WHAT IMPACT IS GLOBAL WARMING HAVING ON THE GREAT BARRIER REEF?

“Hi there and welcome to the Great Barrier Reef! My name is fins!! It’s an amazing day today, perfect for our adventure, the sun is shining and the water is a beautiful 25 degrees. The adventure we are going on today is to find out what affects Global Warming is having on my friends and I at the Great Barrier Reef, and how we can prevent it!!”

http://www.disegnigratis.biz/Clipart_Disney/Alla%20ricerca%20di%20Nemo/nemo_4.jpg

One of the main threats Global Warming brings to our Great Barrier reef is Coral Bleaching. To understand how dangerous coral bleaching is, we need to know how and why it occurs.

To do this we need to look deep into the coral and find out how it is created and what makes it so colourful.

http://k53.pbase.com/u21/eldarrio/large/35175164.vidadelmar030a.jpg

Coral is a limestone formation formed in the sea by millions of tiny animals called Polyps.

Most coral Polyps live together in colonies. They attach themselves to each other with a flat sheet of tissue called the Coenosarc that connects to the middle of another Polyp body.

Half of the coral Polyp extends above and the remaining half is below the connective sheet.

Coral Polyp & Coenosarc http://www.enchantedlearning.com/cgifs/Coralpolyp_bw.GIF

Coral Polyps remove calcium out of the sea water to build their limestone skeletons. They then deposit calcium carbonate (limestone) around their lower body halves.

When the animals die, they leave limestone "skeletons" that become the foundations of barriers and ridges called coral reefs.

As new Polyps grow, their mass makes the limestone formation larger and larger.

Coral is given its vibrant colour by the animal Zooxanthellae which lives within it. When the water which the coral lives in becomes warmer, the Zooxanthellae leaves the confines of the coral or can even die, causing the coral to lose its beautiful colour and this is what's known as coral bleaching.

Zooxanthellae

http://www.kk.org/thetechnium/solar_sea_slug.jpg

When the water temperature rises it encourages the growth of harmful algae on top of the coral, which kills it, by blocking out the sun. Without the sun, the Zooxanthellae cannot perform Photosynthesis and so they die. Without the Zooxanthellae, the coral Polyps also die. This is how coral bleaching occurs.

This algae is usually eaten by fish, however due to over fishing, there aren't enough fish left to eat all the algae. The pollution we dump in the ocean is what the harmful algae uses to grow, which means that the algae begins to cover the coral and this will eventually kill the reef.

Algae

Photosynthesis

http://gas2.org/files/2008/03/algae-2.jpg

http://techalive.mtu.edu/meec/module19/images/Photosynthesis.jpg

Coral reefs can only survive in waters between 18 degrees and 30 degrees. It has been predicted by reef scientist, Terry Done (2006), that a 1 degree rise in global temperature would cause an 82% of the reef bleached, 2 degrees resulting in 97% bleaching and 3% would mean total devastation.

What can we do to help protect our coral reefs from the dangers of coral bleaching caused by global warming?

• Avoid using chemically enhanced fertilizers and pesticides – as it pollutes water systems and helps algae grow

• Switch lights off and house hold appliances off at the wall - reduces power usage which is one cause of global warming

•Take public transport - pollution from cars is another cause of global warming

Questions:

1. What is Coral?

2. What is the name of the animal that creates the coral?

3. What is the animal that gives coral its colour?

4. What happens when coral bleaching occurs?

5. From the diagram what are the 2 key things needed to create photosynthesis?

6. What are 3 things you are going to do to help prevent Global Warming?

7. Why is the Coenosarc so important?

8. What do Polyps remove out of the sea water to build their limestone skeletons?

9. What temperature can coral live in and what happens when it rises by 3%?