Tracy Day, Senior
The Trophic Position of Pomacea insularum
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Research Summary: My proposed research aims to determine the trophic position of island apple snails, Pomacea insularum,
in the food web of Texas coastal wetlands. I plan to accomplish this goal through combining a stable isotope approach
with gut content examinations and laboratory experiments. Overall, I want to examine the magnitude to which apple snails
exist as predators, prey and competitors.
Stable isotopes studies utilize N15 and C13 to determine interactions within ecological communities, such as trophic levels
and food webs. Trophic levels reveal energy flow and the roles an organism plays within its community. Trophic level can be
determined using the mean change in N15 values between an organism and its diet as 3.4%. Alternatively, diet can be determine
using C13 values which have a mean difference of 0.0% between an organism and what it eats. However, these values depend on ranges.
Therefore, when beginning a stable isotope study, the importance of a baseline indicator cannot be undervalued and its value
multiplies especially when multiple species have overlapping diets that making it impossible to discern their trophic level
or differentiation. I spent Spring 2011 preparing stable isotope samples from Armand Bayou Nature Center to see if we can
discern the trophic position of island apple snails.
Where I've been and Where I'm going:
