The number of recreational divers learning to dive and diving in tropical waters adjacent to reefs is increasing as are the number of researchers using diving practises as standard methodology. Concern is increasing about the effects of divers on the habitats they are visiting as more and more heavily dived areas become degraded and the travel companies continue to search for the few unspoilt sites still available. Over a million new divers were certified by PADI (the Professional Association of Diving Instructors-the largest training organisation in the world) in the year 2000, and growth in the tourist market involving scuba is increasing.

Studies have identified that the key attractions for tourist divers are the quantity and diversity of fish and coral life (Inglis et al, 1999), and for this reason a direct assessment of these would be the starting point for the research. A study of the direct impact of divers on the coral and ability to recover, together with the ecological diversity information would be combined to produce a model for the sustainability of diving on these sites. Strategies for calculating so called carrying capacities have been developed and refined in a number of studies including Davis and Tisdell (1995) and Hawkins and Roberts (1997) though none of these studies have been able exercise complete control over their survey sites as will be the case in this study.

Recreational diving in the Wakatobi Marine Park is still at very low intensities. However, as access to the area becomes easier and information about the quality of diving becomes widely available, numbers will increase substantially. The project aims to quantify the current level of damage, make projections of future damage in line with developing tourism in the area, estimate and test a carrying capacity for reefs in the area and develop strategies to reduce the impact of scuba diving on the reef.

A number of quadrats have been established at two sites near Pulau Hoga. One site is a reef already impacted by heavy diving numbers and the second is a pristine, un-impacted site. These quadrats have been surveyed for coral, invertebrates and fish to determine species diversity and abundance on the dived and undived sites.

A large scale study of the behaviour of divers in the water has been conducted involving observation of divers of all levels of training and experience under a variety of conditions. Details of current, visibility, group size, depth, reef topography, activity, gender, camera use and whether a group is being guided are all recorded. The number of times a diver contacts the reef are recorded by anonymous observers along with details of whether the contact was by fin, hand, kit or other part of the body. Observers also record the type of substratum contacted. Data will be analysed to determine whether certain factors increase the likelihood of contact with the reef and from this information a package of measures will be developed and tested in the field next year. After testing, the package would be made available to dive operators worldwide for use as a tool in reducing impacts on a global basis.

Initial analysis of the data from surveys of the quadrats indicates that diversity and abundance of corals and invertebrates differs significantly between the dived and undived reefs. Percentage cover is significantly higher on the undived reef and statistical analysis of the diversity data is likely to indicate a considerably higher diversity index as well. On the undived site there is also a greater variety of growth forms whilst the dived site is dominated by the faster growing branching forms. These results confirm the view that heavily dived sites appear degraded with a reduction in diversity and increase in dominance of a single growth form. The diversity and abundance of fish species does not appear to be significantly different on the dived and undived sites.

The study has so far accumulated 9,000 minutes of observations making it the largest study ever conducted. Initial analysis shows an overall mean rate for contacting live substratum on the reef of 0.43 contacts per 10 minute segment, compared to a worldwide average of 1.6 per 10 minute segment. This may be due to a number factors including the high level of ecological awareness among divers at Operation Wallacea and the high numbers of women divers, who have been shown by this study and others to do significantly less damage to the reef than men. Other groups who appear from the results to be high risk are camera users, divers in large groups, divers being guided by a divemaster and those engaged in work close up to the reef. There appears to be no correlation between the levels of training and experience of a diver and the rate at which they contact the reef. This confirms earlier studies and is attributed to the willingness of more experienced divers to approach the reef more closely. Novice divers tend to be more wary and hover clear of the substratum.

Detailed statistical analysis is required to assess the significance of other factors which will be completed at the University of Essex in December 2001.

Dive practises and training at Operation Wallacea are of a high standard and this combined with the high ecological awareness and high proportion of female divers results in a very low level of physical impact to the reef around Hoga Island. One site is becoming impacted by weight of numbers, and steps are being taken to reduce the numbers on this site. All sites are now marked with buoys, negating the need for anchoring and the potential damage this can cause. The generally recognised carrying capacity for coral reefs is estimated at between 4,000-6,000 dives per site per year and Operation Wallacea is still well below these figures. Also, the low level of impact by divers at Operation Wallacea means that the carrying capacity could be raised substantially if that level of impact were maintained. Furthermore, the implementation of the measures to reduce impacts in the 2002 season should ensure a decrease in impacts which may be substantial.

Davis, D. and Tisdell, C 1995 Recreational scuba diving and carrying capacity in marine protected areas. Ocean Coastal Management 26, 19-24

Dixon, J.A. and Sherman, P.B. 1990 Economics of protected areas: A new look at benefits and costs. Earthscan Publications U.K..

Hawkins, J.P. and Roberts, C.M. 1997 Estimating the carrying capacity of coral reefs for scuba diving. Pages 1923-1926 in H.A.Lessios and L.G. Macintyre (eds.), Proceedings of the 8th international coral reef symposium, Panama, June 1996. Smithsonian Tropical Research Institute, Republic of Panama

Inglis, G. J., Johnson, V. I. and Ponte, F. 1999 Crowding norms in marine settings: A case study of snorkelling on the Great Barrier Reef. Environmental Management Vol. 24, No. 3, pp.369-381 1999.

Report

This work is part of a 2 year study which will produce a report entitled Physical impacts by scuba divers around Hoga island and strategies for their reduction which will be produced by Julian Jensen, University of Essex, by December 2002.