What is Coral Bleaching?

Coral bleaching is when the symbiotic relationship between algae and their host coral becomes disrupted and causes the coral to expel the algae. Algae, which lives inside of the coral, is what gives it its colour, energy and its source of nutrients. When the algae leaves, what is left behind is the limestone skeleton of the bleached coral, which is what we see when there is coral bleaching.

The relationship between coral and algae can become disrupted due to several factors, including rapid temperatures increase, pollution and severe weather, that can cause the coral and algae to become stressed. Temperatures that increase by more than 1 degree Celsius per every 4 weeks, an influx of fresh water due to a cyclone or water run-off with pesticides and pollution in it are strong contributing factors to a stressed reef.  

Once stressed, coral will expel the algae from its polyps as a way of protecting itself. Due to stress, the algae begins to produce toxins that can harm the coral, so the coral must rid itself of it until the environment returns to normal. Once the algae is gone and the coral is left exposed, it begins to starve, as there is no algae to convert energy for the coral. If the algae does not return in time, the coral will die. However, if the algae does return before this happens, the coral may return to its original health and colouring.

The Great Barrier Reef has been victim to coral bleaching in the past with major events happening in 1998, 2002 and now in 2015-2016. While there are sections that are experiencing severe bleaching, the reefs in the Whitsundays have been lucky enough to have only minor bleaching. Severe bleaching is taking place in the northern reef where the waters are warmer and stay warmer for longer periods of time. Since the Whitsundays are further south and have experienced less severe temperature increases, many of our reefs remain in good health.

Because there is minimal bleaching in the Whitsundays, most of the reefs are still vibrant, colourful and full of marine life. Local tour operators say that visitors will be able to have the full Great Barrier Reef Experience; in fact unless you’re keeping a close eye out you’re not likely to notice any bleaching at all.

Without healthy coral, the Great Barrier Reef would cease to exist. As the building blocks of the reef, without them there would be nowhere for marine life to feed, breed or survive. Professionals and scientists continue to monitor the reefs to ensure their health and the survival of the reef in hopes that they return to their natural state without permanent damage.