WHY DO
DISAPPEAR
Chytrid fungus
Batrachochytrium dendrobatidis
Batrachochytrium dendrobatidis
FROGS
Nearly a third of the world's amphibians are in danger of extinction
The chytrid fungus is a killer of frogs
FROGS
300-350
200
32%
is the common name for a group of animals in the order of the tailless amphibians
Approximately that many frog species have disappeared since 1970
million years ago
At the end of the Devonian period of the Paleozoic Era, the first amphibians appeared on Earth; frogs survived three mass extinctions, including the one that wiped out the dinosaurs
Of the approximately 6,000 amphibian species, 12 percent of bird species and 23 percent of mammal species are endangered compared with 12 percent of bird species and 23 percent of mammal species
Solving the amphibian extinction crisis represents the greatest problem of species conservation in human history
why does
this tragedy
happen?
In some places, the decline in frog populations is due to habitat destruction, pollutants, climate change, and the introduction of alien predators, parasites, and competitors
Chytridiomycosis
1998
Now chytridiomycosis is the worst animal epidemic known to mankind!
Every year there are many publications devoted to this problem, for which there is still no solution
Researchers have identified a chytrid fungus called Batrachochytrium dendrobatidis (Bd). The fungus has infected more than 500 amphibian species, mostly in North and South America and Australia, and destroyed as many as 90 species
Since 1893, there had been mass extinctions of frogs and toads in Australia unlike anything scientists had seen before. It went so far that streams were literally swamped with the corpses of animals!
And to infect the next individual, contact with water where the zoospores float, contact with an infected frog, or even contact with soil where the frog has walked or jumped
The fungus infects the amphibian's skin and starts growing inside it, the skin begins to keratinize, which results in stopping the amphibian from working. The amphibian slowly suffocates or dies from kidney failure, or simply from cardiac arrest
"You are working in your clearing with, let's say, 30 species of frogs jumping around at the same time. Suddenly, your colleague finds a dead frog a kilometer away from the clearing, clearly dead from chytridiomycosis.
And you realize that in a couple of days in your whole clearing where you've been doing years of scientific work, instead of 30 species there will be two. And everything will be covered with the decomposing corpses of the other 28 species of frogs..."
17-50
km/year
Distribution of the fungus Batrachochytrium dendrobatidis worldwide
FUNGUS
appearance
It most likely came to the U.S. with spore frogs (Xenopus) from Africa. Until the 1960s, they were used as a test for pregnancy: adding a pregnant woman's urine, containing certain hormones, to the aquarium causes the frogs to drop their eggs
After the advent of modern pregnancy tests, these frogs became unnecessary, and they were simply thrown into water bodies. Except that they turned out to be infected. Spurred frogs themselves do not dying from violent pathogen: most likely, in the process of evolution they have learned to coexist
frogs need
land AND
water
Natural droughts cause serious damage to a population or even an entire species. There is evidence of the effects of climate change on frog survival rates and abundance
They are very sensitive to habitat changes because they spend their time migrating between land and water throughout the year. Water sources such as wetlands, ponds, and streams are necessary for laying eggs and raising young, but many adults spend most of their time on land.
human impact
