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Threats to Biodiversity

Threats to Biodiversity

The number of threats to the Earth's biodiversity continues to rise, with us altering our natural surroundings for own selfish gains. So, where exactly are we heading?
Abhijit Naik
Last Updated: Feb 16, 2018
Right from microscopic bacteria to gigantic blue whales, millions of plants and animals inhabit the planet. The fact that the number of species on the planet easily exceeds the million mark, may give the impression that the extinction of a species of two won't make a big difference. That, however, is far from true. The extinction of a single species can affect the balance of the ecosystem; the repercussions of which will start showing on the various other species dependent on it.

Extinction of Species

Since it came into existence, the planet has been subjected to five mass extinctions, resulting in the extinction of 99.9 percent of plant and animal species that have ever existed on the planet. The last of these mass extinctions, the Cretaceous-Tertiary extinction―notorious for having wiped off the dinosaurs―occurred approximately 65 million years ago.

Now, the extinction of species is not unusual. Over the last 200 million years, we have lost a species or two every year. What is unusual, is the rate at which extinctions are occurring over the last few centuries. In fact, it has even left the environmentalists worried, with some of them suggesting that we are closing in on yet another mass extinction.

Major Threats to Biodiversity

The list of threats to the global biodiversity is quite lengthy, and has to its credit threats like habitat loss, over hunting, invasive species, climate change, etc. The details of each of these factors, which threaten the existence of various plants and animals on the planet, are discussed below.

Habitat Loss
Human encroachment in the wild has resulted in wide-scale destruction of the natural habitat for wild animals, thus leaving them with no place to live. A large part of this destruction is caused due to the large-scale deforestation to suit the vested interests of agricultural and logging sectors. Besides habitat loss, habitat fragmentation, as a result of construction of roads in the forests, has also contributed to the extinction of animals in the wild, primarily by making it difficult for them to breed.

The extinction of the Javan tiger―endemic to the island of Java in Indonesia―is the best example of extinction triggered due habitat loss.

Over Hunting
Over hunting has brought several animal species to the brink of extinction. Humans have resorted to the practice of hunting for food since prehistoric times. More recently, however, hunting for food has taken a back seat, while poaching of animals for their body parts, i.e., their skin, tusks, bones, etc., has gained prominence.

The failure to curb poaching has resulted in severe depletion in the population of various animals, including rhinos and tigers, thus making them vulnerable to extinction.

Invasive Species
The invasion of non-native species in a particular region is also a threat for species endemic to that region. When a new species is introduced in a particular region, it either feeds on the native species or competes with it for food. In either case, the end result is extinction of the species endemic to the region, either due to predation or food scarcity.

In what is considered one of the best examples of this phenomenon, when the Nile Perch was introduced in Lake Victoria in Africa, it led to the extinction of endemic cichlid fish species.

One of the major environmental issues on the planet, pollution is also a prominent factor when it comes to extinction of species. While the contamination of water bodies can result in the extinction of animal species, the contamination of soil can lead to the extinction of plants. Species with limited geographic range are most vulnerable to extinction due to pollution.

One of the best examples is the extinction of the Chinese river dolphin which fell prey to industrial pollution and water transport in its natural habitat, the Yangtze River.

Climate Change
Over the last few decades, the global surface temperature has experienced an average increase of 1.8 °C, thus affecting plant and animal species in various parts of the world. On one hand, the rise in temperature is melting polar ice, thus resulting in loss of habitat for polar bears and Arctic foxes, and on the other, it is accelerating the evaporation of water bodies in the tropical areas, thus resulting is loss of habitat for fish and amphibian species.

Of the numerous examples of extinction triggered by climate change, that of the Monteverde toad, endemic to the tropical rainforests of Costa Rica, in particular stands out.

At the end of the day, it is the cumulative impact of all these threats that is making the problem worse. It's high time we understand the importance of biodiversity and come up with measures to save it. As we mentioned earlier, if a single species becomes extinct, its repercussions are felt by all the other species depending on it directly or indirectly.

A Hypothetical Example: The loss of tiger will lead to an increase in the number of deer species, which, in turn, will feed on grass and plants, and destroy the vegetation cover. In the turn of events, the absence of vegetation cover will alter the precipitation pattern for the region.
Hunting Lion