An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

CADDIS Volume 1

Figures: Stressor-Response Relationships from the Field

Figure 3-6a. Stressor-Response Relationships from the Field, Supports

The impairment (dead fish) is greatest where the causal agent (the effluent) is most concentrated, and the impairment diminishes (more live fish) as the agent is diluted.

                     Figure 3-6a. shows how closer to the impairment site, there are dead fish but not downstream where it has dissolved.Figure 3-6a. Stressor-Response Relationships from the Field, Supports the Case
 


Figure 3-6b. Stressor-Response Relationships from the Field, Refutes

The impairment (dead fish) increases as the causal agent (the effluent) is diluted, and the impairment is absent where the agent is most concentrated as well as upstream.

Figure 3-6b. shows how closer to the impairment site, there are live fish but not downstream where it has dissolved - these are dead.Figure 3-6b. Stressor-Response Relationships from the Field, Refutes the Case
 


Explanation of the Types of Evidence Illustrations

This description applies to each of the types of evidence illustrations. These illustrations provide graphic explanations of the types of evidence. They are somewhat abstract to convey that they are representative of the concept rather than illustrations of particular applications. The live fish (green and upright) represent unimpaired organisms, populations or communities of all types, not just fish. The dead fish (white and belly-up at the surface) represent all biological impairments, not just dead fish. The pipe represents all sources and the yellow effluent plume represents all causal agents (stressors), not just effluents or even chemicals. Clock faces represent the passage of time, not the particular time difference illustrated. Fish in beakers represent laboratory tests. Other graphic elements used in particular illustrations are explained in the caption.

Top of Page