Ecotoxicological indicators of water quality: Using multi-response indicators to assess the health of aquatic ecosystems

As sensitive and ecologically relevant measures of environmental conditions , bioindicators can be used to assess the health of aquatic ecosystems whic h may be compromised by a variety of environmental stressors such as contam inants, sediments, nutrients, and varying temperature, salinity, and hydrol ogic regimes. The bioindicators approach is a proven bioassessment method t hat uses responses of key (sentinel) aquatic organisms both as integrators of stress effects and as sensitive response (early-warning) indicators of e nvironmental health. This integrated approach involves measuring a suite of selected biological and ecological responses at several levels of biologic al organization from the biomolecular and biochemical to the community leve ls. When properly designed and applied in field situations, bioindicator st udies can help identify causal mechanisms between environmental stressors a nd population and community-level effects, and serve as a basis for which t he effectiveness of remedial actions on the health of aquatic organisms can be evaluated. Rapidly-responding sensitive biomarkers, such as biomolecula r and biochemical responses, and slower-response ecologically relevant bioi ndicators, such as population and community responses, can be included in f ield bioassessment programs to provide measurement endpoints for use in env ironmental compliance, regulatory decision-making, and ecological risk asse ssments. This bioindicators approach should be particularly relevant in hel ping to identify and diagnose sources of stressors in environments impacted by multiple stressors. To demonstrate use of bioindicators in addressing w ater quality issues, spatial and temporal patters in various biological res ponses are related to spatial and temporal patterns of contaminants in two aquatic systems compromised by different stressors.