Editorial.- Editorial.- Principles of Bio-Indication.- The Need of an Ecological Quality-Concept.- Ecotoxicology.- Ecotoxicology and Environmental Quality.- Animal Indicators for Side-Efects of Chemical Vector Control.- Bio-indicators and Chemical Pollution of Surface Waters.- Toxicological Assessment of River Water Quality in Bioassays with Fish.- Indicators for the Quality of Air.- Biological Indicators of Air Pollution.- Higher Plants as Indicators and Accumulators of Gaseous Air Pollution.- Lichens as Indicators for Air Quality.- Indicators for the Quality of Soil.- Soil Properties Indicative for Quality.- Problems in Characterizing the Ecological Quality of Soil in Relation to Human Activities.- Bioindication of a Surplus of Heavy Metals in Terrestrial Ecosystems.- Soil Fauna and Soil Microflora as Possible Indicators of Soil Pollution.- Indicators for the Quality of Water.- General Remarks with Regard to Biological Indicators Used in Water Pollution Studies.- The Dynamics of Dissolved Oxygen Concentration for Water Quality Monitoring and Assessment in Polder Ditches.- Hydropsychidae as Bio-Indicators.- Zooplankton and Its Grazing as Indicators of Trophic Status in Dutch Lakes.- Bio-Indicators and the Quality of the Wadden Sea.- Indicators in Complex Systems.- Indicators in Complex Systems.- Vegetation as an Indicator of Environmental Changes.- Taraxacum Species as Environmental Indicators for Grassland Management.- Meadow Birds as Indicators.- Concluding Remarks from a Political Viewpoint.- Ecological Indicator Organisms for Environmental Protection Policy.- List of Authors.
