THE variable harlequin frog (Atelopus varius) was widespread in Costa Rica and Panama until an 
introduced fungus 
from Asia 
decimated its 
populations.
THE variable harlequin frog (Atelopus varius) was widespread in Costa Rica and Panama until an 
introduced fungus 
from Asia 
decimated its 
populations.

Governments are largely unaware of the scale of the devastation caused by humans- study

By Sheree Bega Time of article published Jun 8, 2020

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With their bright, blazing skin, Costa Rica’s golden toads were described as little “dazzling jewels” as they gathered to breed on the floor of the cloud forest of Monteverde.

After their discovery in the 1960s, annual population sizes of around 1500 adults, who lived almost entirely in moist burrows underground, were recorded.

But by 1987, only 11 golden toads were spotted and in 1989, just one solitary male. Despite extensive searches, the enigmatic species had hurtled into oblivion and was later declared extinct.

“The symbol of the amphibian holocaust is the loss, soon after it was discovered, of the gorgeous golden toad,” write researchers from Stanford University and the National Autonomous University of Mexico in a new paper on the extinction crisis, published in the Proceedings of the National Academy of Sciences this week.

Their study, Vertebrates on the Brink as Indicators of Biological Annihilation and the Sixth Mass Extinction, warns how thousands of critically endangered vertebrate animal species have been lost in a century, indicating the sixth mass extinction is human-caused, accelerating and may be a "tipping point for the collapse of civilisation".

Frogs and toads are the “champions” of recent, rapid species extinctions with hundreds of species suffering population declines and extinctions. The principal culprit is thechytrid fungus, which is sometimes spread by human activities and affects populations weakened by climate disruption particularly rapidly.

Millions of plant and animal populations have vanished in the past century with most people unaware of their loss yet such losses have become extremely severe in the last few decades.

“These losses are not simply happening to obscure organisms of little interest to anyone. Instead, they include many large and conspicuous animals and plants, from lions and tigers to elephants and cacti.”

The researchers examined 29400 species of terrestrial vertebrates and determined which are on the brink of extinction - those that have fewer than 1000 individuals - finding 515 species in this grim category. “Our results emphasise the extreme urgency of taking massive global actions to save humanity’s crucial life support systems."

Humanity needs the life support of a relatively stable climate, flows of fresh water, agricultural pest and disease vector control, pollination for crops - all provided by functional ecosystems, says the study.

The Sumatran rhino (Dicerorhinus sumatrensis) is one of the most endangered mammals on Earth. Approximately 80 individuals remain in northern Sumatra, Indonesia, but poaching for their tusks and habitat loss threaten them with extinction. | RHETT BUTTLER / Mongabay


“Around 94% of the populations of 77 mammal and bird species on the brink have been lost in the last century. Assuming all species on the brink have similar trends, more than 237000 populations of those species have vanished since 1900.”

The acceleration of the extinction crisis “is certain because of the still fast growth in human numbers and consumption rates”.

Species are links in ecosystems, “and as they fall out, the species they interact with are likely to go also.

"The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilisation, because it is irreversible", state the researchers.

“It’s probably the most serious environmental problem because the loss of a species is permanent - each of them playing a greater or lesser role in the live systems on which we all depend.”

Co-author, Stanford biologist Paul Ehrlich, states that “when humanity exterminates populations and species of other creatures, it is sawing the limb on which it is sitting, destroying working parts of our own life support system”.

To slow the sixth mass extinction, the authors call for immediate global action, such as outlawing the wildlife trade and listing species with populations under 5000 as critically endangered on the International Union for Conservation of Nature’s Red List.

As population extinctions continue, some of the species on the brink will likely become extinct, and some of the under-5000s will be pushed to the brink.

The research shows that proportionally, more bird species are imperilled, followed by amphibians, then mammals and reptiles. In regions where disappearing species are concentrated, regional biodiversity collapses are likely occurring.

The Española Giant Tortoise (Chelonoidis hoodensis), a species endemic to the Galapagos Islands, is threatened by introduced species. Recent conservation efforts have increased the number of the tortoises, but only about 200 remain.| GERARDO CEBALLOS


The human-caused sixth mass extinction is likely to be accelerating for several reasons. “First, many of the species that have been driven to the brink will likely become extinct soon.

“Second, the distribution of those species highly coincides with hundreds of other endangered species surviving in regions with high human impacts, suggesting ongoing regional biodiversity collapses. Third, close ecological interactions of species on the brink tend to move other species towards annihilation when they disappear - extinction breeds extinctions.”

As humanity’s numbers have grown, this has come to pose an “unprecedented threat” to the vast majority of its living companions, through habitat loss and fragmentation, illegal trade, overexploitation, pollution and toxification “with climate disruption becoming a major cause of species endangerment.

“Today, species extinctions are hundreds or thousands of times faster than the ‘normal’ or ‘background’ rates prevailing in the last tens of millions of years. Every time a species or population vanishes, earth’s capability to maintain ecosystem services is eroded to a degree, depending on the species or population concerned.

“Each population is likely to be unique and therefore likely to differ in its capacity to fit into a particular ecosystem and play a role there. The effects of extinctions will worsen in the coming decades, as losses of functional units, redundancy, and genetic and cultural variability change entire ecosystems.”

Consider that more than 400 vertebrate species became extinct in the last 100 years - extinctions that would have taken up to 10000 years in the normal course of evolution.

“The reason so many species are being pushed to extinction by anthropogenic causes is indicated by humans and their domesticated animals being some 30 times the living mass of all the wild mammals that must compete with them for space and resources.

"And when the number of individuals in a population or species drops too low, its contributions to ecosystem functions and services become unimportant, its genetic variability and resilience is reduced and its contribution to human welfare may be lost.” These are “ecological zombies - still there but not significant for ecosystem function”.

The growing human population, increasing rates of consumption and projected growth in the future "can only accelerate the rapid disappearance of species, now a stream, to a rushing torrent - a problem for survival that only human beings have the power to alleviate”.

The extinction crisis poses an existential threat to civilization. “Although it’s more immediate than climate disruption, its magnitude and likely impacts on human well-being are largely unknown by governments, the private sector and civil society. The conservation of endangered species should be elevated to a national and global emergency for governments and institutions equal to climate disruption.”

Scientists should metaphorically take to the streets to address and publicise the extent of the extinction crisis and the impacts on the loss of biodiversity, ecosystem services, and human well-being “aspects still rather ignored by most people. “There is time but the window of opportunity is closing. We must save what we can or lose the opportunity to do so forever. There is no doubt, for example, that there will be more pandemics if we continue destroying habitats and trading wildlife for human consumption as food and traditional medicines.

“It's something that humanity cannot permit as it may be a tipping point for the collapse of civilisation. What is at stake is the fate of humanity and most living species. Future generations deserve better from us.”

‘Ban Wildlife trade for human consumption’

It is imperative that wildlife trade for human consumption is considered a “gigantic” threat to both human health and wildlife conservation and has to be completely banned, writes the team of researchers in their paper.

Many of the species endangered or on the brink of extinction are being decimated by the legal and illegal wildlife trade, which “poses a fundamental threat for human health and well-being, is a major cause of population and species extinctions, and is eroding the ecosystem services that we require to survive".

“The horrific coronavirus disease (Covid-19) pandemic that we are experiencing, of which we still do not fully understand the likely economic, political and social global impacts, is linked to wildlife trade.”

The wildlife trade needs to be banned and the ban strictly enforced, “especially in China, Vietnam, Indonesia and other countries in Asia”.

“It’s also imperative that steps are taken to provide food for the poor that conservation measures may deprive of bushmeat, particularly in Africa,” write the researchers.

The Saturday Star

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