Campus Only Senior Thesis
Bachelor of Arts
W.M. Keck Science Department
Environment, Economics and Politics
© 2014 Hannah B. Cotter
The Tamana Cave system in Trinidad is relatively unaffected by the environment outside of the cave walls, like most cave ecosystems. Since a very limited amount of light can enter the cave, bat movement controls the temperature cycle rather than the solar radiation that controls it in the surrounding forest. Similarly, the ecosystem cannot be sustained by energy from photosynthesis and so the main source of energy comes from the guano produced by the insectivorous bat species, N. tumidirostris. The frugivorous bat species, P. hastatus, also roosts inside of the cave, but the wetness of the top level of its guano prevents the guano from being suitable for cockroach consumption and therefore ends the flow of energy through the system. STELLA software was used to create a model consisting of three stacked logistic growth equations that demonstrate the ecosystem of Tamana cave. The model focuses on the population of insectivorous bats, on the guano that this species produces, and on the cockroach species, E. distanti. The model provides insight into the population dynamics and environmental processes at play in the cave, and is useful in predicting the behavior of the ecosystem. After running the model under a number of different scenarios, the graphs were used to visually display the effects of altering inputs in the system. These altered inputs represent hypothetical changes that could occur in a natural system such as a lowered intrinsic rate of increase bat population, an increase in initial bat population, or a decrease in the amount of guano that each cockroach needs to survive.
Cotter, Hannah B., "Simulation Modeling of a Tropical Cave Ecosystem" (2015). Scripps Senior Theses. 561.
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