Our corals are the canaries in the coalmine of climate change. Dr Anjani Ganase is warning of the disease that can wipe out our impressive boulder brain corals.
Stony Coral Tissue Loss Disease (SCTLD) is officially in the Southern Caribbean. Curaçao, Bonaire, Venezuela and even Grenada have reported outbreaks. It is only a matter of time until SCTLD reaches Trinidad and Tobago, and we are not ready.
SCTLD was first recorded in Grenada in 2015, with many confirmed sightings in 2018 and 2019. Bonaire and Venezuela made observations at the end of 2022, and Curaçao at the beginning of 2023.
Within a single year, many of the reefs of Bonaire and Curaçao have suffered mass die-off of their precious brain corals. The rate of mortality is much higher than any previous disease outbreak encountered on Caribbean corals.
White-band disease killed over 80 per cent of the Acropora corals (two species) found throughout the Caribbean within a decade. Acropora corals still have not recovered to date.
SCTLD is likely to exceed this. It targets and can kill over 20 susceptible species, most of which are brain coral, but extends to other massive species, such as the great star coral, and the pillar coral.
First Florida
SCTLD is caused by an unknown pathogen, although there is some consideration that it may be a type of bacterium. After ten years of investigations, scientists continue to be baffled by the disease-causing agent.
This is not unusual, as many coral disease pathogens continue to be unidentified.
As its name suggests, once infection happens, it results in the formation of lesions in the tissue of the corals which expand very quickly until the lesions get so big that they fuse together, eating away all the tissue of the coral colony, killing it.
The process of infection is quick; it results in death in a matter of weeks or months. By comparison, corals suffering from black band or yellow band disease might take months to years to die.
SCTLD was first discovered in Florida in 2014. Today more than 96,000 acres of the Florida reef tract (over 50 per cent) have been devastated by the disease (30 per cent mortality) and about 45 species of corals have been infected.
In Curaçao, the disease has infected 22 species of corals within its first year of infection. Smaller colonies were killed in a matter of weeks to months, while larger colonies took longer simply because there was more tissue to infect. The spread started from the ports and by 2023 reached the two tips of the island – East Point and West Point – where the more pristine and remote reefs are located.
It only takes a handful of coral colonies to be infected on a reef to result in widespread outbreak. It was estimated that Curaçao will lose 25 per cent of its live coral cover in the coming years (Carmabi Foundation, Curaçao).
Now Tobago
The big concern for Tobago is that most of the reefs are made up of brain coral species, which is highly vulnerable to the disease.
Furthermore, Tobago has a much smaller diversity of corals compared to n
