Exploring the factors associated with an amphibian die-off at Bousson Environmental Research Reserve: analysis for the presence of ranavirus

Yesko, Emma

Exploring the factors associated with an amphibian die-off at Bousson Environmental Research Reserve: analysis for the presence of ranavirus

Persistent URL

https://dspace.allegheny.edu/handle/10456/56725

Author(s)

Yesko, Emma

Date Issued

April 2023

Abstract

Ecological population crashes occur for a variety of reasons, including disruptions in population density and the abiotic factors of the environment, as well as parasites and pathogens. In the summer of 2022, there was a mass die-off event of wood frog (Lithobates sylvaticus) tadpoles observed at Bousson Environmental Research Reserve, a property owned and maintained by Allegheny College. This mortality event was localized to a single permanent pond; species in other adjacent ponds appeared in good health prior to and during the die-off. I initially hypothesized that this mortality event could have been attributed to population density, parasites, water conditions, or infection with a fungal pathogen (Batrachochytrium dendrobatidis; “Bd”). Throughout necropsy of the tadpole samples collected, monitoring of the abiotic conditions of the water over the course of the summer, screening for parasites, and quantitative polymerase chain reactions (qPCR) to detect Bd DNA, these factors were determined to not be likely responsible for the event. I then hypothesized that ranavirus could be the cause of the die-off event at Bousson. Ranavirus is a viral infection that is known to cause mass mortality and extinction events around the world in various ectothermic vertebrates. For my senior comp research, I further dissected the samples collected during the summer to remove the livers, as ranavirus has been shown to accumulate in this location. I extracted DNA from these samples and performed qPCR analysis to determine if ranavirus was present. All 40 samples that were analyzed were positive for the presence of ranavirus DNA. This result, combined with the information that ranavirus infections are virtually 100% lethal in wood frog tadpoles, indicates that the mortality event that occurred at Bousson can be attributed to ranavirus. Future research can determine whether or not ranavirus will remain in the ecosystem at Bousson and continue to cause die-off events, or if it will begin to affect other species in the various pond and terrestrial habitats on the property.

Major

Biology

Honors

Biology, 2023

First Reader(s)

Venesky, Matthew D.