Date of Award

Spring 5-6-2024

Document Type

Honors Thesis



First Advisor

Jacob Kerby

Second Advisor

Jeff Wesner

Third Advisor

David Swanson


Selenium, Batrachochytrium dendrobatidis, American bullfrogs

Subject Categories



Most amphibians in today’s world are exposed to a variety of environmental stressors. This project’s main objective was to determine any effects of selenium on Batrachochytrium dendrobatidis (Bd) and infection levels in South Dakota amphibians. I selected American bullfrogs (Rana catesbeiana) as they are susceptible to Bd and are found throughout eastern South Dakota. The secondary objective of this project was to measure any impact of Bd and selenium, combined, on growth measures of the frogs. The third objective was to see if survival rates were reduced when amphibians were exposed to Bd and selenium. Tadpoles were collected (n=225) from the Gavins Point Fish Hatchery in Yankton, SD and were separated into nine groups (25/treatment). Ventral-cloacal swabbing was performed and analyzed using qPCR to determine Bd levels. Growth was recorded (mass and SVL) via the use of electronic calipers. Survival data were collected daily throughout the experiment. I found the highest levels of Bd infection where individuals were exposed to both selenium and Bd, yet no impact of time was found (Table 1 and Figure 1). Tadpoles decreased in mass while increased in SVL across all treatment groups. I found no effects of treatment on either measure of growth or on survival, yet do highlight that the survival rates was lower overall (~50%). These data indivate that low levels of selenium might not otherwise impact American Bullfrog tadpoles, but do not appear to lead to increased infection levels when exposed to Bd. This finding suggests that further attention should be paid to this important contaminant in understanding its role in disease dynamics in South Dakota.

Included in

Biology Commons



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