All around the world, animal species are declining and disappearing at an alarming rate. Human activity, pollution, climate change and extreme weather events are shrinking habitats and putting entire species under threat.
The International Union for Conservation of Nature says that more than 28,000 species of animals and plants are threatened with extinction. An intergovernmental report on the biodiversity crisis estimated that extinction threatens up to a million animal and plant species, known and unknown.
Experts now believe we’re in the midst of a mass extinction event – a ‘short’ period of geological time in which a high percentage of biodiversity dies out. (In geological time, this can span thousands or even millions of years). But unlike previous mass extinctions, this one (believed to be the sixth the Earth has experienced), is being caused by humans, thanks to our unsustainable use of land, water and natural resources, and our impact on the changing climate.
Many species are already experiencing the devastating impact.
Over the past couple of decades, some species have already been driven to extinction.
In 2018 the last male northern white rhino died from old age and an infection, leaving behind two females, which are unable to give birth, making it highly unlikely that we will be able to introduce a new generation of the species. Scientists are working on using harvested sex cells and in-vitro fertilisation to bring forth a lab-created northern white rhino, but poaching and habitat destruction has driven this species to the brink of extinction. And they’re not the only ones.
When it comes to the demise of a species, there’s extinction in which the population gets so low that the animal then disappears from the wild forever (like the northern white rhino), and then there’s functional extinction.
When an animal is functionally extinct, it can mean a few things. Either the species no longer plays an effective role in their ecosystem or they no longer have a viable population (due to low population numbers that affect the production of healthy offspring). Functionally extinct can also refer to such a limited population that, although still breeding, is suffering from inbreeding that can threaten its future viability.
When an animal no longer plays an effective role in an ecosystem, it can negatively affect many other species by upsetting the balance. And unfortunately, functional extinction often leads to an animal going completely extinct.
Researchers at Linköping University in Sweden ran a number of analytical models to determine how often and in what circumstances functional extinctions occur. They found that larger animals are more likely to become functionally extinct. Functional extinction can occur following a population decline of as little as 30%, meaning that a species only has to lose a third of its members before other plants and animals in the same food web may start to disappear.
While the study is theoretical, relying on models rather than data and observation of any particular species, the authors note that this phenomenon has already been observed by other researchers in cases such as that of the sea otter. The health of the sea otter population correlates to the health of kelp forests, as sea otters keep the populations of sea urchins and others that feed on kelp in check.
Which animals are already functionally extinct?
In 2006, the Baiji dolphin, a species found in the Yangtze River, (the longest river in Asia), was declared functionally extinct. This was the first time in history that an entire species of dolphin had been wiped off the planet because of human activity.
A 2020 report suggested that sharks – hunted in such vast numbers that more than 50% of shark and ray species are considered Threatened or Near Threatened with extinction – are now ‘functionally extinct’ at 20% of the world’s coral reefs, largely due to destructive and unsustainable fishing.
In 2019, the Australian Koala Foundation announced that it believes “there are no more than 80,000 koalas in Australia,” which would make the species functionally extinct. Koala numbers in many places are in steep decline, and genetic studies on the Koala Coast, 20kms south-east of Brisbane, show that the population is suffering from reduced genetic variation.
And in August 2022, the dugong (or “sea cow”) – the species said to have inspired the myth of the mermaid, has been declared functionally extinct in Chinese waters. According to research by the Zoological Society of London (ZSL) and the Chinese Academy of Sciences, fishing and ship strikes have caused a rapid decline of the species since the 1970s and there has been no evidence of their presence in China since 2008. Their research said “this is the first functional extinction of a large mammal in China’s coastal waters”.
What can we do to stop mass extinction?
These are some of the actions we can take to curb human impact on biodiversity:
- Ramp up our commitments to cutting carbon emissions under the Paris Agreement and limit global warming to 1.5 degrees Celsius.
- Reduce waste and pollution – one of the most harmful environmental issues. Each year, 8 million tonnes of plastic makes its way into the ocean, where it traps and tangles sealife as well as getting ingested by crucial marine animals.
- Protect wildlife habitats – curb deforestation, protect coral reefs and push for habitat restoration and rewilding.
- Learn about wildlife conservation and support wildlife conservation charities.
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