Subscribe to Diving Deeper

Ocean Service Feeds

What is a Podcast?

A podcast is a an audio file published on the web. The files are usually downloaded onto computers or portable listening devices such as iPods or other players.

Read more about podcasting from

Find other podcasts from the US government

Diving Deeper: Episode 20 (February 24, 2010) —
Why are coral reefs valuable?

HOST: Welcome to Diving Deeper where we interview National Ocean Service scientists on the ocean topics and information that are important to you! I’m your host Kate Nielsen.

Today’s question is….Why are coral reefs valuable?

Coral reefs are some of the most biologically rich and economically valuable ecosystems on Earth. They provide food, jobs, income, protection, and many other important services to billions of people worldwide. Unfortunately, coral reefs are threatened by an increasing array of impacts including pollution, habitat loss, diseases, and global climate change.

To help us dive a little deeper into this question, we will talk with Kacky Andrews on the value of coral reefs – why they are so important, what the current threats are, and what we can all do to help. Kacky is the director of NOAA’s Coral Reef Conservation Program. Hi Kacky, welcome to our show.

KACKY ANDREWS: Hi Kate, thanks for inviting me here today. Always happy to talk about coral reefs, one of my favorite subjects.

HOST: Kacky, first can you give us a little more background on coral reefs. I know we are all familiar with the many beautiful underwater images that we see of reefs, but can you tell us where coral reefs are found?

KACKY ANDREWS: Yes. We could probably spend all of our entire time today just talking about general coral reef information, but let me start off with my favorite fact concerning coral reefs. Even though coral reefs only cover about one-tenth of one percent of the ocean floor, they provide habitat for over 25 percent of marine species. This is astounding biodiversity that rivals the rainforests. This gives you somewhat of a sense of the rich and concentrated biodiversity out there, but it also means that focusing on coral reefs as indicators can give us a good sense of overall ocean health.

So coral reefs are primarily found in tropical waters, they’re found throughout the United States and the Atlantic and the Caribbean. The biodiversity hotspot for coral reefs is in Southeast Asia near Indonesia and the Philippines.

HOST: Are corals plants or animals?

KACKY ANDREWS: If I had to choose one, I would say animals, even though they might sometimes resemble plants and are often mistaken for rocks. Many of the reef-building corals that people are most familiar with from the tropical vacations or the photographs are colonial organisms which means that they are made up of hundreds to thousands of individual animals called polyps.

Like other animals, polyps need to eat and each polyp has a stomach that opens at one end and is surrounded by tentacles to help catch the food. The food enters the stomach through the mouth and after eating, waste products are expelled through the same opening.

These coral animals are heavily dependent on a symbiotic algae called zooxanthellae that actually live in the corals and help them feed and get nutrients. So even though corals are animals, there’s also a component of plants that help them maintain their health. 

HOST: It’s amazing that while corals make up such a small percentage of the ocean floor like you just mentioned, that they provide habitat for so many different species.  Can you expand more on some of these environmental or ecosystem benefits of corals?

KACKY ANDREWS: Certainly Kate. The environmental benefits from coral reefs is really enormous. Coral reefs provide spawning, nursery, breeding, and feeding grounds for more than one million species – like fish, lobsters, sharks, seahorses, sponges, sea turtles – just to name a few. Healthy coral reefs also have rough surfaces and complex structures that dampen much of the force of incoming waves, buffering shorelines from currents, waves, storms, and even tsunamis to help prevent erosion.

After the tsunami in the Indian Ocean in 2005, some modelers at Princeton University did a study which showed that the healthy coral reefs were able to absorb twice as much wave energy as areas where the coral reefs were not so healthy because of the roughness of the structure. So, it’s not just about the fish, it’s also about real, live, direct benefits to humans that live near these areas.

HOST: Kacky, is it possible to assign a number, something that helps us better understand the significance and just what the economic benefits are of coral reefs to us all?

KACKY ANDREWS: Yeah, that’s a great question and one that I’m not sure everyone really is aware of the full value of coral reefs. Healthy coral reefs support commercial fisheries as well as jobs and businesses through tourism and recreation. Approximately half, half of all federally managed fisheries depend on coral reefs and related habitats for some portion of their life cycle. The NOAA National Marine Fisheries Service estimates the commercial value of U.S. fisheries from coral reefs is over $100 million.

And I know that an economic study was done of the value of the coral reefs in the state of Florida and it was literally over $1 billion of value to the state of Florida. So these are resources that have direct, positive economic benefits to the communities that live near them.

HOST: Kacky, what are some of the benefits for maybe our non-coastal listeners today from coral reefs?

KACKY ANDREWS: I think we really need to be aware of the fact that these benefits do extend past the folks who live right next to coral reefs. So if folks like to eat seafood or fish, chances are the fish you’re eating is dependent on coral reefs to make it to your dinner plate.

And the aesthetic value of coral reefs should also not be underestimated as millions of people travel, in the U.S. alone, travel down to coral reef ecosystems to just take a look through snorkeling or scuba diving. And if the listeners out there have not done this, I highly encourage it, because a healthy coral reef ecosystem will absolutely knock your socks off if you can actually see it in the water.

HOST: Thanks Kacky for touching on the fact of why corals are important to all of us, even those of us not living along the coast. Why is it important for us to study coral reefs? It seems that we have a lot of information. Is it to get a better understanding of some of the threats they’re facing that we mentioned or is it for science exploration?

KACKY ANDREWS: Well, it’s a little bit of all of that. Through research we are improving our understanding of how corals are reacting to some of the current threats in the environment. We are continuing to explore, through sustainable research and discovery, medicinal treatments from coral reefs for heart disease, cancer, arthritis, viruses, and other diseases.

Much more knowledge is needed in this area, and we need it fast to fuel science-based conservation efforts. As I mentioned earlier these ecosystems have remarkable biodiversity which means they’re very complex, and so understanding these complex ecosystems takes a lot of science, so we know exactly how best to manage these areas.

HOST: Kacky, during our initial definition we mentioned a list of threats that coral reefs face. What is the greatest threat to coral reefs today?

KACKY ANDREWS: Unfortunately Kate there is a lot of threats to coral reefs. I do think that the scientists are in general agreement that the three greatest threats are climate change, adverse impacts of fishing, and pollution from land-based sources. For the adverse impacts of fishing, fish play a very important role in the ecosystem, particularly the herbivores. The herbivores essentially act like the lawnmowers for coral reefs cleaning them from the algae that can accrue on them. And this helps keep them clean and lets the coral polyps grow. And so if we take too many herbivores off the reef, they cannot play the function in the ecosystem of the lawnmower for the coral reefs.

With land-based sources of pollution particularly in the island environments where coral reefs tend to be, is you can get a lot of deforestation and with a big rain event you can get huge loads of sediment coming off these high island topographies washing massive amounts of sediments into the ocean and burying essentially the coral reefs.

But I think everyone would agree that the greatest threat, the single greatest threat, to coral reefs is climate change. There’s just no doubt about it. The impacts from climate change take primarily, I think, two different avenues. One is warmer water temperatures which can result in massive coral bleaching. What this means is, particularly during the summers when the waters get too warm and the seas get too hot, the corals will expel that symbiotic algae I talked about earlier, the zooxanthellae, and they will turn absolutely white. And so this is why it’s called coral bleaching. When a coral bleaches, it does not necessarily mean that it’s dead, it can survive a bleaching event, but it does mean that it’s under a great deal more stress and is subject to mortality.

So, for example, in 2005, just about four and a half years ago, in the Caribbean, the U.S. lost half of its coral reefs in one year due to a massive bleaching event. That is a stunning and startling statistic.

The second avenue of impact from climate change is ocean acidification, essentially, the early results seem to indicate that corals will not be able to grow as fast with ocean acidification. Ocean acidification means corals calcify kind of like seashells and with ocean acidification we’re changing the chemistry of the ocean water which means corals are not able to grow as fast as they use to be able to do.

So, given these two massive impacts from climate change, I think it’s fair to say that climate change is the greatest threat to coral reefs.

HOST: So corals really have a lot stacked up against them it sounds like.

KACKY ANDREWS: Unfortunately yes.

HOST: I know that there’s a lot of ongoing research and evidence on the current state of coral reefs in the U.S. today and around the world. What can you tell us about how our reefs are doing either here in the U.S. or globally?

KACKY ANDREWS: Well Kate, I wish I had better news to report on this front. An ongoing NOAA effort to assess the condition of the nation's coral reef ecosystems is a report called The State of Coral Reef Ecosystems of the United States. The most recent report in 2008 found that approximately half of the coral reef ecosystems under U.S. jurisdiction are considered by scientists to be in only 'poor' or 'fair' condition and they have declined over time due to several natural and anthropogenic threats that I spoke of earlier.

Also, reef habitats adjacent to populated areas are subject to more intense threats from coastal development and recreational overuse, but even remote reefs far from human settlements are still at risk from illegal fishing, marine debris, and the climate-related impacts that I spoke of just a few minutes ago.


HOST: Kacky, what is the role of NOAA in protecting our coral reefs?

KACKY ANDREWS: Well Kate, there are many offices and agencies across NOAA that work to make up the Coral Reef Conservation Program. This includes the National Ocean Service, the National Marine Fisheries Service, the Oceanic and Atmospheric Research, and then NESDIS the satellite arm of NOAA.

The Program came about after a series of high-profile events. In 1995, there was major worldwide bleaching and coral die-off on a global scale; in 1997, the world celebrated the first International Year of the Reef; in 1998, President Clinton issued an Executive Order on coral reef protection; and then in 2000, Congress passed the Coral Reef Conservation Act, supplying funding and expanding the mandate for NOAA to help protect these resources.
So essentially the Coral Reef Conservation Program now exists to help implement the Coral Reef Conservation Act as mandated by Congress.

HOST: I know that these things can take a long time, but are we able to measure or state how successful the NOAA efforts have been so far?

KACKY ANDREWS: Well, we have made really measurable progress, but much more needs to be done. Much of what the program has focused on to this point has been assessing coral reef ecosystems, and we know vastly more than ever before about the extent and locations of corals and the states of their health. And we are using that information in conservation and restoration activities.

But like I mentioned before, in the face of such severe threats to corals, we are shifting emphasis more towards action that fend off threats and bring corals back because we want to ensure that we’re doing more than just documenting the demise of corals, but we’re doing all we can to ensure that we’re conserving these resources for future generations.

HOST: Kacky, are there actions that our listeners can take to preserve and protect coral reefs?

KACKY ANDREWS: Yes, there are many actions that we can all take to help protect coral reefs in our own way. Whether you live along the coast or not, we all benefit from coral reefs and we all stand a chance to interact with corals either during vacation or other travel. It is important that we all play a hand in their protection. Let me just give a few specific examples so the listeners know how they may be able to help.

One is get educated, learn about coral reefs. These are amazing resources.

Two, support organizations that protect coral reefs. There are many really wonderful organizations both at a national scale and in the international arena that work to help protect these resources.

Three, you can volunteer for a reef cleanup. As you know there is a lot of marine debris out on reefs and there’s many organizations that ask folks to come out and help clean up the reefs.

Four, if you dive, don’t touch the reefs as these are really remarkable resources and sometimes people like to break off a branch to take home as a souvenir, but if everyone out there diving and snorkeling did that, which number in the millions, that has a really big impact.

And lastly, is everyone can do their bit to reduce their carbon footprint. Climate change is the greatest threat to reefs and so anything you can do to help reduce the climate change will hopefully improve coral reef condition over the long term. 

HOST: Thanks Kacky. Do you have any final closing words for our listeners today?

KACKY ANDREWS: I think the last point I would like to make is that with the increasing threat of climate change, we all need to rethink the management of our coral reef ecosystems. What has worked in the past will simply not be sufficient in the future. So we are going to have to change to help protect these resources and that can be difficult because these are resources that millions of people are dependent on for their livelihoods. So, I’m not saying that this will be easy to change the way that human beings interact with these resources, but if we want to help protect these resources in the face of climate change over the long term, then we need to really up our game in the management of these resources in really new and novel ways.

HOST: Thank you Kacky for joining us on today’s episode of Diving Deeper and talking more about coral reefs, their importance, and what we can do to protect these valuable ecosystems. To learn more about coral reefs, please visit  

That’s all for this week’s show. Please join us for our next episode in March.