The combined effects of ocean acidification and marine tourism place intense pressure on sensitive coral reefs and threaten their ecological and economic sustainability. The combination of the world’s highest coral cover and diversity, combined with the contribution of diving-related tourism to local economies, suggest these interactions may be disproportionately important for areas of South East Asia.

Through this project, the researchers surveyed coral reefs in four regions of South East Asia and developed a vulnerability index to establish the relative risks to breakage from scuba diving and climate-change-related events, including ocean acidification. The study also surveyed the dive industry in each of these regions to assess their perceptions of the major risks to local coral reefs, their knowledge of ocean acidification, and the level of environmental stewardship in the industry. Dive stakeholders were also surveyed, using an online method, to provide insights into how and why they choose dive locations and their perceptions of the major threats, including ocean acidification.

The project outcomes reveal that sites with relatively high vulnerability to ocean acidification and breakage occur in Tioman Island (Malaysia) and Maluku Province (Indonesia). Tioman Island and Hon Mun Island in Nha Trang (Vietnam) have the largest SCUBA dive tourism industries of the areas surveyed, with suggestions by most Dive Masters and Dive Company Managers that current activities exceed carrying capacity of the reefs in Nha Trang. Decline in the state of reefs was noted by all dive industry stakeholders across all regions.

The main threats were identified as destructive fishing practices in all regions except Australia. Climate change was identified as a threat by some stakeholders in each region, but ocean acidification was rarely mentioned. SCUBA divers were generally less aware of ocean acidification than other threats to coral reefs. However, in all regions except Maluku, the SCUBA dive industry was aware of the concept of ocean acidification. Similarly, the majority of Dive Masters in Maluku Province were less aware of the impacts from diver-induced damage to coral. Most dive operators in all regions provide pre-dive training and briefings, although few are trained to intervene underwater when required to protect corals. Overall, most dive operators participate in environmental programs and SCUBA divers prefer providers with good environmental stewardship.

These results highlight an opportunity to further engage Dive Masters in education on ocean acidification to empower them in non-regulatory controls for protecting coral during dive activities. We also recommend good governance of areas of high coral diversity, particularly those dominated by sensitive growth-forms. Such governance would provide opportunities to manage a range of threats, and should include appropriate regulation of the dive industry to ensure best practice, and nomination of a suitable carrying capacity to ensure long-term ecological and economic sustainability.