Australia's Great Barrier Reef is one of the greatest natural wonders of the world and is home to thousands of different species - including fish, seaweed, birds and turtles.

For a long time conservationists have been worried that this unique ecosystem is being destroyed - by overfishing and climate change. But now it looks as if rules that banned fishing in big areas of the reef - may be working.

Research shows that some fish species there have doubled in the six years since the rules were brought in. But the experts say the long-term survival of the Great Barrier Reef is not guaranteed, and think climate change still poses a big threat.