1. STREAM ECOSYSTEMS

2. What is a stream?
A flowing body of water confined within a bed and banks
Does a stream really end at the edge of the water?

3. Dynamic Nature of Streams
Streams are constantly changing:
Upstream water flows downstream
Amount of water fluctuates
Stream bed changes over time
Anything that affects a watershed will eventually impact the stream

4. Important Aspects of a Stream Ecosystem
Stream morphology
Parts of the stream
Substrate
Riparian buffer zone
Biological communities
Physical & chemical properties of water

5. Stream Morphology Size and shape of the stream Described by the:
Longitudinal slope
Dimensions of cross section
Meander pattern

6. Parts of the Stream
Riffle – section where water is more shallow and the flow is turbulent

7. Parts of the Stream
Run/Glide – section with smooth flow

8. Parts of the Stream
Pool – section where water is deeper with a slower flow

9. Substrate Composition of the stream bottom is very important
Provides important habitat for aquatic life
Organisms show preferences for various substrates
The higher the substrate diversity, the more habitats available

10. Types of Substrate Inorganic substrate: Organic substrate:
Bedrock > Boulder > Cobble > Gravel > Pebble > Sand > Silt > Hardpan
Organic substrate:
Detritus
Muck

11. Large Woody Debris Refers to all wood located within the stream bed
Key aspect of a
healthy stream:
Provides important
habitat (esp. for fish)
Impacts flow, creating pools
Stabilize banks & minimize erosion
In general, it should not be removed from a stream

12. Leaf Packs Accumulation of leaves in a stream Provide input of energy
Organic molecules leach out, creating a nutrient rich “tea”
Biological communities colonize leaves
Smaller pieces of processed leaves provide nutrients downstream

13. What is a riparian buffer zone?
Area of vegetation along the banks of a river or stream
“Green Zone”
Can be forest, wetlands, etc.

14. Importance of Riparian Buffer Zones
Slow down the movement of water, minimizing flooding & erosion
Stabilize banks, reducing streambank erosion
Act as filters, reducing non-point source pollution

15. Importance of Riparian Buffer Zones
Provide important habitat to terrestrial & aquatic species
Canopy provides shade to help regulate water temperature
Leaves of trees are an important food source for many macroinvertebrates

16. Impacts on Riparian Buffer Zones
Over half in US have been destroyed
Most have been degraded or removed due to agriculture or development

17. Biological Communities of Streams
Many streams rely on input of riparian vegetation as base of food web
In-stream producers may include:
Algae (periphyton & phytoplankton)
Aquatic plants
Consumers include a variety of fish and macroinvertebrates

18. What are aquatic macroinvertebrates?
Invertebrates that live in an aquatic ecosystem and are visible with the naked eye
Also referred to as benthos
EPA – Benthic Macroinvertebrates in our Waters

19. Aquatic Invertebrate Life Cycle
Complete Metamorphosis
Incomplete Metamorphosis

20. Identifying Aquatic Macroinvertebrates
Key to Macroinvert. Life in the River
Key to the Orders of Benthic Insects
Aquatic Macroinvertebrate Key
EEK! – Water Critter Key

21. Functional Feeding Groups of Aquatic Macroinvertebrates
Macroinverts. can also be classified based on their role in an ecosystem
Shredders
Grazers/Scrapers
Collectors (filterers, miners & browsers)
Piercers
Predators

22. Fish Communities in Streams
Types of fish vary based on :
stream temp., flow, dissolved oxygen
types of aquatic invertebrates present or other food sources
Primary Headwater Habitat Stream Organisms in Ohio
Fish Identification & Life Histories
Fishes of Ohio’s State Scenic Rivers

23. Biological Communities of Streams
Decomposers have a very important role!
Fungi and bacteria break down leaves
Consumer that feed on the leaves get nutrition from the decomposers
Decomposers also break down dead organisms, recycling the nutrients

24. The River Continuum Concept
Holistic view of a river as a gradient
Parts of a river are linked by flow
First proposed by Vannote and others in 1980

25. The River Continuum Concept
What happens upstream affects what happens downstream
Links between land & aquatic communities are strongest in headwaters
Predictable changes occur in the physical, chemical, and biological aspects of the river

26. Stream Order Measure of the relative size of a stream
Stream order increases when two streams of the same order join

27. Upper Reaches 1st, 2nd, and 3rd order streams
Narrow & shaded by riparian canopy
Low & consistent temp.
Dissolved oxygen conc. high
Coarse substrate
Swift current

28. Upper Reaches Biological Communities: Low diversity
Primary producers are rare
Food chain relies on organic input from trees in riparian zone
Macroinvertebrates are mostly shredders (feed on leaves & debris) & collectors
Fish adapted to cool, swift water feed primarily on insects

29. Middle Reaches Stream orders 3 – 6 Wider stream channel
Temperature is variable
Dissolved oxygen conc. varies
Smaller substrate
Current not as fast

30. Middle Reaches Biological Communities: High diversity
Primary producers (mostly periphyton) are dominant source of energy
Macroinvertebrates are mostly grazers & collectors
Higher diversity of fish that feed on other fish, insects, and periphyton

31. Lower Reaches 6th order streams and above Wide stream channel
Fine substrate
Light penetration is limited due to higher levels of plankton & suspended solids
Higher temperatures
Slow current (but a much larger volume)

32. Lower Reaches Biological Communities: Low diversity
Food chain supported by phytoplankton & organic matter from upstream
Macroinvertebrates are primarily collectors
Fish adapted to warmer water with slower current
More bottom feeders

33. Credits
Thanks once again to Professor Kimberly Royal at Tri-C East for the Power Point presentation materials.
Course: “Promoting Watershed Stewardship” for Environmental Science Educators