Two products better known for cleaning pools and moisturizing dry skin can help protect Earth’s corals and reduce antibiotic resistance and pollution in the ocean. A paste made from chlorine and cocoa butter could be a future treatment for Atlantic corals affected by stony coral tissue loss disease (SCTLD). The experimental findings are described in a study published Nov. 14 in the journal Boundaries in Marine Sciences.
What is stony coral tissue loss disease?
Coral reefs around the world are in serious trouble due to ocean warming, habitat degradation, pollution and disease. SCTLD is a very deadly disease in corals that was first noted in 2014. According to NOAAIt affects more than 20 coral species and is present on reefs in 18 countries and territories. It usually appears as a lesion on the coral that then destroys the soft tissue. SCTLD is particularly serious because it is transmitted very quickly, spreads to many hosts, and has a high mortality rate. It usually kills corals within weeks or months after you become infected.
[Related: Caribbean coral is getting sick and dying. A probiotic could help.]
Antibiotics such as amoxicillin are the most common treatment method marine biologists use to stop the spread of SCTLD. However, this is associated with side effects such as increased resistance to antibiotics, just like in humans.
“Antibiotic pollution is a problem worldwide, so we are working to develop a non-antibiotic treatment that would slow diseases involving tissue loss,” study co-author and Qatar University marine biologist Greta Aeby. said in a statement.
Amoxicillin vs. chlorine
In the new studya team compared the effectiveness of different SCTLD treatments by applying them to infected corals from Horseshoe Reef, near the British Virgin Islands. Some groups were treated with amoxicillin. The others were treated with a paste mixed from chlorine and cocoa butter.
“In this mix, the active ingredient is sodium hypochlorite, an antiseptic often used to kill bacteria or viruses,” Aeby said. “The chlorine powder we used in our treatment is the same powder used to kill germs in swimming pools. The cocoa butter was just the delivery mechanism that allowed us to spread the chlorine onto the coral lesions.”
They applied both types of treatments directly to corals, checking the reef every four to five weeks. During these visits they have measured and described any lesions and reapplied the treatment if necessary. After about 80 daysthe average percent tissue loss was 17.6 percent for chlorine-treated coral colonies and 1.7 percent for amoxicillin-treated coral colonies.
A better choice for the ocean
Although traditional antibiotic treatment has been more successful in containing the spread of SCTLD, these treatments come with unwanted side effects. They can lead to more antibiotic-resistant bacteria and using something like chlorine treatment can help minimize that risk.
“Any organism – crabs, fish, even humans – in that same environment has a higher risk of encountering bacteria that are now antibiotic resistant,” Aeby says.
In addition, antibiotic treatments can also be used major impact on the environment. They can be toxic to other organisms and lead to further resistance, making bacterial diseases difficult to treat. The chlorine and cocoa butter paste is more easily biodegradable and the power of the chlorine is naturally deactivated within 24 hours. The ingredients also make it much cheaper to produce, as the ingredients can be found in hardware stores and pharmacies.
“The antibiotic paste is not only tedious to produce, but is often too expensive for conservationists, who operate with minimal funding on Caribbean islands,” said Argel Horton, co-author of the study and marine biologist at the Ministry of the Environment, Natural Sciences. Resources and Environment. Climate Change of the British Virgin Islands, said in a statement.
Cleaner oceans fight diseases
However, not all corals in the study responded equally well to the treatments. Of more than 6,000 known coral speciesthere are numerous corals from different environments that could not be included in this study. The team hopes that future studies can test the effectiveness of different treatment methods on other corals.
[Related: World’s largest known deep-sea coral reef is bigger than Vermont.]
While treating diseases can help, it does not remove the virus from a coral population, just as simply treating a cold does not remove the virus from circulation in humans. More direct treatments can reduce pathogens in the environment, but treating coral colonies individually and by hand, as the team did in the study, is not feasible long term or on a large scale.
“The best strategy would be to improve environmental conditions so that corals have a better chance of fighting diseases on their own,” says Aeby. “This includes cleaning up water pollution and rebalancing the ecosystem.”
