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: Calculated GIS-based human disturbance values and established criteria cutoffs Calculated GIS-based human disturbance values and established criteria cutoffs Reviewed and critiqued aerial images at EPA using Global Explorer 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  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)

Reference Sites

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  Goal: identify unquestionably stressed sites – no marginal ones  74 stressed sites finalized in June  31 mnts, 23 plains & 20 xeric

Stressed Sites

O/E Model Progress  Predictor variables calculated  OTU’s assignments redefined Improved resolution 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 6 sites suggested for removal based on additional aerial image review – WQCD agreed

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 Used presence/absence of taxa among sites  Investigating 2 alternate groupings: 3 classes – Ecoregions 3 classes – Ecoregions 13 classes – Bioclasses 13 classes – Bioclasses

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

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

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

Performance Plot  Sites are coded by the group assignments  Different types of streams vary in predicted and observed richness  r 2 = 0.85

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

Preliminary Findings  Tetra Tech’s ordination similar to Utah State’s Geographic ecoregions not a perfect fit 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

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

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)

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

Example  How we might identify bioclass membership Bioclass xyz >100 km 2 Watershed Area <250 km 2 > 1250 m Elevation <2000 m >ddd.ddLongitude<eee.ee

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 – predictive modeling O/E – estimating probability of capture (pc) & E O/E – estimating probability of capture (pc) & E MMI – metric calculations MMI – metric calculations

Questions? Drunella doddsi Baetis tricaudatus Mayfly

Information  Utah State website on Predictive Models: x?tabindex=2&tabid=27 x?tabindex=2&tabid=27  Bioassessment tool info and PowerPoint presentations: