Deadly pathogen responsible for massive decline in amphibians

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Decline of amphibians is harming biodiversity
Decline of amphibians is harming biodiversity( Credits - Wikimedia Commons)

For several years, biologists at various sites around the world reported many species of frogs had disappeared. It was reported in Costa Rica in 1987 that the golden toad was missing. The next year in 1988, Arthur’s stubfoot toad had disappeared. Such incidents were piling up. Frogs disappeared without any proper reason. And this was not random, a pattern across the globe was observed.

A new study published in the Science magazine made a comprehensive report of the damage in the amphibian world. The total comes up to a staggering 501 species of amphibians. The chytrid fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) are responsible for this catastrophic damage in amphibians. Scientists were clueless that chytrid fungi can cause so much damage.

Ben Scheele, an ecologist at Australian National University has firsthand experience of the damage caused by the fungus. He reported about an Australian site with favourable conditions for mass breeding of frogs. Before the fungus, the area was very much abundant with alpine tree frog population but the species cannot be found anymore.

Scientists are now calling chytrid fungus as the most destructive pathogen ever, which is a grave reason for concern. The majority of the damage occurred in the 1980s. It was at this time that the disease was circulated worldwide. Central and Southern America were affected to a great extent with considerable damage in Europe, North America, Australia and Africa. It is quite intriguing to know that there has been no such damage in Asia, where the fungus has been for millions of years.

Chytrid fungi have many species and most of them are just decomposers. But Bd is an exception. It preys on the skin of amphibians. And we humans are responsible for its worldwide circulation through activities such as trade and global war.

Bd attacks the skin of the amphibians which they use for activities such as breathing and maintaining the water levels. What makes it so lethal is that it is very effective in spreading. Bd can infect a wide variety of species, and it kills the amphibian very slowly. It can also spread by means of touch or by water and lives on the host body for several months at a time.

Researchers identified Bd as the main reason for the disappearance of the amphibians in the late 1990s but its impact can be traced as far as 1960s. Hence, scientists cannot reverse the damage which has already been done. But we can urge the governments to reduce global trade of amphibians and improve the screening procedures.

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