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Macroinvertebrate Bioassessment Tools

Macroinvertebrate Bioassessment Tools. Aquatic Life/Nutrient Workgroup August 11, 2008. Discussion Topics. Reference and stressed site status O/E (RIVPACS) preliminary results MMI (multimetric index) preliminary results Bioclasses. Reference Site Review. Two part process:

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Macroinvertebrate Bioassessment Tools

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  1. Macroinvertebrate Bioassessment Tools Aquatic Life/Nutrient Workgroup August 11, 2008

  2. Discussion Topics • Reference and stressed site status • O/E (RIVPACS) preliminary results • MMI (multimetric index) preliminary results • Bioclasses

  3. Reference Site Review • Two part process: • Calculated GIS-based human disturbance values and established criteria cutoffs • Reviewed and critiqued aerial images at EPA using Global Explorer • 11 additional ref sites added to fill obvious spatial gaps and large rivers in plains and xeric bioregions

  4. Reference Sites • 168 reference sites finalized in April (90 mnts, 39 plains, 39 xeric) • 4 xeric, 4 plains and 1 mnts sites removed later • All USFS sites (n=16) retained – midges ID’ed down to genus • 12 additional sites w/ low taxa counts could be removed (USU and TT testing)

  5. Reference Sites

  6. Stressed Site Review • Flagged human disturbance values (GIS derived) that exceeded “acceptable” conditions and further reviewed with Google Earth images • Sites exhibiting clear characteristics of stressed condition retained after image review

  7. Stressed Sites • Goal: identify unquestionably stressed sites – no marginal ones • 74 stressed sites finalized in June • 31 mnts, 23 plains & 20 xeric

  8. Stressed Sites

  9. O/E Model Progress • Predictor variables calculated • OTU’s assignments redefined • Improved resolution • Replicate #’s organized & sample IDs selected • Reference sites reviewed by Utah St staff • 6 sites suggested for removal based on additional aerial image review – WQCD agreed

  10. O/E Preliminary Modeling • USU modeling based on 143 ref sites and 282 taxa (OTU's) • Rare taxa not used (106 taxa remained) • Cluster analysis/ordination • Used presence/absence of taxa among sites • Investigating 2 alternate groupings: • 3 classes – Ecoregions • 13 classes – Bioclasses

  11. O/E Preliminary Modeling • Spatial distribution of samples coded by 3 bug-defined classes

  12. Performance Plot • Sites coded by bioregion • Good agreement between what the model predicts at a site and what is observed

  13. O/E Preliminary Modeling • Spatial dist. of samples coded by 13 bug-defined classes

  14. Performance Plot • Sites are coded by the group assignments • Different types of streams vary in predicted and observed richness • r2 = 0.85

  15. MMI Preliminary Modeling • Tetra Tech keeping in sync with Utah State work • Same OTU designations, predictor variables, reference sites and samples used • Retained rare taxa – Tetra Tech investigating further

  16. Preliminary Findings • Tetra Tech’s ordination similar to Utah State’s • Geographic ecoregions not a perfect fit • Biology is sensitive to the natural gradients in temp. and water amount across the landscape • Bioclasses may work better than ecoregions

  17. Bioclasses • Not defined by geographic regions • Defined more by broad habitat characteristics • Doesn’t lend itself to drawing lines on a map

  18. Bioclass Example • Primary predictors appear to be summer water temperature and amount of water • Amt of water = ƒ (watershed area, precipitation) • Stream temp = ƒ (amount of water, elevation, latitude)

  19. Bioclasses • Two sites, close together geographically, can be in two very different bioclasses • Mainstem (large watershed) vs. tributary (small) • We do some of that already with mainstems separated from “all tribs,” but not consistently

  20. Example • How we might identify bioclass membership

  21. Upcoming Work • Tetra Tech will try further classifications by removing rare taxa • Critically reviewing how to standardize analysis & treatment of data • Move deeper into the modeling processes • O/E – predictive modeling • O/E – estimating probability of capture (pc) & E • MMI – metric calculations

  22. Questions? Drunella doddsi Mayfly Baetis tricaudatus Mayfly

  23. Information • Utah State website on Predictive Models: • http://129.123.10.240/WMCPortal/DesktopDefault.aspx?tabindex=2&tabid=27 • Bioassessment tool info and PowerPoint presentations: • http://www.cwqf.org/Workgroups/Aquatic.asp

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