Sadly, it’s something I hear regularly from locals. ‘The reef has been bleached, there’s hardly any fish life left,’ they say with a shrug. ‘What does “coral bleaching” even mean?’ I used to think. ‘Does it even matter?’
And then I’d forget. After all, how often do coral reefs pop up in everyday life? Then, I became a diver.
The precious underwater world
In Spring 2015, I took my PADI Advanced Scuba Dive certificate and a whole new world of exploration opened up to me. I realised there was so much beauty under the water and – as a scuba diver – it was possible to watch this world unfold.
You see, that’s what Scuba diving is about. Exploring our amazing seas, seeing marine life in their natural environment – without causing any disruption. When taking the PADI course, we learn how to keep positive buoyancy (to neither sink or rise in depth) so as not to accidently brush against live corals or the sandy bottom of the ocean. We move naturally in small currents (and avoid big ones) and never hold on to corals in passing. It’s all about observation, and it’s the most wonderful experience.
But through this experience, I have learnt that our coral reefs are in danger. Without them, the very beginnings of our food chains will cease to exist. But what is coral bleaching? And what does climate change have to do with it? Please allow me to explain…
What is a coral reef?
It’s hard to believe, but the colourful coral structures that form reefs are actually invertebrate animals. They are known specifically as ‘hard’ corals and extract calcium carbonate from the salt water to create a tough exoskeleton for protection.
Each individual coral is called a polyp, and each newly formed polyp develops its hard exoskeleton on an existing parental structure. Basically, reefs grow one polyp at a time and can take centuries to become the beautiful features you see in photographs. Most corals survive thanks to a symbiotic relationship with algae called Zooxanthellae. The polyp gives the algae protection by allowing it to live inside the exoskeleton and take in carbon dioxide produced by the polyp. In turn, the algae produce food through photosynthesis for the polyp to consume. The Zooxanthellae also provides the beautiful bright colours you often see in corals.
How big is a reef?
You may have heard of the Great Barrier Reef in Queensland, Australia. At 1,800 miles long, it is the biggest reef system in the world. Along with many smaller reefs just like it, it’s home to everything from different species of coral and over 1,500 species of tropical fish – to giant clams, sea turtles, rays, dugongs and dolphins. The Great Barrier Reef is also a known breeding region for humpback whales.
What’s the big deal?
A reef is the starting point of the marine food chain. Marine plankton and tiny crustaceans such as krill feed on the algae within the coral. As with any food chain – the line of survival grows through molluscs and seahorses, small fish and bigger fish – right up to the big predators such as sharks, mammals such as whales and even birds. Basically, without reef systems, ecosystems would collapse.
What is coral bleaching and why is it happening?
We’ve all heard about climate change. The term used to be ‘Global Warming’ and literally refers to the fact the Earth’s temperature is changing; mainly rising. Human activities such as ‘burning fossil fuels like coal, oil and gas, and cutting down forests’ pollute our atmosphere and warm our planet.
The effects are not yet catastrophic, but they could be very soon. The temperature change is already causing an increase in extreme weather conditions and sea levels to rise (thanks to melting ice caps and the natural expansion of the water’s mass). Along with the inevitable warming and acidification of the oceans. The high amount of carbon dioxide in the atmosphere (due to the burning of fossil fuels) stops the polyp from forming their protective exoskeleton, which in effect means coral reefs are procreating less. The rising sea temperature causes the polyp to expel the algae – their only source of food. This leaves just the remains of the white exoskeleton and no colouring. This is coral bleaching. Many corals that have been bleached die, stunting the growth of the reef. As we know, the reef is the starting point of a great food chain.
Is it happening everywhere?
This year, I saw coral bleaching for myself. During a dive trip along Sri Lanka’s west coast in October, I was taken aback by how much this small part of the Indian Ocean reef had been bleached. Much of it was already dead. Just eight months ago, in March, I was diving in the same region – and much less reef had been affected. Friends have experienced the same thing in the Maldives and throughout Indonesia. Including in the region known as the ‘Coral Triangle’ – one of the world’s most biodiverse and loved dive spots. It’s devastating.
According to the Climate Council, a massive 93% of the Great Barrier Reef has been affected by Climate Change and coral bleaching. That’s a frightening amount. We have to face facts – our reefs are being destroyed, and it’s happening fast. What happens when there are very few reefs left? What happens to our turtles, sea horses, fish and sharks? Or our many wonderful species of whale?
Sadly, as described by WWF experts, ‘our precious wildlife and ecosystems can’t adapt fast enough’. It’s time we took climate change very seriously – so spread the word, share information and educate your friends. Now, more than ever, our planet needs ambassadors.