Reef Q&A: What is coral bleaching? Your Great Barrier Reef questions answered ft. Roger Beeden
Jul 21, 2026 · 20 min · 11 segments
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Roger BeedenGuestLincoln MottoliHost
Jul 21, 2026 · 20 min · 11 segments
Test
Roger BeedenGuestLincoln MottoliHostFirstly, we talk about the impacts of coral bleaching on the Great Barrier Reef quite a lot and becoming more and more frequent.
Our first question is, what does bleaching do to coral? Can you explain it in simple terms? What is coral bleaching and how does it affect the Great Barrier Reef?
They're like a jellyfish that people would be familiar with that actually you turn that over and put it inside a cup of calcium carbonate, like chalk cup.
But the thing about corals that's kind of special is that they have this relationship with little tiny algae that live inside them.
And the best thing about those algae is that they produce through sunlight to produce sugars.
And so that relationship is so effective and so successful corals that allows them to build structures that you can see from space.
So the reality of coral bleaching is what happens is that that relationship between the little algae and the coral animal is temperature sensitive, sensitive to other things as well.
But when temperatures get too high for too long, and we particularly see this increasingly as a result of climate change driven changes in ocean temperatures, then that relationship can break down.
But think of it like Goldilocks, you know, the corals like and the algae like it to be at the right temperature.
And if it isn't at the right temperature, then the corals push the algae out from inside their tissues.
And what that then means is that the greeny brown algae are lost And actually what you can then see through the transparent tissue of the coral, which is still alive at that point, is the actual, like it's skeleton underneath, which is actually chalky white.
So that process is called bleaching because it goes from being very vibrant colours down to being able to see this white skeleton, which really what it is, is a stress response in corals.
So a common misconception around that is that bleached coral is actually dead coral, but it's not precisely the case is that bleached coral can recover, but there's certain conditions that sort of need to be met.
Firstly, we talk about the impacts of coral bleaching on the Great Barrier Reef quite a lot and becoming more and more frequent.
Our first question is, what does bleaching do to coral? Can you explain it in simple terms? What is coral bleaching and how does it affect the Great Barrier Reef?
They're like a jellyfish that people would be familiar with that actually you turn that over and put it inside a cup of calcium carbonate, like chalk cup.
But the thing about corals that's kind of special is that they have this relationship with little tiny algae that live inside them.
And the best thing about those algae is that they produce through sunlight to produce sugars.
And so that relationship is so effective and so successful corals that allows them to build structures that you can see from space.
So the reality of coral bleaching is what happens is that that relationship between the little algae and the coral animal is temperature sensitive, sensitive to other things as well.
But when temperatures get too high for too long, and we particularly see this increasingly as a result of climate change driven changes in ocean temperatures, then that relationship can break down.
But think of it like Goldilocks, you know, the corals like and the algae like it to be at the right temperature.
And if it isn't at the right temperature, then the corals push the algae out from inside their tissues.
And what that then means is that the greeny brown algae are lost And actually what you can then see through the transparent tissue of the coral, which is still alive at that point, is the actual, like it's skeleton underneath, which is actually chalky white.
So that process is called bleaching because it goes from being very vibrant colours down to being able to see this white skeleton, which really what it is, is a stress response in corals.
So a common misconception around that is that bleached coral is actually dead coral, but it's not precisely the case is that bleached coral can recover, but there's certain conditions that sort of need to be met.
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