecological risk assessment for contaminants is to provide knowledge that can be used to protect ecosystems (and their components) from chemical-stress. To achieve this, cooperation is required between environmental
chemists, (eco)toxicologists and ecologists. In addition, an integrative approach is required based on observation, experimentation, extrapolation and prediction. Adequate
decision support tools have to be developed for ecological risk assessment procedures,
but also to evaluate omissions in basic knowledge of ecosystem structure and functioning (hypothesis generating tools). The development of computer simulation models is probably the most reliable approach,at least if based on adequate observations in natural ecosystems and experimentation in the laboratory and under semi-field conditions (Figure 1). Ideally, laboratory tests, micro- and mesocosm experiments and field observations should be performed in cocert for developing decision support tools in the form of fate and effect models. An important obstacle in
the construction and application of fate and effect models on contaminants in aquatic ecosystems, however, is the lack of hard input data (Health Council
of the Netherlands, 1997). This includes system and process parameters that influence the bioavailability of contaminants in ecosystems, as well as data on the sensitivity (concentration-effect relationships), ecophysiology and life-histories of the essential key species and functional groups. Consequently, an integrative
approach also requires sufficient communication between model builders and scientists that perform the basic research, and between biologists active in the
fields of descriptive and experimental ecology.