Amphibian pathogens at northern latitudes: presence of chytrid fungus and ranavirus in northeastern Canada

Abstract

Infections by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and members of the genus Ranavirus (Rv) are increasingly reported as significant determinants of amphibian population die-offs. The complexity associated with their transmission and spatial distribution leads to an increase in demand for comprehensive reporting systems and global mapping of their distribution. Here, we document the distribution of these 2 pathogens in a remote northern temperate lowland where environmental sensitivity is high, providing important insight into the pathogens' natural history and infection patterns. Wood frog Lithobates sylvaticus tissues were collected from the James Bay area in northeastern Canada and were screened for the presence of Bd and Rv using conventional and real-time PCR. Both pathogens were present in the study area, which is the northernmost record in eastern North America. Interestingly, different patterns of distribution were observed between the eastern and western coasts of James Bay, suggesting differences in the spatial and transmission dynamics for each pathogen. Anthropogenic introduction may still influence the distribution patterns observed, even at these latitudes. The presence of infections in this remote area also raises further questions on the risk these pathogens pose to northern amphibian communities. We encourage further research in remote locations for a better understanding of these pathogens, their transmission dynamics, and especially their respective impacts on amphibian populations worldwide.

Spatiotemporal heterogeneity decouples infection parameters of amphibian chytridiomycosis

“…Despite the presence of Bd within Ontario, Canada (D'Aoust‐Messier, Echaubard, Billy, & Lesbarrères, ; St‐Amour, Wong, Garner, & Lesbarrères, ), chytridiomycosis‐driven declines are yet to be definitively reported within populations of R. pipiens . Yet, outside Ontario, chytridiomycosis has been reported as the cause of mass mortality events within this species (Green, Converse, & Schrader, ; Voordouw, Adama, Houston, Govindarajulu, & Robinson, ).…”

“…Despite the presence of Bd within Ontario, Canada (D'Aoust- Messier, Echaubard, Billy, & Lesbarrères, 2015;St-Amour, Wong, Garner, & Lesbarrères, 2008), chytridiomycosis-driven declines are yet to be definitively reported within populations of R. pipiens. Yet, outside Ontario, chytridiomycosis has been reported as the cause of mass mortality events within this species (Green, Converse, & Schrader, 2002;Voordouw, Adama, Houston, Govindarajulu, & Robinson, 2010 In order to measure environmental variation at a scale relevant to the host, temperature and precipitation were averaged across two specific time points: (a) period prior to host breeding and (b) during host breeding.…”

Detection of spatiotemporal variation in ranavirus distribution using eDNA

“…Many pathogens are harmful to amphibians, including Saprolegnia ferax, Ribeiroia ondatrae , and Batrachochytrium dendrobatidus ( Bd ) (Daszak et al, ; Johnson et al, ; Kiesecker, Blaustein, & Belden, ; Romansic, Diez, Higashi, Johnson, & Blaustein, ). Among these pathogens, ranaviruses are notable given their known impacts on amphibian populations, affecting both larval and adult life stages (D’Aoust‐Messier, Echaubard, Billy, & Lesbarrères, ; Duffus et al, ). Ranavirus (family Iridoviridae ) is a genus of double stranded DNA viruses that circulate in the host's bloodstream and cause systemic infections (Gantress, Maniero, Cohen, & Robert, ).…”

Effects of host species and environmental factors on the prevalence of Batrachochytrium dendrobatidis in northern Europe

“…Few studies have investigated factors affecting Bd infection risks in cool temperate or boreal regions with relatively low summer temperatures (but see [ 45 – 48 ]) where climate and, consequently, disease dynamics differ from those in warmer regions. In Sweden, Bd was first discovered in 2010 [ 49 ], followed by records on several amphibian species in southernmost Sweden and the Stockholm area, providing the northernmost records of Bd in Europe (S. Meurling et al, in prep.).…”