Scuba diving pressure is not responsible for decadal coral decline in the Bonaire National Marine Park

Following many reports of negative impacts of diving activities on coral reefs in recent decades, a range of approaches to curtail damage have been devised, but their effectiveness is understudied. In the Dutch Caribbean Island of Bonaire, diving has increased threefold since the late 1990 s and tourism funds a marine park that has surrounded the whole island since 1979. We repeated a study from 1994 to assess scuba diver impacts, taking advantage of the park’s no-diving zones and gradients of diving intensity moving away from moorings on designated dive sites. Using quadrats, we surveyed coral cover, disease prevalence and types of diving-related damage in zones open to diving and fishing, open to diving but closed to fishing, and open to fishing but closed to diving. Between 1994 and 2022, coral cover decreased by 38 % across six study sites. Unexpectedly, coral cover decline in sites closed to diving was significantly higher than in those open to both diving and fishing. In contrast, there was no significant increase in coral damage attributable to divers with some types of damage falling in many sites, despite the calculated growth of diver numbers. Whilst the amount of diseased coral increased from affecting 0.038 % coral colonies in 1994 to 1.96 % in 2022, it was significantly more prevalent in areas of low diver use compared to high diver use. Bonaire’s reefs, like those across the Caribbean, have seen a dramatic loss of coral, but we found no detectable signal of diving pressure on patterns of loss or damage to the island’s reefs.