Surveys for Three Pathogens Reveal No Chytrid Detections But First Detection of Ranavirus in Southern Torrent Salamanders (Rhyacotriton variegatus) in Northern California, USA.

Abstract

This study investigated the prevalence of widely researched amphibian pathogens within the Rhyacotritonidae, a salamander family endemic to the Pacific Northwest of the US. We tested skin swabs (n=309) from southern torrent salamanders (Rhyacotriton variegatus) in northern California, US, for the presence of three pathogens: Batrachochytrium dendrobatidis, Batrachochytrium salamandrivorans, and ranavirus (frog virus 3-like). Using quantitative PCR assays, we detected ranavirus DNA in 16% of swabs but did not detect either Batrachochytrium spp. Prevalence of ranavirus ranged from 0% to 40%, and was significantly different across nine sites in Humboldt and Del Norte counties. Viral load was significantly and positively associated with the water temperature of the microhabitat. Nevertheless, overall viral loads were generally low (none higher than 782 viral particles per swab), and we did not observe any animals exhibiting clinical signs typically associated with ranavirus disease. Further research is needed to determine if this species can develop ranavirus-associated disease.