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Large Rivers Chapter 20

Large Rivers Chapter 20. Large Rivers. Important longitudinal, horizontal, vertical interactions within rivers. Large Rivers. e.g., FPOM - fine particulate organic matter inputs from upstream, floodplain Heterotrophic ---- collector invertebrates ----- fish production.

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Large Rivers Chapter 20

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  1. Large RiversChapter 20

  2. Large Rivers • Important longitudinal, horizontal, vertical interactions within rivers

  3. Large Rivers • e.g., FPOM - fine particulate organic matter inputs from upstream, floodplain • Heterotrophic ---- collector invertebrates ----- fish production

  4. Impacted by Human Modifications • Multiple-use conflicts • Fishing, other recreation • Navigation • Flood control • Water source

  5. Impoundment • Flood control, navigation, hydropower

  6. Navigation/Flood Control Aids • Dikes, levees, channel stabilization • Floodplain reduction - 90% in lower Mississippi River

  7. Boat Traffic • Wave action, turbulence, sediment suspension, erosion, dewatering

  8. Hydropower Hydrographs • Altered seasonal, daily flows

  9. Cooling Water • Intakes, outflows • Impingement, entrainment • Heated water

  10. Pollution • Sediment, PCBs, sewage

  11. Flow Diversions • Irrigation, public needs

  12. The Fishery - Sport Fish • Cold large rivers • Salmon, trout

  13. The Fishery - Sport Fish • Cool large rivers • Walleye, smallmouth bass, northern pike

  14. The Fishery - Sport Fish • Warm large rivers • Bluegill, crappie, largemouth bass, catfishes

  15. The Fishery - Sport Fish • Best in unmodified reaches • e.g., Missouri River - 2 to 2.5 X more productive

  16. Unmodified vs. Modified

  17. The Fishery - Sport Fish • Modified reaches • Best in tailwaters (walleye, sauger), main channel border (sunfish, bass, pike)

  18. Modified Mississippi River

  19. The Fishery - Commercial Fish • Often same as sport fish • Conflict as sport fishing pressure increases

  20. The Fishery - Commercial Fish • Typical catch in upper Mississippi River • Common carp • Catfishes • Freshwater drum

  21. Mississippi River Catch

  22. The Fishery - Commercial Fish • Problem - benthophagic fish • Uptake of contaminants from sediments • PCBs • Management concern

  23. PCBs in the Mississippi River

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