A bacterial probiotic helped slow the spread of a deadly disease on great star coral, one of the largest and most resistant corals still surviving in the Florida Reef Tract, a 560-kilometer (350-mile) barrier reef off the coast of Florida, U.S., a recent study found.
The treatment involved sealing live great star coral (Montaststraea cavernosa) colonies inside large, weighted plastic bags filled with a probiotic seawater solution, creating a temporary aquarium. The corals treated in this way lost an average of 7% of their tissue, compared with 35% in untreated control corals.
“It’s important to understand that this is the very beginning,” lead author Kelly Pitts, a researcher at the Smithsonian Marine Station, told Mongabay by phone. “This is definitely not a cure-all, but we’re definitely moving in the right direction.”
Stony coral tissue loss disease (SCTLD) has caused extensive death for more than 30 species of reef-building corals in Florida’s coral reef and is now spreading to other reefs in the Caribbean Sea.
Pillar coral (Dendrogyra cylindrus), a species known for its finger-like spires, is now considered functionally extinct in Florida due to SCTLD. Other species have lost up to 97% of their colonies.
Researchers had tested two delivery methods to combat its spread with probiotics: a paste and the seawater solution. Both used a bacterial strain called McH1-7, which was isolated from a healthy coral and cultivated in a lab.
The paste treatment, where divers applied the probiotic directly onto infected tissue and then spread it by hand over the lesions, failed to slow the disease. But it would be better for real-world uses, as it is faster and more practical to apply. Pitts said the next step is to develop a paste that works.
So far, treatment has largely relied on antibiotics, which don’t prevent reinfection and may cause antibiotic resistance over time.
“SCTLD is a very serious threat — arguably the most devastating coral disease we have encountered in the Caribbean to date,” Phanor Montoya-Maya, the reef restoration program manager at the Coral Restoration Foundation, a Florida-based coral conservation nonprofit, told Mongabay by email.
“I’m genuinely encouraged by the development of probiotics as an alternative treatment to antibiotics for coral diseases,” said Montoya-Maya, who was not involved with the study.
Florida’s corals are severely degraded compared with their historic, healthy conditions, Montoya-Maya said. The degradation is largely a result of warming oceans and pollution that intensify coral disease outbreaks, including SCTLD, he added.
“We’ve lost the majority of our corals,” Pitts said. “We have to figure out what the corals need that can help them fight these stressors.”
Banner image: Researcher Kelly Pitts samples tissue from a great star coral. Image courtesy of Hunter Noren.
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