Ecotoxicology: Problems and Approaches

Ecotoxicology is the science that seeks to predict the impacts of chemi­ cals upon ecosystems. This involves describing and predicting ecological changes ensuing from a variety of human activities that involve release of xenobiotic and other chemicals to the environment. A fundamental principle of ecotoxicology is embodied in the notion of change. Ecosystems themselves are constantly changing due to natural processes, and it is a challenge to distinguish the effects of anthropogenic activities against this background of fluctuations in the natural world. With the frustratingly large, diverse, and ever-emerging sphere of envi­ ronmental problems that ecotoxicology must address, the approaches to individual problems also must vary. In part, as a consequence, there is no established protocol for application of the science to environmental prob­ lem-solving. The conceptual and methodological bases for ecotoxicology are, how­ ever, in their infancy, and thus still growing with new experiences. In­ deed, the only robust generalization for research on different ecosystems and different chemical stresses seems to be a recognition of the necessity of an ecosystem perspective as focus for assessment. This ecosystem basis for ecotoxicology was the major theme of a previous pUblication by the Ecosystems Research Center at Cornell University, a special issue of Environmental Management (Levin et al. 1984). With that effort, we also recognized an additional necessity: there should be a continued develop­ ment of methods and expanded recognition of issues for ecotoxicology and for the associated endeavor of environmental management.

I Ecotoxicology: Problems and Approaches.- 1 Ecotoxicology: Problems and Approaches.- 2 Indicators of Ecosystem Response and Recovery.- 2.1 Stress, Ecosystem Response, and Recovery.- 2.2 A Focus on Useful Ecological Endpoints.- 2.3 Ecosystem Indicators.- 2.4 Conclusion.- II Responses of Ecosystems to Chemical Stress.- 3 Effects of Heavy Metals in a Polluted Aquatic Ecosystem.- 3.1 Approaches.- 3.2 Some Background on Metal-Polluted Foundry Cove.- 3.3 Effects of Heavy Metals on the Composition of the Macrobenthos.- 3.4 The Evolution of Resistance to Heavy Metals.- 3.5 Heavy Metal Accumulation and Detoxification in Resistant Biota.- 3.6 Conclusion.- 4 Determining the Ecological Effects of Oil Pollution in Marine Ecosystems.- 4.1 Acute Toxicity, the LD50 Approach.- 4.2 Ecosystem-Level Approaches.- 4.3 Effects of Oil Pollution on Benthic Communities.- 4.4 Effects of Oil Pollution on Planktonic Communities.- 4.5 Significance of the Observed Ecosystem Effects.- 4.6 Conclusions.- 5 The Effects of Chemical Stress on Aquatic Species Composition and Community Structure.- 5.1 Information Required for Effective Resource Management.- 5.2 Methodologies Used in the Study of Chemical Stress Effects.- 5.3 Early Studies of Community Composition and Structure as Indicators of Chemical Stress: The Historical Context.- 5.4 Structural Changes.- 5.5 Conclusions.- 6 Theoretical and Methodological Reasons for Variability in the Responses of Aquatic Ecosystem Processes to Chemical Stresses.- 6.1 The Global Significance of Ecosystem Processes and Chemical Stresses.- 6.2 The Detection of Ecosystem Responses to Stress.- 6.3 Terminology.- 6.4 Methodological Issues.- 6.5 Mechanistic Issues.- 6.6 Effects of Chemical Stress on Functional Networks.- 6.7 Chemical Stress Effects on Interactions Between Functional Networks.- 6.8 Indices of Ecosystem Health.- 6.9 Conclusions.- 7 The Effects of Chemicals on the Structure of Terrestrial Ecosystems: Mechanisms and Patterns of Change.- 7.1 Mechanisms of Chemical Exposure.- 7.2 Effects of Disturbance on Organisms.- 7.3 Consequences of Organism Injury to Alterations in Ecosystem Structure.- 7.4 Conclusions.- III Methods and Models.- 8 Models in Ecotoxicology: Methodological Aspects.- 8.1 Physical and Biological Scales.- 8.2 Aggregation, Simplification, and the Problem of Dimensionality.- 8.3 Equilibrium and Variability.- 9 Mathematical Models―Fate, Transport, and Food Chain.- 9.1 Components of Model.- 9.2 Transport, Salinity, and Solids Analyses.- 9.3 Organic Chemicals in the Water Column.- 9.4 Application to Kepone in the James River.- 9.5 Food Chain.- 9.6 Application to James River Striped Bass Food Chain.- 9.7 Conclusion.- 10 Deterministic and Statistical Models of Chemical Fate in Aquatic Systems.- 10.1 Theory.- 10.2 Steady-State Simplification.- 10.3 Deterministic Time Variable Models.- 10.4 Statistical Variation in Fish.- 10.5 Conclusions.- 11 Bioaccumulation of Hydrophobic Organic Pollutant Compounds.- 11.1 Physical-Chemical Considerations and Bioavailability.- 11.2 Biological Uptake, Retention, Metabolism, and Release.- 11.3 Bivalve Molluscs.- 11.4 Fish, Crustacea, and Polychaetes.- 11.5 Dietary Source of Organic Pollutants.- 11.6 Conclusion.- 12 Environmental Chemical Stress Effects Associated with Carbon and Phosphorus Biogeochemical Cycles.- 12.1 Carbon Cycle.- 12.2 Phosphorus Cycle.- 12.3 Simple Cycle Models.- 12.4 Analysis of Environmental Stresses in Carbon and Phosphorus Cycles.- 12.5 Stresses and Perturbations in the Carbon and Phosphorus Cycles.- 12.6 Sensitivity of Nutrient Flows to Biotic and Mineral Controls.- 12.7 Conclusion.- 13 Biomonitoring: Closing the Loop in the Environmental Sciences.- 13.1 Biomonitoring Programs for Ecosystems.- 13.2 Improving Biomonitoring Programs.- 13.3 Ecotoxicological and Biomonitoring Systems.- 14 The Role of Terrestrial Microcosms and Mesocosms in Ecotoxicologic Research.- 14.1 Historical Perspective.- 14.2 Microcosms as an Appropriate Technology.- 14.3 Mesocosms as an Appropriate Technology.- 14.4 Relationship to Mathematical Modeling.- 14.5 Ecotoxicological Applications of Microcosms and Mesocosms.- 14.6 Conclusions.- 14.7 Summary.- 15 The Role of Aquatic Microcosms in Ecotoxicologic Research as Illustrated by Large Marine Systems.- 15.1 Types of Microcosms.- 15.2 Applicability of Microcosm Results to Nature.- 15.3 Comparison of Microcosms with Other Experimental Approaches.- 15.4 Representative Results from Microcosms.- 15.5 Conclusion.- IV Ecotoxicological Decision Making.- 16 Ecotoxicology Beyond Sensitivity: A Case Study Involving “Unreasonableness” of Environmental Change.- 16.1 Potential Impacts on Seagrasses as an Ecotoxicological Case Study.- 16.2 Beyond Sensitivity: Raising the Acceptability Issue.- 16.3 Conclusion and Prospectus.- 17 Regulatory Framework for Ecotoxicology.- 17.1 Toxic Substances Control Act (TSCA).- 17.2 Clean Water Act (CWA).- 17.3 Clean Air Act (CAA).- 17.4 Resource Conservation and Recovery Act (RCRA).- 17.5 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or Superfund.- 17.6 Safe Drinking Water Act (SDWA).- 17.7 Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).- 18 Environmental Decision Making in the Presence of Uncertainty.- 18.1 Regulatory and Ecological Endpoints.- 18.2 Effects of Chemicals on Ecosystems.- 18.3 Sources of Ecological Uncertainties.- 18.4 Environmental Decision Making.