A study conducted by researchers at Qatar University has developed a mixture of chlorine and cocoa butter that acts as an antiseptic to kill bacteria or viruses in corals. This paste is the same that we use to kill germs in water.
In the tropical Atlantic, Stony Coral Tissue Loss Disease (SCTLD) is one of the most severe coral diseases. As it spreads very swiftly, it results in very high mortality rates. In case of such outbreaks, conservationists often use the most common treatment – antibiotics.
Though the use of antibiotics is effective, its repetitive use increases antibiotic resistance of bacteria. Antibiotic resistance is a global problem and could disrupt the delicate marine ecological balance. Therefore, researchers are keen to develop an antibiotic-free approach to treat infected corals.
“Our study shows that direct treatment of SCTLD can help corals survive a disease outbreak and highlights that active management of disease is possible in the field,” said the senior author Dr Greta Aeby. “Antibiotic pollution is a problem worldwide, so we’re working to develop a non-antibiotic treatment that would slow down tissue loss diseases.“
To develop an antibiotics-free cure, the international team conducted a series of tests on the corals of Horseshoe Reef near the British Virgin Islands. As chlorine with cocoa butter paste covered with a clay band effectively sterilizes bacteria, researchers applied corals with this paste. To compare its efficiency against the traditional treatment, a few corals were treated with antibiotics.
After treating the corals, they were carefully observed for over 80 days. Researchers re-visited the reef every four or five weeks to measure the progress. In rare cases, reapply the treatment as necessary.
The observations concluded that the tissue lost was 17.6% for the paste treatment, and and 1.7% for amoxicillin. While the researcher detected no significant difference in survival probability among treatments, the chlorin-based medicine will lessen the antibiotic-resistant bacteria.
While the resistant bacteria might not affect corals, they could pose very serious threats to other marine organisms. On the contrary, the chlorine and cocoa butter paste mixture degrades easily. Meanwhile, the chlorine is seen to deactivate within a day.
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“In this mix, the active ingredient is sodium hypochlorite, an antiseptic commonly used to kill bacteria or viruses. The chlorine powder we used in our treatment is the same used to kill germs in swimming pools. The cocoa butter was just the delivery mechanism allowing us to spread the chlorine on the coral lesions,” explained Aeby.
Additionally, the mixture paste can be produced easily. The ingredients used are readily available in drug and hardware stores. This medicine could offer conservationists a reliable alternative to expensive treatment.
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Journal Reference
- Forrester, G. E., Arton, L., Horton, A., & Aeby, G. (2024). The relative effectiveness of chlorine and antibiotic treatments for stony coral tissue loss disease. Frontiers in Marine Science, 11, 1465173. DOI: 10.3389/fmars.2024.1465173
