Figure 2-3. Lower levels of biological organization are more tractable for testing than higher levels, but are less ecologically relevant

protect abiotic ROC is quite straightforward. If a standard is not met, it is assumed

that the abiotic ROC the standard is intended to protect is at risk unless it can be

clearly demonstrated otherwise. In this case, some type of management action may

be appropriate.

The case of biotic ROC is much more complex. The state of the art of

predictive biological testing and evaluation is such that standard laboratory tests

address changes at the organism or suborganism level, while effects on ROC

occur in the field at higher levels of biological organization. Predictive tests are

usually conducted under laboratory conditions, or occasionally under "controlled"

field conditions. Thus, interpretation of results in terms of an effect on a biotic

ROC requires extrapolation from laboratory to field conditions, as well as

extrapolation from lower to higher levels of biological organization and perhaps

from surrogate species to the ROC. Figure 2-3 is a conceptual illustration of the

hierarchy of biological organization in relation to ecological relevance and

tractability of testing. The most tractable tests address responses at the cellular,

organ, and individual levels (i.e., levels 1 through 4) of biological organization.

Population, community, and ecosystem levels of biological organization (levels 5

through 7) are much more difficult to test and evaluate predictively but are the

levels at which the potential for effects should be evaluated. Most of the

biological evaluations in the UTM are at the life history level of organization

(level 4), measuring effects on survival, growth, and reproduction of individual

organisms under laboratory conditions. Some tests may be conducted at lower

levels of biological organization, and there is ongoing scientific attention to

prediction of population-level responses from individual life history data. At

present, however, evaluation of the potential for effects should be based on results

of laboratory tests at the level of individual organisms extrapolated to populations,

communities, and ecosystems in the field.

Figure 2-3. Lower levels of biological organization are more tractable for testing

than higher levels, but are less ecologically relevant

Whether risks to individual organisms imply that management actions are

needed to protect ROC at the population, community, or ecosystem level depends

on many factors, all of which should be considered, because none are singularly

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Chapter 2 Structure and Approach of the UTM