What Divers are Roughest on the Reef?

Many divers damage coral, but are some more likely than others to do so? In this study, published last year in the journal Biological Conservation, we see who the culprits are. Undercurrent has substantially edited the study and we take all responsibility for any changes.

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Divers damage corals with their hands, body, equipment, and fins. Although the damage is often minor, the cumulative effects can cause significant localized destruction. Studies have shown that individual divers vary greatly in the damage they cause. In a 1990 study by Helen Talge of 206 divers in the Florida Keys (reported in Undercurrent), about ninety percent had one or more physical interactions with reef benthos, but fewer than two percent actually damaged corals. Variation in competence, the activities pursued, the extent of predive instruction, waves and currents, and site characteristics affect the frequency with which divers contact and break fragile coral. Anecdotal accounts suggest that underwater photographers are particularly problematic.

Identifying simple risk factors

Our study involved independent observations of 214 divers visiting the Great Barrier Reef in an area with a large covering of branching corals. For ten minutes we observed how often each diver contacted the substratum, broke or damaged corals, and kicked up sediments. Contact or damage was classified according to whether it was made by the diver’s hands, fins, knees, gauges, or other equipment, and by the type of substratum involved. Then, fifty-nine divers (thirty-three males, twenty-six females) were issued a Kodak Fun Flash (a single-use camera) at the start of the diving day, ostensibly as a prize for booking a dive trip with the charter operator.

Results

Of the 214 divers observed during the first part of the study, 150 (seventy percent) came into direct physical contact with benthic substrata during the tenminute period. On average, each diver made 5.4 contacts. Most contacts were fin kicks (fifty-eight percent) or resulted from deliberately holding on to corals (thirtytwo percent). Thirty-two divers (fifteen percent) broke corals, with fin kicks the major cause of damage (ninety-five percent). Overall, the mean number of damaging contacts per diver was relatively small (0.4 contacts per ten minutes). There was no correlation between the diver’s experience and the number of times divers contacted or damaged corals. Experienced divers were just as likely to damage coral as inexperienced divers.

Usually, divers were most likely to break corals in the first ten minutes of a dive, and damage was more likely to be caused by male divers than by female divers. Female divers made proportionately fewer fin contacts than males, but were more likely to touch corals and other substrata with their hands.

Thirty-nine of the 214 divers (eighteen percent) used a camera during the observed dive. While similar proportions of photographers and nonphotographers broke corals, photographers who did break corals caused more damage (1.6 breaks in ten minutes) than divers without cameras (0.3 breaks).

Effects of cameras and gender on diver behavior

In the second part of the study, fifty-nine divers were given cameras; they had variously completed between two and 200 dives. Use of a camera had no detectable influence on the rate at which they contacted or damaged corals. However, male divers with cameras were more likely to break corals, and they caused significantly more damage than female divers. Again, female divers were more likely to hold or to touch benthic substrata than their male counterparts, and divers who did touch tended to be more experienced than those who did not touch the bottom with their hands.

Discussion:

The divers who were issued cameras were characteristic of the increasing number of dive tourists who purchase and use cheap, singleuse cameras. They were relatively naive underwater photographers who may not have developed the specialized behaviors exhibited by more experienced diving photographers. The experiment showed that the normal dive behavior and impacts caused by naive divers were not unduly affected by use of an underwater camera. In the hands of relatively naive divers, the cameras do not necessarily create a greater risk of damage to sensitive dive locations.

More specialized underwater photographers typically use bulkier and more expensive camera equipment. These divers, represented in the first part of our study, were the most damaging of all the divers we observed. They often attempted to steady themselves on the substratum while taking a photograph. Although this did not lead to more contact with living organisms, the physical contacts that they made caused more damage than those made by nonphotographers.

As individuals get more committed to underwater photography, their level of personal and financial investment increases. They become increasingly directed toward achieving their photography goals, which can occurs at the expense of their personal values. For example, many exercise less caution about damaging fragile corals. Experienced underwater photographers make evaluations about appropriate behaviors based on their own knowledge and values. They may be less likely to modify their behavior if it means not meeting their photography goals, particularly if they perceive that the damage that they may cause is relatively minor.

Our data suggest, however, that the greatest risk of impacts occurs at sites with a large cover of fragile organisms, and during the first ten minutes of a dive, when the divers are adjusting their buoyancy.

Gender differences were the most consistent finding. Male and female divers display distinctly different underwater behaviors, with women contacting the reef significantly less than their male counterparts. They were more cautious about venturing close to the substratum, and when they did so were more likely to use their hands rather than their fins to support themselves.

This is consistent with other studies of the environmental attitudes and behavior of male and female recreationists, which have shown that men tend to be more adventurous and more likely to take risks than women, less likely to follow instructions, and have a greater propensity toward delinquent behavior. Our observations suggest that males in a mixed-gender “buddy-pair” also usually led the dive and were more likely to enter caves and overhangs, where there is a greater chance of physical contact with the substratum.

There were no strong relationships between dive experience and damage. However, another study has found that less experienced divers were generally more cautious, and therefore were less likely to get into situations where they might damage corals, while another found that divers with more advanced levels of training made fewer impacts.

Recommendations:

Our findings should allow divemasters to target on-site management of divers more effectively so that they reduce the risk of impacts. This may involve giving more explicit predive warnings to male divers and specialist underwater photographers about the extra care they should take during their dives, particularly in the first ten minutes. Briefings are likely to be more effective if they stress the potential for cumulative damage from the relatively minor effects of many individual divers, rather than by simply focusing on elements of individual behavior.

Other approaches could include provision of safe entry and exit points that allow divers to correct their buoyancy without causing damage before they proceed to more sensitive areas of the site, and by visiting particularly sensitive dive sites later in the trip, once divers have become familiar with their equipment and surroundings.

A. B. Rouphael, G. J. Inglis, School of Tropical Environment Studies and Geography and CRC Reef Research Centre, Janes Cood University, Townsville 4811, Australia “Take only photographs and leave only footprints?” This article discusses an experimental study of the impacts of underwater photographers on coral reef dive sites. Biological Conservation 100(2001) 281-287.