1. How do Stream Confluences Influence Stream Diversity and Function?
By Jeremy Brooks
For University of Montana Undergraduate Research Conference

2. Aquatic Communities

3. 4 Functional Community Groups
Shredders – eat large plants (i.e. leaves)
Grazers – eat algae off of rocks
Collectors – Filter feed particles of food
Predators – eat other insects

4. Why do we need to be more specific?
Biomonitoring of Pollution
How has the community changed?
Restoring an Ecosystem-
What is the goal?

6. River Continuum Concept is Simplified

7. River Continuum Concept is Simplified
Tributaries mean:
More nutrients
More water
New Temperature
New Community

8. How do stream confluences affect aquatic communities?
Will they:
Increase the diversity of the main channel community?
Shift the functional community?
Increase proportion of predators and collectors?
Do pairwise comparisons differ more with confluences?

9. Overview
Methods
Results
Discussion

10. Site Location

11. Four Mile Creek Sampled in August 2016

12. Sample at each confluence
10-20 ft

13. Collect Habitat Data Temperature Average Substrate Size Canopy Cover
Slope

14. Identifying Insect Samples in Lab
1: Randomly pick 300 insects from each sample
2: Identify down to Genus
3: Quality Control (Rhithron): $600 for 3 samples
4: Redo sample to increase accuracy
5: Assign Functional Feeding Group Value
August*4 Mile Creek * 4 sites *5 samples *300 insects
= 6,000 insects

15. Results

16. Simpson’s Diversity Index
Four Mile Creek: Site 4
Simpson’s Diversity Index
Diversity: 4.7
Diversity: 7.6
Diversity: 8.9
Diversity: 7.4
Q1: Do stream confluences increase the diversity of the main
channel community?
Diversity: 10.9

17. Q2: Do stream confluences shift the functional community?
Four Mile Creek: Site 4
Non-metric multidimensional scaling analysis 1 3 2 4 5

18. Four Mile Creek: Site 4
Q2: Do stream confluences increase the proportion of predators and collectors?
= Collector/Gatherer
= Grazer
= Predator
= Shredder
= Collector/Filterer

19. Q2: Do functional pair-wise comparisons differ more with confluences?
Four Mile Creek: Site 4
Main
Trib
Main-Below
Trib-Below

20. Simpson’s Diversity Index
Four Mile Creek: Site 3
Simpson’s Diversity Index
Diversity: 7.2
Diversity: 14.3
Diversity: 9.8
Diversity: 10
Q1: Do stream confluences increase the diversity of the main
channel community?
Diversity: 5.3

21. Q2: Do stream confluences shift the functional community?
Four Mile Creek: Site 3 1 3
Non-metric multidimensional scaling analysis 2 4 5

22. Four Mile Creek: Site 3
Q2: How does functional diversity change in tributaries vs main channel?
= Collector/Gatherer
= Grazer
= Predator
= Shredder
= Collector/Filterer

23. Q2: Do functional pair-wise comparisons differ more with confluences?
Four Mile Creek: Site 3
Main
Trib
Main-Below
Trib-Below

24. Discussion Results show high spatial variation along river
Predictions for any site may depend upon habitat variation
Tributary influences:
Watershed area
Habitat (substrate, canopy cover, slope)

25. No match with the RCC = Grazer = Predator = Collector/Filterer
= Collector/Gatherer
Site 4
= Grazer
= Predator
= Shredder
Site 3
= Collector/Filterer

26. Thanks to: Davidson Honors College for the Irene Ever’s Scholarship
Five Valleys Audubon Society and the College of Forestry for the Phillip Wright Scholarship
Lisa Eby and my Committee for their Mentorship
Wildlife of Montana

27. Main:
Sub mm
Canopy 40%
Slope 7%
W. Area: 5.1 sq miles
Trib:
Sub: 10-50mm
Canopy 60%
Slope: 9%
W. Area: .7 sq miles
= collector/gatherer
Below:
Sub mm
Canopy: 40%
Slope 7%
W. Area: 5.8 sq miles
= grazer
= predator
= shredder
= collector/filter
Q3: How does the habitat influence the community composition?

28. Q3: How does the habitat influence the community composition?
Main:
Sub mm
Canopy 40%
Slope 7%
W Area: 3.7 sq miles
Trib:
Sub: 10-50mm
Canopy 60%
Slope: 9%
W. Area: 1 sq mile
= Collector/Gatherer
Below:
Sub mm
Canopy: 40%
Slope 7%
W. Area: 4.7 sq miles
= Grazer
= Predator
= Shredder
= Collector/Filterer