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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

Macroinvertebrate Bioassessment Tools

Aquatic Life/Nutrient Workgroup

August 11, 2008

discussion topics
Discussion Topics
  • Reference and stressed site status
  • O/E (RIVPACS) preliminary results
  • MMI (multimetric index) preliminary results
  • Bioclasses
reference site review
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
reference sites
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)
stressed site review
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
stressed sites
Stressed Sites
  • Goal: identify unquestionably stressed sites – no marginal ones
  • 74 stressed sites finalized in June
  • 31 mnts, 23 plains & 20 xeric
o e model progress
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
o e preliminary modeling
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
o e preliminary modeling1
O/E Preliminary Modeling
  • Spatial distribution of samples coded by 3 bug-defined classes
performance plot
Performance Plot
  • Sites coded by bioregion
  • Good agreement between what the model predicts at a site and what is observed
o e preliminary modeling2
O/E Preliminary Modeling
  • Spatial dist. of samples coded by 13 bug-defined classes
performance plot1
Performance Plot
  • Sites are coded by the group assignments
  • Different types of streams vary in predicted and observed richness
  • r2 = 0.85
mmi preliminary modeling
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
preliminary findings
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
  • Not defined by geographic regions
  • Defined more by broad habitat characteristics
  • Doesn’t lend itself to drawing lines on a map
bioclass example
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)
  • 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
  • How we might identify bioclass membership
upcoming work
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

Drunella doddsi


Baetis tricaudatus


  • Utah State website on Predictive Models:
  • Bioassessment tool info and PowerPoint presentations: