A mysterious ailment has devastated Florida’s coral reefs since 2014 and is rapidly spreading throughout the Caribbean. However researchers with the Smithsonian’s National Museum of Natural History have just announced the discovery of the first effective bacterial probiotic for treating and preventing stony coral tissue loss disease (SCTLD).
Since its discovery in Florida in 2014, cases of SCTLD have been confirmed in at least 20 countries. The precise cause of the malady remains unknown but once a coral is infected, its colony of polyps can die within weeks. SCTLD afflicts at least two dozen species of so-called hard corals, which provide essential habitat for innumerable fishes and marine animals.
“It just eats the coral tissue away,” said Valerie Paul, head scientist at the Smithsonian Marine Station at Fort Pierce, Florida, and senior author of the study. “The living tissue sloughs off and what is left behind is just a white calcium carbonate skeleton.”
Though the precise cause of SCTLD is unknown, the efficacy of antibiotics such as amoxycillin as a treatment suggested pathogenic bacteria were somehow involved in the progression of the disease. With this in mind, the research team aimed to identify which, if any, naturally occurring microorganisms were protecting some disease resistant corals from SCTLD. One bacterial strain in particular, named “McH1-7”, stood out. The team then conducted chemical and genetic analyses to discover the compounds behind McH1-7’s antibiotic properties and the genes behind those compounds’ production. Finally, they tested McH1-7 with live pieces of great star coral. These lab trials provided the final bit of decisive proof: McH1-7 stopped or slowed the progression of the disease in 68.2% of 22 infected coral fragments and even more notably prevented the sickness from spreading in all 12 transmission experiments, something antibiotics are unable to do.
The potential of this newly identified probiotic to help Florida’s embattled corals without the danger of inadvertently spawning antibiotic resistant bacteria represents some urgently needed good news.
Image: The remaining live tissue on this great star coral colony (Montastraea cavernosa) in Florida is being destroyed by stony coral tissue loss disease (SCTLD). The bright white margin surrounding the dark brown, living coral tissue is where the coral is bleaching and dying due to the disease. Credit: Kelly Pitts
More information: Chemical and genomic characterization of a potential probiotic treatment for stony coral tissue loss disease, Communications Biology (2023). DOI: 10.1038/s42003-023-04590-y
Journal information: Communications Biology