Date of Award

January 2014

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Stephen C. Richter

Department Affiliation

Biological Sciences

Abstract

A key characteristic of the ridge-top ecosystem in eastern Kentucky is the presence of ephemeral wetlands. Ephemeral wetlands of the ridge-top ecosystem support an amphibian community assemblage characterized by species with short larval periods (e.g., Wood Frogs [Lithobates sylvaticus] and Marbled Salamanders [Ambystoma opacum]). Over the last 25 years, hundreds of wetlands have been constructed within the ridge-top ecosystem as permanent water sources for wildlife (i.e., game species). Consequently, the modified ridge-top ecosystem contains hundreds of constructed wetlands interspersed among natural, ephemeral wetlands. The altered ecosystem has been colonized by several amphibian species with larval periods that require a long hydroperiod (e.g., Eastern Newts [Notophthalmus viridescens], American Bullfrogs [L. catesbeianus], and Green Frogs [L. clamitans]). The new members of the amphibian community assemblage are top predators known to consume various amphibian life stages. Some ephemeral wetland species will breed in constructed wetlands; thus, the recent species additions could have negative impacts on the amphibian species historically associated with the ridge-top ecosystem. My study objectives were to: (1) determine if species of the ephemeral wetland and constructed wetland amphibian communities interact, and (2) evaluate the direction of species interactions (i.e., positive or negative impacts) within the communities. I selected Eastern Newts and Wood Frogs as representatives of the constructed and natural amphibian communities, respectively. I sampled six constructed and six ephemeral wetlands throughout 2013 and 2014. I counted Wood Frog egg masses and estimated survival bi-weekly throughout the breeding season (February-May) at each wetland in each year. I sampled Eastern Newt populations once per month in May, July, September, and November 2013 and January-May 2014. I measured (i.e., SVL, Mass, and sex) newt captures to determine body condition. Data were analyzed using Wilcoxon Mann-Whitney U-tests and stepwise regression models. Eastern Newts and Wood Frogs interact within constructed wetlands. Wood Frog reproductive success was negatively impacted when eggs were laid in constructed wetlands: eggs were consumed (15% - 70%) a higher number of Wood Frog larvae were found in natural wetlands than in constructed wetlands (W = 186.00, p = 0.039). Eastern Newts benefited from Wood Frog presence: newts in constructed wetlands with Wood Frog eggs had higher body condition (W = 402,474.00, p < 0.001). The creation of permanent constructed wetlands has allowed for colonization by amphibians that require long hydroperiods and are top predators. Wetland construction techniques need to be altered to have a more ephemeral hydroperiod, which can limit predation pressure and allow for use by ephemeral breeders. Understanding the impacts of how amphibian species interact as habitat loss and modification increase will continue to be critical for amphibian conservation.

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