Author ORCID Identifier

https://orcid.org/0000-0001-7056-8062

Document Type

Dissertation

Date of Award

12-2021

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

First Advisor

Jacob L Kerby

Abstract

Climate change and anthropogenic stressors have contributed to rapid declines among various taxonomic groups; however, amphibian declines have been particularly intense and primarily stemmed from warming temperatures, habitat loss, exposure to contaminants, disease, and their subsequent interactions. Several climate mitigation strategies, like Bioenergy with Carbon Capture and Storage, have been proposed to alleviate the impact of rising temperatures; however, these proposals often fail to recognize and quantify the true impact on fauna, including changes in species distributions. To address this critical gap in knowledge, this research identified current amphibian distributions in the Upper Missouri River Basin and projected distribution changes under two future climate and land-use change scenarios. This work revealed that climate change will have a more detrimental effect on amphibian distributions compared to anthropogenic variables and that montane amphibian species are at a higher risk of declines compared to low-land amphibians. To further investigate how amphibians are impacted by anthropogenic stressors on a population scale, this research investigated how agricultural practices, including tile drainage systems, contribute to the release of selenium and neonicotinoid insecticides into nearby wetlands. Following confirmation that tile drains contribute to elevated levels of neonicotinoids in wetlands, laboratory and field-based studies were conducted to determine whether neonicotinoids cross the blood-brain barrier in amphibians and measured behavioral-impacts. This research showed that neonicotinoids (i.e., imidacloprid) can cross the blood-brain barrier, is accumulated at high concentrations in amphibian brains, and results in slower reaction times. Moreover, this research confirmed elevated selenium concentrations in water, sediment, invertebrate, and vertebrate samples at wetland sites connected to tile drainage systems. Lastly, this research investigated the impact of selenium and neonicotinoids on the growth of the deadly amphibian pathogenic fungus, Batrachochytrium dendrobatidis. This work highlighted the anti-fungal properties of selenium and demonstrated that selenium negatively impacts B. dendrobatidis growth. Additionally, this study showed neonicotinoids had less of an impact of fungal growth; however, exposure still resulted in changes in growth over time. Collectively, this work spans several disciplines including machine learning, ecotoxicology, neurobiology, and disease ecology and further emphasizes the importance and need of interdisciplinary studies to address complex ecological issues.

Subject Categories

Biology | Ecology and Evolutionary Biology

Keywords

Amphibians, Batrachochytrium dendrobatidis, Machine learning, Neonicotinoids, Neurotoxicology, Selenium

Number of Pages

163

Publisher

University of South Dakota

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