We are drawn to coral reefs. They are colorful, beautiful, and filled with vast amounts of biodiversity that we love to watch and observe. Coral reefs exist in warm tropical regions around the equator that we love to visit when we travel [1]. While ecotourism has the potential to be a sustainable way to support coastal communities and economies in reef regions without negatively impacting natural resources, in many cases, tourism has caused a great deal of damage to coral reef habitats.
While most diving and snorkeling activities have little physical impact on coral reefs, physical damages to corals can and do occur when people stand on, walk on, kick, touch, trample, and when their equipment contacts corals. Coral colonies can be broken and coral tissues can be damaged when such activities occur. Divers and snorkelers can also kick up sediment that is damaging to coral reefs.
Boats grounding in coral reef habitat can damage corals, as can anchors. Anchors can cause a great deal of coral breakage and fragmentation, particularly from large boats like freighters and cruise ships. Heavy chains from large ships can break or dislodge corals. The coral organisms attempt to repel the invaders, but this also results in coral bleaching, which occurs when corals expel the brightly colored algae that live inside them and become fully white.
Seagrass and mangroves—shallow-water plant species important to the survival of the marine ecosystem—are often endangered by coral stress because the destruction of one ocean system affects all others. Sedimentation is another major issue that coral reefs face. When dirt and debris end up in the water, they pollute aquatic habitats and prevent algae from getting the sunlight they need to photosynthesize.
The immobile coral reefs bleach and die when light is blocked. Dredging, logging, irrigation, and tourism-driven coastal growth are all causes of sedimentation in Costa Rica, for example. If better management principles are not implemented, sedimentation will continue to devastate Pacific reefs.
In the next five to ten years, scientists expect that half of all coral reefs in Latin America will be degraded. Vessels grounding and colliding with shallow coral reefs may cause significant habitat damage. In nearshore environments, propeller scarring, anchoring, and other physical impacts are becoming increasingly problematic. In Florida alone, manatees died last year after being hit by speeding watercraft. Anchors can dislodge, crush, and fragment the benthic ecosystem, displacing resident fish and obliterating critically significant topographic complexity and habitat structure that takes hundreds of years to recover.
Corals may be harmed by uninformed and careless divers, snorkelers, and swimmers touching and standing on them. The coral polyps can be suffocated by kicking up sand. Corals, despite their rock-like nature, are extremely vulnerable to injury and disease. Eating, chasing, and touching marine life can change their behavior, the frequency with which they visit the area, and even their home range.
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.
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. 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. She told me about her trips to the gorgeous local beaches. Everything she described sounded beautiful: the clear blue water, hermit crabs that left their shells to eat breakfast in the early morning hours, sweet fruits that fell onto the smooth sand and the lush trees that offered shade from the hot Costa Rican sun.
But her mood changed suddenly from bliss to concern when she told me about how her co-worker swam too close to a coral reef one afternoon and badly cut his thigh.
She was concerned by how unprepared their tour guide was to handle the medical situation, and by how irresponsible it seemed that tourists with no diving experience were allowed to swim so close to the reef.
In addition to the physical danger to humans, accidents like these can have a severe impact on sensitive marine ecosystems like coral reefs. But 93 percent of the reefs in Costa Rica are in danger , and tourism is a significant factor in their degradation. When tourists accidently touch, pollute or break off parts of the reef, corals experience stress. The coral organisms try to fight off the intrusion, but this process often leads to coral bleaching—when corals expel the brightly colored algae that live in them and become completely white.
Once corals are bleached, they die and can no longer contribute to the biodiversity of the reef community.
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