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The Stressor Identification Process

The Stressor Identification Process. Detect or Suspect Biological Impairment. Stressor Identification. Define the Case. List Candidate Causes. Decision-maker and Stakeholder Involvement. As Necessary: Acquire Data and Iterate Process. Evaluate Data from the Case.

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The Stressor Identification Process

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  1. The Stressor Identification Process

  2. Detect or Suspect Biological Impairment Stressor Identification Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected The causal analysis framework

  3. Fish kills • Organismal anomalies • Changes in community structure • Low biotic index values • Violation of biocriteria Detect or suspect biological impairment Stressor Identification Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  4. POTW Willimantic River case study • ‘98 303(d) List • Public-Owned Treatment Works (POTW) main focus • TMDLs target Cu, Pb, Zn

  5. Willimantic River case study MR1 MR3 • Impaired site MR3 (↓ EPT taxa) • Less impaired site (MR1) upstream of MR3 POTW

  6. moderately impaired Triggering the causal analysis 6

  7. Detect or Suspect Biological Impairment Stressor Identification • What biological effects are observed? • Where are they occurring? • Where are comparable reference sites? Step 1: Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  8. Example: defining the biological impairment in the Willimantic case study 8

  9. Making the impairment specific • The more specific you can make—or the more narrowly you can define—the impairment, the better. • Specific = better discrimination across candidate causes • Can consider multiple impairments

  10. Detect or Suspect Biological Impairment Stressor Identification Define the Case • Make a map • Gather information on potential sources, stressors, & exposures • Develop a conceptual model • Engage stakeholders Step 2: List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  11. Listing candidate causes • Focus on stressor(s) that may be causing biological impairment • May have causal scenarios, with several stressors acting in combination • Candidate causes may include: • Mechanisms or modes of action • Sources 11

  12. industrial facility farms woods Stafford Springs MR1 MR3 POTW Example: the Willimantic River case study 12

  13. industrial facility POTW dams subdivision dairy farm ↓ EPT richness Example: using models for communication ↑ other toxics ↑ NH3 ↓ dissolved oxygen ↑ Zn ↑ temperature

  14. industrial facility POTW dams subdivision dairy farm ↓ EPT richness Example: using models for communication Evidence? Evidence? ↑ other toxics ↑ NH3 ↓ dissolved oxygen ↑ Metals ↑ temperature Evidence?

  15. Detect or Suspect Biological Impairment Stressor Identification Define the Case • EVIDENCE FROM THE CASE • Co-occurrence • Exposure or mechanism • Causal pathway • Stressor-response relationships from field • Manipulation • Lab tests of site media • Temporal sequence • Verified predictions • Symptoms List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Step 3: Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  16. Spatial/Temporal Co-Occurrence Upstream Downstream Comparison Supports Weakens

  17. Spatial/Temporal Co-Occurrence a 8/28/00 b 7/23/01

  18. Spatial/Temporal Co-Occurrence a 8/28/00 b 7/23/01

  19. Spatial/Temporal Co-Occurrence a 8/28/00 b 7/23/01

  20. Impoundment filling and particle export loss of interstitial habitat due to settled particles Proportion of substrate composed of sand was half More EPT taxa at the amount MR2 downstream Road Bank observed at the Impoundment from dam and Sanding Failure upstream from upstream MR3 reference site X X X Bank Particle Increased stability score settling algae was unchanged from upstream; stream banks Increased armored by amount of riprap and fine particles granite walls Decreased inter- Fine particles fill interstitial gravel dissolved spaces oxygen Loss of Loss of suitable invertebrates habitat

  21. Detect or Suspect Biological Impairment Stressor Identification Define the Case • EVIDENCE FROM ELSEWHERE • Stressor-response relationships (from lab, other field studies, or ecosystem models) • Mechanistically plausible cause • Manipulation at other sites • Analogous stressors List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Step 4: Evaluate Data from Elsewhere Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  22. Stressor-Response Relationships from Laboratory Studies Weakens Supports Strengthens

  23. Stressor-Response Relationships from Laboratory Studies

  24. Lacking Sufficiency from Analogous Situations • Impairment is so great, exposure to some agent at highly adverse levels must be occurring. • Natural variability could not account for this.

  25. Prediction fromAnalogous Situations • Experience suggests that highly toxic exposures are involved. • 1. Bracket site, look for origination of impairment. • At the origination, there should be a point source, not non-point source. • 3. The point source will intermittently release a highly toxic pollutant or precursor.

  26. Verified Predictions of Source Illicit discharge observed upstream from impairment

  27. Manipulation of Source/Exposure SUPPORTS Impairment occurs when stressor present and does not occur when stressor is removed WEAKENS Impairment occurs when stressor present and when stressor is removed

  28. Mean number of EPT taxa before (1999-2000) & after (2001-2002) rerouting of illicit discharge 15 10 1999-2000 2001-2002 5 0 MR2 MR3 WL1 Manipulation of Source/Exposure

  29. Weigh strength of evidence for each cause • eliminate if you can • diagnose if you can • Compare strength of evidence across causes Detect or Suspect Biological Impairment Stressor Identification Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Step 5: Identify Probable Cause Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

  30. Example: strength of evidence analysis

  31. How to evaluate consistency of evidence

  32. POTW dams subdivision dairy farm DO higher at impaired site vs. reference after rerouting industrial discharge had decreased concentrations of Zn & other toxics, increased EPT taxa richness ↓ EPT richness NH3 same at impaired site and references. Cd greater at impaired site vs. reference, but not at levels sufficient to cause impairment Example: using models for communication industrial facility ↑ other toxics ↑ NH3 ↓ dissolved oxygen ↑ Cd ↑ temperature

  33. Detect or Suspect Biological Impairment Stressor Identification Define the Case List Candidate Causes Decision-maker and Stakeholder Involvement As Necessary: Acquire Data and Iterate Process Evaluate Data from the Case Evaluate Data from Elsewhere Identify Probable Cause • Causal analysis is one step in management process… • After causes are identified, sources & management actions must be identified • Biological monitoring verifies that actions are effective Identify and Apportion Sources Management Action: Eliminate or Control Sources, Monitor Results Biological Condition Restored or Protected

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