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 This website is no longer updated and links to external websites and some internal pages may not work.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

Example Stressor-Response Relationships Table

Stressor Characterization of Exposure: Intensity, Time, and Space Stressor-Response Relationships
Toxic chemical External concentration in medium Internal concentration in organism Biomarker Concentration-response or time-response relationships from controlled experiments or field observational studies; ecological process models.
Dissolved oxygen and oxygen-demanding contaminants (e.g., BOD, COD) Dissolved oxygen concentrations Concentration-response relationships from controlled experiments or field observational studies; ecological process models.
Suspended particles Suspended concentration (e.g., TSS) Concentration-response relationships from controlled experiments or field observational studies.
Settled particles (bed load) Degree of embeddedness, texture Embeddedness- or particle size-response relationships from controlled experiments or field observational studies.
Thermal energy Temperature Thermal tolerances from controlled experiments or field observational studies.
Mineral nutrients Dissolved concentration Concentration-response relationships from controlled experiments or field observational studies. Ecological process models of eutrophication.
Habitat Structural attributes Attribute-response relationships from field observational studies; ecological process models; habitat suitability models
Water withdrawal/drought Hydrograph and associated summary statistics (e.g., 7Q10) Field observational studies; in-stream flow process models.
Pathogen Presence or abundance of pathogen Controlled laboratory exposures or field observational studies relating pathogen presence with disease or symptoms
Non-indigenous invasive species Presence or abundance of the species Ecological process models (food web, energetic, predator-prey, etc.) or field observational studies.
Effluent Dilution of effluent Effluent dilution - response in the laboratory (e.g., WET)
Contaminated ambient media Location and time of collection Analysis of medium - lab or in situ tests using the medium.