Diseases are devastating coral reefs around the world and local and regional scientists are searching frantically for cures and preventative measures before reefs disappear and the fish disappear along with them.
Erin Muller of the Mote Marine Laboratory in Florida told an audience last week at the National Park Services’ Guinea Company Warehouse in Christiansted that 80 percent of the coral reefs from Florida to the southern Caribbean have been wiped out since the 1970s.
Reefs are important because they absorb wave energy before it reaches land, produce medical components to fight disease, feed one billion people and produce over $96 million a year in tourism dollars.
Also in the 70s, coral diseases appeared, caused by biological stressors such as bacteria, fungi and viruses and non-biological stresses, such as sea surface temperature, ultraviolet radiation and pollution, according to NOAA. First was black coral disease, then others including white-band, red-band and yellow-blotch.
“You don’t see a reef dominated by healthy coral anymore,” Muller said. “Over the last 50 years or so, especially in the Virgin Islands, disease has affected the way reefs look.”
Now there’s a new deadly infection that showed up in Florida in 2013 and spread up and down the east coast of the state by 2019. The Stony Coral Tissue Loss Disease affects at least 20 species, but not elk horn or stag horn corals. The “incredibly devastating disease” spreads quickly and “melts” the living tissues off the skeleton, Muller said. The disease is difficult to contain and seems to be transmitted through water and direct contact. She thinks it is a pathogen. Fortunately, it does not affect humans.
SCTLD was discovered on the south shore of St. Thomas in January 2019. Now it has spread around the entire south shore and wrapped around the northwest side of the island and recently crept east to Hull Bay. Magens Bay and Hans Lollick so far have not been affected. The disease has been found north of Cruz Bay and Gallows Point in just the last few weeks.
“It’s very widespread in St. Thomas and there are reports of it in St. John,” said Kitty Edwards, educational outreach coordinator for V.I. Coastal Zone Management.
So far, Buck Island National Park has been spared. The suspected pathogen is thought to be spread by water and direct contact. St. Thomas waters may have been infected by ballast from a ship carrying yachts from Florida shortly before the disease was observed in the area, according to Marilyn Brandt, research assistant professor of marine service at the University of the Virgin Islands.
“As of right now, St. Croix is unimpacted by the disease, but coral bleaching and other diseases are flaring up,” she said.
The Virgin Islands coral cover has been reduced from 30 percent to seven percent in a little over a year and there are no signs of surviving pillar coral, Brandt said. Coral cover is the amount of the reef’s sea floor that is populated by live corals.
Brandt works on St. Thomas with a team of University employees – graduate student scuba divers trained to treat the stony disease coral. She said there is no known prevention so the team of around 20 is trying to treat the affected corals as soon as they’re discovered.
Currently, the team is working on the infected coral found recently at Hull Bay. The treatment is an antibiotic paste applied to the affected areas. The paste is expensive and staff needs to be paid during a dive, Brandt said. Fortunately, so far dive boats have donated the use of their vessels.
Brandt estimates it is about $800 a day to combat the coral diseases and there is no funding earmarked for it. Grants have been applied for but not yet received.
“We can’t keep up with it – we really need personnel,” she said.
Another treatment the UVI team uses is “culling,” or amputating small, sick plants. The coral is treated at UVI and if the skeletons are unaffected, they will attempt to re-skin/clone the coral and put it back in the sea after the disease subsides.
“Trenching” is another way to contain an infection, but because it is labor intensive and not as effective as antibiotics, it is currently not being used by the UVI team, Brandt said.
“Like Florida, we have a lot of stressors and corals haven’t been doing well,” Edwards said. She cited stressors such as pollution, runoff, climate change, bleaching, plastic garbage and damage from anchors.
Muller and the National Park Service are working together on a two-year project to test strategies for reducing the spread and severity of coral disease.
The Mote researchers explored Buck Island Reef for more than a week to evaluate the status of the reef areas. They treated infected coral by trenching, injections of hydrogen peroxide and amputation.
When they return to the Mote, the researchers hope to discover some preventatives before there is a catastrophic event. Healthy corals are better able to deal with the effects of a hurricane or earthquake than diseased. One plan is to try to develop disease resistant clones and another is to investigate using probiotics.
Brandt said that although trained technicians are needed to treat the coral, the public can be a big help and alert CZM when they spot diseased coral while snorkeling or diving. Volunteers are also conducting in-water surveys.
Report suspicious corals and locations to the Department of Planning and Natural Resources.
“We want volunteers to report signs of disease, but we want trained personnel to apply paste who have seen it and worked with it,” Brandt said.
Swimmers, divers and snorkelers should not touch coral and boats should not drop anchors on reefs, Brandt said.