White-Nose Syndrome: Why It’s Killing Bats

By TreeLiving Bats in the United States are under threat from a lethal fungus. White-nose syndrome is killing native bats in their millions, with five and half million casualties to date. The epidemic is spreading westwards from state to state and species to species. The first cases were observed in Albany, N.Y, but the disease is now affecting bats in Canada. With no cure in sight, and serious practical d ifficulties to overcome even if it were treatable, the future for the bat is looking very bad indeed. Bats affected by the killer fungus display a white growth around the muzzle which gives the syndrome its name. The culprit is a cold-loving fungus that thrives in the depths of caves – the very habitats that are home to most bats. Relatively mild temperatures in the last year have not slowed the contamination, as environmental experts and other scientists had hoped. The spread of the disease even to the warmer southern US states has also been a disturbing observation and cause for pessimism. The most likely organism causing the epidemic has been identified as Geomyces destructans – and in the US it lives up to its name, being rampantly destructive. Strangely, the same organism in Europe does not seem to have caused the same levels of mortality. It is possible that it is an alien species that has mutated in the US context. The fungus eats away the fragile skin on the face, ears and wings of the bats, but the ultimate cause of their deaths remains uncertain. Dehydration is one possibility, as is the depletion of winter fat reserves. What is clear is that the spread of the disease is virtually impossible to contain. Also clear is the role that humans have played in the spread of the disease. The first outbreak in Albany took place in a tourist cave visited by thousands. Public access to infected caves is being restricted. Cavers are now being made aware of the enormous problems of the fungal spread, and are being asked to take care and disinfect clothing after caving in what may be a belated and futile effort to contain the problem. At least six of the forty-five North American bat species have been affected so far, with numbers of some species, such as the common brown bat, plummeting dramatically in the five or six years since the syndrome was recognised as a major issue. The environmental impact is hard to estimate, but some predictions suggest likely outcomes. Bats are animals that feed on insects. The various species eat thousands of tons of insects every year, so it’s a fair bet that the winner in this eco disaster will be the bugs. As well as the bats, that means the farmers are also likely to lose out, as are consumers. Farmers might resort to more pesticide use, which is far from the green ideal; and the impact on crops could lead to shortages and price increases for consumers. However, the real environmental disaster is just as much about the disruption of the ecological balance – very likely helped by human ignorance. Image Courtesy of Defenders of Wildlife