What are Major Threats to Biodiversity?

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson first defines biodiversity for you. Then you'll learn about the numerous threats to this biodiversity, such as deforestation, poaching and many others.

What is Biodiversity?

People are pretty diverse. There are all sorts of languages, body types, places we live and so on. Plants and animals are even more diverse with respect to their numbers, shapes, genetic variations and natural environments. This is what we mean when we talk about biodiversity.

Unfortunately, biodiversity is under threat. Let's take a look at the major reasons why.

Habitat Destruction

To learn about the threats to biodiversity we are going to attach a very small and lightweight camera to a bird we've name Bob. Bob's going to fly around the world and we'll get to see what's endangering the world's biodiversity.

Bob starts off his journey in the Amazon. As we fly over the Amazon we can see a lot of deforestation taking place. Deforestation is the felling of large sections of whole forests. This destroys the homes of many animals. There's just nowhere else to live. Deforestation has occurred in every part of the world. Some places more than others. For example, in the last 40 years, 20% of the Amazon rain forest has been cut down!

Deforestation in South America.

Bob heads due north across the Caribbean Sea. As we fly over, we see that there are fishing ships that drag nets across the sea floor, destroying marine habitats in the process. This can catch fish and other marine life that isn't supposed to be caught and destroy coral as well. By destroying coral, we destroy the habitat and homes of countless other species.

As Bob keeps going north, he enters the wetlands of the Southern United States. A lot of these have been purposefully drained for real estate development. So, drainage of wetlands as well as mangroves and estuaries is another major threat to biodiversity. Over the centuries, the US has lost millions of acres of wetland. In many states that's over half of their wetlands, in others, it's more than 85%, especially as a result of drainage.

Bob takes a westwardly course to the Western portion of the U.S. where there are a lot of dams that have been built on various rivers. This has flooded the habitats behind the dam, destroying them in the process. Dams also end up blocking important natural fish routes and lead to fish stock declines as a result.

Poaching & Invasive Species

While habitat destruction of all sorts is the leading cause of biodiversity loss, there are plenty of other ones. Bob keeps going west and eventually makes it to Asia, where we see a lot of unregulated and excessive industrial, agricultural and sewage run-off and air pollution. This ends up killing plants, animals and entire ecosystems.

Bob then flies over to Africa, where we see the sad sight of wild animals being illegally hunted, or poached, often to support trade in Chinese medicine. Recently, 100,000 elephants were poached over a three year period in Africa.

Eventually, our bird flies back home to Australia. Here he sees that lots of foreign species have been brought to the nation, wreaking havoc on the local ecosystems and biodiversity.

Invasive species, particularly successful foreign species, are another kind of threat to biodiversity. One such species is the cane toad. This toad is native to Central and South America, but was brought over to Australia to control a beetle population devastating cane sugar farms in the 1930s. They now number over a billion and a half, and predators can't even eat them due to their toxicity!

The cane toad is an invasive species in Australia.
cane toad

Climate Change

Climate change threatens biodiversity all over the world. For instance, with melting icecaps, everything from polar bears to penguins to whales depend on these areas for sustenance are threatened.

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