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Part XVII : Human Influences on Populations Index

Extinction of Species
Some Human Activities which Modify Habitats
Introduced Species
How Humans Can Help
Natural Parks in France

Topic Chapters Index

 

 

The Great Barrier Reef as an Example of Biodiversity

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

The Great Barrier Reef, which is found close to the eastern Australian coastline, is home to a wide variety of animals. All coral species are animal species, even though the adult forms do not move. Coral filters plankton from the surrounding water. Each tide brings with it a fresh supply of plankton. Other animals, such as the giant clam, also make their homes in a coral reef. The parrot fish feeds on coral. Many other species of fish visit coral reefs in order to feed and because they find coral a good hiding place when escaping from predators.

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

A coral reef is a good example of our planet's biodiversity. There are many species of animals living in coral reefs which have not been classified. Unfortunately, a coral reef is very susceptible to pollution. Many coral reefs are dying because of pollution.

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

Scene from the Great Barrier Reef, Queensland, Australia © Shirley Burchill

 

 

Hippos, Kenya © Shirley Burchill

Hundreds of thousands of tourists visit Kenya each year. In 2000, tourism brought in 26300 millions of Kenyan shillings (or about 180 million pounds sterling).

Antelope, Kenya © Shirley Burchill

HUMAN INFLUENCES ON POPULATIONS

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Biodiversity

Drawing of a dinosaur (T Rex) © Shirley Burchill

 

Life has been evolving on Earth for over 3 billion years. Scientists have identified about 1,4 million different species. There are many more waiting to be identified, perhaps millions. This collection of vastly varied living organisms is our planet's biodiversity.

The richest parts of the planet's biodiversity are also the least well-known. It is estimated that 97% of all species on Earth live in the oceans below the zone where sunlight penetrates the water. On the continents, it is estimated that 50% of all land-dwelling species live in tropical rainforests. The first step towards preserving life on Earth is getting to know and understand it.

Throughout the history of the Earth, as new species evolve, other species become extinct. Overall, as time has progressed, there are more and more different kinds of organisms. The dinosaurs became extinct 60 million years before humans walked the Earth. What caused their extinction is still not fully understood but it was some sort of natural catastrophe.

Human activities today are exterminating species up to 10 times faster than they would naturally disappear. As the numbers of people increase, the numbers of species decrease.

 

Why should humans save species?

If animals and plants become extinct naturally, why should humans worry about the ones that they exterminate? There are several good reasons to worry:

 

(a) Plants are a natural resource

Rain forest plants, Costa Rica © Shirley Burchill

Many plants can make things that we cannot produce for ourselves in laboratories or factories such as medicines, oils or perfumes.

 

(b) Animals and plants are a source of pleasure

Mountain view © Paul Billiet

Seeing an eagle soaring above a mountain or walking through a forest in springtime can be a great pleasure. In some parts of the world wildlife is an important source of income because tourists come to see the exotic organisms which live there. Kenya's savannas and Australia's coral reefs are just two examples. One does not need to go very far, however, to appreciate what nature has to offer.

 

(c) Humans are special animals who have a special responsibility

Humans are the only animals which are able to make judgments about what is right and what is wrong from a moral or ethical point of view. Humans need to ask themselves:

Have we got the right to make a species disappear forever?

 

 

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