41% of amphibian species are threatened with extinction – 10/04/2023 – Environment

The effects of climate change and habitat degradation due to human action are among the main causes that have driven around 41% of the world’s known amphibian species to extinction.

Between the years 2004 and 2022, the study period, there has been little change in the factors contributing to threats to amphibians globally: climate change is the main cause for 39% of species assessed to date, and this number is expected to increase , since the long-term effects of the climate crisis on most animals is still unknown.

Habitat degradation is the main threat to 93% of species already considered critically endangered. Diseases and other human-associated impacts, such as pollution, are also among the main causes of extinction threat.

In the case of Brazil, a country that has the largest amphibian biodiversity in the world (1,200 of just over 8,600 described species), these impacts come mainly from the devastation of areas preserved for agriculture and the fragmentation of forests.

These were the findings of a global study with more than one hundred researchers, led by the association Re:wild, based in Austin (Texas), and with participants in the coordination of the IUCN Red List of Threats to Extinction (International Union for Conservation of Nature, in the English acronym). The article was published this Wednesday (4) in the scientific journal Nature, the most prestigious in the world.

The assessment is the second carried out for this group of animals, with the first, in 2004, already pointing out global threats to the conservation of amphibians. “Amphibians are considered the second animal group, and the first vertebrate group, when we talk about threat risk,” explains Jennifer Luedtke, study leader and study manager at Re:wild.

According to IUCN data, 40.7% (2,873 species out of 8,011 assessed) of amphibians have some degree of threat. In the previous phase, with data up to 2004, 39.4% (2,788) of the amphibian species assessed had some degree of threat, a number that was already higher than that found in 1980, when the first list was made, of 37.9% ( 2,681).

“Our study shows that we cannot continue to underestimate this threat. Protecting and restoring forests is critical not only to safeguard biodiversity, but also to combat climate change,” said Luedtke.

Among vertebrates, rays and sharks occupy the second position among the most threatened (37.4%), followed by mammals (26.5%), reptiles (21.4%) and birds (12.9%).

There was also an incorporation of 2,286 species in the new list, a considerable effort by more than a thousand specialists who contributed to the survey. This also reduced the proportion of species classified as data deficient (when there is not enough information to know whether the species is at risk of extinction), from 22.5% in 2004 to 11.3% in 2022.

In the case of the diversity known for Brazil, there is a notable contribution from dozens of researchers spread across the country. “Brazil is the country with the greatest amphibian diversity in the world, but almost a third had not been assessed globally”, says Iberê Machado, president of the Boitatá Institute, and coordinator of the amphibian assessment linked to IUCN in the country.

According to him, the new assessment revealed a worrying increase in the number of threatened species, from 37 in 2004, with some degree of threat, to 189 in 2022. There were also 26 assessed species classified as possibly extinct, since which have not been seen in natural areas since the 1980s.

On the other hand, conservation actions were successful in improving the classification of at least nine species in the national territory, such as the Alcatrazes tree frog (Ololygon alcatraz) and the Alcatrazes rock frog (Cycloramphus faustoi), both endemic to the island of Alcatrazes, off the coast of São Paulo.

In addition to habitat fragmentation, the global epidemic of fungi of the genus Batrachochytriumknown for causing inflammation on the skin of amphibians (chytridiomycosis) and thus causing damage to their respiratory and circulatory system – amphibians use their skin to exchange air with the atmosphere – have caused population declines in several countries around the world, especially the United States. United States, Australia and Latin American countries.

One of the groups particularly vulnerable to fungal infection are salamanders, amphibians with tails and four legs that live in regions of Asia, Europe and the USA (there is a single genus in Brazil with three species, Bolitoglossa caldwellae, B. madeira It is B. tapajonica). The survey researchers expressed concern about the invasion of a species of fungus, Batrachochytrium salamandrivoranson the American continent.

About three in five salamander species are threatened with extinction, mainly caused by habitat devastation and climate change. But the fungus is also one of the factors that have led to this increase in population decline, since one of the mechanisms through which climate change affects this group is by increasing the temperature in the forest, facilitating the spread of the fungus.

“Amphibians suffer from habitat devastation, but we also need to understand that we need them, whether it’s for discovering new medical compounds, or as predators that help control insect populations,” explains Kelsey Neam, data coordinator for Amphibians. species at Re:wild and one of the study’s lead authors.

“And while our study focused on assessing how climate change threatens amphibians, the opposite is also true; preserving and restoring amphibian populations is one of the solutions to the global climate crisis, since they have a key role in the health of ecosystems”, he adds.