The great barrier reef, the largest coral reef in the world

Last year, in 2019, I spend half a year in Australia for my bachelor. I was doing my internship in Cairns and used part of my free time to get my PADI and go snorkelling and diving on the great barrier reef as much as possible. Many of the dive companies in Cairns, you have to opportunity to sign up for a volunteer list. You can join day boats and in exchange for working on the boat, such as helping with serving the food, welcoming the guests and cleaning. In exchange for the help, you get free dives or can go snorkelling. I went with Divers den for the volunteer trips and did my dive course with Pro Dive, both located in Cairns.

Before I did my diving course, I went with them once, because I really liked it on the reef and knew I had limited time in Australia. I was a tough, hard and long day but the hours spent in the water, swimming above the reef and watching all the fish and corals that live there is definitely worth it. The great barrier reef is the biggest coral reef and is composed of more than 2900 individuals reef. Stretching over 2300 km kilometres and can be seen from outer space. This always blows my mind, no wonder it is labelled as one of the seven natural wonders of the world.

The diversity of the great barrier reef

The great barrier reef supports an extraordinary diversity of life. Many of this species are vulnerable or endangered species. And some species are endemic to the reef, they can not be found anywhere else. You can find around 400 different types of corals, bot soft and hard. More than 1500 different species of fish live there, such as the famous clownfish from the movie ‘Finding Nemo’. Six different sea turtles can be found, and these are one of my favourite animals to see! A stunning 215 species of birds use the islands to visit or nest. Around 125 species of shark, stingray, skates and chimaera life on the reef as well all nine different seahorse species. I saved the greatest number for last; there are close to 5.000 species of mollusc, including the giant clam. And these are truly giant.

The numbers I just mentioned are not even all the species that live on the great barrier reef, but if I would list all of them you would be reading for several hours. the numbers are not doing in true justice until you have seen it with your own eyes.

The threats

The great barrier reef faces many different threats; pollution, fishing, crown-of-thorns starfish, shipping accidents, oil spills and tropical cyclones. As of this is not already enough, the biggest threat these days is climate change. Due to the warming of the earth, the ocean temperature is rising with it. These higher temperatures cause bleaching in the thermally sensitive coral, dying of the algae that live in symbioses with the coral. Without this algae, the coral turns white and if the high temperatures stay, the coral will be unable to survive.

Temperature about 1 °C (or 2 °F) above average can already cause bleaching, in the last few years, there have been numerous bleaching events on the great barrier reef, with 2016-17 being the biggest. The bleaching killed between 29 and 50 % of the reef’s coral. With a third bleaching event last year, in 2019. Due to the rising temperatures bleaching events becoming more and more frequent, at the moment there is still enough coral that is healthy. But for how long?

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