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Coral reefs aren’t fazed by bleach

A remote coral reef has managed to fully recover, despite being exposed to large amounts of bleach, proving that the colonies are sturdier than previously thought.

Anyone who has gone scuba diving in tropical water knows that corals are incredibly fragile. Touch them, and you’ll likely crush the individual polyps against their razor sharp skeletons. This, in turn, sets off a chain reaction, where the neighboring polyps die and in the worst cases, the entire coral eventually succumbs. They are equally fragile to temperature change and just a few degrees off from their comfort zone will kill most of them. Light, also, is a requirement, and if you go too deep, the corals begin to dwindle. It is quite surprising then, that bleach doesn’t seem to keep them down.

Scott reef is a remote coral reef some 250km from the Australian coast. It was long believed that individual reefs like Scott reef had a hard time recovering from catastrophes, because neighboring reefs aren’t around to help rebuild the structure. However, Scott has proven this to not be the case, as it has recovered fully from a bleaching catastrophe in just 12 years.


Scott Reef – what a badass


The catastrophe, which took place in 1998, killed 80% of the coral polyps on the reef, and it was thought that the reef would only be rebuilt through recolonization from other reefs far out in the ocean. "The initial projections for Scott Reef were not optimistic," says Dr James Gilmour from the Australian Institute of Marine Science.


The reef was monitored for the next 15 years to study the recovery of the reef, and the researchers were surprised to discover that after only 12 years, the reef had regained the biomass and diversity it had before the disaster. Dr. Gilmour explains that one reason the reef recovered so well was not in spite of its remoteness, but because of it. Because very few factors, primarily human interaction, interfered with whatever polyps did settle on the dying reef, they had an excellent reproduction and survival rate.


Dr. Gilour goes on to explain that, despite the excellent recovery, we can’t forget that it took a decade to get there. Corals are still fragile and it’s very easy to wipe them out. However, with the right knowledge, like what happened to Scott’s reef, there are things we can do to help them. "By preventing illegal fishing and enhancing water quality on coral reefs in all regions we will give these reefs a greater capacity to recover from major disturbances." Says Gilmour.

David F.
A grad student in experimental physics, David is fascinated by science, space and technology. When not buried in lecture books, he enjoys movies, gaming and mountainbiking

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