The Great Barrier Reef and The Great Bleaching Event

Waking up to the sounds of sea birds squawking and the golden sun hovering slightly above the horizon, I found it hard to believe where I was. After travelling 10,000 miles to the east coast of Australia, I’d found myself welcoming the day sat on a pontoon at the edge of Hardy Reef; part of the Great Barrier Reef and forty nautical miles from land. After having already spent a day snorkeling amongst brightly coloured fish and the night sleeping under the stars, I was very excited to see it all again and so, after quickly eating breakfast and donning a very fetching snorkeling suit, I crammed my feet into a pair of flippers and slid back into the cool, refreshing water. Almost immediately, I came face to face with a huge shoal of yellow finned fish before heading off towards the beautifully intricate reef itself. It was amazing.

The thought of colourful fish dancing through beautiful corals is something that had always inspired me to visit Australia and to have the opportunity to see it for myself and not through the eyes of a filmmaker was incredible. However, it saddens me to read that the reef is under such threat that other people may not be able to share my delight in the future. According to an aerial survey conducted in April 2016, by the ARC Centre of Excellence for Coral Reef Studies, a devastating 93 percent of the Great Barrier Reef is suffering from coral bleaching. 520 individual reefs were surveyed and it was discovered that 95 percent were placed in the two most severe bleaching categories, with 99 percent identified as suffering from it. Scientists have continued to express their dismay and shock at the condition of the reef with Professor Terry Hughes, who was part of the survey, claiming that he had “never seen anything like this scale of bleaching before”. Clearly this is a shocking result and is likely to have a catastrophic impact on the many dependent marine species that live on the reef.

What is coral bleaching?

Corals are well known for their bright and dazzling colours and the Great Barrier Reef is renowned for it. However, this colour is not from the coral itself but a tiny species of marine algae known as zooxanthellae. These minute creatures live inside the coral’s tissue and provide food, contributing heavily to the energy that the coral requires in order to reproduce and develop. When ocean temperatures rise or there is a change in the water’s salinity, this relationship breaks down and the zooxanthellae leave, resulting in the coral’s bright white skeleton being exposed; hence the term ‘bleaching’. Not only do the corals lose their stunning colours, they also lose the ability to feed efficiently, and so if the bleaching incidents continue for a lengthy period of time, they starve to death. With 93 percent of the reef having already been affected, the worst damaged being the more remote and northern reefs, what could be the cause of this catastrophic event?

There are three possible culprits affecting the bleaching of the Great Barrier Reef: El Nino, global warming, or UV radiation from the sun. Each of these has an impact on the reef environment. However, it is the threat of global warming that appears to be one of the most significant contributing factors. As CO2 concentrations in our atmosphere continue to rise and temperatures increase including those of the sea. As the water heats up, corals and their zooxanthellae begin to suffer with heat stress leading to the breaking down of the symbiotic relationship which leaves them exposed and unable to feed. Now, if the increase in temperature lasts only a short amount of time, in some cases, the coral are able to rebuild this relationship, and survive. However, even if this happens, they are still very likely to suffer from reduced growth and reproduction as well as an increased vulnerability to disease and death. If the heat stress continues for eight weeks or more, there is a very high chance that the corals will die.

Ocean acidification is also a very prominent threat linked to our growing emission issues. Rising carbon dioxide levels in the water means that there has been a decline in calcium carbonate, leaving MARINE AWARENESS Written by Arianne Kenworthy Keppel Bleaching Produced by Kirsten Hintner Graphic Design by Kirsten Hintner calcifiers such as corals, struggling to form their hard outer layers. As a result, when the sea temperature rises, the coral is unable to protect itself as well, resulting in yet more significant heat stress events.

If we want to continue enjoying the spectacle and beauty that is the Great Barrier Reef, then we all need to make a change to our lifestyles and reduce our carbon impact.

So what can we do to help?

Without a doubt it is important to say that we need to reduce our carbon emissions and try to keep in mind the effect our lifestyle is having upon the world around us. Six marine turtle species, 30 species of cetaceans, and over 1,500 species of fish rely upon the Great Barrier Reef to survive, and so if it were to be lost, the impact on the resident wildlife would be appalling. Of course, it is important to note that some people argue that the reef is not in as bad a state as we think, and that it’s simply suffering from stress and will eventually bounce back. As I, and many others, understand, it still means that we are having a truly awful impact on the natural world. The most recent bleaching event has been described as similar to a sunburn and that the coral will recover completely but after repeatedly being warned of the dangers of burning, I’m not entirely sure that I agree. Yes coral can survive, though it does take a lengthy period of time to do so, and yes they can be resilient but there will always be an impact somewhere down the line – whether that’s growth or reproduction or something completely different. Things do not just bounce back.

If our gas emissions continually rise at the current rate, in the next 40 years they are projected to rise by a total of 0.5 degrees C, a temperature change with potential terrible consequences. Corals can and do adapt to heat changes but over hundreds of years, not decades, and so it’s very unlikely that they will avoid the effects. It is believed that if something doesn’t change soon, the beautiful corals of the Great Barrier Reef could be completely lost to bleaching by the 2050’s. We need to take responsibility and do something to help.

If we were to lose the Great Barrier Reef then we would not only lose one of our most treasured UNESCO World Heritage Sites, we would also lose an incredibly important part of our environment. To not have the opportunity to see fish darting past, turtles gliding and groupers drifting over the intricate coral, would be a devastating loss. I’ve seen the reef for myself, and I will never forget just how stunning it was. I hope other people get to experience it too.

The world is warming and it’s time we warmed to making a difference, if not for our sake, for the sake of the wildlife around us.

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