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

BS, Kent State University, 2013, College of Arts and Sciences / Department of Biological Sciences

Amphibians fill many niches within an ecosystem and have important interactions with other species in their habitats. In this study, wood frog (Lithobates sylvaticus) tadpole growth and development was monitored until metamorphosis under four different leaf litter treatments; red oak (Quercus rubra), red maple (Acer rubrum), American beech (Fagus grandifolia), and a mixture of the three in artificial pools that simulated their typical vernal pool habitat. While tadpole size, morphology, and developmental stage changed significantly over time, there were no significant effects of leaf litter treatment, nor were there significant time*treatment interaction effects. Following completion of the experiment, leaf chemistry analyses were also conducted to compare biochemical characteristics associated with different leaf litter treatments that might have implications for tadpole populations. Of the biochemical analyses, % polar extractives, % lignin, lignin:N, and % C were significantly different among treatments. Thus, despite leaf litter differences, tadpoles showed no significant treatment effects. These data indicate that wood frog tadpoles exhibit broader plasticity relative to vernal pool conditions than might be expected. Ultimately, this may make L. sylvaticus more resilient to changing upland forest communities, particularly with respect to tree species present.

Committee: Mark Kershner (Advisor); Chris Blackwood (Committee Member); Dan Ross (Committee Member); Paul Sampson (Committee Member) Subjects: Biology; Conservation; Ecology; Environmental Science; Evolution and Development; Freshwater Ecology; Organismal Biology; Plant Biology; Wildlife Conservation