Date of Award
5-2026
Culminating Project Type
Thesis
Styleguide
apa
Degree Name
Biological Sciences - Ecology and Natural Resources: M.S.
Department
Biology
College
College of Science and Engineering
First Advisor
Jennifer Y. Lamb
Second Advisor
Matthew P. Davis
Third Advisor
Amy C. Kinsley
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Keywords and Subject Headings
Batrachochytrium dendrobatids, Chytrid, Ranidae, Anurans, Minnesota
Abstract
Batrachochytrium dendrobatidis (Bd) is an aquatic, pathogenic fungus that has caused many amphibian populations to decline worldwide. This study investigates how Bd affects species within the family Ranidae that inhabit a variety of ecological niches across an aquatic-terrestrial gradient. I ask how Bd presence and infection intensities (load) vary with day of the year, precipitation, air temperature, and a species’ Aquatic–Terrestrial Index score. A combination of generalized linear mixed effect and generalized linear models were used to explore how these covariates influence Bd presence and load across individuals, respectively. Models were ranked with Akaike’s Information Criterion adjusted for small sample sizes (AICC). A total of 435 individuals were swabbed at sampling locations across central and northern Minnesota in 2024 and 2025. Swabs were analyzed via quantitative Polymerase Chain Reaction by collaborators at the U.S. Geological Survey National Wildlife Health Institute. Bd was detected in all species sampled, but not at all sampling locations. The top models identified by AICC included precipitation, ordinal day, and year as important covariates for Bd presence, and precipitation, ordinal day, and air temperature for Bd load. Aquatic–Terrestrial Index scores did not influence either response variable. However, species identity, a random effect, did influence Bd presence. Precipitation was positively correlated with Bd presence and load. Ordinal day and air temperature were negatively correlated with Bd presence and load. Bd was significantly more prevalent in 2024 compared to 2025. Other factors that were not accounted for could be influencing this pathogen across species and locations. These factors include aspects of a species’ life history (e.g., movement patterns, time of first emergence) and physiology (e.g., composition of the skin mucus, immune system response). Structures and communities within a landscape, like canopy cover and non-amphibian vectors could also influence the persistence and growth of Bd. This study represents one of the largest sampling efforts for Bd in the state.
Recommended Citation
Beers, Kerri, "Presence and Infection Intensity of Batrachochytrium dendrobatidis (Bd) Among Minnesota’s True Frogs (family Ranidae)" (2026). Culminating Projects in Biology. 95.
https://repository.stcloudstate.edu/biol_etds/95
Comments/Acknowledgements
I would like to say the biggest thank you to my advisor and committee chairperson, Dr. Jennifer Y. Lamb. I have had the wonderful opportunity to be able to work and learn from her since my time as an undergraduate researcher. She has taught me so much on what it takes to be a great scientist and professional in this field. I could not have done any of this without her guidance and wisdom. Thank you to my thesis committee members, Dr. Matthew P. Davis and Dr. Amy C. Kinsley, for their academic support and guidance throughout this process. Thank you to my collaborators from the United States Geological Survey (USGS), Dr. Daniel Grear and Megan Winzeler, who performed all the laboratory work and supported this research. Thank you to the volunteers who aided me in this research, Emily Banks (University of Minnesota Veterinary student), Adam Maray (University of Minnesota Undergraduate Research student, BIOL 451), Jordan Barkley (SCSU Undergraduate volunteer), Noor Ali (SCSU Undergraduate volunteer), and Camp Ripley biologists (Andrew Herberg & Kaysie Maleski) and interns (Ryan Miller, Nick Granberry, Sawyer Kenning, Ren Carlson, Zack Bryan, Logan Spencer).
To my friends (past and present) of the Lamb Herpetology Lab including Jack Kosloske, Sam Skinner, Morgan Miedema, Roman Jordan, Dayton Johnson, Lexi Runde, and Kevin Heikkila, thank you for your help in and out of the field, and the silly shenanigans and adventures we’ve had. I am beyond grateful for you guys. Thank you to my amazing parents who always believed in me and told me that I could be anything I wanted to be. Thank you to all my friends, family and my partner, Sean Mahaffy, who have supported me through this journey. To my little big sister, Kayla Borman, thank you for teaching me patience, to live life to the fullest and to turn my somedays into reality.
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Minnesota Aquatic Invasive Species Research Center (MAISRC) and the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Additional funding was provided by St. Cloud State University’s (SCSU) Student Mentor Grants (2024, 2025) and the Midwest Partners in Amphibian and Reptile Conservation (MWPARC) Travel Grant (2024). Thank you to the SCSU Department of Biology and Chemistry for the use of space. Permits that supported this work include MN DNR Special Permits for Research with Reptiles and Amphibians (No. 35353; 36267), MN DNR Parks and Trails Division Research Permits (No. 202457; 202529), MN State Forest Special Use Permits, Sherburne National Wildlife Refuge Research & Monitoring Activity Special Use Permits (No. FY24_R_010; FY25_R_015 ), and an SCSU Institute for Animal Care and Use Committee Protocol (No. 17-149).
This information in this thesis document is preliminary and is subject to revision. It is provided to meet the need for timely best science. The information is shared on the condition that neither the U.S. Geological Survey nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.