Starting in late 80s, herpetologists began noticing that various kinds of frogs were declining and/or disappearing. There was & is a geographical pattern: Wiki says “Declines have been particularly intense in the western United States, Central America, South America, eastern Australia and Fiji. ” Many were hard to understand in terms of human impact. “For example, the Golden toad (Bufo periglenes) endemic to Monteverde, Costa Rica, featured prominently. It was the subject of scientific research until populations suddenly crashed in 1987 and it had disappeared completely by 1989. Other species at Monteverde, including the Monteverde Harlequin Frog (Atelopus varius), also disappeared at the same time. Because these species were located in the pristine Monteverde Cloud Forest Reserve, and these extinctions could not be related to local human activities. ”
For a few years the herpetologists were concerned yet happy. Concerned, because many frog populations were crashing and some were going extinct. Happy, because confused puppies in Washington were giving them money, something that hardly ever happens to frogmen. The theory was that amphibians were ‘canaries in a coal mine’, uniquely sensitive to environmental degradation.
Possibly frogs were being killed by an increase in UV radiation (from CFCs). Of course you could always put out a fucking ultraviolet photometer and measure the UV anywhere and anytime you wanted, but that would be the easy way out. Why do that when you could be paying graduate students to play with frogs?
In 1993, people discovered an odd fungus [ Batrachochytrium dendrobatidis] infecting frogs in Queensland. Since then it has been linked to many dramatic population declines in “western North America, Central America, South America, eastern Australia, East Africa (Tanzania) and Dominica and Montserrat.” Some species it bops, others it exterminates. Frog species with few offspring and high parental investment, such as mouth-breeding frogs, seem particularly vulnerable. It works like an STD, which can propagate when population density is low. Frogs congregate in ponds to mate, which allows transmission, as long as the frogs mate at all.
It took some time for herpetologists to admit that this chytrid fungus is the main culprit – some are still resisting. First, it was a lot like how doctors resisted Semmelweiss’ discoveries about the cause of puerperal fever – since doctors were the main method of transmission. How did this fungus get to the cloud forests of Costa Rica? On the boots of herpetologists, of course.
The second problem is Occam’s butterknife: even though this chytrid fungus is the main culprit, it’s just got to be more complicated than that. Even if it isn’t. People in the life sciences – biology and medicine – routinely reject simple hypotheses that do a good job of explaining the data for more complex hypotheses that don’t. College taught them to think – unwisely.
It looks if it infected the African clawed frog (Xenopus laevis) for a long time, well before the current epidemic, and was spread by worldwide use of that frog in human pregnancy testing.
Look at the broad pattern of areas affected: the Americas, Australia, islands. Amphibians in those areas were profoundly isolated from the Old World, just as their human inhabitants were. North America is not isolated when it comes to birds or mammals – there has often been an exchange of species thru Beringia, during glacial periods – but amphibians can’t survive salt water or glaciers. They’ve been isolated from Old World amphibians for a long long time – more than 100 million years, looks like. And since the Old World is bigger, with more intense biological competition*, invasive biological trouble is more likely to originate there than in the Americas or Australia.
People are still talking about environmental factors. Used to be UV (wasn’t true), herbicides ( also untrue – kind of silly way out in the jungle). Now, of course, it has to be climate change .
* if you can make it there, you can make it anywhere!