The effect of recreational SCUBA divers on the structural complexity and benthic assemblage of a Caribbean coral reef

Abstract

The effect of recreational SCUBA diving on coral reefs is likely secondary to many of the commonly cited stressors that threaten the long-term survival of coral reefs, such as rising temperatures. However, recreational SCUBA diving has had documented effects on various benthic organisms. Most research on the effect of SCUBA divers has focused on broken and abraded benthic organisms or the rate at which divers contact the benthos. We tested for differences in the structural complexity and benthic assemblage between pairs of heavily and lightly trafficked dive sites in Bonaire, a popular Carribbean diving destination. There was roughly 10 % less structural complexity in areas of heavy traffic. This is alarming given that the structural complexity of shallow reefs in Bonaire is substantially lower than in the 1970s. Different functional groups of benthic organisms were affected differentially by diving traffic. For instance, massive corals such as Orbicella annularis were 31 % less abundant at heavy than light diver traffic areas, while gorgonians and sponges had similar abundances at heavy and light diver traffic areas. Our results match those of previous studies on the resistance and resilience of tropical benthic reef organisms to physical disturbances that suggest that stony corals are more prone to physical damage than gorgonians and sponges. We provide a number of possible management strategies that could reduce the effects of recreational SCUBA divers on Bonaire Communicated by

Diving for science ‐ science for diving: volunteer scuba divers support science and conservation in the Mediterranean Sea

“…Nonetheless, it is now clear that unregulated diving can produce serious environmental impacts, too. These include the abrasion or breakage of long‐lived sessile organisms, disturbance of fish and mammals, and altered microscale sedimentation patterns that, in the long run, can lead to community shifts (Di Franco et al , ; Luna et al , ; Bravo et al , ; Lyons et al , ). Many marine protected areas (MPAs) are favoured diving destinations and need to balance conservation with local economic ambitions.…”

Behaviour of recreational spearfishers and its impacts on corals

“…Spearfishing may add to local stressors on corals and other fragile benthic organisms, especially at sites with high visitation rates. Although the potential damage produced by individuals is minor, there is evidence that cumulative effects of disturbances caused by divers can have adverse effects on corals, such as loss of cover (Fava, Ponti, Scinto, Calcinai, & Cerrano, ; Hawkins et al , ) and consequently loss of structural complexity (Lyons et al, ). Injured corals are more susceptible to diseases, predation and competition interference from algae and other organisms (Guzner et al, ; Lamb et al, ).…”

Recreational Diving and Its Effects on the Macroalgal Communities of the Unintentional Artificial Reef Zenobia Shipwreck (Cyprus)

“…It has been demonstrated that exhaustive pre-dive briefings and underwater interventions are two of the best and easiest ways to reduce coral damage [65,[92][93][94][95] reducing the number of contacts by 20-80% [70,93]. Similarly, Di Franco et al [80] propose to start the dives in low vulnerability habitats to give divers enough time to make their comfortable and managing with their buoyancy control.…”

“…Similarly, Di Franco et al [80] propose to start the dives in low vulnerability habitats to give divers enough time to make their comfortable and managing with their buoyancy control. Supporting this approach, it has recently been demonstrated that physical contacts are more likely during the first 10 min of dives [92].…”