The diet of the Eastern Musk Turtle (Sternotherus odoratus) as it pertains to invasive snail consumption in a freshwater spring habitat in Texas

The diets of animals are often reflective of the availability, preference, presence, and even absence of food resources within ecosystems. Turtles are known to feed across a wide variety of fauna and flora. The diets of bottom dwelling turtles such as musk turtles have been documented to be composed mainly of benthic macroinvertebrates. In this study we investigated the diet of the Eastern Musk Turtle (Sternotherus odoratus) in Comal Springs, a spring fed lake system located in the hill country region of Texas. Due to high numbers of invasive snails in this system, we focused on consumption of invasive snails. Across the globe there are many instances of invasive species becoming prevalent in their new ecosystems. While this is true across a variety of taxa, invasive mollusks are often particularly abundant in freshwater ecosystems. In Comal Springs the most abundant taxa present in the fecal samples were gastropods. In particular, three species of invasive snails, the Red-rimmed Melania (Melanoides tuberculata), the Quilted Melania (Tarebia granifera), and the Giant Ramshorn Snail (Marisa cornuarietis) were the most abundant items identified. We found fragments of M. tuberculatashells in the majority of the samples (77% male samples; 80% female samples; 78% total), opercula from M. cornuarietisin a smaller number of samples (20% male samples; 10% female samples; 16% total samples) and fragments of the T. graniferashells in half of the fecal samples (50% male samples; 50% female samples; 50% total). No sexual difference in diet was apparent. Total consumption of mollusks was high relative to most other reports of Sternotherus odoratusdiet. We suggest the diet of S. odoratusin Comal Springs has shifted toward invasive molluscivory as the result of a probable three decade presence of these invasive species.  Key Words: Sternotherus odoratus, Melanoides Tuberculata, Marisa Cornuarietis, Tarebia granifera,predation, invasive, Texas, Comal Springs, Diet