Many of you probably saw the recent media coverage of the “Tattered Wings” research paper (see USGS Press Release and podcast). This excellent paper explores the effects of WNS on bats’ wing tissue, and how this damage could lead to the mortality of WNS-affected bats. Paul Cryan, lead author and Research Biologist at the USGS Fort Collins Science Center, talks a little bit about his experiences with the research behind this paper.
It was four years ago this winter that cavers and biologists started noticing very strange things happening with bats hibernating at a few caves near Albany, New York: bats with white fungal growth on their bodies, unusual activity of bats that should have still been hibernating, and mass mortality unlike anything previously documented. As white-nose syndrome (WNS) quickly spread in the following winters and left declining bat populations in its wake, conservation organizations, resource managers, and researchers all scrambled to find out its cause. For almost an entire year, there was considerable uncertainty as to what might be at the root of the problem. Eventually through some unconventional forensic detective work, disease researchers discovered a mysterious fungus consistently infecting the skin of WNS bats. The fungus was named Geomyces destructans, which roughly translates from Latin to ‘the destroying soil fungus.’ How could skin infection by a soil fungus kill bats? This question has been a major component of the WNS investigation and a particular research focus of USGS, the primary science-support agency for the U.S. Department of Interior.
One of the most exciting parts of doing science is sharing ideas and searching for solutions to problems with people who have very different backgrounds of experience and knowledge. It was from such a group that a recent paper published in BMC Biology was conceived. The effort integrated ideas from researchers with expertise in wildlife diseases and pathology, fungal biology, and bat hibernation physiology. The title of the paper is ‘Wing pathology of white-nose syndrome in bats suggests life-threatening disruption of physiology’. In a nutshell, it points out that the wings of bats play very important roles in keeping them healthy during hibernation and that Geomyces destructans is unlike any fungus we have ever seen before—combine the vulnerable skin wings of bats with a fungus that is adept at destroying cold skin and you get a recipe for disaster. Bats rely on their wings for much more than just getting around during winter. Wings are body organs that help hibernating bats maintain healthy balances of water, air, and heat in their bodies during the 6-8 months of hibernation when food is not available and they must live off of body fat. The BMC Biology paper drew together the sometimes subtle evidence on the importance of hibernating bat wings and the serious nature of fungal wing infection, and then proposed several testable hypotheses linking fungal skin infection to death. Our hope is that this paper will inspire other researchers to rigorously test some of the explanations we proposed and winnow away those that are wrong, bringing us closer to the truth of how a soil fungus could be causing such a disastrous disease for hibernating bats. If we can clearly determine the chain of events that lead from fungal particles first touching a bat to its eventual death, we will undoubtedly find certain links in that chain that are weaker than others. Perhaps targeting management and conservation actions at those weak links will help lessen the impacts of this devastating disease on hibernating bats in North America.