Deadly stony coral disease spreads to West Bay

This map shows the progression the stony coral tissue loss disease, which has now been found at the Macabuca dive site. - Image: DoE

The Department of Environment has confirmed that stony coral tissue loss disease has spread as far as dives sites on the northwestern coast of Grand Cayman.

Divers have found evidence of the disease, which can kill infected stony coral within weeks, at the popular Macabuca site off North West Point Road in West Bay.

The disease was first found at the Penny’s Arch site near Rum Point last summer. The DoE closed down dive sites along the North Wall for several months and created a ‘firebreak’ at the Ghost Mountain site, but last month the disease spread beyond that point.

According to the latest data, it has spread along the northwest tip of the island as far as Macabuca.

Earlier this month, the DoE began appealing to divers and snorkellers to ensure they disinfect their gear in a bid to help stop the spread of the disease, as it is suspected that one of the modes of transmission is particles being spread by divers, as well as by discarded boat bilge water.

Tammi Warrender, the DoE officer who is heading up efforts to combat the disease, acknowledged that it may be also be spread by fish or currents, but she says that while nothing could be done to prevent marine animals or currents from being the means of transmission, efforts could be made to reduce the risk of bacteria and other microorganisms being carried in divers’ neoprene gear, such as wetsuits, booties, and gloves, or in buoyancy compensation devices (BCDs).

According to the Atlantic and Gulf Rapid Reef Assessment programme, pathogens from stony coral tissue loss disease can adhere to dive and snorkel gear, “especially when the diver directly contacts the bottom and touches corals and other benthic organisms.

Pathogens on dive gear may survive for extended periods and can be transferred among reefs on subsequent dives, and, potentially, transmitted to reefs internationally, unless your gear is disinfected.”

It advises, “Just like handwashing is a common practice to prevent the spread of disease among humans, disinfecting gear and following other best practices is recommended to prevent the accidental transmission of coral disease between reefs. Particular attention needs to focus on decontaminating wetsuits and the internal bladders of BCDs because of their ability to trap water that can house transmissible pathogens.”

This photo shows a stony coral tissue loss disease lesion on a local coral. The lesion is surrounded by white antibiotic paste which prevents the disease pathogens from spreading to the healthy part of the coral. – DoE

Warrender told the Cayman Compass that the DoE is “pushing hard for people to disinfect their dive gear after diving/snorkelling anywhere in the Cayman Islands”.
She added that disinfecting stations were being set up at key shore diving spots along the west side of the island.

The DoE and a group of trained volunteers have been administering an antibiotic to infected corals, in a bid to stop the spread of the disease.

Stony coral tissue loss disease first appears as white patches or lesions on brain, star, mountain or other stony corals, which indicates the sections that have died. The amoxicillin antibiotic paste has been found to be 100% effective in stopping the pathogen from spreading to unaffected parts of the coral.

Scientists have identified at least 25 coral species that are susceptible to the highly transmittable disease, which was first identified in Florida in 2014. Since then it has spread to several Caribbean Islands and was found in Cayman in June last year.

Disinfecting equipment

The DoE advises that divers should disinfecting their equipment following their dives to ensure that the pathogen is not unwittingly spready by diving equipment.

The following is specific advice on decontaminating all dive gear.

Non-sensitive equipment: After each dive, soak equipment (weight belts, tools, etc.) for 10 minutes in a 1% bleach solution (1/2 cup bleach per 2 gallons water). Rinse with fresh water; air dry.
Wetsuits, BCDs, mask and fins: After each dive, soak for 10 minutes in one of the following: 0.5% RelyOn (four 5 gram tablets/gallon water), 1% Virkon S (1.3 oz./2 gal. water), 6.6% Lysol (1 qt./gal. water), or an equal concentration of another quaternary ammonium disinfectant. Soak in fresh water for 10 minutes; air dry.
BCD internal bladders: Pour approximately ½ litre of disinfecting solution into the mouthpiece of the exhaust hose while depressing the exhaust button, inflate BCD, and gently rotate in all directions. Allow to sit for 10 minutes. Flush twice with fresh water.
Regulators, computers, gauges, underwater cameras and other sensitive scientific equipment: Soak for 20 minutes in a solution of warm water and antibacterial dish soap or OdoBan (5 oz./gal.). Rinse in fresh water; air dry. Additionally or alternately, thoroughly wipe with isopropyl alcohol.

Dispose of disinfectant solutions and rinse water in a sink, tub or shower. Never pour them into the ocean or a storm drain.

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