Towards the definition of environmental quality standards for biota : the influence of food web structure and dynamics on bioaccumulation and biomagnification

With the implementation of the Water Framework Directive and the daughter directive on Environmental Quality Standards (EQS), the development of EQS values for biota has become an important issue. However, for certain hydrophobic compounds, bioaccumulation and biomagnification in the food chain may occur. In this case, it is important to analyze, if depending on the food web and diet preferences, bioaccumulation values could be different for the same species in different ecosystems. To analyze this effect, we have studied four terrestrial and aquatic trophic network models generated previously for three similar lakes and a costal lagoon. In addition a simple ecological plus bioaccumulation model has been developed for analyzing diet preferences which could not be assessed using the developed trophic food webs. The objective was to assess if the similarities and differences between calculated trophic level could have consequences on the bioaccumulation and biomagnification potential of contaminants. The results indicate that differences of around two orders of magnitude can be expected for similar ecosystems. These results are important since they indicate that the ecosystem structure should be first assessed for the development of EQS for biota and that without this information intercomparison exercises between EU ecosystems are not possible.