STREAM ECOSYSTEMS

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 aStream Ecosystem • Stream morphology • Parts of the stream • Substrate • Riparian buffer zone • Biological communities • Physical & chemical properties of water

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

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: 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 Communitiesof 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 Communitiesof 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. 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 The River Continuum Concept

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