Putting The Pee In MPA

Compile a short list of some of the biggest threats to coral reefs today and you might include climate change, coral bleaching or disease, coastal development, and unsustainable fisheries. Admittedly, these are global threats and can seem daunting or formidable for local communities to try to reduce on their own. But part of my approach to coral reef conservation is also working with local communities in project sites to identify their top perceived local threats to their reefs which they they could, through community-based conservation projects, measurably reduce or eliminate. This sort of list is always fascinating to compile and uniquely representative of the destination. Recently I've been noticing two perceived local threats to reef health appearing more and more often: too much pee and too much sunscreen from tourists.

A little background is needed before we get into pee-talk. The majority of marine protected areas (MPAs) that have been established in coral reef destinations are set-up for multiple use. Which generally means that while the area receives either formal or informal protection (no collecting/extraction, monitoring and research, etc.) other activities or uses (such as marine tourism or limited/seasonal fishing) can occur there as well. In fact, it's because of their popularity as dive or snorkel attractions that MPA status is sought in the first place. In theory, the MPA allows for the natural resources to be effectively and actively managed. Or that's the idea, anyway.

How does the multiple use protected area model work on land? Anyone who has visited Yosemite National Park, especially during the Memorial Day weekend, knows it can be a madhouse. The park loop road is often gridlock, parking is nonexistent, and popular spots like Yosemite Falls or the Half Dome views are packed with Ansel Adams wannabes. It's practically impossible to find a solitary moment with nature in the park. As a result of all the car traffic, air quality in Yosemite valley can be worse than in a city. And other than habituated black bears looking for that bag of Doritos in your car, no self-respecting wildlife bothers to hang around the valley with all the noise and congestion.

By comparison, the island of Cozumel in Mexico, Bonaire in the Dutch Antilles, and Honolua Bay in Hawaii are all tremendously popular "parks" as well, albeit marine parks. They are all designated, in whole or in part, as MPAs. And just like the situation I described for Yosemite, visitors to these MPAs can generally expect an absolute cluster-fuck of users. In Hawaii, for example, a 2003 study of tourist traffic through MPAs found that between 28,000 and 100,000 people visited just four coral reef sites per year, with diving and snorkeling being the most popular marine recreation activity. A 1999 study of tiny Honolua Bay on the northwest coast of Maui showed an average traffic of 250 tourists per day and up to 700 per day during peak season. I can say with confidence these numbers have increased.

It's a surreal experience to watch a catamaran pull into Honolua Bay and begin disgorging dozen after dozen of its snorkelers onto the shallow reefs. If I weren't so close to the whole conservation thing, I'd probably find the scene comical. So many clumsy snorkelers all in the same place at the same time... fins slapping each other as they attempt to swim, heads bumping, and the periodic gagging as inexperienced snorkelers swallow another pint of seawater. And with so many humans packed together, the odds are pretty good that more than just a few are "peeing in the pool," as it were. (I promised I'd get back to the pee-talk.)

Now don't sit there feeling all superior like you've never pee'd while swimming. I've done it. You've done it. We all do it. It's not like it's planned. There's just something about being in water that gets the plumbing flowing. Hell, I've pee'd in many a wetsuit while diving just to stay warm! Now a single bladder-full of human urine is no big threat to ocean health. Besides, nitrogen––a major component of urine––is limited in the ocean, and pee is likely to be used quickly in any of a variety of animal or plant metabolisms.

But what about a boat-load of urine? Or many boatloads of urine each day, 365 days a year? Is that a problem? And as an added complexity, what about the fact that almost every one of those happy tourists dropping into the water is wearing sunscreen or sunblock. After all, this is the tropics. Sunscreen is specifically designed to block ultraviolet radiation. A good portion of that same invisible spectrum of light is used by zooxanthellae, the algal endosymbiont living within coral tissue, and is necessary for photosynthesis to occur. So what happens if that sunscreen washes off those hundreds of bodies each day? Could it possibly float as a film on the surface of the water and effectively block corals from photosynthesizing?

These are fair questions, and like I said earlier the perceived potential coral threat from pee and sunscreens seems to be a growing concern to stakeholders I talk to. My job is to listen to stakeholders and help where possible. So is there any science out there to provide some guidance? The research and evidence to date has been lacking or inconclusive. Many factors contribute to making an easy answer difficult. A few of these might include volume and frequency of human traffic, amount of snorkelers wearing sunblock, physical parameters of the destination (embayment, open water, shallow, deep, etc.) and degree of wave action and oceanic circulation in the site. Finally, what sort of equation or methodology do you use to estimate how many snorkelers or divers are actually peeing? Exit interviews? Would you be honest? While I have at least seen a few papers raise the question of the impact of urine on coral reef health, I've yet to find one that addresses the sunscreen issue. If readers know of any, I'm all ears.

Lacking conclusive evidence, I prefer to take a precautionary approach and encourage snorkelers to empty their bladders before suiting-up and to avoid sunblocks altogether and invest in an inexpensive snorkel/surf skin or suit (an ultra-thin Lycra or Spandex material that is close-fitting to the skin and blocks 100% of harmful UV radiation.) These shirts and suits are also known as rash guards as they are effective at preventing stinging marine life (jellies and their kin) from using their nematocysts to sting.

However, even if no empirical link can be made between pee, sunscreen, and coral health, the fact that they have risen in people's perceived ranking of coral threats is still an interesting sociological phenomenon. And there remains the very real consideration of a coral destinations' capacity to support mass tourism. This consideration is known as the tourism carrying capacity (borrowing an ecological term of the same name referring to the number of individuals in a population that the resources of a habitat can support) and requires a comprehensive site analysis. The idea behind conducting tourism carrying capacity studies is in part to determine whether visitation caps might be required to maintain the ecological integrity of a coral destination. But these sorts of studies don't have universal buy-in from reef resource managers around the world. Some managers have said tourism carrying capacity studies are more art than science.

The state of Hawaii has invested in numerous tourism carrying capacity studies for popular coral reef destinations. The incredibly popular tourist attraction of Hanauma Bay on Oahu has put these findings into practice and capped visitation,

In order to protect the quality of Hanauma Bay Nature Preserve, no more than 2,000 people may access the lower level of Hanauma Bay Nature Preserve at any one time. This number may be adjusted based on future studies or reports.

In addition, Hanauma Bay is closed to the public every Tuesday to allow for at least some degree of recovery. With tourism generating more than $10.1 billion to the economy annually, the state is caught between providing for the seven million visitors they receive each year, and preserving its coral reefs—a primary attraction for those visitors. And if the urine threat proves to be valid, I presume that will also mean investing in a few more Porta Potties for the MPA parking lots.