Integrated Plankton Ecology

I. Plankton distribution
    A. Regional –
            Biogeography

            Understudied in general for plankton vs. other organisms
            1. tropics vs. arctic
            2. flowing versus still water -- negative correlation of plankton size, diversity and numbers with water velocity
            3. lake size
            4. endemism
                Baikal 


            5. chemistry – look at lake districts of crater lakes (reduce differences in lake morphometry)

                a. Lake District                                                     % similarity of rotifers among lakes
                      Cameroon                                                                               22
                      Bali                                                                                         34
                      Germany/France                                                                      63  (most similar chemistry)
                      Australia                                                                                  13 (greatest differences in
                      Arizona/Mexico                                                                       17          chemistry – saline to FW)

                b. Changing chemistry over time
                    Grand Coulee Dam
                       Year                 Lake Lenore                              Soap Lake
                        1945                  16.9 g/L TDS                               37.1
                        1961                    3.1                                             18.9
                        1945                 Diaptomus sicilus                       Moina
                                                 Diaptomus nevadensis               Hexarthra
                        1961                 Daphnia                                     Moina
                                                  rotifers                                       Diaptomus sicilus

                c. conductivity
                    At conductivity >400 mS, start to lose zooplankton species
                d. Specific Ions –
                    1. e.g., Changes in [Fl-] in East Africa; copepods
                    2.  calcium
                e. Acidity

        6. geography
            a. mountain ranges – may prohibit movement of species
            b. events not now apparent
                i. plate tectonics
                ii. climate events
                    1. Daphnia in the lakes of Cameroon (40 crater lakes)
                        alternative hypotheses

                    2. glacial relict species
                        a. Mysis relicta (opossum shrimp)
                        b. Limnocalanus
        7. other abiotic factors
            a. temperature
            b. lake morphology – variability in habitat
        8. biotic controls
            a competition
            b. predation
    B. Local
        1. horizontal
            a. pelagic versus littoral -- 'avoidance of shore'
            b. patchiness – random, uniform, clumped
                (1) uniform – spacing effect of territories
                (2) clumped or random – currents, clumped resources, predators, seiches…
                (3) scales of patchiness
                    a. large scale >1km (e.g., windward vs. leeward)
                    b. small scale, wind induced circulation; Langmuir circ.
                    c. swarms (biotic)
        2. vertical – zooplankton can adjust their depth
            a. patterns
                (1) increased lake transparency – increased vertical migration
                (2) increased organism body size – increased migration
                (3) migration related to life history
                (4) seasonal patterns
            b. types -- diel vertical migration
                (1) nocturnal
                (2) twilight
                (3) reversed
            c. causal evaluation
                (1) proximate cue is light
                (2) ultimate or adaptive (plankton towers at Plon)
                    (a) metabolic boost hypothesis
                    (b) protection from damaging light
                    (c) protection from predation
                            vertebrate predators are visual predators
                            why come up ever? Food – production is at surface

II. Role of predation
    A. Size structuring of fish – large bodied versus small bodied zooplankton
        -Hrbacek, 1962, reservoirs in Poland and Czechoslovakia; fish species were
                correlated with zooplankton species
        -Brooks and Dodson, – Alosa (blue-backed herring) efficient predator on zooplankton:
            lakes with Alosa – Bosmina, small Cyclops and Tropocyclops – small zooplankton;
            lakes without Alosa – large Daphnia, Diaptomus, Epischura, Leptodora – large zooplankton – correlational evidence
        -1941 Crystal Lake – no Alosa, large bodied zooplankton
        -1950’s Alosa added to the lake
        -1964 Crystal lake resampled – found small bodied zooplankton

        -arctic – depth of the lake determines the presence/absence of fish <2 m freeze to the bottom, so no fish –
            fish lakes have small bodied zooplankton, fishless lakes have large bodied zooplankton
        -are exceptions – lakes with lots of piscivorous fish – effect of an extra trophic level
        -better to be small in the face of vertebrate predation - size selective predation
            WHY AREN’T ALL ZOOPLANKTON SMALL?

    B. Size-efficiency hypothesis –
        - Brooks and Dodson – large zooplankton are competitively superior
        - can take a larger size range of food
        - allometric (changes with body size) respiration function – lower respiration rate at larger size
        - works sometimes, but not always (e.g., between cladocera and rotifers)
        - other things going on – INVERTEBRATE PREDATION
 

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