| ||Format||Pages||Price|| |
|PDF (136K)||8||$25||  ADD TO CART|
|Complete Source PDF (8.1M)||550||$65||  ADD TO CART|
The procedures for assessing the toxic effects of potential environmental contaminants are hierarchical, being composed of the following four sequential steps: (1) single-species acute and chronic toxicity tests, (2) tests of ecological interactions with simple communities in laboratory microcosms, (3) experiments on chemical-induced changes in ecosystem structure and function, in which replicate pond and artificial stream ecosystems are used, and (4) use of techniques for assessment of the actual impact of the contaminant on natural ecosystems.
Experiments involving semicontrolled artificial ecosystems in ponds and streams are carried out over the course of one or two years to identify the magnitude of (1) the primary direct effects of contaminants on the principal elements of the biological community and (2) the secondary or indirect effects of stress due to changes in critical structural or functional variables of the ecosystem. The results from ecosystem-contaminant studies can be used to establish the applicability of laboratory bioassays, to examine the qualities that enable ecosystems to resist contaminant stress and recover from it, and to answer questions on the effect of long-term stress of chemicals with herbicidal or insecticidal properties.
hierarchical assessment, ecosystem-level contaminant research, indirect toxic effects, community structure analysis, community function analysis, aquatic toxicology, hazard assessment
Leader, Ecosystem Research Section, U.S. Fish and Wildlife Service, Columbia National Fisheries Research Laboratory, Columbia, MO