Epidemiology of an emerging virus in western tiger salamanders (Ambystoma mavortium) in southwestern Alberta

Abstract

Emerging infectious diseases are one of the factors that have contributed to global amphibian population declines over the past few decades. The recent emergence of the highly virulent Amybstoma tigrinum virus (ATV) in tiger salamanders at three sites in Alberta has led to concerns regarding the population status of this prairie icon. Results from my population surveys showed that tiger salamanders occurred in approximately 50% of 15 sites in southwestern Alberta, but densities were low. In a longitudinal survey of a salamander population in Livingston Lake, Alberta in 2013 and 2014, ATV was strongly seasonal, increasing from 0 to 100% prevalence between early July and metamorphosis in mid-August. Despite a consistent seasonal pattern of exposure to ATV, host mortality was high in one year, but low in the next. These results suggest that ecological factors (i.e. triggers) act in addition to ATV exposure to contribute to ATV outbreaks and to variability in infection outcome in host populations.