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A tourist boat pulls up to a mooring at a shallow tropical reef, and begins the daily ritual of introducing the splendors of a coral reef to people for the first time. “Coral is a living animal”, explains the guide, “so don’t touch…it will die” The guide continues with a brief lecture, and stops to let the beginners discover on their own. Some are timid at first, but then squeals of awe cajole the rest of the passengers to join in the fun; soon the deck is empty and several dozen bodies are in the water with snorkel gear, pointing out a colorful fish or an interesting coral formation. Inevitably, many of the inexperienced snorkelers make contact with the reef—most not on purpose. Some stand in the shallow water to clear water from a mask or to scope for their companions. Others make a hasty grab with a hand to avoid being shoved into the reef with the surge of a wave.
This scene could be from any one of the hundreds of popular coral reef destinations the world over. But as more and more remote tropical destinations open up to the ecotourist, we must question the effects that people have on the very thing they gain so much pleasure in visiting.
“What happens to corals when you touch them?”, is a common question asked by countless reef visitors, and is often answered by an assumed “corals die” response. Yet, in reality, we don’t fully know the direct or indirect impacts of touching corals. For instance touching a coral may not directly kill it but it may weaken it and leave it vulnerable to overgrowth, or predation. How much touching does it take to affect the health of a coral species? Understanding these questions is vital to protecting coral reefs. While there have been many studies on reef-wide coral damage from pollution, storms, trampling, sedimentation, and even experimentally inflicted breakage. I have not found one on the effects of touching on corals. In this ongoing research, we are experimentally applying touching treatments to two species of Porites (one of the most common genera in Hawaii) Porites compressa and Porites lobata. We are experimentally touching the corals with different levels of applied pressure (heavy and light). Biologically, the main difference between light and heavy treatments is that heavy treatment tends to remove the mucous membrane from the coral surface. Light treatment leaves the mucous membrane on the treated area largely intact. What are our results? To date, we have discovered that resistance to human touch varies between species, and between treatment types. Some of the heavily touched specimens of Porites compressa developed visible scarring, which is still evident after three months (see figures below). Porites lobata specimens, on the other hand, showed little visible effects several weeks after the initial treatment. Light touching seems to have little noticeable effect on either species after 75 days. Corals on heavily visited reefs are often subject to being touched, brushed, and leaned against many times a day. Our preliminary results showing some impacts has led us to pursue a more intensive and detailed examination. Among the experiments now in progress is one to test the effects of multiple treatments (long-term repeated touching) on Porites sp. corals.
We hope that the results of this and other research will be an incentive both to the tour companies to create effective management strategies that minimize impacts, and to the individual reef visitor who wishes to return to the same healthy reef. Conserving reefs is everyone’s business remember as a diver:
— Be correctly weighted and use good buoyancy control
— Avoid damaging reefs with anchors, diving equipment, and poor diving skills
— Don’t collect plants or animals
Porites compressa
November 23rd, 1996: before treatment
D. Kent Backman is a marine biologist and underwater videographer currently at U. Hawaii, Hilo. He was a biologist and videographer on SEI’s Montserrat project.
St. Barthelemy, Research and Discovery Montserrat, Coral Reefs under the Volcano Are you interested in helping SEI scientists?
© 2000 Sustainable Ecosystems
Institute  comments: sei@sei.org |
