No Change Detected in Culturable Fungal Assemblages on Cave Walls in Eastern Canada with the Introduction of Pseudogymnoascus destructans

Studies of fungi in caves have become increasingly important with the advent of white-nose syndrome (WNS), a disease caused by the invasive fungus Pseudogymnoascus destructans (Pd) that has killed an estimated 6.5 million North American bats. We swabbed cave walls in New Brunswick, Canada, in 2012 and 2015 to determine whether the culturable fungal assemblage on cave walls changed after the introduction of Pd and subsequent decrease in hibernating bat populations. We also compared fungal assemblages on cave walls to previous studies on the fungal assemblages of arthropods and hibernating bats in the same sites. The fungal diversity of bats and cave walls was more similar than on arthropods. The diversity and composition of fungal assemblages on cave walls was significantly different among media types and sites but did not differ over time. Therefore, no change in the culturable fungal assemblage present on cave walls was detected with the introduction of Pd and subsequent disappearance of the hibernating bat population over a 3-year period. This suggests that fungi documented in caves in the region prior to the outbreak of Pd do not require regular transmission of spores by bats to maintain fungal diversity at these sites.

Psychrotolerant Microfungi Associated with Deer Mice (Peromyscus maniculatus) in a White-nose Syndrome Positive Bat Hibernaculum in Eastern Canada

With the exception of recent work on bats, no reports on the fungi present on live mammals in underground habitats have been published. We cultured psychrotolerant fungi from the external surface and faeces of live Deer Mice (Peromyscus maniculatus), and from the intestinal contents of a single freshly killed P. maniculatus, overwintering in a white-nose syndrome positive bat hibernaculum and from adjacent summer forest in eastern Canada. A low diversity of psychrotolerant fungi was cultured from P. maniculatus compared with that found in previous studies of the mycoflora of bats and arthropods occupying bat hibernacula in the region. Although the grooming habits of P. maniculatus may reduce the accumulation of a diverse psychrotolerant fungal assemblage on their external surface, we demonstrate that active euthermic mammals in underground habitats can carry viable spores of psychrotolerant fungi, both externally and internally. Small rodents using cave habitats may also play a role in dispersing psychrotolerant fungi between caves and suitable low-temperature habitats (i.e., burrows) in adjacent forest.