LAKE MORPHOMETRY AND ZONATION

I. Morphology of Lakes
    A. Bathymetric maps

            contour lines = isobaths (iso-equal; bathy-depth)

            surveying and sonar

    B. Morphometry
        1. Maximum depth = zm
        2. Maximum length = l
        3. Maximum width = b
                at right angles to the maximum length line
        4. Area
                A0 - surface area
                Az - area of contour at depth z
        5. Volume
                V = volume of the whole lake
                Vz = volume below depth z
        6. Mean depth average depth symbol
    
        7. Relative depth
                ratio of maximum depth (z) to the mean diameter of the lake at the surface, expressed as a percentage

        8. Shoreline development.
                L = length of shore line

        9. Hypsographic curve
                area at each depth – m2 or %
                can use to calculate the volume

        10. Depth-Volume curve
                volume at each depth – m3 or %
                sediment water interactions
 
 

II. Lake and Stream  Zonation  -- See page 132 of Wetzel
     A. Lakes
        1. Epilittoral -
        2. Supralittoral -
        3. Littoral - extends from the seasonal high water level down to where the vegetation doesn't grow due to a lack of light
             eulittoral
             upper littoral
             middle littoral
             lower littoral 

        4. Littoral-Profundal - no higher plants (can be algae)
        5. Profundal - sediment free of vegetation; low light
        6. Pelagic - open water
            a. trophogenic (euphotic) - enough light for production > respiration
            b. tropholytic - darker – respiration > production
     B. Streams
        1. Eucrenon - the origin of the stream
        2. Hypocrenon
        3. Rithron - stony stream zone
        4. Potamon - lower energy part of the stream - river
        5. Riparian zone
        5. Drainage classification
             stream orders

   C. Biological groups associated with zones (lakes only)
        1. Pelagic
            a. Seston - all particulate matter in the open water
                (1) bioseston -- the living component
                (2) tripton -- non living seston = detritus
            b. Nekton - can swim against currents
            c. Plankton - movement influenced by turbulence
                (1) euplankton - spend whole life cycle in open water
                    (a) bacterioplankton
                    (b) phytoplankton

                    (c) zooplankton
                (2) meroplankton - periodically enter the plankton, but can't spend their whole life cycle there
                (3) pseudoplankton - organisms that don't really live in pelagic, but are swept there accidentally
          2. Benthos - organisms that live on the sediment water interface
            a. Phytobenthos - 'macrophytes' higher plants; algae
            b. Zoobenthos
          3. Other
            a. Pleuston - at the air-water interface
            b. Neuston - microscopic pleuston
            c. Periphyton - plants (and bacteria) that live on the substrates
                (1) epiphytic
                (2) epipelic
                (3) epilithic
                (4) epipsammic
            d. Psammon - interstitial fauna -- they live between sediment grains
 

BONUS QUESTION OF THE WEEK (Due at beginning of class 3 Sept. 2003):

Name a lake formation type that often has very irregularly shaped basins.  Would you predict that lakes of this type tend to be eutrophic or oligotrophic? (Say which and describe why in one or two sentences)


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