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July 22, 2013 | By:  Alexis Rudd
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What risks do Tourists Pose to Coral Reefs? Are We Loving the Reefs to Death?

Imagine that you're on an island in the middle of the Pacific Ocean. It's a beautiful day. The ocean is crystal-clear and warm, and you're snorkeling above the most beautiful coral reef you've ever seen. Yellow butterfly fish dart in and out of the coral, while thousands of iridescent blue fish float in clouds above the reef.


You are just starting to think you might have died and gone to heaven when another snorkeler swims up next to you. And breaks off a big branch of the beautiful staghorn coral. And then stands on top of the reef to examine the broken branch he's just broken off.


Although it may look and feel like it's just a rock, coral is a very fragile animal. What we normally think of as coral is actually a colony of thousands of tiny organisms, each of which has a tiny cup-like skeleton made up of calcium carbonate, called a calyx. The coral animal sits inside the calyx, and can even pull its soft body inside the skeleton when they are under stress. Every so often, the coral will lift off the base of its calyx, and build a new floor out of calcium carbonate. This is how coral skeletons grow. Even though the coral's inner skeleton is hard, the polyps are fragile. Even touching them with your fingers can damage them. In fact, as Jessica (SaltySci's coral expert) explained to me, the skeleton itself is not only hard, but very sharp - made of lots of little pointy bits. The coral's tissue is just a very thin layer on the top of this hard, pointy skeleton, so when the polyps are pushed against the skeleton, they essentially can be impaled on their own skeleton. OUCH.


The National Oceanographic and Atmospheric Administration (NOAA) ranked tourism and recreation-related threats as medium or high in nine of fourteen locations. Living in Hawaii and the tropical Pacific, I have seen the effects of people on coral repeatedly. In just a cursory search for literature that looks at the damage of tourism, I came up with research papers from locations as far ranging as Thailand, Egypt, the Mediterranean, French Polynesia, the Caribbean, and Hawaii. People are spending large amounts of money to travel to these far-flung locations to see the coral reefs, and then being careless with their love. Careless divers and snorkelers can damage coral in many different ways. Divers can grab corals with their hands, kick the corals with their fins, kneel on them to take photographs, and drag equipment (like cameras and dive depth gauges) over the corals. People kick up sand onto the corals, smothering them. Some people even scratch their names in the coral, killing the living polyps.


Unlike the graffiti example, much of the damage done by visitors to coral reefs is unintentional, and people are often unaware of the consequences of their actions. Most of the people I see standing on the reef or damaging coral are there because they wanted to enjoy the wonder and beauty of snorkeling in a coral reef. The coral is the reason for their visit, but their knowledge of what a coral looks like and how to protect it is sadly lacking. In one study, 95% of the divers were concerned about the state of the world's coral reefs. This same study found that detailed conservation briefings reduced the amount that divers touched the reef. However, these discussions need to be detailed: another study found that one sentence included in a dive briefing did not make any difference. Reminders from the dive leader during the dive did make a big impact in reducing coral damage. This is the reason why I often stop snorkelers to talk to them about what they are doing, much to the embarrassment of my family and friends. It's important to remember to be friendly - most people have good intentions (as the study I mentioned above showed).


Direct impact of humans on coral reefs is only one among many threats. Global warming threatens to increase the frequency and severity of bleaching, and sea level rise may put them out of reach of the sun needed by their symbiotic algae, called zooxanthellae. Diseases are a growing concern, and may wipe out entire reefs. Pollution from coastal development and runoff smothers them under sediment and poisons their water. So why should I care about a few handsy divers and snorkelers?

I care because I believe this is a glaring symptom of how important education and awareness of your actions and surroundings is to ocean conservation. Healthy coral reefs are extremely important, and if you don't know what a coral looks like, and how delicate it is, you will probably have no problem standing on it to fix your goggles. If you're not paying attention to where you're kicking your feet, you may kick the branches right off a staghorn coral. The importance of awareness reverberates through many aspects of reef conservation, from buying pets (did your new fish come from a coral reef?) to driving your car (do you really need to drive three blocks to the grocery store?).

What kind of actions in your day-to day life could you be more aware of to help protect coral reefs (and the ocean)?

Alexis Rudd is on twitter as @SoundingTheSea


Barker, N. H., & Roberts, C. M. (2004). Scuba diver behaviour and the management of diving impacts on coral reefs. Biological Conservation, 120(4), 481-489.

Camp, E., & Fraser, D. (2012). Influence of conservation education dive briefings as a management tool on the timing and nature of recreational SCUBA diving impacts on coral reefs. Ocean & Coastal Management, 61, 30-37.

Dearden, P., Bennett, M., & Rollins, R. (2007). Perceptions of diving impacts and implications for reef conservation. Coastal Management, 35(2-3), 305-317. (Paywall)

Marion, J. L., & Rogers, C. S. (1994). The applicability of terrestrial visitor impact management strategies to the protection of coral reefs. Ocean & coastal management, 22(2), 153-163. (Paywall)

Poonian, C., Davis, P. Z., & McNaughton, C. K. (2010). Impacts of Recreational Divers on Palauan Coral Reefs and Options for Management 1. Pacific Science, 64(4), 557-565.

Rouphael, A. B., & Inglis, G. J. (1997). Impacts of recreational scuba diving at sites with different reef topographies. Biological Conservation, 82(3), 329-336.

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