Disease remains a major threat to the health of coral reefs. For example, the recent outbreak of stony coral tissue loss disease is an obvious waterborne disease known to affect at least 20 stony coral species. The disease was first detected in Miami-Dade County in 2014 and has since spread to most coral reefs throughout Florida and into multiple Caribbean countries and territories. Some reef living tissue areas in the northern section of Florida reefs have lost as much as 60 percent of their area.
A new study by researchers at the Harbor Oceanographic Institute at Florida Atlantic University reveals how a common antibiotic used to treat bacterial infections in humans treats disease-affected care M in situ. Cavernosa corals. M. cavernosa, also known as the Great Star Coral, is a type of hard coral or stony coral that is widely present throughout the tropical western Atlantic, including several areas currently affected by stony coral tissue loss disease. Thanks to M. Cavernosa's high abundance and role as a major reef builder in the northern section of Florida's coral reefs protect M. Cavernosa is particularly important.
During treatment, the researchers applied antibiotic therapy (white paste) to the grooves around lesions at the edge of coral populations. Grooves are the white inner edges of coral tissue, while lesions are pale/white tissue at the edges of coral groups. The therapeutic effects were then compared with the chlorinated epoxy resin (brown paste) loaded into the ditch formed on the coral group and on the lesion itself.
A paper published in Scientific Reports experimentally evaluated the effectiveness of two interventions: chlorinated epoxy resins and amoxicillin combined with Core Rx/Ocean Alchemists Base 2B compared to untreated controls. The results showed that the Base 2B plus amoxicillin treatment had a 95% success rate in curing individual lesions. However, over time, it does not necessarily prevent new lesions in the treated corals. There was no significant difference between the chlorinated epoxy treatment and the untreated control population, suggesting that the chlorinated epoxy treatment was an intervention technique that was ineffective against stony coral tissue loss disease.
The authors explain the emergence of new lesions in the corals that have healed in the study. It is possible that the causative bacteria of the stony coral tissue loss disease are still present in the environment and are re-infecting stationary stony corals. It may also be that the duration and dose of this antibiotic intervention is sufficient to prevent stony coral tissue loss at the treatment of the lesion, but not enough to eliminate its pathogen from other areas of the coral population.
The study was conducted about 2 kilometers from the Lauderdai Sea in Broward County, Florida, with a maximum depth of 10 meters. Both colony disease status and post-treatment lesion status are analyzed independently, which allows for an assessment of the effect of treatment on blocking individual lesions, while also determining whether treatment has any effect on the entire colony. Over a period of 11 months, the researchers regularly monitored the coral population to assess treatment effectiveness by tracking lesion development and overall disease status.