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After extensive observation, I have found the cause behind the sudden disappearance of apparently healthy amphibians.
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After extensive observation, I have found the cause behind the sudden disappearance of apparently healthy amphibians.

During the initial global congress of herpetology, as we sat and conversed in a hotel bar, the experts on amphibians came to the realization that a significant issue was at hand. Across the globe, thousands of frogs, toads, salamanders, and newts were vanishing, with no one able to comprehend the cause.

No speaker at the 1989 conference held at the University of Kent addressed the peculiar disappearance of global amphibian populations. However, multiple scientists shared the same observation: these creatures were going missing from regions ranging from Central America to Australia.

I was employed as a veterinary pathologist at the Zoological Society of London the previous year. My responsibilities included determining the cause of death for animals. Not long after starting my role, members of the community contacted London Zoo about numerous unexplained frog fatalities in their gardens. These reports continued to increase in frequency. As part of my PhD research, I conducted tests on the deceased frogs and discovered the presence of a ranavirus spreading through the frog population in England.

Even though the existence of ranavirus was previously discovered in the United States, this marked the debut of its impact on wild frog populations in Europe. My discoveries were shared, resulting in a request to travel to Australia and aid in solving a perplexing problem. A graduate student was investigating a series of unexplained amphibian fatalities in a rainforest in Queensland.

Two common frogs in a pond with vegetationView image in fullscreen

None of the animals found dying at the location showed any signs of illness. Their tissues were undamaged, there was no evidence of parasites, and they had been screened for viruses and bacteria with negative results. Despite this, they were still deceased.

As I examined the proof, I recognized that I had encountered this situation previously. During a previous trip to Melbourne Zoo, I was presented with tadpoles from a species of frog in Queensland that was in danger of dying out. The tadpoles flourished, but once they transformed into frogs, they perished. The pathology reports all indicated that the frogs were in good health, except for the presence of an unidentified organism on their skin.

I observed the frogs’ skin from the Queensland rainforests with the master’s student. Using a microscope, we discovered the same peculiar organisms described in the pathology reports from Melbourne Zoo. As an experiment, we exposed a few healthy frogs to the infected skin, and unfortunately, they all perished with the organism growing in their skin.

Andrew Cunningham at a work bench in a laboratory

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Simultaneously, I was aware that my colleagues in Panama were investigating the identical issue. I suggested they examine the skin of their deceased frogs to determine if they also had the infection. After conducting their own research, they confirmed the presence of the same fungus. Combining our findings, we collectively released a publication in 1998, revealing to the world that a fungus, now known as Batrachochytrium dendrobatidis, was responsible for the widespread infection and death of amphibians. This fungus attacked their skin, ultimately leading to sudden heart failure and mortality.

Subsequent studies have corroborated our findings and have also identified numerous variations of the fungus. The strain responsible for the highest mortality rate seems to have emerged within the last 100 years, potentially spread globally by human activity, and is still causing devastating declines in amphibian populations.

In the past 50 years, nearly 100 types of amphibians have gone extinct and hundreds have experienced a decrease in population. One species that has been impacted is the mountain chicken frog, previously abundant in the Caribbean but now only with about 30 remaining in the wild. It is possible that they will not survive much longer. This illness serves as a reminder of the harmful effects that humans can have on our planet and its diversity of life. It is likely that this illness would not exist without human intervention. It is crucial that we learn how to coexist and maintain a harmony with the diverse and wonderful species that inhabit the Earth.

by Brian

According to Brian, he informed Patrick Greenfield.

Source: theguardian.com