It may be helpful to put the current pandemic into the broader context of ecology and history. SARS CoV-2 is not as deadly as the Bubonic plague that killed sixty percent of the population of Europe in the fourteenth century, nor is it as lethal as the swine flu pandemic of 1918-20 that killed 50 million worldwide. Ebola killed more than 11,000 in West Africa in 2016. All of these infectious diseases however, pale in comparison to the fungal infection known as Bd after
Batrachochytrium dendrobatidis, a
fungus that kills amphibians by eating their sensitive skin and causing fatal heart attacks.
 |
| baby limosa harlequin frog, Daily Mail |
The
latest estimate by researchers published in Science is that the cytrid fungus, identified twenty years ago, is responsible for the decline of a shocking 501 amphibian species and is presumably responsible for the extinction of 90 species. Another 124 have declined more than 90% and probably will not recover. Lead researcher Ben Steele of Australia National University, told the
Atlantic, “It rewrote our understanding of what disease could do to wildlife.”
When one considers that amphibians are a major class on the tree of life that have been in existence for some 370 million years the scale of destruction wrought by one organism in five decades is mind bending. Amphibian experts are rightfully "freaking out" about the lost of so many species, so quickly. The mysterious disappearance of frogs from the rain forests of the Americas and Australia in the '70s was noted by wildlife experts, but the cause was debated. By the time the fungus was isolated in 1998, it had killed 60 amphibious species. Epidemiologists at Imperial University (sound familiar?) conducted a genetic study that suggested the fungus originated in Asia and quickly spread to five continents.
 |
| adult harlequin, Daily Mail |
Bd is the perfect frog killer, undiscriminating, persistent and able to convert nutrients found on amphibian skins, it spreads through the water. There is another factor in the ability of the fungus to kill so many species around the world: the increasing interconnections artificially created by man's global transportation network. Steele compares it to a recreation of
Pangaea, the super continent existing in the Paleozoic Era. A result of this condition is that fungal infections that might have stopped at the shoreline are showing up across the oceans, infecting a range of fauna
from bats, snakes, salamanders and others. Included in this artificial transmission is the largely illegal wildlife trade in which foreign organisms are introduced to a defenseless ecosystem for the sake of profit. Besides the obvious ecological impact of too many rabbits or pythons, the pathogens they carry do the most damage to biodiversity.
There is a glimmer of hope for amphibians. Some decimated populations are increasing and the rate of decline for sixty species appears to be easing. So far Papua New Guinea, rich in amphibious species has escaped the fungal plague. Perhaps frog evolution has found a way to combat Bd. Nature may have to provide an effective defense because there is no easy way for man to combat the disease. There are
captive breeding programs, research on hybridization, and genetic manipulation of the fungus itself. None of these strategies are close to being deployed in Nature, and there are always unintended consequences to artificial solutions. What the Bd scourge tells man, is there is no escape from natural processes that tend to restore ecological balance, no matter how successful the species.
