1. Are Canyon Tree Frog (Hyla arenicolor) Populations in Zion National Park Affected by Chytrid Fungus? Madalynne Fedoruk, Darian Carey Department of Physical Sciences Dixie State University ABSTRACT RESULTS INTRODUCTION Chytrid fungus (Batrachochytrium dendrobatidis) has been suspected to have been the cause of a massive decline in amphibian species worldwide. Canyon Tree Frog (Hyla Arenicolor) population sizes in Zion National Park do not seem to be affected by chytrid fungus. Due to having several months to gather data, a mark- recapture study was performed to determine whether increases in temperature over the study period had a necrotic effect on the chytrid fungus. METHODS Visited nine canyons during the summer of 2014 Hyla Arenicolor were sighted and counted in order to determine population sizes Population sizes were compared to those of the previous three years Mark-recapture study was performed in the Subway canyon to determine whether climate variables were the cause of H. Arenicolor ridding themselves of Batrachochytrium dendrobatidis. In Misery Canyon the population in 2011 was 26 and by 2014 had increased to 155. In Misery Canyon, 90% of the frogs tested positive for Chytrid – demonstrating that canyon tree frog population size is not dependent on Chytrid fungus. DISCUSSION The presence or absence of Batrachochytrium dendrobatidis had no effect on H. arenicolor population sizes in Zion National Park. H. arenicolor survive despite infection of Batrachochytrium dendrobatidis ACKNOWLEDGEMENTS We would like to acknowledge the support of Curt Walker, David Jones, and the Department of Biological Sciences throughout the duration of both collecting and analyzing data. We also recognize previous students for their support in gathering data. For at least three decades, infection with chytrid fungus (Batrachochytrium dendrobatidis) has been a major cause of population decline in amphibians worldwide. This pathogen has been found in canyon tree frogs (Hyla arenicolor) in Zion National Park; previous studies suggested that population sizes decreased in frogs infected with the fungus; but our studies indicated that these frogs were resistant. We hypothesized that chytrid infection in the Zion Canyon tree frogs were not lethal, but other environmental factors caused populations to fluctuate. Canyon tree frogs were captured and swabbed in each of nine canyons in and around Zion National Park during the summer of 2014, and total frog populations were counted in each study canyon. The swabs were analyzed for the presence of chytrid DNA, and infection rates and population sizes were compared with data from 2011-2013. We found that the presence or absence of chytrid had no influence on population size in a particular canyon; population sizes were more dependent on precipitation. The Zion canyon tree frogs resist this normally lethal disease; how they evade it will be the goal of future studies. Tag Figure 1. Demonstrating mark-recapture tag Figure 2. Demonstrating Canyon Tree Frog in it’s natural habitat FUTURE RESEARCH Future mark-recapture studies performed in multiple canyons to investigate the presence of chytridiomycosis. Further research on H. arenicolor to understand how they are evading the lethal effects of Batrachochytrium dendrobatidis.