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GREAT BARRlER REEF - Saint Ignatius' Moodle Community

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The Great Barrier Reef is not a single structure. It is a complex ecosystem made<br />

up of around 2900 coral reefs, 900 islands and thousands of plant and animal<br />

species. Like all coral reefs, the Great Barrier Reef ecosystem is very fragile.<br />

How is the Great Barrier<br />

Reef formed?<br />

It took thousands of years for the Great Barrier<br />

Reef to form. All coral reefs are made by<br />

small animals called hard coral polyps. They<br />

attach to a solid surface and make hard outer<br />

skeletons to support their<br />

bodies. After they die, their<br />

skeletons remain and these<br />

form the coral reef.<br />

Why is the Great Barrier Reef<br />

fragile?<br />

Corals get energy to survive from tiny plants living inside<br />

them. These plants need sunlight to make that energy.<br />

Coral bleaching happens when the corals become<br />

stressed and eject the coloured plants. The corals’ white<br />

skeletons become visible, making them appear bleached.<br />

Coral bleaching can be caused by unusually high or low<br />

water temperature, light levels and salinity, as well as<br />

pollution and disease. Corals may or may not recover<br />

from bleaching, depending on how long the cause of<br />

stress continues.<br />

Healthy communities of<br />

marine life require a healthy<br />

environment and we need<br />

to ensure that our activities<br />

do not have any detrimental<br />

impacts on the rich and<br />

diverse communities that<br />

make Australian seas such<br />

special habitats.<br />

Dr Tony Ayling, marine biologist<br />

on the Great Barrier Reef, 2008<br />

How old is the<br />

Great Barrier<br />

Reef?<br />

The current living Reef is<br />

thought to be between 6000<br />

and 8000 years old.<br />

6<br />

Coral polyps have tentacles that catch small<br />

pieces of food floating in the water.<br />

The Great Barrier Reef is a complex ecosystem. Changing even one aspect of<br />

the Reef’s ecosystem could upset the balance of the whole Reef.<br />

7<br />

Macmillan Digital Library: What’s the Issue? Set 2 © Michelle Atkins, Julie Murphy, Greg Reid, Geoff Thompson, Ashten Warfe/Macmillan Publishers Australia 2011 ISBN 978 1 4202 9209 1 Macmillan Digital Library: What’s the Issue? Set 2 © Michelle Atkins, Julie Murphy, Greg Reid, Geoff Thompson, Ashten Warfe/Macmillan Publishers Australia 2011 ISBN 978 1 4202 9209 1

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