Researchers are on the lookout for a disease that could be a threat to Bermuda’s coral population — although no cases have been spotted locally.

Robbie Smith, curator for the Natural History Museum at the Bermuda Aquarium Museum and Zoo, said stony coral tissue loss disease has spread throughout the western Caribbean since it was first identified in 2014.

Dr Smith said in the Spring edition of the Envirotalk newsletter that the cause of the disease is not known, but it is suspected that it was a waterborne bacteria carried by ocean currents.

SCTLD kills the tissue that covers the infected coral — usually brain coral or star coral — which leaves the white skeleton behind.

While the impact appears similar to black band disease, which is found on some corals in Bermuda’s waters, BBD rarely kills the infected coral.

Dr Smith said: “By 2018, the disease had spread to reefs in Mexico and by 2019 it was in the Bahamas, Turks and Caicos, Cayman Islands and had spread eastward to the US Virgin Islands.

“By this time coral reef scientists were much more informed on the disease and how lethal it was for infected corals — not 100 per cent, but still very high.

“A number of treatments were devised and the most successful was a paste that included an antibiotic which was applied to the infected coral underwater and remained in place for a few weeks.

“Given that brain and star corals are abundant across all our reefs, from shallow to very deep, the threat of a new and more lethal disease seemed ominous and potentially catastrophic.”

Last summer researchers went to Castle Roads, at Castle Harbour, after a colleague from the US Virgin Islands said she saw coral that appeared to be infected with SCTLD.

However the researchers found the coral had more likely been damaged by marine debris.

Further searches in November and December similarly revealed no cases of the disease.

“Our initial sense of the data is that the corals are healthy and the fish communities are as well, including a surprising number of red hinds on our lagoon patch reefs,” Dr Smith said.

He said that while SCTLD is not presently a threat to the island’s coral, it is possible that warming waters caused by climate change could make them more vulnerable to threats.

“Coral bleaching and subsequent mortality has been a clear symptom of the increasing frequency of bleaching episodes in the Caribbean and Indo-Pacific over the past two decades,” Dr Smith said.

“Bermuda has been much less affected to date and may be less vulnerable due to the generally cooler waters at our latitude. But this will change over the next few decades.

“We do not know if disease incidence and bleaching stress are related but that is only because we only have so few years of SCTLD data to look at and bleaching does not happened every year.

“We do know that our black band disease becomes much more frequent in our summer months and declines with water temperature in the fall, so we should be concerned that heat stress on corals will increase over time, with climate change.”

Dr Smith added that the spread of SCTLD in the Caribbean also increased the likelihood that it would reach Bermuda’s waters.

He said: “Our challenge is to use Bermuda’s Coral Reef Action Plan to continue to monitor our reefs and water quality to understand the scope of all stresses to our reefs, from reduced water quality, sediment re-suspension by shipping traffic and overfishing, so that they can be reduced.

“This may allow for some level of resilience to the predicted effects of climate change and coral diseases.”

Lord Zac Goldsmith, Britain’s Minister of State for the Pacific and the International Environment, told the UK Parliament that funding had been provided to Overseas Territories to help to support SCTLD treatment and management options.