Bachelor of Science, Wittenberg University, 2021, Biology

Glyphosate has been shown to impact not only amphibian survival, but also their development, phenotypic response to predators, and overall behavior. Dicamba, another herbicide, was permitted for use by the EPA in 2016. However, less is known about its potential environmental impact. Being an extremely volatile chemical, dicamba poses a risk to aquatic organisms in areas that may experience runoff or overspray. It can also harm yields of neighboring crops, leading the EPA to ban dicamba use part way through this experiment in June 2020. We investigated the effects of an environmentally relevant dosage of two forms of dicamba on grey treefrog tadpole development and behavior. We also investigated how dicamba impacted the response of tadpoles to predator cues. Herbicide treatment significantly decreased growth compared to the control. The presence of predator cues also significantly decreased growth, and there was no interaction between herbicide treatment and predator treatment. Tadpoles exposed to predator cues generally had wider tails, and the introduction of dicamba caused similar morphological changes. The presence of commercial dicamba also significantly reduced startle responses, potentially increasing the risk for predation. Dicamba has the potential for sublethal impacts on the development and behavior of tadpoles, and therefore should be further studied.

Committee: Amber Burgett (Advisor); Richard Phillips (Committee Member); Doug Andrews (Committee Member) Subjects: Agricultural Chemicals; Animal Sciences; Animals; Aquatic Sciences; Biology; Environmental Science; Statistics; Zoology

Doctor of Philosophy, Miami University, 2022, Ecology, Evolution and Environmental Biology

Infectious diseases of wildlife, which have been increasing in both frequency and severity in recent decades, threaten host species with decline and extinction. Disease dynamics are moderated by both abiotic and biotic environmental conditions, which have the capacity to influence hosts, pathogens, and how they interact. Any factors that are favorable to a pathogen or unfavorable to a host have the capacity to exacerbate the negative effects of pathogens. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been recognized as one of the most devastating infectious diseases of wildlife to date, yet it coexists with hosts in some populations without causing apparent declines. I examined how abiotic and biotic environmental conditions influence Bd-anuran interactions in a system where the pathogen is present but pathogen-associated declines are not evident. My central hypothesis was that environmental characteristics that are unfavorable to Bd or favorable to anurans would mitigate negative effects of disease. To test this hypothesis, I conducted laboratory experiments and a field study measuring abiotic and biotic environmental conditions and landscape characteristics. My results showed that temperature, pH, ultraviolet radiation, and invertebrates can influence the abundance and infectivity of Bd through impacts on pathogen abundance and host responses to this pathogen. Furthermore, my research highlights that favorable conditions for hosts, such as high food availability, increase the probability of a host successfully combatting infection by Bd. Infection appears to come at a high metabolic cost and results in decreased growth in the majority of hosts tested. Further, overwintering may be the period when amphibians in the Midwest are most at risk of disease-associated mortality, and in some species such as American toads, Bd infection may devastate populations over winter. My laboratory studies suggested that environmental conditions may predict B (open full item for complete abstract)

Committee: Michelle Boone (Advisor); David Berg (Committee Member); Tereza Jezkova (Committee Member); Craig Williamson (Committee Member); Jing Zhang (Committee Member) Subjects: Biology; Ecology; Wildlife Conservation

Master of Science (MS), Bowling Green State University, 2016, Biological Sciences

Animals living within aquatic habitats regularly encounter chemical pollution as a result of anthropogenic activities. Typically, the toxicity of a chemical pollutant or toxicant is determined by the median lethal concentration (LC50). However, LC50 values do not provide an accurate representation of exposure to a pollutant within natural systems. In their native habitats, animals experience exposure as a fluctuating concentration as a result of turbulent mixing. Edwards and Moore (2014) showed that more turbulent environments produce exposures with a high degree of fluctuation in frequency, duration, and intensity. In order to more effectively evaluate the effects of pollutants, we created a more ecologically relevant exposure paradigm, utilizing both flow and substrate within a small mesocosm. A commonly used pharmaceutical, naproxen, was used as the toxicant and female crayfish (Orconectes virilis) as the target organism to investigate changes in fighting behavior as a result of dynamic exposure. Crayfish underwent either a static or a dynamic exposure to naproxen in 23 hour long trials. Following exposure, the target crayfish and an unexposed size matched opponent underwent a 15 minute fight trial. These fight trials were recorded and later analyzed using a standard ethogram. Results indicate that exposure to sublethal concentrations of naproxen, in both static and flowing conditions, negatively impact aggressive behavior. Results also indicate that a dynamic exposure paradigm has a greater negative impact on behavior than a static exposure. Turbulence and habitat structure play important roles in shaping chemical exposure. Research in the future should incorporate features of chemical signals, such as intermittency and number of peaks above the mean concentration in order to form a more comprehensive image of chemical exposure and predict the resulting sublethal effects from exposure.

Committee: Paul Moore (Advisor); Jeff Miner (Committee Member); Rachelle Belanger (Committee Member) Subjects: Biology; Ecology