Researchers at the Smithsonian Marine Station in Fort Pierce, Fla., have made a breakthrough in saving great star corals from a deadly disease using probiotics. The disease, known as stony coral tissue loss disease, causes white lesions that lead to the loss of polyps and eventually the death of the coral. This disease emerged in Florida in 2014 and has since spread rapidly throughout the Florida Keys and the Caribbean.
The exact cause of the disease is still unknown, but researchers were able to halt its progression using beneficial bacteria that attack or displace invading pathogens. In a study published in Frontiers in Marine Science, the team describes how they successfully treated infected great star coral colonies with probiotics.
The probiotics used in the study were derived from corals that showed resistance to the disease in lab tests. One particular bacterium, known as McH1-7, was found to have antibacterial properties that could neutralize the pathogens causing the disease. The probiotics were delivered to infected colonies by divers, who covered the corals with plastic bags to immerse them in the probiotic solution. The paste containing the beneficial bacteria was also applied directly to the lesions caused by the disease.
Over the course of two and a half years, the researchers monitored the health of the treated corals. They found that the probiotics were able to slow or stop the disease from spreading in all eight colonies treated inside bags. On average, the progression of the disease was limited to only 7 percent of tissue in treated colonies, compared to 30 percent in untreated colonies. However, the paste applied directly to the coral had no significant effect on the disease.
While the results of the study are promising, coauthor Valerie Paul warns against declaring the probiotics a cure for the disease. She believes that the practicality of using plastic bags to treat corals may be limited, and that the study was only conducted on one species of coral when the disease affects over 30 species.
Despite these limitations, lead microbiologist Blake Ushijima sees the study as a proof of concept for the use of coral probiotics in combating disease in the wild. He believes that this research opens the door to a new field of study and holds promise for the future of coral conservation.
