What is coral bleaching?
When we mine and burn coal we produce dangerous greenhouse gas pollution that causes our planet, including our oceans, to heat up. If the water stays too hot for too long, our vulnerable corals lose their colour (bleach) and often die.
Corals are actually tiny animals called polyps. Microscopic algae called zooxanthellae live inside their cells. These algae turn sunlight into energy and up to 95% of the nutrients they make are leaked to the coral.
In return, the zooxanthellae have a safe place to live and receive nutrients from the coral’s waste. However, in certain conditions this mutually beneficial relationship becomes destructive.
When the water is hotter than the average for as little as four weeks, combined with bright sunshine, the algae go into overdrive and can produce toxic levels of oxygen.
As a self-defence mechanism the corals shed the algae, and their colour along with it. (Coral polyps are actually clear, it is the algae that give coral its beautiful colour.)
Without the algae, the coral's bright white skeleton is revealed through its transparent tissue. This is what we call ‘bleaching’.
If temperatures return to normal relatively quickly, corals can regain their algae and survive. But if not, corals no longer receive enough food. They go into a downward spiral, losing fat and other energy reserves, becoming weak, and susceptible to disease.
When bleaching happens across a whole reef it is known as ‘mass bleaching’ and when bleaching is prolonged, whole reefs can die.
It is possible to maintain the rich vibrancy, health, and true colours, of our beautiful Reef.
But only if we rapidly shift to clean, renewable energy. The window to save the Reef is closing and we need to act fast.
Australia must speed up the transition to clean energy
Beyond addressing global warming, improving water quality and proper fisheries management are also vital to reef recovery.
Because of this WWF is dedicated to establishing a fund to repair Great Barrier Reef catchments and assist farmers to adopt cleaner, more profitable practices.