An EPA Sponsored Literature Review Database to Support

Stressor Identification

Benjamin Jessup

Cathy Cresswell

Tetra Tech, Inc.

Patricia Shaw-Allen, Ph.D.

Bhagya Subramanian

Susan Cormier, Ph.D.

EPA,

Office of Research and Development

• What is Stressor Identification?• Stressor Identification = Causal Analysis• Structured, consistent strategy for identifying the

cause(s) of a biological impairment

• Why perform Causal Analysis?

• The Causal Analysis/Diagnosis Decision System (CADDIS) home to the Causal Analysis/Diagnosis LITerature database (CADLit)

StructureData detailUser interface and queriesCurrent focus and future

directions

Overview

The CADLit

The Stressor Identification Strategy

• Logically eliminate causes when you can• Diagnose causes when you can• Use strength of evidence for the rest• Do not claim proof of causation• Identify the most likely cause• Use a consistent process• Document the evidence and inferences

EPA Guidance in 2000http://www.epa.gov/ost/biocriteria/stressors/stressorid.pdf

Why Causal Analysis?

Causal Analysis uses biological assessment data to identify the cause(s) of impairment

• In 2002, All States and several Tribes were using biological assessments for streams and small rivers.

• Identified 1,440 waters with biological impairments

- representing 30,499 river miles with unknown cause(s)

• TMDL Program escalates! - TMDL lawsuits- States need help: What are the causes of observed

biological impairment?

Causal Analysis/Diagnosis Decision Information System (CADDIS)

A web based decision support system providing information and guidance to assist State and Tribe investigators in identifying causes of biological impairments.

What will CADDIS Contain?

1. A web-based, step by step guide to Stressor Identification Worksheets• Examples• Links

3. Analytical tools for users• Regional associations• Stressor-specific tolerance values

4. Conceptual model library Web based model builder in the future

and….5. Database of empirical stressor-response studies

• Sediments• Toxic metals• Other stressors

aka…The CADLit!

The Causal Analysis/Diagnosis LITerature database (CADLit)

• Stores source, stressor, and response information from scientific publications

• Summarizes the usefulness of each reviewed paper to SI

• Documents relationships between sources, stressors, and responses

• Allows investigators to query the database for relevant source, stressor, response, and location variables

Criteria for Data InclusionMust be useful for Causal Analysis by supporting at least

one of the following lines of evidence:

– Stressor-response (thresholds or response curves),

– Association (finding association or failure to find association consistently),

– Experiment – recovery or failure to recover after removal of a stressor in a real habitat or a mesocosm,

– Description of mechanism of how exposures result in responses, or

– Specificity of effects – evidence that an observed response can be used diagnostically

Low dissolved oxygen has been shown to cause mortality with fish in controlled studies.

DO levels at the site are at a concentration shown to cause mortality.

Plausible Stressor ResponsePlausible Stressor Response

Strength of Evidence Strength of Evidence Considerations based on other situations or biological Considerations based on other situations or biological

informationinformation

ExperimentExperiment

Controlled mesocosm or field experiments demonstrate that the candidate cause can induce the observed effect

Strength of Evidence Strength of Evidence Considerations based on other situations or biological Considerations based on other situations or biological

informationinformation

Given what is known about the biology, physics and chemistry of the stressor (low dissolved oxygen), the receiving environment, and the affected organism, it is plausible that the stressor caused the impairment and behavior of gulping air at the water surface.

Plausible MechanismPlausible Mechanism

Strength of Evidence Strength of Evidence Considerations based on other situations or biological Considerations based on other situations or biological

informationinformation

SpecificitySpecificity

Strength of Evidence Strength of Evidence Considerations based on other situations or biological Considerations based on other situations or biological

informationinformation

The impairment (jagged cut) observed in the fish can only occur from a boat propeller or other mechanical hazard. Therefore, one of these stressors must be the actual cause.

Database StructureCitationAuthors, title

Data Set 2Toxicity tests on stream waters sampled above and below mine discharges

Data Set 2 Descriptor“Waters sampled above and below mine

discharges”

Data Set 1Survey of stream macroinvertebrates sampled at sites throughout region with extensive mining

Data Set 1 Descriptor“Sites throughout region with extensive

mining”

Sources, stressors, responses Sources, stressors, responses

Relevant publications are complex, often reporting results from multiple study designs and many environmental stressor and non-stressor parameters

Database Structure: Exposures

Data Set

Exposure Set1 set for each independent stressor gradient in data set

Exposure Parameters1 parameter for each exposure measurement made (e.g., Cu, pH, DO, habitat, etc.)

Exposure Class DetailsCharacterize classes (range, class means, etc.) for each parameter

Database Structure: Responses

Data Set

Response Set1 set for each response type in data set: community, toxicology, physiology, behavior, accumulation

Measured Response1 parameter for each response measurement (e.g., IBI, diversity, mortality, respiration, etc.), including stressor/response statistics

Response Class DetailsCharacterize classes (range, class means, etc.) for each parameter

Stressor/Response DetailsResponse effect levels, thresholds, or regression slopes, and statistical tests

Data Entry

Response Details

User Interface

Effects Cause/Stressor Source/ Land Use

All Keywords Geographic Area

Search for Known Associations

Select specific term(s) from any category (or categories) for known associations

Associations

Display Associations OnlySearch List All

Source Query

Query Output

Consistency of AssociationConsistency of Association

Strength of Evidence Strength of Evidence Considerations based on other situations or biological Considerations based on other situations or biological

informationinformation

The impairment (dead fish) is observed together with the stressor () at different locations across the country.

Current CADLIT Focus• Peer reviewed scientific publications

• Freshwater aquatic life• Priority metals (As, Cd, Cr, Cu, Pb, Hg, Se, Zn)

• Clean sediments (Suspended and bedded)

Future Directions• Include additional stressors in CADLit

• Include grey literature (as appropriate)• Available through the CADDIS Website

Proposed release: 2005 – 2006