Date of Award

January 2022

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Cy L. Mott

Department Affiliation

Biological Sciences

Second Advisor

Valerie E. Peters

Department Affiliation

Biological Sciences

Third Advisor

Amy Braccia

Department Affiliation

Biological Sciences

Abstract

Consumptive (direct) effects of predation have been well-studied in most aquatic systems, but non-consumptive (indirect) effects on prey have only recently received limited attention in some groups. As aquatic consumers, tadpoles have traditionally been considered strict herbivores, leaving their predatory impacts via consumptive and non-consumptive interactions on aquatic invertebrates largely unexplored. The objectives of this study were to quantify omnivory among wood frog (Lithobates sylvaticus) tadpoles, determine their consumptive and non-consumptive effects on invertebrate communities, and investigate whether such effects are mediated by habitat shading and tadpole body size. Lithobates sylvaticus tadpoles and egg masses were randomly sampled from 11 ponds in the Daniel Boone National Forest, eastern Kentucky, USA. Tadpoles were dissected to quantify the frequency of omnivory, while egg masses were reared to hatching to create size structure. Hatched tadpoles were then employed in a fully factorial mesocosm design that manipulated tadpole presence (absent, caged, or free-swimming), body size (large or small), and canopy cover (shaded or unshaded) to determine effects on invertebrate communities. Over 70% of tadpoles in natural ponds engaged in omnivory, primarily on zooplankton. Tadpoles in mesocosms exhibited consumptive and non-consumptive effects on invertebrate communities, with generally reduced invertebrate abundance under shaded conditions and in the presence of larger tadpoles. Larger tadpoles in unshaded conditions also exhibited higher survival and maintained larger sizes, but smaller tadpoles in unshaded conditions grew more quickly. This study stresses the ecological importance of tadpoles, given their roles as predators of, and competitors with, aquatic invertebrates.

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