Increased disease prevalence in a warming peripheral reef setting (Abu Dhabi, Persian/Arabian Gulf)

Coral reefs in the Persian/ Arabian Gulf (PAG) are subject to extreme heat stress. Moreover, effects of temperature induced bleaching on local coral assemblages are being further compounded by coral disease. This manuscript explores taxonomic and seasonal variation in disease prevalence, at Ras Ghanada, Abu Dhabi, from 2010–2024. Thirty-two image-based surveys were conducted across winter, spring and summer seasons which looked at active diseases, partial mortality, bleaching, encroachment by neighboring biota and general health from images. Seafloor temperature was also recorded across the monitoring period. Elevated disease prevalence in 2013, 2019, 2021, and 2024 followed marked summer heat stress with significant coral bleaching. Disease was most prevalent in winter after summer thermal stress. Porites harrisoni showed highest disease prevalence, while species within the genus Dipsastraea spp. were more resilient. Acropora spp. suffered moderate disease prevalence after bleaching and disappeared from Ras Ghanada after 2015 likely as a result of both stressors. Relative prevalence of diseases increased from 1.42% in 2010 to 5.66% of all corals in 2024. Coral diseases on PAG marginal reefs are chronic stressors that contribute to community shifts and structural loss.