Explanation:

• The Great Barrier Reef Marine Park, which spreads across a length of over 2,300 km and is roughly the size of Italy, is home to about 3,000 coral reefs, 600 continental islands, 1,625 type of fish, 133 varieties of shark and rays and 600 types of soft and hard corals.
• Scientists have warned that the Great Barrier Reef will face a critical period of heat stress over the coming weeks, following the most widespread coral bleaching the natural world has ever endured i.e.Warming ocean temperatures, a sign of climate change, is associated with the deteriorating health of the Reef. 
• The Great Barrier Reef, which covers an area of 344,400 sq km makes up roughly 10 per cent of the world’s coral reef ecosystems. Today, the reef is a Marine Park and World Heritage Area and supports a range of activities and contributes over AUD $5.6 billion each year to the Australian economy and is also responsible for creating over 70,000 jobs.