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Limnology lentic lakes and ponds; lotic streams and rivers

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Limnology lentic lakes and ponds; lotic streams and rivers

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    1. Limnology (lentic = lakes and ponds; lotic = streams and rivers) Properties of Lakes Origins Water Balance Light Heat and Stratification Oxygen Nutrients: Nitrogen and Phosphorous

    2. Origins of lakes Tectonic Volcanic Landslides Glacial action Solution of rock River activity Shoreline activity Biological (beavers) Human

    3. The distribution of reservoirs

    4. Limnology: water balance Water inputs: Precipitation, surface runoff from basin, groundwater, diversion Water losses: Drainage, seepage, evaporation and evapo-transpiration (plants), diversion

    5. Global water supply

    6. Limnology: light

    7. Heating and cooling Sources of heat: Direct solar radiation (most important) Groundwater and springs Ground (minor) Losses of heat: Thermal radiation (primary) Conduction Evaporation Outflow

    8. Heat and the density of water

    9. Distribution of heat Horizontal distribution is primarily driven by wind Vertical stratification is seasonal, driven by the relationship between density and temperature

    10. Limnology: heat

    11. Limnology: heat

    12. Limnology: heat The distribution of heat within a lake depends on water movement Surface waves Langmuir circulation waves River Influents

    13. Dissolved Oxygen

    14. Dissolved Oxygen Air contains 300 mg O2/L; the rest is mostly nitrogen Water contains 14.6 mg O2/L Gasses diffuse slowly in water, so distribution is governed by circulation, not diffusion Eutrophic Lakes: hypolimnion depleted by decomposition (biotic processes) Oligotrophic Lakes: Distribution governed by physical processes

    15. Dissolved Oxygen Winter Kill: Occurs when a shallow lake is ice-covered and hence dark for a long period. The DO demand of plants can drive levels below the 2 mg/l required by most fish. Summer Kill: Occurs when dense concentrations of macrophytes die at the end of their growing season. Decomposition can drive DO levels down. If the lake is shallow and macrophytes are found over the whole surface, a “squeeze” between warm surface temperatures and low DO levels on the bottom in late summer can kill fish.

    22. Limnology: Nitrogen and Phosphorous

    23. Primary and secondary production may be limited by Nitrogen or Phosphorus

    24. Natural and human sources for Nitrogen and Phosphorous

    25. Objectives Determine empirical relationships of fish yield with abiotic factors Provide fisheries managers with an easily applied technique for first approximation of annual fish yield. Provide a fundamental conceptual base for the global synthesis for production process in aquatic systems.

    26. Morphoedaphic Index

    27. Morphoedaphic Index

    29. The Morphoedaphic Index needs to be adjusted for regional climate conditions

    30. Morphoedaphic Index

    32. Limnology: light

    33. Limnology: light

    34. Limnology: Nitrogen and Phosphorous

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