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CADDIS Volume 1: Stressor Identification

Summary Table of Scores

Type of Evidence Finding Interpretation Score
Types of Evidence that Use Data from the Case
Spatial/Temporal Co-occurrence
The effect occurs where or when the candidate cause occurs, OR the effect does not occur where or when the candidate cause does not occur. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because the association could be coincidental. +
It is uncertain whether the candidate cause and the effect co-occur. This finding neither supports nor weakens the case for the candidate cause, because the evidence is ambiguous. 0
The effect does not occur where or when the candidate cause occurs, OR the effect occurs where or when the candidate cause does not occur. This finding convincingly weakens the case for the candidate cause, because causes must co-occur with their effects. - - -
The effect does not occur where and when the candidate cause occurs, OR the effect occurs where or when the candidate cause does not occur, and the evidence is indisputable. This finding refutes the case for the candidate cause, because causes must co-occur with their effects. R
Temporal Sequence
The candidate cause occurred prior to the effect. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because the association could be coincidental. +
The temporal relationship between the candidate cause and the effect is uncertain. This finding neither supports nor weakens the case for the candidate cause, because the evidence is ambiguous. 0
The candidate cause occurs after the effect. This finding convincingly weakens the case for the candidate cause, because causes cannot precede effects (note that this should be evaluated with caution when multiple sufficient causes are present). - - -
The candidate cause occurs after the effect, and the evidence is indisputable. This finding refutes the case for the candidate cause, because effects cannot precede causes. R
Stressor-Response Relationship from the Field
A strong effect gradient is observed relative to exposure to the candidate cause, at spatially linked sites, and the gradient is in the expected direction. This finding strongly supports the case for the candidate cause, but is not convincing due to potential confounding. + +
A weak effect gradient is observed relative to exposure to the candidate cause, at spatially linked sites, OR a strong effect gradient is observed relative to exposure to the candidate cause, at non-spatially linked sites, and the gradient is in the expected direction. This finding somewhat supports the case for the candidate cause, but is not strongly supportive due to potential confounding or random error. +
An uncertain effect gradient is observed relative to exposure to the candidate cause. This finding neither supports nor weakens the case for the candidate cause, because the evidence is ambiguous. 0
An inconsistent effect gradient is observed relative to exposure to the candidate cause, at spatially linked sites, OR a strong effect gradient is observed relative to exposure to the candidate cause, at non-spatially linked sites, but the gradient is not in the expected direction. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening due to potential confounding or random error. -
A strong effect gradient is observed relative to exposure to the candidate cause, at spatially linked sites, but the relationship is not in the expected direction. This finding strongly weakens the case for the candidate cause, but is not convincing due to potential confounding. - -
Causal Pathway
Data show that all steps in at least one causal pathway are present. This finding strongly supports the case for the candidate cause, because it is improbable that all steps occurred by chance; it is not convincing because these steps may not be sufficient to generate sufficient levels of the cause. + +
Data show that some steps in at least one causal pathway are present. This finding somewhat supports the case for the candidate cause. +
Data show that the presence of all steps in the causal pathway is uncertain. This finding neither supports nor weakens the case for the candidate cause. 0
Data show that there is at least one missing step in each causal pathway. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because it may be due to temporal variability, problems in sampling or analysis, or unidentified alternative pathways. -
Data show, with a high degree of certainty, that there is at least one missing step in each causal pathway. This finding convincingly weakens the case for the candidate cause, assuming critical steps in each pathway are known, and are not found at the impaired site after a well-designed, well-performed, and sensitive study. - - -
Evidence of Exposure or Biological Mechanism
Data show that exposure or the biological mechanism is clear and consistently present. This finding strongly supports the case for the candidate cause, but is not convincing because it does not establish that the level of exposure or mechanistic action was sufficient to cause the effect. + +
Data show that exposure or the biological mechanism is weak or inconsistently present. This finding somewhat supports the case for the candidate cause. +
Data show that exposure or the biological mechanism is uncertain. This finding neither supports nor weakens the case for the candidate cause. 0
Data show that exposure or the biological mechanism is absent. This finding strongly weakens the case for the candidate cause, but is not convincing because the exposure or the mechanism may have been missed. - -
Data show that exposure or the biological mechanism is absent, and the evidence is indisputable. This finding refutes the case for the candidate cause. R
Manipulation of Exposure
The effect is eliminated or reduced when exposure to the candidate cause is eliminated or reduced, OR the effect starts or increases when exposure to the candidate cause starts or increases. This finding convincingly supports the case for the candidate cause, but it may be given a lower score if it could have resulted from other factors (e.g., removal of more than one agent or other unintended effects of the manipulation). + + +
Changes in the effect after manipulation of the candidate cause are ambiguous. This finding neither supports nor weakens the case for the candidate cause. 0
The effect is not eliminated or reduced when exposure to the candidate cause is eliminated or reduced, OR the effect does not start or increase when exposure to the candidate cause starts or increases. This finding convincingly weakens the case for the candidate cause, because such manipulations can avoid confounding. However, effects may continue if there are impediments to recolonization or if another sufficient cause is present. - - -
The effect is not eliminated or reduced when exposure to the candidate cause is eliminated or reduced, OR the effect does not start or increase when exposure to the candidate cause starts or increases, and the evidence is indisputable. This finding refutes the case for the candidate cause, given that data are based on a well-designed and well-performed study. R
Laboratory Tests of Site Media
Laboratory tests with site media show clear biological effects that are closely related to the observed impairment. This finding convincingly supports the case for the candidate cause. + + +
Laboratory tests with site media show ambiguous effects, OR clear effects that are not closely related to the observed impairment. This finding somewhat supports the case for the candidate cause. +
Laboratory tests with site media show uncertain effects. This finding neither supports nor weakens the case for the candidate cause. 0
Laboratory tests with site media show no toxic effects that can be related to the observed impairment. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening, because test species, responses or conditions may be inappropriate relative to field conditions. -
Verified Predictions
Specific or multiple predictions of other effects of the candidate cause are confirmed. This finding convincingly supports the case for the candidate cause, because predictions confirm a mechanistic understanding of the causal relationship, and verification of a predicted association is stronger evidence than associations explained after the fact. + + +
A general prediction of other effects of the candidate cause is confirmed. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because another cause may be responsible. +
It is unclear whether predictions of other effects of the candidate cause are confirmed. This finding neither supports nor weakens the case for the candidate cause. 0
A prediction of other effects of the candidate cause fails to be confirmed. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening, because other factors may mask or interfere with the predicted effect. -
Multiple predictions of other effects of the candidate cause fail to be confirmed. This finding convincingly weakens the case for the candidate cause. - - -
Specific predictions of other effects of the candidate cause fail to be confirmed, and the evidence is indisputable. This finding refutes the case for the candidate cause. R
Symptoms
Symptoms or species occurrences observed at the site are diagnostic of the candidate cause. This finding is sufficient to diagnose the candidate cause as the cause of the impairment, even without the support of other types of evidence. D
Symptoms or species occurrences observed at the site include some but not all of a diagnostic set, OR symptoms or species occurrences observed at the site characterize the candidate cause and a few others. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because symptoms or species are indicative of multiple possible causes. +
Symptoms or species occurrences observed at the site are ambiguous or occur with many causes. This finding neither supports nor weakens the case for the candidate cause. 0
Symptoms or species occurrences observed at the site are contrary to the candidate cause. This finding convincingly weakens the case for the candidate cause. - - -
Symptoms or species occurrences observed at the site are indisputably contrary to the candidate cause. This finding refutes the case for the candidate cause. R
Types of Evidence that Use Data from Elsewhere
Mechanistically Plausible Cause
A plausible mechanism exists. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because levels of the agent may not be sufficient to cause the observed effect. +
No mechanism is known. This finding neither supports nor weakens the case for the candidate cause. 0
The candidate cause is mechanistically implausible. This finding strongly weakens the case for the candidate cause, but is not convincing because the mechanism could be unknown. - -
Stressor-Response Relationships from Laboratory Studies
The observed relationship between exposure and effects in the case agrees quantitatively with stressor-response relationships in controlled laboratory experiments. This finding strongly supports the case for the candidate cause, but is not convincing because the correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and the laboratory. + +
The observed relationship between exposure and effects in the case agrees qualitatively with stressor-response relationships in controlled laboratory experiments. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because the correspondence is only qualitative, and the degree of correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and the laboratory. +
The agreement between the observed relationship between exposure and effects in the case and stressor-response relationships in controlled laboratory experiments is ambiguous. This finding neither supports nor weakens the case for the candidate cause. 0
The observed relationship between exposure and effects in the case does not agree with stressor-response relationships in controlled laboratory experiments. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because there may be differences in organisms or conditions between the case and the laboratory. -
The observed relationship between exposure and effects in the case does not even qualitatively agree with stressor-response relationships in controlled laboratory experiments, or the quantitative differences are very large. This finding strongly weakens the case for the candidate cause, but is not convincing because there may be substantial and consistent differences in organisms or conditions between the case and the laboratory. - -
Stressor-Response Relationships from Other Field Studies
The stressor-response relationship in the case agrees quantitatively with stressor-response relationships from other field studies. This finding strongly supports the case for the candidate cause, but is not convincing because the correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and elsewhere. + +
The stressor-response relationship in the case agrees qualitatively with stressor -response relationships from other field studies. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because the correspondence is only qualitative, and the degree of correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and elsewhere. +
The agreement between the stressor-response relationship in the case and stressor-response relationships from other field studies is ambiguous. This finding neither supports nor weakens the case for the candidate cause. 0
The stressor-response relationship in the case does not agree with stressor-response relationships from other field studies. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because there may be differences in organisms or conditions between the case and elsewhere. -
There are large quantitative differences or clear qualitative differences between the stressor-response relationship in the case and the stressor-response relationships from other field studies. This finding strongly weakens the case for the candidate cause, but is not convincing because there may be substantial and consistent differences in organisms or conditions between the case and elsewhere. - -
Stressor-Response Relationships from Ecological Simulation Models
The observed relationship between exposure and effects in the case agrees with the results of a simulation model. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because models may be adjusted to simulate the effects. +
The results of simulation modeling are ambiguous. This finding neither supports nor weakens the case for the candidate cause. 0
The observed relationship between exposure and effects in the case does not agree with the results of simulation modeling. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening, because it may be due to lack of correspondence between the model and site conditions. -
Manipulation of Exposure at Other Sites
At other sites, the effect is consistently eliminated or reduced when exposure to the candidate cause is eliminated or reduced, OR the effect is consistently starts or increases when exposure to the candidate cause starts or increases. This finding convincingly supports the case for the candidate cause, because consistent results of manipulations at many sites are unlikely to be due to chance or irrelevant to the site being investigated. + + +
At other sites, the effect is eliminated or reduced at most sites when exposure to the candidate cause is eliminated or reduced, OR the effect starts or increases at most sites when exposure to the cause starts or increases. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because consistent results of manipulation at one or a few sites may be coincidental or irrelevant to the site being investigated. +
Changes in the effect after manipulation of the candidate cause are ambiguous. This finding neither supports nor weakens the case for the candidate cause. 0
At other sites, the effect is not consistently eliminated or reduced when exposure to the cause is eliminated or reduced, OR the effect does not consistently start or increase when exposure to the cause starts or increases. This finding strongly weakens the case for the candidate cause, but is not convincing because failure to eliminate or induce effects at one or a few sites may be due to poorly conducted studies, or results may be irrelevant due to differences among sites. - -
Analogous Stressors
Many similar agents at other sites consistently cause effects similar to the impairment. This finding strongly supports the case for the candidate cause, but is not convincing because of potential differences among the agents or in conditions among the sites. + +
One or a few similar agents at other sites cause effects similar to the impairment. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because of potential differences among the agents or in conditions among the sites. +
One or a few similar agents at other sites do not cause effects similar to the impairment. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because of potential differences among the agents or in conditions among the sites. -
Many similar agents at other sites do not cause effects similar to the impairment. This finding strongly weakens the case for the candidate cause, but is not convincing because of potential differences among the agents or in conditions among the sites. - -
Evaluating Multiple Lines of Evidence
Consistency of Evidence
All available types of evidence support the case for the candidate cause. This finding convincingly supports the case for the candidate cause. + + +
All available types of evidence weaken the case for the candidate cause. This finding convincingly weakens the candidate cause. - - -
All available types of evidence support the case for the candidate cause, but few types are available. This finding somewhat supports the case for the candidate cause, but is not strongly supportive because coincidence and errors may be responsible. +
All available types of evidence weaken the case for the candidate cause, but few types are available. This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because coincidence and errors may be responsible. -
The evidence is ambiguous or inadequate. This finding neither supports nor weakens the case for the candidate cause. 0
Some available types of evidence support and some weaken the case for the candidate cause. This finding somewhat weakens the case for the candidate cause, but is not convincing because a few inconsistencies may be explained. -
Explanation of Evidence
There is a credible explanation for any negative inconsistencies or ambiguities in an otherwise positive body of evidence that could make the body of evidence consistently supporting. This finding can save the case for a candidate cause that is weakened by inconsistent evidence; however, without evidence to support the explanation, the cause is barely strengthened. + +
There is no explanation for the inconsistencies or ambiguities in the evidence. This finding neither strengthens nor weakens the case for a candidate cause. 0
There is a credible explanation for any positive inconsistencies or ambiguities in an otherwise negative body of evidence that could make the body of evidence consistently weakening. This finding further weakens an inconsistent case; however, without evidence to support the explanation, the cause is barely weakened. -

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