Fluvial aquatic ecology 

of the Colorado River (...especially Lees Ferry) Jeff Muehlbauer with Ted Kennedy, Charles Yackulic, and many othersGrand Canyon Monitoring and Research Center Southwest Biological Science Center 

U.S. Department of the Interior U.S. Geological Survey 
Unpublished data, subject to change, do not cite 

 How the 

ecosystem “works” 

A conceptual model 
Unpublished data, subject to change, do not cite 

 How the 

ecosystem “works” 

A conceptual model 

My talk: Bugs, light, shear stress, HFEs 
Unpublished data, subject to change, do not cite 

 How the 

ecosystem “works” 

A conceptual model 

Charles’ talk: Nutrients 
Unpublished data, subject to change, do not cite 

 How the 

ecosystem “works” 

A conceptual model 

Ted’s talk: Bugs, flows, fish 
Unpublished data, subject to change, do not cite 

Project 5 

 Studies all life stages  Identifies drivers / 

constraints of insects 

 Estimates food 

availability for fishes 

 Describes feeding habits 

of fishes 
Unpublished data, subject to change, do not cite 

Lees Ferry drift research  Entrainment of bugs in water column  Critical life stage/behavior  Food for fish Mmm, 

drifting bugs... 

Invertebrate drift: 
Unpublished data, subject to change, do not cite 

Drift in space  Shear stress effects on drift (longitudin

River mile 

Shear stress

(N/m2 ) 

Midge drift

(#/m3 ) 0 10 

20 

20 

0 

40 60 80 
Unpublished data, subject to change, do not cite 

Drift in space  Increasing drift with distance from Dam 

(longitudinal) 
Unpublished data, subject to change, do not cite 

 ~ Every mile mon

Dam to Lees Fer

 Began Nov. 2013  Capture adult aq

insects 

 Effective monito

tool for food bas

Lees Ferry sticky trap monitorin

(No, this is not Lees Ferry) 
Unpublished data, subject to change, do not cite 

Light effects?  Fishermen notice 

hatch patterns at Ferry 

 Strong light 

pattern in LCR 
Unpublished data, subject to change, do not cite 

Lees Ferry sticky trap monitorinChannel orientation River mile (longitu

Not much of a pattern... 
Unpublished data, subject to change, do not cite 

Lees Ferry sticky trap monitorinSeasonal 

 Strong phenolo

pattern 

 Peaks in June  Very little Aug. t See larger patte

they exist 
Unpublished data, subject to change, do not cite 

Lees Ferry sticky trap monitorinYear-to-year 

 Stable year-to-y But is that “goo

 Let’s come bac
Unpublished data, subject to change, do not cite 

Lees Ferry drift monitoring  Monthly every ~ 3 miles, Dam to Lees F Now a long-term dataset (~ 10 years)  Mid-2016: Ferry to Badger Rapid too  Let’s look at HFE effects! 
Unpublished data, subject to change, do not cite

Spring HFE improved food base 

Unpublished data, subject to change, do not cite 
Unpublished data, subject to change, do not cite

Fall HFEs do not improve food b

Unpublished data, subject to change, do not cite 

SprinFall H
Unpublished data, subject to change, do not cite 

2012-15: Trout target midges and 

What we expect them to eat 

What they actually eat 
Unpublished data, subject to change, do not cite 

Summary  Sticky traps: cheap, effective monitorin Drift: Good 2008-11, tanking since 2012 

 Spring HFE: Good for bugs  Fall HFEs: Neutral to bad 

 Only a few bugs to eat  A house of cards... 
Unpublished data, subject to change, do not cite 

Go fish!  Tailwater invertebrates of 

Glen Canyon and Flaming Gorge Dams 

 Full deck: 

Flaming Gorge 

 Clubs only: 

Glen Canyon Dam