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    Summary of Tiselius and Moller (2017)

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    RubyHudkins
    The research studied trophic cascades over eight years in the Gullmar Fjord by measuring the impact of the predator Mnemiopsis leidyi on lower trophic levels. Key findings included demonstrating top-down control of predators on plankton biomass and that trophic cascades can be observed over more than two trophic levels in marine environments. Copepod biomass increased when Mnemiopsis was absent but decreased when it was present due to predation. When copepod biomass declined, ciliates and nanoflagellates increased, demonstrating a trophic cascade effect across multiple levels.

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    Summary of Tiselius and Moller (2017)

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    RubyHudkins
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    The research studied trophic cascades over eight years in the Gullmar Fjord by measuring the impact of the predator Mnemiopsis leidyi on lower trophic levels. Key findings included demonstrating top-down control of predators on plankton biomass and that trophic cascades can be observed over more than two trophic levels in marine environments. Copepod biomass increased when Mnemiopsis was absent but decreased when it was present due to predation. When copepod biomass declined, ciliates and nanoflagellates increased, demonstrating a trophic cascade effect across multiple levels.

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    The research studied trophic cascades over eight years in the Gullmar Fjord by measuring the impact of the predator Mnemiopsis leidyi on lower trophic levels. Key findings included demonstrating top-down control of predators on plankton biomass and that trophic cascades can be observed over more than two trophic levels in marine environments. Copepod biomass increased when Mnemiopsis was absent but decreased when it was present due to predation. When copepod biomass declined, ciliates and nanoflagellates increased, demonstrating a trophic cascade effect across multiple levels.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    24 views1 page

    Summary of Tiselius and Moller (2017)

    Uploaded by

    RubyHudkins
    The research studied trophic cascades over eight years in the Gullmar Fjord by measuring the impact of the predator Mnemiopsis leidyi on lower trophic levels. Key findings included demonstrating top-down control of predators on plankton biomass and that trophic cascades can be observed over more than two trophic levels in marine environments. Copepod biomass increased when Mnemiopsis was absent but decreased when it was present due to predation. When copepod biomass declined, ciliates and nanoflagellates increased, demonstrating a trophic cascade effect across multiple levels.

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    Noya Hudkins

    Summary of Tiselius and Moller (2017)

    The research, which was completed over the course of eight years at the mouth of the permanently
    stratified Gullmar Fjord, was published in 2017. The major goal was to determine whether trophic level
    cascades could be measured in a marine environment as opposed to a lake setting. The primary reason to
    test this due to trophic level cascades in lakes having received greater attention because to their simpler
    and easier sampling procedure and the accurate results from the few species found in each trophic level.
    In contrast to the oceans, where a predator's effect on an entire trophic level occupied by a larger number
    of species will be negligible or nonexistent. In addition to proving that observations of trophic cascades
    over more than two trophic levels can be made in marine environments, the key conclusion was that top-
    down control in marine pelagic systems is just as important as the effect of nutrients (down-top control).
    Their findings supported this by demonstrating that although biomass (chlorophyll a) decreased when
    predation was encountered, primary production (photosynthesis) was constant, meaning that it had no
    effect on biomass decline and favored the impact of predation. Additionally, the findings demonstrated
    that copepod biomass rose in the absence of Mnemiopsis, reaching its peak in July. Hence, in the months
    of July and September, there was a low zooplankton biomass compared to when ctenophores were
    discovered. Adult Mnmeiopsis consume copepods, which along with Mnemiopsis larvae, consume
    phytoplankton such as diatoms and ciliates. According to the findings, Mnmeiopsis larvae were able to
    thrive by outcompeting copepods in the fight for phytoplankton in years where adult Mnmeiopsis were
    present. This was because they consumed copepods and decreased their biomass. The copepods were
    eliminated by the time these Mnmeiopsis larvae matured into adults, allowing the ciliates to flourish and
    expand and resulting in a decrease in the biomass of nanoflagellates. When copepod biomass fell to its
    lowest point, Mnemiopsis decreased and the cycle resumed once more, boosting copepod biomass, and
    decreasing ciliates as a result. These results were reached by measuring primary production using C-14,
    chlorophyll a as a proxy for photosynthesis filtering it and observing its fluorescence using a
    fluorometer.This study contains several great and effective techniques. In order to report the amount of
    zooplankton biomass by mass and not by number of individuals, the copepod biomass was measured by
    measuring their length and calculating the amount of carbon. The choice of predator was also a very
    strong choice, since Mnemiopsis leidyi is one of the most researched species that participates in top-down
    control in marine planktonic ecosystems, which makes it easier to interpret the findings. Advection, a
    significant aspect impacting biomass as it delivers new biomass to replace the dead one, is not excluded
    by the fact that this research was natural and not artificial like most research, making it more trustworthy.
    The research, however, has several drawbacks. Despite being a useful method, quantifying biomass by
    chlorophyll a does not indicate how much of it belongs to which trophic level. Future studies will need to
    test the following trophic levels in order to determine whether or not their theory that the predator
    affects more than three trophic levels, including nanoflagellates and picoplankton, is true.

    Reference to the article:


    TISELIUS P, LENE FRIIS MØLLER L.F. 2017. Community cascades in a marine pelagic food web controlled
    by the non-visual apex predator Mnemiopsis leidyi. J. Plankton Res. 39 (2); 271–279.

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