Effectiveness of topical antibiotics in treating corals affected by Stony Coral Tissue Loss Disease

Since 2014, Stony Coral Tissue Loss Disease (SCTLD) has led to mass mortality of the majority of hard coral species on the Florida Reef Tract. Following the successful treatment of SCTLD lesions on corals in closed aquaria using water dosed with antibiotics, two pastes were developed as vehicles for direct antibiotic treatments on wild corals. These pastes were tested as placebos and with additions of amoxicillin via topical applications over active SCTLD margins on multiple coral species. The effectiveness of the pastes without antibiotics (placebo treatments) was less than 10%. Adding amoxicillin to both pastes increased effectiveness. For one of the two pastes, which was silicone based with a time-release mechanism for the antibiotics, effectiveness in halting disease lesions reached 86% when amoxicillin was added. Topical antibiotic application is a viable tool for the preservation of priority corals affected by SCTLD.