Dead coral in the Strait of Florida near Key Largo showing signs of stony coral tissue loss disease. A similar disease, known as white plague, was identified in the 1970s, but SCTLD first appeared near Miami in 2014. It has since spread south along the Florida Keys and is now found across the Caribbean Sea, nearly reaching South America. It is highly contagious and kills coral tissue, leaving a bare white limestone skeleton behind
A snorkeller swims over dead coral on the seabed in the strait of Florida near Key Largo. Initially thought to be caused by bacteria, some research suggests viruses are to blame. The disease has an unusually high mortality rate among the 30 or so coral species most susceptible to it. Since 2014, SCTLD has caused mass die-offs in nearly half of stony coral species in Florida
In efforts to protect the corals from extinction, scientists are recreating the reef habitat found in southern Florida to find disease- and climate-resistant corals, preserving diversity by creating gene banks and propagating corals to help restore degraded reefs. SCTLD hampers coral growth and reproduction. Genome sequencing is being used to find the cause of the disease
A jellyfish swims over dead coral near Key Largo. Many factors are believed to be contributing to the problem, including rising sea temperatures, pollution and nitrogen runoff from fertilisers, but recent research has identified ballast or waste water from ships as a key factor. Stony corals form the base of coral reefs, which in turn support a quarter of all marine life
A shark swims by a couple in the sea off Islamorada, in the Florida Keys. There are fears that the poor health of the corals will hit tourism in the area. Visits to the barrier reef off south-east Florida for fishing and diving generate $6.4bn (GBP4.7bn) in local sales and income, according to the US National Oceanic and Atmospheric Administration
Beneficial algae that live in coral tissue and give them their colour are the first to die, then coral cells rupture, disintegrate and die. Biologists are now taking healthy corals from affected reefs and caring for them in saltwater tanks at 22 different sites, including the Florida Coral Rescue Center in Orlando
Aaron Gavin, a marine biologist at SeaWorld, uses a pipette to feed shrimp to some of more than 700 corals, from 18 species, living in the laboratory tanks. They are also treated with antibiotics, in the hope of later returning them to the sea
Researchers are working to understand the genetics of the rescued creatures, in an effort to cultivate robust coral with greater resistance to the disease, as well as other threats such as warming water temperatures. However, SCTLD spreads very fast – a 2019 study found that the entire Mexican Caribbean was hit by the disease within a few months
A gigantic 300-year-old coral off Fort Lauderdale, known as ‘Big Mama’, succumbed to SCTLD in just four months. As the disease swept south along Florida’s reef, biologists collected 410 corals from the Dry Tortugas national park for transfer to aquaria to prevent them becoming infected before SCLTD reached the western end of the Florida Keys
