Development of Toxicity Indicators

1. Sediment Quality Objectives For California Enclosed Bays and Estuaries Development of Toxicity Indicators Scientific Steering Committee Meeting July 26, 2005

2. Presentation Overview • Objectives • Selection of candidate test methods • Evaluation of candidates • Recommendations • Application and integration issues

3. Toxicity Indicators • Many available data and methods • Several challenges to effective use • Differential sensitivity/ reliability of methods • Confounding factors • Ecological relevance

4. Objectives • Select a suite of recommended acute and chronic toxicity test methods • Describe sensitivity, reliability, and ecological relevance for each method • Develop thresholds for use in MLOE framework

5. Attributes of Toxicity Indicator Suite • Protective of benthos and ecologically relevant • Sensitive at the scale of benthic impacts • Dependable • Results are reproducible and comparable among labs • Diverse endpoints • Mortality and sublethal response • Different taxa • Greater representation of benthos • Diverse exposure conditions • Matrix and duration

6. Approach for Test Selection • Establish a list of candidate methods • Potential to meet desired attributes • Compile and synthesize information about tests • Relate to desired test characteristics • SQO database, literature, lab studies, other scientists • Select recommended tests • Match indicator attributes • Best combination of desired characteristics

7. California Test Data

8. Candidate Test Characteristics • Well-documented and feasible for use in California • Appropriate exposure method • Good sensitivity and precision

9. Candidate Toxicity Indicators • Short-term survival • Multiple species of amphipods • Direct sediment exposure • Widely used in California • Short-term/embryo development and fertilization • Sea urchins and mussels • Frequently used in California • Pore water or sediment-water interface exposure • Chronic/sublethal response • Usually species with limited use in California • Diverse endpoints and exposure methods

10. Growth Tests • Polychaete • 28 day exposure, fed • Dry weight • Frequently used in California • Seed clam • 7 day exposure, fed • Dry weight • Not used in California

11. Life Cycle Tests • Amphipod • 28 day exposure, fed • Dry weight, offspring • Occasionally used in California • Copepod • 14 day exposure, fed • Offspring • Not used in California

12. Cell Stability Test • Oyster • 4 day exposure, fed • Digestive gland cell stability • Not used in California

13. Candidate Tests • Amphipod survival (10 day sediment exposure) • Ampelisca abdita • Eohaustorius estuarius • Leptocheirus plumulosus • Rhepoxynius abronius • Growth/Reproduction (28 day sediment exposure) • L. plumulosus • Neanthes arenaceodentata (polychaete) • Sea urchin fertilization (1 day pore water exposure) • Purple sea urchin (Strongylocentrotus purpuratus)

14. Candidate Tests Continued • Embryo development (2-3 day pore water or sediment-water interface exposure) • Purple sea urchin • Mussel (Mytilus galloprovincialis) • Copepod life cycle (14 day sediment exposure) • Amphiascus tenuiremus • Clam growth (7 day sediment exposure) • Mercenaria mercenaria • Oyster lysosomal stability (4 day sediment exposure) • Crassostrea virginica

15. Presentation Overview • Objectives • Selection of candidate test methods • Evaluation of candidates • Recommendations • Application and integration issues

16. Evaluation Process • Separate evaluation for short-term survival and sublethal test methods • Short-term survival • 10-day amphipod tests are accepted • Species selection is primary issue • Sublethal tests (many issues) • Feasibility • Consistency • Confounding factors • Sensitivity • Relevance • Cost

17. Evaluation Process • Short-term survival tests • Compared attributes of four species typically used in 10-day amphipod tests • Technical feasibility and supply • Sensitivity • Confounding factors

18. Amphipod Survival Test Characteristics * Special permit needed ** Higher test failure rate

19. Amphipod Survival Ampelisca is markedly less sensitive to CA sediment samples

20. Amphipod Species Recommendations • Recommended • Eohaustorius estuarius • Leptocheirus plumulosus • Not recommended • Rhepoxynius abronius • Limited availability • Grain size sensitivity • Ampelisca abdita • Low sensitivity • Low test success rate

21. Evaluation of Sublethal Tests • Compared characteristics of candidate tests • Technical feasibility and supply • Relevance to program objectives • Reproducibility and precision • Documentation and history • Sensitivity • Cost • Sequential process

22. Sublethal Test Characteristics

23. Sublethal Test Characteristics * Compared to 10 day amphipod test

24. Sublethal Tests: Relative Sensitivity

25. Sublethal Tests: Relative Sensitivity

26. Sublethal Tests: Relative Sensitivity

27. Sublethal Tests:Feasibility and Supply • Not recommended • Copepod life cycle test • No commercial test lab capability in California or U.S. • Technically difficult • No information on reproducibility • No standard method • Oyster lysosome stability • No commercial test lab capability in California or U.S. • Technically difficult • No information on reproducibility • No standard method

28. Sublethal Tests:Exposure Method • Not recommended • Interstitial water tests with sea urchins or mussels • High sensitivity to confounding factors • Less realistic exposure scenario • Remaining candidates have differing combinations of desirable attributes for use in SQO program • Clam growth • Polychaete growth • Amphipod growth/reproduction • Embryo development at sediment-water interface

29. Sublethal Tests:Documentation and History • Not recommended • Juvenile clam growth test • No standard method • Limited applied experience with method in California

30. Sublethal Tests:Sensitivity and Cost • Not recommended • Leptocheirus reproduction and growth • Higher relative cost • Lower relative sensitivity

31. Recommendations • Conduct both acute survival and sublethal test to evaluate sediment toxicity • Acute survival test • Either • E. estuarius • L. plumulosus • Sublethal response test • Either • Polychaete growth test (N. arenaceodentata) • Sediment-water interface test using mussel or sea urchin embryos

32. Application and Integration Issues • Thresholds • How to interpret results of each test • Integration of results • Multiple tests • Weighting • Applications • New studies • Past data

33. Thresholds • Several options for establishment • Statistical • Significant difference from control • Variability • Biological • Magnitude of response • Association with benthic community response • A combined approach is recommended • Unaffected (good) vs. affected (bad) • Desire confidence in choice • Statistically-based threshold • Severity of effect • Magnitude and ecological relevance of response is important • Biological-based threshold

34. Proposed Thresholds • Response not statistically significant different from control • Response different from control, but less than test-specific minimum significant difference (msd) • Result may be within test variability • Clear effect, but below level associated with high probability of benthic effects • Up to 50% effect relative to control (if benthic association unknown) • Above level associated with likely benthic community impacts • > 50% response relative to control (if association unknown) • Reference/no effect • Low effect • Moderate effect • High effect

35. Integration of Results • A combination of concordance and magnitude of response • Sublethal test results receive less weight • Four categories of effect

36. Integration of Results

37. Proposed Integration FrameworkLOE Category

38. Applications • New studies • Should use both types of tests • If only one used • Reject information? • Only amphipod survival: use result as LOE classification? • Only sublethal data: Use conditionally with modified weighting? • Other test methods used • Ancillary information, not a substitute for specified tests

39. Applications • Past data • Incomplete test suite? • Other amphipod species? • Other methods?