Scientists are racing to pin down a new coral disease that’s “annihilating” whole species from Caribbean reefs.
Last January, divers were studying Caribbean reefs off the U.S. Virgin Islands. Suddenly, they noticed something alarming on one reef. Lesions were eating into the colorful tissues of hundreds of corals. By the next day, some were dead. Only stark white skeletons remained. Others took two weeks to die. Within four months, more than half of the reef near the island of St. Thomas was dead.
The prime suspect is a disease first discovered off Florida in 2014. Known as stony coral tissue loss disease, scientists have nicknamed it “skittle-D” — like the candy. But skittle-D is far from sweet. It is responsible for one of the deadliest coral disease outbreaks on record.
Stony corals are the building blocks of reefs. Skittle-D is now ravaging one third of the Caribbean’s 65 stony coral species. Scientists don’t know if the infection is due to a virus, bacterium or some mix of microbes.
Whatever the cause, “it’s annihilating whole species,” says coral ecologist Marilyn Brandt. She works at the St. Thomas campus of the University of the Virgin Islands. There, she heads a science team investigating the outbreak from many angles.
Other coral diseases near St. Thomas have cut coral cover by up to half within a year, she notes. But this new epidemic has done the same damage in half that time. It is spreading faster and killing more corals than any past outbreaks here.
“It marches along the reef and rarely leaves corals behind,” Brandt says. “We’re pretty scared.”
Stony coral tissue loss disease, nicknamed skittle-D, can kill corals in just days or weeks. Here, a lesion eats away at a large brain coral over six weeks. CREDIT: Sonora Meiling
