1. Riverine Ecosystems Energy sources: allochthonous + autochthonous
Interrelated
Utilized by different functional groups of organisms
How do the relationships change from headwaters to mouth?

2. X-section of a typical stream
Photosynthesis
Geology
Temperature
Nutrients
Current
Photosynthesis
Detritus
CPOM
Plants
Algae
FPOM
1o Production
Grazers Collectors Shredders
Predators
2o Production

3. River continuum Concept (RCC)
Vannote, R.L., G.W. Minshall, K.W. Cummings, J.R. Sedell, and C.E. Cushing The River Continuum Concept. Can. J. Fish. Aquat. Sci. 37:
General outline of how a river changes along its length
Physical dimensions
Changing energy inputs
Changes in community of organisms

4. River Continuum Concept

5. Shaded headwater stream, Ohio
Shaded headwater stream, Ohio

6. Outlet to Crescent Lake, Pocono Watershed, Monroe Co., PA

7. What are some features of headwater streams?

8. Hypothetical headwater stream conditions
Typical of Eastern deciduous forest
Flows through heavily shaded forest riparian canopy
Narrow
Stream bottom rocky or sandy: depends upon geological characteristics of drainage

9. Where does the energy come from?

10. Hypothetical headwater stream conditions
Low light + low nutrients:
Low algal and macrophyte growth
Mosses 1o primary producers
CPOM from terrestrial environment enters strea
Leaves (1o autumn), twigs & branches
Respiration exceeds primary production:
Heterotrophic stream reach
Energy from terrestrial sources

11. Which Guilds Should We See?

12. Which Guilds do we see? Diversity of functional groups Shredders: 35 %
Collectors: 45%
Grazers: few to 5%
Predators: 15%
Diversity pattern?
large CPOM supports shredders
FPOM generated by shredders and mechanical breakdown supports collectors
No plants = no grazers

13. Headwaters fishes Minnows Trout Sculpins
Brown trout
Minnows
Trout
Sculpins
Other fishes tolerant of seasonal and daily cold temperature regimes
Sculpin

14. Mid-reach streams: Salmon and Lemhi in Idaho

15. How should conditions change in the mid reaches?

16. Mid-reach Conditions: Structure
Stream wider, bottom well lit, temperatures and [nutrients] increased
Stream bottom: rubble, rocks, pebbles with sand and silt in low current areas

17. Where does the energy come from?

18. Mid-reach Conditions: Energy
Bottom algae proliferate (filamentous greens or diatoms)
Where protected -> sediment accumulates and rooted aquatics grow
Primary production > respiration = autotrophic reach

19. What FFGs do you expect to find?

20. Mid-reach functional groups
Collectors = 50%: export of FPOM from headwaters + that generated in mid-reach
Shredders = 5%: low input of CPOM
Grazers 30%: more algae on stream bottom
Predators = 15%
Export of FPOM to lower reach

21. Mid-reach fishes
Typically tolerate wider fluctuations in daily and seasonal temperature
Overlap with some headwater species
Examples
Trout
Suckers
Minnows
Blue suckerfish

22. Lower reach river: Confluence of Snake & Columbia River at Oregon/Washington Border

23. What physical features do you expect in lower reaches?

24. Lower Reach Conditions: Physical
Slow-flowing, deeper, lake-like
Increased turbidity & fine-grained, shifting bottom

25. Where does the energy come from in the lower reaches?

26. Lower Reach Conditions: Energy
No sunlight on bottom = no algal growth
Autochthonous production from phytoplankton + macrophytes along the margins
Terrestrial input of CPOM small
Water column has high FPOM from mid-reach
Respiration > primary production -> heterotrophic reach

27. Which FFGs do you expect in lower reaches?

28. Lower Reach Functional Groups
Collectors (filterers + gatherers) = 85%
Sediment dwellers: mollusks or dipteran larvae
Shredders and grazers absent: lack of CPOM and periphyton
Predators = 15%

29. Lower Reach Fishes
Adapted to environments where temperatures fluctuate widely
Suckers
Carp
Chubs
Exotic

30. Problems with RCC Different geomorphologies
Shorter streams in New Zealand: CPOM flushed by floods, few shredders in many streams
Western US streams in dry areas often less shaded, even in headwaters
Anthropogenic changes to streams interrupt continuum:
Logging or removal of riparian vegetation
Damming: change in temperature depending whether water release is surface (warm) or bottom (cold)

31. Reset mechanisms Changes in a river below a confluence
Makes receiving stream more like a stream higher in the continuum
FFGs closer to that of tributary
Will revert below the inlet of the tributary
Removal of riparian buffer in headwater
Change to pattern of mid-reach

32. Hyporheic community
Organisms occurring in the interstitial spaces between rocks and stones on bottom
Examples: insect larvae
Stoneflies (Plecoptera)
Midges (Chironomidae)

33. Water on the Web
This presentation includes material from Water on the Web (WoW)
WOW Water on the Web - Monitoring Minnesota Lakes on the Internet and Training Water Science Technicians for the Future - A National On-line Curriculum using Advanced Technologies and Real-Time Data.
University of Minnesota-Duluth, Duluth, MN
Authors: Munson, BH, Axler, R, Hagley C, Host G, Merrick G, Richards C.
I would also like to thank Dr. Jewett-Smith for her contributions to this presentation