Fish biomarkers for environmental monitoring within the Water Framework Directive of the European Union

In the past 25 years, numerous biomarkers have been developed with the objective to apply them for environmental biomonitoring. Recently, the Water Framework Directive (WFD) of the European Union specified monitoring programs required to assess the achievement of good chemical and ecological status for all water bodies by 2015. This article reviews the potential of biomarkers for ecotoxicological status assessment in WFD monitoring programs. For this purpose, we define the roles and the functions of biomarkers as biomonitoring tools. We also highlight the importance of defining a clear reference system to be confident that biomarkers represent a quantitative assessment of the effects of contaminants.