Trophic Energy Lab Report

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Ecosystem Dynamics and Trophic Energy
Marc Mueseler
BIO111 Biology Laboratory

Abstract: The purpose of this experiment is to study different ecosystems and observe the change in the number of organisms at each trophic level as well as the energy transfer to each of these levels. It was observed that the number of organisms dropped off significantly from level to level as the energy transfer efficiency was approximately 10% at each heterotrophic level. Each ecosystem was only able to support about four levels before all of the energy in the system was essentially depleted. The number of organisms in each ecosystem was dependent upon the number of producers available to make their own energy thereby making that energy available to

Experimental Procedure: Start by choosing one of the five ecosystems in the drop down menu. Place the animal or plant in the appropriate trophic level in the ecosystem pyramid. Check that all names are in the correct location by clicking the check button. Repeat until all names are correct. Click the Pyramid of Energy button and record numbers on the data table. Next, click on the Pyramid of numbers button and record these numbers on the data table. Calculate the conversion efficiency for each trophic level for the ecosystem and record in the data table. Click the reset button and repeat for two different ecosystems.

Results and Discussion: As seen in the data table below, the energy flows to each level of heterotrophs at an efficiency rate of approximately 10%. The number of producers directly affects the number of heterotrophs at each level as only so much energy is available to support life. It can be observed that the energy can only support 4 trophic levels before energy is depleted. Virtually all energy is eventually lost as heat, the small amount remaining is returned to the soil by decomposers for