Mahurin Honors College Capstone Experience/Thesis Projects



Document Type



Amphibian populations are threatened by increasing levels of environmental pollution resulting from human activities. Areas with mixed land use that include agriculture and urban development experience increased contamination from surface herbicide and road deicer application. Upon entering water sources, these chemicals have the capacity to disrupt the natural dynamics of aquatic ecosystems. This study aimed to evaluate the effects of these contaminants on amphibian populations. I used the spotted salamander (Ambystoma maculatum) as a model, rearing larvae from hatching to metamorphosis. I subjected larvae in each of the treatment groups to varying levels of herbicide and salt concentrations. Larval survival was assessed every day, larval size measurements were recorded every 10 days, and the experiment ended when all larvae had died or completed metamorphosis. Treatment effects were assessed via analysis of variance (ANOVA) of linear models relating treatment combinations to response variables including survival, growth, mass-at-, length-at-, and time-to-metamorphosis. Salt concentrations had a greater effect on larval length and mass at metamorphosis than the herbicide concentrations. Higher salt concentrations also appeared to reduce growth and delay time to metamorphosis more so than higher herbicide concentrations. These results indicate that environmental road deicer contamination more negatively impacts amphibian growth and development than glyphosate-based herbicide contamination. These results confirm previous literature regarding the harmful impact of both road salt and glyphosate-based herbicide. However, the effect of herbicide concentration on amphibian populations did not seem to be as strong as the effect of road salt at the concentrations tested. No synergistic negative effects were detected. The results of this study are significant in that they give insight into how anthropogenic land use may be contributing to the global decline in amphibian populations.

Advisor(s) or Committee Chair

Jarrett Johnson, Ph.D.


Biology | Ecology and Evolutionary Biology | Toxicology