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Climate change
Reef health

It is with only a touch of irony that the Great Barrier Marine Park Reef Authority’s newly appointed Chief Scientist, Dr Roger Beeden, who oversees an area roughly the size of Germany, originally hails from the cold climes of western Europe. 

“I’m from the other GBR,” he says wryly. 

“Great Britain!” 

But growing up on a self-confessed diet of Jacques Cousteau movies and David Attenborough documentaries, it seems it was only a matter of time before the majesty of the Great Barrier Reef prompted a move to the southern hemisphere… five years in New Zealand notwithstanding.

“It took me a while to get here but once I did it really exceeded all expectations,” he says.

“We came for 18 months and 20 years later we're still here because it's still spectacular. It’s as close as going into space as most of us are going to get and just one of those things that is genuinely a wonder of the world.” 

As Roger and his colleagues at the Reef Authority confront the challenge of supporting Reef resilience in the face of looming threats from climate change and warming ocean temperatures, he admits it’s time to set the record straight around one very complex question: Is the Reef dying? 

“One of the best quotes I've heard recently is that ‘the Reef is neither dead nor is it fine’, and that's actually the true state of play at the moment,” he says. 

Although famous for its spectacular coral ecosystems, the Great Barrier Reef also comprises a complex network of estuaries, seagrass beds, mangroves and wetlands, deep ocean areas and vegetated islands. But, Roger says, coral is the foundation on which Australia’s greatest natural wonder is built. And that foundation is under siege. 

“Climate change is causing some really severe pressures to the coral foundations of the reef. That's why we're so concerned about it.” 

Dr Roger Beeden underwater at Moore Reef

There are around 1,000 species of soft coral and at least 450 species of hard coral that build the foundations of the Great Barrier Reef. Most hard corals are actually a collection (colonies) of numerous individual coral polyps, that range in size from just a few millimetres to many centimetres. Polyps resemble upside down jellyfish nestled in a structure like an egg cup - that the corals make – which form the solid foundations of the Reef. 

On an even smaller scale, different types of microscopic algae grow in the tissues of coral polyps. These algae not only provide the coral with much of their colour, but also feed the coral by processing sunlight and turning coral waste products into food.   

“[The] relationship between the animals and those little ‘plant like’ algae that are inside them is temperature sensitive. They're like Goldilocks; they need it to be about the right temperature for that relationship to keep going,” Roger says.

If temperatures are too high (or too low) the relationship breaks down. Excess heat essentially causes some algae to produce an oversupply of energy which can damage the coral tissue, forcing the coral to actively expel the algae which reveals the bright white calcium carbonate skeleton underneath.  

This phenomenon is known as coral bleaching and causes Roger and his team the most concern.

“It’s a stress response. The coral is not actually dead when they're bleached. But if those conditions go on for long enough, and the warm temperatures go on for long enough, then the polyps starve and can die.” 

It’s the fact that corals are colonies of individuals, Roger says, that makes explaining the health of the Great Barrier Reef a little tricky, particularly as the effects of climate change become more prevalent. 

And he’s at pains to point out that because corals are animals that stay still - like trees - they can survive major damage or ‘partial mortality’ and grow back. 

“In the case of corals, they grow back through the replication of the remaining polyps,” he said. 

“And it’s only when all of the individual polyps die that the entire colony is ‘really’ dead, and its only when whole colonies are lost over large areas that we see reef scale impacts.

“The capacity to tolerate major damage and recover is different among different coral species but overall, it makes corals incredibly resilient. If some polyps survive and there is enough time then colonies can, and do, recover. As a result, it’s important to understand that a coral bleaching event, even a severe one in one area does not mean that coral colonies won’t recover, nor does it reflect the health of the entire Great Barrier Reef.” 

However, as the warmer summer months approach so too does the threat of cyclones and El Niño weather patterns, which can impact the ability of coral to bounce back. 

“While the Great Barrier Reef is around five to ten thousand years old, coral species have been around for a very long time – the ancestors of some modern corals date back 500 million years. That means they’ve evolved through extinction events before. But the reality is climate change is accelerating so quickly that we’re changing the boundaries in which they thrive really, really quickly.” 

Dr Roger Beeden ready to get in the water at Moore Reef

And so, the real question Roger says, is not whether the Reef is alive or dead, but rather can it maintain its tolerance and ability to recover into the future. 

“One of the advantages of being in the Marine Park Authority for a few years is you do get to see recovery, and it can be really rapid,” Roger says.

“For example, an area that was impacted a few years ago can look absolutely spectacular again in a short amount of time. And in most places, it does right now.

“So, the capacity to bounce back is still there, even though the pressures are there and mounting. That's why it's so important that we take action to support their ability to bounce back into the future.

“One of the things that's really positive is that we have more knowledge than we've ever had. We can model climate and ocean systems.

“Weather forecasts are incredible these days and we have access to them on daily, weekly or monthly scales and that's because of the climate models that underpin them; we can see what’s coming and use that to focus our management actions.” 

This includes targeted culling of coral eating crown-of-thorns starfish, localised action to manage water quality and reduce residential and industrial runoff into catchment areas and ultimately onto the Great Barrier Reef, as well as sustainable recreational and commercial fishing practices. 

And perhaps most importantly, Roger says combatting climate change on a grand scale to protect the Reef now and into the future, starts at home.

“We as Individuals can do all we can to reduce our carbon footprint. 

“Climate change affects eight billion people, and the solution starts with eight billion people taking action!” 

Check out the Reef Authority’s new Reef in Focus podcast and hear more from Roger on the current health and state of the Reef.

Reef in Focus Episode 3: Wanted dead or alive ft. Dr Roger Beeden

Updated 10 Nov 2023
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