Great Barrier Reef has lost half of its corals

Stretching over 2,300km (1,400 miles), the great barrier reef, a world Heritage site, has enormous scientific value. It also provides fantastic habitat for young fish with its many large, intricately structured coral species.

We used to think the Great Barrier Reef was protected by its sheer size but now even the world's largest protected reef system is in decline.

All types of corals had suffered a decline due to warmer seas especially the branching and table-shaped corals. The reef has lost more than half of its corals since 95’ with three bleaching events in five years, the steepest falls happening after the massive bleaching events of 2016/2017.

Although corals look like rocks, they are a symbosis of jellyfish-like animals and algae. Bleaching happens when corals get stressed and kick out the algae, the algae is what gives them colour and so without them they become white.

The problem is they also get most of their energy and disease protection from the algae as well and since a reef is just made of many coral colonies living next to and on top of each other the bleaching results in coral mortality and the collapse of the entire reef ecosystem.

Once the corals bleaches, other sea life disperse and, in their place, comes invasive smothering seaweed that chokes out the remaining coral.

The reef can recover but its resilience is compromised, damaged coral colonies struggle to regenerate because most of the adult corals had died, fewer breeding adults and a lot less babies.

The UN warns another 0.5c increase will mean 90% of the worlds coral reefs will be wiped out and all that will be left to look at will be moss- like seaweed on the ocean floor.