The use of environmental DNA (eDNA) to Detect the Emergent Infectious Pathogens in Amphibian Populations

The use of environmental DNA (eDNA) to Detect the Emergent Infectious Pathogens in Amphibian Populations

Principal Investigator: Dr. James Julian, Pennsylvania State University

Years Funded: 2016-2018

Project Description:
Ranavirus (RV) and Batrachochytrium dendrobatidis (Bden) are invasive, emergent infectious pathogens that have been documented in hundreds of species of amphibians, spread through the international trade of animals, and have been implicated in the mass mortality of over 20 species. Disease-induced mortality events often occur at breeding ponds where amphibians congregate in larger numbers. Detection can prove difficult in these areas because dead animals are quickly consumed by conspecifics or decompose before investigators can collect the tissue samples needed for genetic detection of these pathogens. However, the collection of environmental DNA (eDNA) from the water column of infected ponds has been shown to detect these pathogens before, during, and after active outbreaks. We propose a program that will teach eDNA collecting techniques to NGO staff, environmental educators, citizen scientists, and government agencies who could serve as early response units to diagnose amphibian disease outbreaks.

In the spring of 2016, we will establish protocols to detect RV and Bden from eDNA samples by using extracted DNA from infected individuals and filtered water samples from sites where these diseases have been detected. In the spring of 2017, we will conduct a day-long workshop that will train participants on how to collect eDNA samples, and educate them on preventing disease transmission. Afterwards, participants will be assigned ponds that have experienced disease outbreaks, and will collect eDNA samples from ponds before, and after, tadpoles complete metamorphosis. We will evaluate participant-sampling efficiency by collecting independent samples within 48-hours of participant-collected samples. In total, we will screen 12 ponds where diseases have been detected, and 12 ponds that are either in close proximity to those sites, or ponds that experience active mortality events.

Photo Credit: Dr. James Julian, Pennsylvania State University