Page 28 - The World About Us

Reef channels
1.1.1
2.1.5

What are the features of the Great Barrier Reef?

The Great Barrier Reef is the largest
living structure on the planet. It
stretches 2,300 km from the northern
p of Queensland, Australia, south
along the coastline for 14° of la tude.
The Barrier Reef is in fact 200
individual reefs, as well as 600 islands,
300 coral cays and inshore mangrove
islands. Much of the inland areas of the
Barrier Reef have a depth of water no
greater than 35 metres, but at the N Great
Barrier
outer eastern edge of the con nental Reef
shelf the reef sits above a slope Queensland
stretching down for 2,000m.
AUSTRALIA
The Great Barrier Reef began its life
around 20 million years ago, with coral
polyps colonising the shores of north- 1000km
east Australia. Over millions of years
sea levels have risen and fallen. The last fig.75 The Great Barrier Reef from space - 200 reefs, 600 islands and more.
me this happened was during the
most recent glacia on. As sea levels fig.76 Biodiversity on the Great Barrier Reef.
fell, coral was le above the protec ve Animal group No of species Animal group No of species
water, died and was eroded away by Hard Corals 450 Fish 1,625
ocean waves. New reefs formed along So Corals 150 Sharks and rays 133
the newly exposed coastline. Jellyfish 100 Whales and dolphins 30
Molluscs 3,000 Snakes 14
As the last glacia on came to an
end and the world’s ice began to melt, Starfish and urchins 650 Turtles 6
Worms 500 Birds 215
much of it over north America and
Europe, the global sea level began to was created in 1975 to protect and sand and communi es of sponges.
rise. The coral polyps were able to manage this natural wonder of the The Great Barrier Reef is a
reproduce and grow upwards, keeping world. The park covers 344,000 km², biodiversity hotspot. This means that
pace with the rising sea surface. This which is roughly the size of Germany or there are a very large number of
growth has created the network of reef, the Democra c Republic of Congo. different species present. Figure 76
islands and cays we see today. Within the park there are areas of sea shows how many iden fied species visit
The Great Barrier Reef Marine Park grass, mangrove forests, stretches of or make their home on the reef.

fig.77 450 species of hard coral give the Great Barrier reef is structure.
1. Describe how nutrients are
cycled throughout coral reef ecosystems. (6)
2. Explain the biological role and importance of
Zooxanthellae algae to the corals found in
shallow water reef systems. (6)
3. Outline why reef management organisations
may also wish to include mangrove forests and
eel grass beds in their management plans. (4)
4. Describe the size and location of the Great
Barrier Reef. (3)
5. Describe why coral reef systems are useful to
humans as a resource. (4)
6. Outline why the Great Barrier Reef is
considered to be a biodiversity hotspot. (3)

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Biodiverse ecosystems are under threat from human activity.