The Great Barrier Reef is alive! There’s been no shortage of bad press and some seriously misleading media coverage.
Rest assured the Reef is still amazing. Coral bleaching has occurred. It’s a natural event actually. But the Reef is big and the bleaching is comparatively small. There’s still many beautiful locations to explore with ABC Snorkel Charters.
With our small vessel and roaming permit, we’ll take you to some pristine snorkelling sites on Port Douglas’ Outer Reef. Where you’ll explore coral gardens, abundant with life and colour. Our Reef is healthy and beautiful!JUMP RIGHT IN
Has the Great Barrier Reef suffered from coral bleaching in recent years? Yes, there’s definitely been some damage, but the Reef covers a massive area and mortality has not been uniform. Media claims that 93% of the Reef is dead is simply not true. Many areas remain absolutely stunning. A question we often get asked from guests, is ‘what exactly is coral bleaching and how does it happen?’. To answer that, you need to understand the structure of the coral itself, how it feeds and why rising sea temperatures are a contributing factor to coral bleaching.
Coral is made up of three things. An animal part, which is called a polyp, which forms colonies that we look at as the coral structures. These polyps have skeletons made of Calcium Carbonate, or limestone. They filter-feed nutrients from the water; however, tropical water is very nutrient-poor and they can only produce about 10% of their energy needs in this way.
The other 90% of their energy comes from a symbiotic algae called Zooxanthellae (Symbiodinium). This, like all plants in the world, makes energy from the sun and it shares that energy with the coral polyp. It is found living inside the tissues of the polyps and is also responsible for the beautiful colours of the corals.
A number of factors contribute to coral bleaching. Changes in UV rays, visibility, salinity, pH or temperature, the last of which has been the major cause over the last few years. When the water temperature gets too warm, the algae becomes over productive, which results in an increase in toxic waste products. These products damage the coral polyps, which leaves them in a bit of a dilemma. Maintain the algae, while it’s causing harm, or expel it, even though it gives them 90% of their energy.
The lesser of two evils is to expel the algae and they do this by either exocytosis, or digestion. Since the algae contains the colourful pigments, the colour also disappears from the coral, leaving them white. Hence ‘coral bleaching’.
In the early stages the coral is still alive, still producing 10% of its own energy. It’s starving, but still alive, something the media have not been good at reporting. Bleached coral does not mean dead coral. In good conditions, some species can survive like this for over two months (although most species will only last a few weeks).
If conditions return to normal, the coral polyps can acquire more algae and continue living. However, if this doesn’t happen quick enough, then they develop rapid tissue necrosis and eventually die. So, as you can see, there’s more to the coral bleaching story than has been widely reported and said.
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