1. Stream Ecology I Abiotic components Primary producers Invertebrates

2. 1. Abiotic Components
Important starting point for species and abundances
Environments that are structurally simple or extreme tend to support fewer species
High frequency of disturbance tends to diminish biological richness
Consider Four Components
Current
Substrate
Temperature
Water chemistry (sometimes)

3. Current (1) Flow velocity, substrate size, and depth
Illustrates differences in habitat preferences

4. Current (2) Shear stress
Where species are found depends on their ability to hold position and obtain resources
If a large event occurs, their ability to survive and recolonize

5. Substrate (1)
For benthic invertebrates, substrate provides platform and living space to attach, forage, and complete most of life cycle and refuge
Inorganic components
Bars, riffles, pools, and greater range of grain particles benefit many taxa and hyporeos
High silt levels—negative effect, reduces heterogeneity, filling interstitices, coating consumers and food resources
Organic components
Macroinvertebrates increase where fine organic matter occurs
Wood adds to mesoscale habitat

6. Substrate (2)
Invertebrates

7. Substrate (3) For fish, prefer some grain sizes
mud darter; sand darter
Spawning because of DO, sediment can be sculpted into nests
Insects also select particular substrates for oviposition (laying eggs)
Bedload transport likely provides unstable habitat and fewer food resources for benthic organisms

8. Temperature (1)
Determines metabolic rates of organisms, their distributions along a river’s reach, and success interacting with other organisms
Few are able to cope with very high temperature
most warm water fish have an upper limit of 30C
Trout grow rapidly until ~15 C

9. Temperature (2) Temperature will affect species richness
Thermal niche for fish (cold < 19C; cool 19 to 22C ; warm > 22C
Overall fish diversity increases with temperature (all else being equal)

10. Temperature (3)
Temperature controls metabolism of all producers and ectothermic (cold-blooded) consumers
Photosynthesis and microbial activity are strongly temperature dependent, as a macroinvertebrates and fish
Daily growth rate of aquatic insects increases markedly with temperature

11. Importance of Abiotic Components in Stream Restoration
Value of habitat affected by characteristics and availability of abiotic components
Can affect species abundance
Can affect metabolic processes

12. 2. Primary Producers
Acquire their energy from sunlight and materials from non-living sources
In streams
Benthic algae
Macrophytes
Phytoplankton

13. Benthic Algae (1)
Virtually all substrates that receive light can support algae
Categorized based on size
Macroalgae: mature thallus (body) can be seen
Microalgae: cannot be distinguished without a microscope
Where they grow
Stones: epilithon Sediment: epipelon
Sand: episammon Wood: epixylon
Other plants: epiphyton

14. Benthic Algae (2)
Major growth forms of periphytons (algal complex)

15. Benthic Algae (3)
For North America:
35% green algae
24% cyanobacteria

16. Benthic Algae (4)
For North America:
21% diatoms
20% red algae

17. Benthic Algae (5) Limiting factors Light—affected by canopy emergence
Nutrients (P, N, SiO2)
Current (brings nutrients, but can dislodge algae)
Substrate (affects size)
Temperature (diatoms: 5 to 20C; green, yellow, brown: 15 to 30C; cyanobacteria: >30C)
Grazers can eat select species

18. Benthic Algae (6)
Effect
of light
Effect of
nutrients

19. Benthic Algae (7) Net Primary Productivity (NPP)
Closed canopy: 0.01 to 0.1 g C/m2-day
Open canopy: 0.25 to 2 g C/m2-day
Most is consumed by herbivores or enters the pool of particulate detritus

20. Macrophytes (1)
Flowering plants, mosses, encrusting lichen, pond weeds, and large algal species
Important role as habitat and refugia for invertebrates and fish
Most found in standing water
Growth form:
Emergents rooted on banks and shoals
Floating-leaved taxa (rooted), margins of rivers
Free-floating (not attached; can form large mats)
Submerged (attached, typically mid-stream)

21. Macrophytes (2)
Ribbonweed
Duckweed

22. Macrophytes (3)
Pondweed
Bullrush

23. Macrophytes (4) Limiting Factors
Coverage: 27 to 47% in mid-sized Appalachian streams
Hardness of water affects species
Current and high-flow events
Light: 90% increase in shade reduces plant biomass by 50%
Nutrients
Herbivory: mostly no effect

24. Macrophytes (5) Primary Productivity
Net Primary Productivity: 3 g C/m2-day for submerged; ~10 to 20 g C/m2-day for emergents
Generally highest in medium sized rivers
Ample light, moderate current, low turbidity, minimal fluctuations in depth and discharge

25. Phytoplankton
Suspended algae in water column: displaced cells from benthos, eroded material (sloughing), some in situ reproduction
Generally abundance  1/Q
Gross Primary Productivity: 0.6 to 1.7 g C/m2-day

26. Importance of Primary Producers in Stream Restoration
Net primary productivity in streams
nutrient uptake
carbon sequestration
Food (benthics)
Limiting factors for growth and abundance (abiotic, nutrients, herbivory)
Macrophytes—refugia and habitat

27. 3. Invertebrate Feeding Food resources and individuals
Periphyton (eaten by scrapers)
Coarse particulate organic matter (CPOM)—eaten by shredders
Fine particulate organic matter (FPOM)—eaten by collectors
Animal prey—eaten by predators
Shaded headwaters—favor POM
Grazers—unshaded, stoney streams
Collectors—large turbid streams

28. Invertebrate Feeding (2)
Based on food sources and acquisition mechanisms

29. Invertebrate Feeding (3)
Herbivory

30. Invertebrate Feeding (4)
Predators

31. Importance of Invertebrates in Stream Restoration
Important trophic level in streams
Indicators of stream impairment and degradation (e.g., indicator species)

32. 4. Vertebrates
Fish
92% predators
8% herbivores

33. Fish and River Connectivity
Because stream fish have evolved in dynamic environments, they take advantage of, and depend on, a variety of habitats
Spawning habitat with incubation of eggs
Refugia from harsh environmental conditions (e.g., extreme temperatures or flows) with unfavorable growth conditions
Mosaic of feeding habitat(s) with favorable growth conditions
Movement to
spawn
refuge
feed
(from Schlosser and Angermeier, 1995)
hab 1
hab 2
hab 3

34. Fish Swim Speed and O2 Consumption
Burst
Turbulent
Sustained
Prolonged
Steady

35. Alteration of Swimming due to Turbulence
10-cm trout, 0.45 m/s flow velocity, cylinder added to flow
(Liao, 2007)

36. (Liao, 2007) Salmon using obstructions Rippled bed and cod
Schooling and wake interference
Trout choosing to swim behind obstructions
Fish entraining on small cylinders
Fish exploiting turbulence
(Liao, 2007)

37. Importance of Vertebrates in Stream Restoration
Essential trophic level in streams
Socioeconomic importance
Connectivity: Fish need a variety of habitats
Fish respond to and exploit turbulence in rivers