The biological condition gradient: updates and opportunities

1. The biological condition gradient: updates and opportunities Michael Paul Jeroen Gerritsen Tetra Tech, Inc. Center for Ecological Sciences

2. Intro Clean Water Act Goal = Integrity: • “Restore and maintain…biological integrity” – 101(a) Interim Goal = Aquatic Life Use: • “…water quality which provides for the protection and propagation of fish, shellfish, and wildlife…” – 101(a)(2)

3. Intro Biological Integrity • The ability of an aquatic ecosystem to support and maintain a balanced, integrated and adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitats within a region REFERENCE CLASSIFICATION

4. Intro Convention – Single Indicator Thresholds Is this the tool we need? Is it a race to the middle? Does is protect the best sites? (Anti-deg, ORW) Does it protect further degradation? Is it a realistic goal for restoration? (TMDL prioritization; setting realistic expectations) What if reference condition varies? x x x

5. Another Option: The Biological Condition Gradient Levels of Biological Condition Biological Condition 1 2 3 4 5 6 Level of Exposure to Stressors • Watershed, habitat, flow regime and water chemistry as naturally occurs. Chemistry, habitat, and/or flow regime severely altered from natural conditions.

6. The Biological Condition Gradient 1 Natural structural, functional, and taxonomic integrity is preserved. Natural Variability Minimal changes in structure & function 2 Evident changes in structure and minimal changes in function 3 Moderate changes in structure & minimal changes in function Biological Condition 4 Major changes in structure & moderate changes in function 5 6 Severe changes in structure & function Increasing Level of Stressors

7. The Biological Condition Gradient Evident changes in structure due to loss of some rare native taxa; shifts in relative abundance; ecosystem level functions fully maintained Natural structure and function of biotic community maintained Natural Variability 1 2 Minimal changes in structure & function 3 Evident changes in structure and minimal changes in function Moderate changes in structure & minimal changes in function 4 Biological Condition Major changes in structure & moderate changes in function 5 6 Severe changes in structure & function Increasing Level of Stressors

8. The Biological Condition Gradient Natural structure and function of biotic community maintained Natural Variability 1 Minimal changes in structure & function 2 Evident changes in structure and minimal changes in function 3 Biological Condition 4 Moderate changes in structure & minimal changes in function Extreme changes in structure and ecosystem function; wholesale changes in taxonomic composition; extreme alterations from normal densities. Major changes in structure & moderate changes in function 6 Severe changes in structure & function - - No Effect - -

9. Intro The Biological Condition Gradient • Conceptual model of aggregated biological knowledge to describe changes with increasing stress • Based on combination of ecological theory and empirical knowledge • Regional calibration • Conceptual model • Quantitative decision model

10. Method Basic idea • What attributes do we expect to see? • Species, abundances • Habitats • Biotopes • Interactions • What attributes do we not expect to see? • What is missing? • What is present that shouldn’t be? • Have experts interpret samples into the BCG classes. • Operationalize their decisions – i.e., “train” a model

11. Method How • Classification (you know….) • Identify reference condition and stressor gradient (you know…) • Expert panel: • Identify attributes and their metrics • Assign sites to levels of BCG • Develop rules for assigning sites (decision criteria) • Develop model(s) for automated replication of panel decisions • Test and iterate

12. Method Evidence for “best” • Present-day conditions • Historical reconstruction • Historical documents (descriptions, journals, charts, aerial images) • Fish/shellfish landings records • Museum collections • Archeological evidence (middens, other digs) • Paleo evidence(diatoms, forams, pollen)

13. Method Attributes • Historically documented, sensitive, long-lived, regionally endemic taxa • Highly sensitive or specialist taxa • Sensitive and common taxa • Taxa of intermediate tolerance • Tolerant taxa • Non-native taxa • Organism condition • Ecosystem Function • Spatial and temporal extent of detrimental effects • Ecosystem connectance

14. Method Attributes: New England Fish Attribute 2 taxa: most sensitive; the first to disappear Sensitive taxa Slimy sculpin Attribute 3 taxa: moderately sensitive Wild brook trout Burbot

15. Method Attributes: New England Fish Attribute 4 taxa: broadly tolerant of many conditions Longnose dace Redbreast sunfish Fallfish Tesselated darter

16. Method Attributes: New England Fish Attribute 5 taxa: Highly tolerant; increased abundance in stressed sites White sucker Blacknose dace

17. Method Assign sites to BCG levels • Panel members assign sites to BCG levels using species composition information • Best sites (reference) are not necessarily Level 1! • Capture critical information for decisions

18. Example site data

19. Method Operationalize the Decisions • Apply fuzzy set theory to expert-derived logic train: • membership functions • Results expressed as membership of levels (0 to 1) • Discriminant function models (Maine DEP) • Requires sizable training set of expert-assigned sites • Calibrate other index models to BCG results

20. Method

21. Complete Partial / In Development Planning Application Columbia Estuary Casco Bay Narragansett Bay Tampa Bay Caribbean Coral Reefs

22. Application Lessons learned • Classification is key! • Struggle against taxonomic chauvinism: bugs don’t work everywhere, fish don’t work everywhere: use taxonomically rich assemblages that can be sampled frugally

23. Recent Developments Multiple Assemblages • Minnesota • Calibrated BCG model for 7 classes of warmwater streams, both invertebrates and fish • Quantitative BCG model incorporated in Access application • Will be used to help set biological criteria for MN waters • Region 5 states and tribes • Calibrated BCG model for cold and cool-transitional streams, both invertebrates and fish.

24. Recent Developments Considerations for estuaries • Several habitat types in an estuary – estuary health not dependent on single habitat • Legacies of overexploitation (fish, shellfish) • Ocean changes • Watershed/ input changes • Direct habitat disruption/conversion • Effects on keystone components

25. Recent Developments Coral BCG • Coral reef scientists new to BCG conceptual model • All have observed reef declines during their careers • Instead of numeric data, participants viewed video transects of shallow water reefs and rated quality of each reef

26. Summary Biological Condition Gradient • A conceptually simple framework for holding enormous, user-defined complexity • Scale up (more general) for communication • Scale down (more detailed) for research • Organizes and prioritizes research needs • Uncovers gaps in knowledge • Uncovers discrepancies in assessment conclusions • Enables hypothesis testing • Enhances communication • Independent of methods • Conceptually complete scale • Translates observation and measurement into shared meaning

27. BCG: A Flexible Application Summary x Exceptional Good x Fair Poor x Very poor Non-reference