Ecotoxicological management and research have several instruments at their disposal. A discriminatory is made between monitoring of chemical, biochemical, toxicological and ecological parameters, and modeling at a simple, intermediate, and complex level. Their usefulness is discussed and illustrated by examples from the Rhine‐Meuse delta.
Each type of instrument has its own benefits. In simple cases, application of one instrument will do. More often, however, the objectives set, the compounds concerned, and the species involved require a combination of tools to be used. Chemical and biochemical parameters are oriented around sources and concentrations of well‐known priority substances. Toxicological and ecological variables, on the other hand, are directed toward species and the impact of these compounds and other factors as well. In the Rhine‐Meuse delta, contamination decreases and more refined instruments are needed to pick out the compounds and species that should get our attention most. An intermediate level of modeling is considered the next logical step after application of simple rules of thumb. © 1997 John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 321–333, 1997.