Paul Marshall, Climate Change
Program manager of Australia's Great Barrier Reef, sheds light on the
problem of coral bleaching and updates the progress of conservation
efforts in Australia.
ANN BOWSER: What is coral bleaching?
PAUL MARSHALL: The microscopic algae that live inside the corals are really important for the corals because they're the food factory. They process sunlight and carbon dioxide (inaudible) that are food for the corals. They also give corals much of their color, so the normal black corals, the greens, the black browns, the colors are all a result of these microscopic algae.
And when this relationship has been broken, and when corals get stressed, the relationship breaks down, and these algae are expelled from the coral, leaving the tissue colorless. You can see straight through the tissue in many cases to the underlying skeleton of the coral, and coral skeleton is bright white, which is calcium carbonate (inaudible), so when these algae leave the tissue because of stress, the coral looks bright white, hence the term coral bleaching.
BETTY ANN BOWSER: Once the coral is dead, is it sort of a gray color, when that light goes away?
PAUL MARSHALL: Very soon after the tissues goes, walks away, then you've got a base coral which is a great place for all the other things in the coral reef to live on, so you get other kinds of algae and scrums and things, quickly colonizing, attaching to the surface of the dead coral's skeleton and starting to discolor it. So when another dies, usually at least (inaudible), it will quickly go from a dead coral to a very spongy skeleton, covered in algae and other things and that's when you go from bright white to a more gray or brown color.
BETTY ANN BOWSER: When the coral gets stressed because of water temperature increases, how fast does this all happen?
PAUL MARSHALL: It can happen very fast. If the temperature increases quickly ... the coral can go from being healthy and bright colored to white in a matter of days and it can die in a matter of days again.
That's not normally what happens. Normally the temperatures increase more gradually and the stress occurs at a slower rate, and so normally what you will see during color bleaching, when the temperatures have got too hot, is you'll see corals will start to fade in color over the course of days or weeks. It will eventually get to that bright white condition if the stress is high enough and eventually stay bleached, sometimes for weeks. And in some cases, months. ... Whether the coral dies or not depends on how hot the water is, how long it's been hot for and how hot the coral was beforehand. So all these things come into play to determine what happens when the water gets hot.
BETTY ANN BOWSER: What makes the water get warmer?
PAUL MARSHALL: It can be a whole lot of different things. And I should say that the stress that leads to bleaching can be caused by lots of different things. The water gets too hot, too cold, too much light, not enough light, chemical, chemical contamination/pollution can all cause bleaching, but the mass of coral bleaching that we've been seeing around the world, since 1997, '98, we've seen for decades now, but most obviously in 1997, 1998, are caused by water that's too hot.
And that's the base, or the base (inaudible) seeing corals over hundreds of kilometers being stressed and bleached, that's caused by hot water that's driven by larger regional phenomena and the increase in incidents of coral bleaching, and the increase in severity of coral bleaching over the last decade, is closely linked with an increase in sea water temperatures that's occurred over that same timeframe and very consistent with the predictions that are being made of the effects of climate change on a tropical oceans.
BETTY ANN BOWSER: How much climate change has there been?
PAUL MARSHALL: That's something difficult for me to answer, but I'm a coral reef expert, and of course there are people who are experts in climate change. We have some at Great Barrier Reef already over the last couple of decades, a gradual increase in temperatures. We've seen an increase of somewhere around half a degree Celsius over the last decade on the Great Barrier Reef, and that may not sound like a lot, but corals have evolved in very stable conditions.
They're not used to large changes in temperature. In particular, they've evolved to have very strict tolerances to temperature maximum, so they are used to water only reaching a certain high point and what's happening is they're now seeing this high point exceeded because of these gradual drifts in temperatures.
BETTY ANN BOWSER: Just a half a degree can make that much difference?
PAUL MARSHALL: Even small increases are enough to cause corals to bleach. On the Great Barrier Reef, that means only an increase of 1-and-a-half to 2 degrees increase in temperatures enough to cause bleaching. ... So if you take something that has a very small increase in temperatures, because corals are so sensitive and what's happening is they're getting gradual drifts and gradual increasing average temperatures, it increases the chance that temperatures will be pushed above those maximum every season. So half a degree might not sound like a lot, but it increases the chance that weather conditions, chance events will push corals over that threshold, and that's why we're seeing a greater increase in the frequency and severity of coral bleaching.
BETTY ANN BOWSER: Of all the things that are affecting coral reefs today, where does bleaching fit on a scale of 1 to 10?
PAUL MARSHALL: Bleaching has to be considered one of the greatest threats to coral reefs right now. There are other very negative threats that are causing damage right now to reefs all around the world, such as water pollution and (inaudible) deficits, and that will remain major threats to reefs.
But what's happening now, it's not so much that one's more important than the other, it's not that they're not one, not two, or three, but another major threat. And so the way these things adding on top of each other because they compare the stress on reefs. That's what we're really worried about. So, coral bleaching, climate change are threats to coral reefs in their own right, but more, more alarming is the (inaudible) to act with the other stresses and there's that multitude of stresses and a multiple fix over them that you're really putting reefs under stress.
BETTY ANN BOWSER: Why (should) we care about this?
PAUL MARSHALL: Coral reefs, I mean if for no other reason, are one of the most beautiful environments on earth. Anybody who's seen a coral reef knows how special they are. That preserves the protection, wants the protection in itself.
But there are many other more practical reasons too. They provide shoreline protection for small island states throughout the world, they're important barriers to ocean waves, and without them, many countries would become inundated. Once corals start to die, they can't maintain that shoreline protection anymore, that's a serious threat, a longer term threat, but a serious threat.
They provide income and sustenance for people all around the world, whether it's in poor developing countries in the Pacific or in the Indian Ocean, or whether it's more wealthy countries like Australia or the US, coral reefs are vast resources that provide immense wealth to people who live up and down the coastline and to entire national economies, so they're incredibly important sources of protein and wealth.
|What can be done?|
BETTY ANN BOWSER: What can be done about this?
PAUL MARSHALL: There are two important things that we can do as people who care about reefs and as reef managers. The first is to make it clear what's happening, that there is this relationship between temperature and the health of coral. That's really important for policy makers to know.
The second thing is something a little more practical. ... It's about making reefs as healthy as possible. A healthy reef is much more likely to survive the coral bleaching event and importantly to bounce back after a bleaching event.
We know that a stressed reef is much less able to bounce back after coral bleaching. And there are many things that are affecting reefs right now to lower their health, lower their resilience, that are in our control, and so coral bleaching, climate change, make it even more important that we do everything in our power to remove all the other stresses from reefs.
So reduce water pollution, prevent overfishing, prevent destructive fishing, help reefs be healthy, because a healthy reef is a dynamic system that has immense capacity for self repair and restoration, so making reefs as healthy as possible is really a mission that's even more important now than ever before.
BETTY ANN BOWSER: Is this problem getting worse?
PAUL MARSHALL: There are clear indications that coral bleaching is becoming a more serious phenomenon and predictions about future climate patents, make us very, very worried. ... We're seeing predictions of coral cover decreasing by 50, 80, 90 percent. So some of these predictions are very dire. It's hard to say how likely they are, but the undeniable fact is the fact that they are possible scenarios for our future and temperature of the seawater can drive many of these changes.
BETTY ANN BOWSER: And is there anything that can be done to keep the temperature from continuing to increase?
PAUL MARSHALL: There are two things that we need to be able to do to
help reefs survive this uncertain future. And one of it is actually
work to make them as healthy as possible, and the other is any delays
that can be made in the rate of temperature increase, will buy time
PAUL MARSHALL: It's real serious. It's all of these same alarming signs. The one, one bell that really rings for us here in the Great Barrier Reef, we've been lucky so far. We've had two major bleaching events, which of course risked the entire system, 2,000 kilometers of Great Barrier Reef have shown signs of stress. But we've been lucky that in the main part that hasn't made lots of coral reef. The temperatures have decreased just in time in both of those periods to prevent widespread coral death.
So we've seen stress over most of the reef ecosystem, and some places,
luckily they are few, we've seen very bad destruction. We've seen 50,
80, 90 percent of the corals killed because of coral bleaching.
PAUL MARSHALL: More resistant coral reef, absolutely. So making a more resilient coral reef has never been more important than now. If we don't do everything we can to make reefs healthy, then we really are giving them a very good chance of surviving the future. And the future's very uncertain. We cannot predict exactly what's going to happen.
If reefs are under stress because of human activities, then they're really vulnerable to these future changes, whether it's climate or something new and unforeseen, either way, keeping reefs as healthy as possible, we need everything in our control to do that has never been more important.
BETTY ANN BOWSER: What do you think's going to happen? Are you an optimist, or do you lie away at night and worry that this is something that's going to be in the history books in 30 years?
PAUL MARSHALL: I do both, a fair bit of worrying, but I just can't help but be an optimist. I can't imagine [reefs] not being there. And that's a dangerous position to take. We can't afford to be naïve about the reef.
When I see those systems and how they can bounce back from things, we've seen them bounce back from things like crown of thorns starfish, which is the starfish that eats corals. We've seen them bounce back from storms. When they're healthy, they can bounce back. If we make them as healthy as possible, while off we're doing whatever we can to raise awareness about the importance of reducing temperature and climate change, then we're doing everything we can to help coral reefs.
And at the end of the day, that's what we can hope to do. As long as we feel that we have honestly done everything possible, and we're a long way from there right now, then I think we can rest a little bit comfortably. And we've seen from the science, when coral bleaching affects every ecosystem ... there are little pockets where the reefs seem to be okay. The coral will be here, alive, amongst the dead ones. There is potential for the resilience to be expressed and coral survive.
The problem is, we don't know how much and we're very aware that we can retime the ability of corals to adjust or evolve, actually takes a long time, and if climate warms too quickly, then coral mightn't have a chance to adjust.
Now all these scenarios talk about doom and gloom, and we shouldn't be very alarmed about degradation to coral reefs. It's important to realize that we're not talking about reefs being obliterated from the face of the planet. They've been around for millions of years and they will be around for millions of years to come.
What we're worried about is the deterioration in reefs that will happen over reasonable human timeframes take out to centuries. We're looking down the bowl here at serious deterioration of coral reefs of the coming decades. We'll see a decrease in the amount of coral.
BETTY ANN BOWSER: So in other words, they're not literally going to all be dead in 30 years? There is some hope?
PAUL MARSHALL: There is hope the corals will survive. But what's so much certain is the quality of coral reefs will be reduced. We will see coral reefs that aren't as pretty in 10, 20, 30 years time as they are today. Normally they're not as pretty, they won't be as good at providing the things that we've come to depend on them for, so productive fisheries, for good tourism venues. These things are going to be compromised in the future scenarios.
So corals and coral reefs under evolutionary timeframes are most certain to sort themselves out. But the next few decades to centuries, coral reefs are going to snuff out because of increased water temperatures, therefore more coral bleaching. ... So we have to acknowledge that we're going to see continued deterioration in the quality of reefs. The task hitting us now is to minimize the amount of damage that occurs by making reefs as healthy as possible.
|Great Barrier Reef Aquarium|
BETTY ANN BOWSER: What are you trying to do here?
PAUL MARSHALL: The Great Barrier Reef Aquarium is a really important educational tool. One of the most critical things we can do to help coral reefs is to help people love them, and to raise awareness about the pressures that they are under.
Everybody can play a role in helping coral reefs. Once people understand how precious they are, how beautiful they are, and that they are under pressure, then they can actually take actions to help. They can take actions by changing their own behavior.
They may be more careful about what they put down the kitchen sink because that goes out in the ocean eventually. They may also use this knowledge to influence the sort of policies that we see at the national or international level and hopefully, therefore, is at a ground level, a ground swell support for measures that will help coral reefs as to some certain future.
BETTY ANN BOWSER: In other words, raise a new generation and they grow up understanding all of this?
PAUL MARSHALL: And that we're already seeing huge come out of schools and go home to parents and tell them all the very things that they shouldn't be doing because they got into compromise the environment or maybe have downstream effects on coral reefs.
So children now are more informed than the generations before them. That's always the way and they really are our heart, and if a facility like this is just essential to helping kids see coral reefs, understand what they're about, and these kids will all one day go out to see a reef, and our best hope for the most important thing we can do, is make sure those reefs are as healthy as possible for those children.
BETTY ANN BOWSER: What is the attachment Australians have to the ocean?
PAUL MARSHALL: Australians have the strongest affinity to the ocean. ... We grow up playing in the sand, swimming in the surf, snorkeling and so it's a really important part of who we are as Australians and we're really lucky that we had so much coastline and so much beautiful marine environment and so not only do we have access to it, but when we see it, you fall in love. And I think most people in Australia, at some time or another, will fall in love with our marine environment.
The other thing that's really important of course, is that the Great Barrier is so large and so beautiful and really quite accessible. I don't think there's be a person in this country who doesn't love coral reefs. Even those who haven't had the good fortune to see them firsthand, and nearly everybody, I suggest everybody aspires to go snorkeling or guiding on the Great Barrier Reef, so even those who don't see it, they who don't live on the shores, really love the Great Barrier Reef.
And that's really important in our efforts to try and raise awareness and protect the reef because after all, we're doing this on behalf of all Australians and the rest of the world, and so that strong attachment to reefs has been a really critical ingredient in our effort to better protect them.
BETTY ANN BOWSER: In terms of what's going on here, as opposed to other parts of the world, just as an outsider, you come in and sense, it says to me, my gosh, if Australians can't save the Great Barrier Reef, then what hope is there for the rest of the world?
PAUL MARSHALL: I think that's really true. We have as much going for us here as anywhere else in the world in terms of efforts to protect coral reefs. It doesn't mean it's easy by a long shot, but that support, that massive national support for coral reefs has given us the power to do some pretty amazing things here on the reef in terms of protecting it and making measures to ensure its future.
And so we've recently seen a rezoning of the Great Barrier Reef which will increase the protection from 5 percent to 30 percent, 30 percent of the Great Barrier Reef where you cannot take things out. That's really important to take part of this, and a really important ingredient in this effort to maximize the health of the reef.
Another recent initiative has been to put a very strong and important proper cooperation between the state and the federal government to protect water quality that enters it.
BETTY ANN BOWSER: Where you're going from 5 percent to 30 percent. That's big!
PAUL MARSHALL: It's really big, and this has been a massive achievement. There are very few places in the world where such a large portion of reefs are really protected from fishing, from shell collecting.
You can go and look, but you can't take out and that's really important for protecting the biodiversity of the reef. And biodiversity is a key ingredient for the resilience of the reef. The other thing that has recently been successful in is actually I'm establishing an agreement to protect the quality of the water that flows into the Great Barrier Reef from the adjacent coastline. This is, as in many places around the world, a major concern for reefs.
Water pollution is very damaging to reefs close to the shoreline and there has been a long held concern that this is causing a problem in the Great Barrier Reef. This historic agreement sets very particular targets for how much pollution can come out of the Great Barrier Reef. So this program -- and to hold and reverse the decline and the quality of the water that's entering the Great Barrier Reef -- these two things are going to be very important strategies for the future of coral, of the Great Barrier Reef in particular.
|Effects of long-term temperature rise|
BETTY ANN BOWSER: But what happens if the temperature keeps going up in spite of all of this?
PAUL MARSHALL: If the temperature keeps going up, we're going to keep
seeing more coral bleaching and we're going to see more coral deaths.
But what we can hope to do is to isolate the stress on the reef to just
this one thing. Coral reefs may well bounce back if it's only coral
bleaching that they're dealing with.
PAUL MARSHALL: Protecting parts, large parts of the reef from extractive activities: fishing, shell collecting, all those things, is really important to keep that reef really healthy. That's good for that part of the reef and it also has flow over effects. So in those areas we'd expect to see more fish, bigger fish, which will be great for that patch of reef, but also those fish can then start to (inaudible) out to other reefs and improve the general health of the reef.
It's also really important to maintain the other things that aren't tied with fishing, so fishes are really important to keep the levels of seaweed down. Seaweed and corals largely compete, especially when it comes to recovery.
So protecting the reef from human activities that are damaging are really essential, to keep that resilience intact, to keep it functioning, to keep the diversity there. It's such a complex system. We don't understand everything that's important about it, but we do know that everything needs to work together. And once we start pulling bits of it out, there's a real risk that it'll collapse. And because we don't know when that's going to happen until it's too late, it's really important we take these proactive measures to protect the ecosystem and keep it functioning and healthy.
BETTY ANN BOWSER: Is there any country in your organization, anybody ever done anything this massive?
PAUL MARSHALL: Well certainly on smaller scales, very impressive, more (inaudible) areas, reserves, where fishing isn't allowed. What's unique about what we've done here, is I guess that's a huge special scale. The Great Barrier Reef is 350,000 square kilometers. It stretches in length all the way from the northern part of the west coast of the U.S., right down to the south. It's a huge area and so protecting 30 percent of that adds up to a huge amount of reef, and that amount of reef under that level of protection is what's really unprecedented.
BETTY ANN BOWSER: Is that another example of how Australians have been drawn to the ocean, to the reefs and that there was so much support to do something so massive?
PAUL MARSHALL: Absolutely, I mean there's always resistance to these types of measures, (inaudible) fishing imposes on what people like to do. Many people love fishing on the Great Barrier Reef, but more people want the reef to be protected in the future. And these measures are not about stopping fishing, they're actually about allowing people to fish into the future, and importantly, making sure that a healthy reef system is there that everybody will enjoy, now and to future generations.