Reef walking on Red Sea reef flats – Quantifying impacts and identifying motives

Reefwalking on the shallow reefflats of fringing reefsis an activity commonly observed on Red Sea coral reefs. Of the 137 in-water observations of reefwalkers made at Ras Um Sidd, Sharm El Sheikh, South Sinai, 12.4% caused coraldamage. Eighteen incidents of coraldamage were recorded, 44.4% being breakages of branching corals, 39.8% abrasions of various growth forms and 16.7% detachments of soft coralcolonies. Sediment was stirred-up on 31.4% of observations. Tramplers broke 0.1 branches per minute and raised 1.5 sediment clouds, thereby causing more damage than reported from divers. Damage caused depended on coralcommunity structure and past tramplinghistory, with communities dominated by fragile branching coralsbeing most susceptible to mechanical damage and communities heavily trampledin the past being less susceptible. Given that main motives for reefwalking included crossing the reefflat, adjusting gear or communicating, managementinterventions, such as the construction of a walkway combined with a public awareness campaign, could reduce the numbers of reefwalkers by up to 39%.