IMPACTS OF RECREATIONAL SCUBA DIVING AT SITES WITH DIFFERENT REEF TOPOGRAPHIES

Increased participation in marine recreation and tourism has been acco mpanied by concern for the impacts that these activities have on coral reef environments. We investigated how the topography of coral reef d ive sites influences the type and amount of damage done by SCUBA diver s to living corals. Independent observations were made on 150 qualifie d SCUBA divers at six dive sites within the Great Barrier Reef World H eritage Area, Australia. Two sites each had reef topographies that wer e characterised by steep slopes ('Pinnacles'), gently sloping (40 degr ees-60 degrees, 'Shoulders'), or near-horizontal substrata ('Gardens') . The number of contacts each diver made with the substratum and the n umber of times corals were broken were recorded and compared across al l six sites and among the three topographic categories. The rate at wh ich divers broke corals varied markedly among dive sites, but was not clearly related to reef topography. Divers broke more corals per 10 mi n interval (1.8 +/- 0.77, mean +/- I SE) at one of the Shoulder sites than at any of the other five locations (0 to 0.28 +/- 0.24). Benthic assemblages at this site contained the largest percentage cover of bra nching corals of all of the sites used in the study (24% +/- 4%, cf. 0 %-10% at the other five sites). All of the breakages that we observed were sustained by corals that had a branching morphology. Our results suggest that the topography of coral reef dive sites is not a useful p redictor of the amount of damage done by SCUBA divers. More important is the morphological composition of benthic assemblages at the site. K nowledge of biological influences on the sensitivity of different site s to impacts of SCUBA divers will allow managers to match high-risk ac tivities, such as diver training, with suitably durable locations. (C) 1997 Elsevier Science Ltd.