Sixth Mass Extinction

Over the course of 4.5 billion year since the first life form exist, the earth is home to many different organisms, these organisms proliferated across the world, creating a lush biodiversity. However, due to catastrophic events, earth was not always stable which leads to the extinction rate being higher than the speciation rate. A mass extinction is an event where there is a large loss of species over a short geological time, since the earth is relatively old, this short period of time is anything lesser than 28 million years. In the past, there were 5 mass extinction event, each resulting in a loss of 60-96% of biodiversity (Fig 3). Currently, more than 500 species of land animals are on the brink of extinction and are likely to be lost within 20 years; the same number were lost over the whole of the last century. At the rate we are losing out biodiversity, we are most likely currently living in the 6th mass extinction.

Figure 3: Past extinction event timeline and causes (National Geography )

Loss of habitat

Image credit: RSPCA

The clearing of habitat for human settlement is one of the main reasons why humans are driving animals to extinction. Unless the animals are relocated prior to habitat clearing, they too will be swept away and killed during the process since large-scale clearing of habitats are usually done haphazardly. With a smaller area the animals can live in, there will be an increase in competition for different resources like food and shelter, eventually leading to the decrease in biodiversity.  Additionally, fragmentation of the different habitats prevents genetic flow between the population of different patches, resulting in dire consequences like inbreeding among the same habitat patch.

 


Wildlife trade and poaching

On 21 July 2019, Singapore experienced one of the largest trafficking of wildlife in recent years. 25.6 tons of pangolin scales, worth $48.6 million, from an estimated 38,000 of the creatures were confiscated alongside 177kg of cut-up and carved elephant ivory worth $17.6 million. Both animals, the pangolin and the elephants have species classified as critically endangered on the International Union for Conservation of Nature (IUCN) red list. If the poaching and trafficking of such endangered animals are not regulated, these animals will no longer walk the surface of the earth in the future.

On earth, everything is interconnected, organisms are related to each other directly or indirectly and this connection is what keeps our planet alive. This means that a collapse of one species will lead to a cascade of issues, affecting organisms of different trophic level. This can be seen from the poaching of sea otters, a keystone species responsible for maintaining the rocky marine ecosystem. With the increase in demand for sea otter fur, more sea otters are captured, leading to a decline in the apex predator of that habitat. With no more sea otters, the population of sea urchin and starfishes are no longer kept in check which leads to the destruction of kelp forest since sea urchin feeds on the roots of kelp. Since other organisms live in this environment, they too are also affected despite how only one species is targeted by humans for poaching. 

Image credit: JASON QUAH, The Straits Time

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