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.- II Responses of Ecosystems to Chemical Stress.- 3 Effects of Heavy Metals in a Polluted Aquatic Ecosystem.- 4 Determining the Ecological Effects of Oil Pollution in Marine Ecosystems.- 5 The Effects of Chemical Stress on Aquatic Species Composition and Community Structure.- 6 Theoretical and Methodological Reasons for Variability in the Responses of Aquatic Ecosystem Processes to Chemical Stresses.- 7 The Effects of Chemicals on the Structure of Terrestrial Ecosystems: Mechanisms and Patterns of Change.- III Methods and Models.- 8 Models in Ecotoxicology: Methodological Aspects.- 9 Mathematical Models-Fate, Transport, and Food Chain.- 10 Deterministic and Statistical Models of Chemical Fate in Aquatic Systems.- 11 Bioaccumulation of Hydrophobic Organic Pollutant Compounds.- 12 Environmental Chemical Stress Effects Associated with Carbon and Phosphorus Biogeochemical Cycles.- 13 Biomonitoring: Closing the Loop in the Environmental Sciences.- 14 The Role of Terrestrial Microcosms and Mesocosms in Ecotoxicologic Research.- 15 The Role of Aquatic Microcosms in Ecotoxicologic Research as Illustrated by Large Marine Systems.- IV Ecotoxicological Decision Making.- 16 Ecotoxicology Beyond Sensitivity: A Case Study Involving "Unreasonableness" of Environmental Change.- 17 Regulatory Framework for Ecotoxicology.- 18 Environmental Decision Making in the Presence of Uncertainty.