The Florida Reef in the United States is threatened by a rapidly spreading disease that has a mortality rate of 66 to 100 percent. The disease has already begun its spread outside the US.
The first case of stony coral tissue loss disease, abbreviated as SCTLD, was observed in 2014 around Miami, Florida. Ever since, the disease has rapidly spread, reaching Mexico and the Caribbeans.
The disease has had the greatest impact on the Florida Reef Tract, the only coral reef of the continental United States. The reef begins at St. Lucie Inlet in Martin County, and extends for approximately 563 kilometres (350 miles) to the Dry Tortugas National Park.
Effects of SCTLD are visible from the outside. Corals with the disease show spots that turn white. This is because of tissue loss that occurs at one or several points on the corals. Tissue loss appears as lesions that lay bare the corals’ white skeleton.
The disease spreads fast and gradually kills the corals and colonies that contact it. Its mortality rate was reported as 66 to 100 percent, and it has been referred to as the deadliest known coral disease.
SCTLD has been observed throughout the Florida Reef and has affected over twenty coral species. Its exact cause is unknown, but scientists hypothesise that the origin is a bacterium or a virus.
The disease has also been associated with ballast water from ships, some claiming that the disease spreads farther than it naturally could have by being carried in the ballast tanks of ships.
A possible spread toward the Pacific Ocean is also a point of concern. Pacific coral reefs are actually home to more stony coral species than those in the Atlantic and Caribbean.
The threat is not just for stony corals. These corals are also known as “reef-building corals,” a rather fitting name as they indeed create coral reefs. They are the building blocks of some of the world’s most diverse ecosystems.
The Florida Reef Tract alone, with over forty stony coral species, is home to millions of marine life. With the stony corals at stake, the whole ecosystem could shift for the worst. This, in turn, would have wide-ranging consequences worldwide.
Aside from the impacts on marine life, Florida residents have already begun facing the SCTLD’s adverse effects on businesses that rely on tourism according to AFP.
Scientists at the Orlando-based Florida Coral Rescue Center have been striving to save some of the stoney coral species in the area before they go extinct. They have removed over seven hundred healthy corals of eighteen species from the Florida Reef Tract to protect them in a controlled environment.
In a lab, the corals are placed in saltwater tanks where their original habitats were duplicated. Over the tanks are lamps that compensate for sunlight, and scientists have created artificial currents within the tanks. There are even local fish species in the water.
"If they were still in the wild, up to 90 percent of them would have been dead," said the lab’s director Justin Zimmerman in an interview with AFP.
Scientists have also been trying to improve the genetic makeup of the corals to make them more resilient to SCTLD, as well as other environmental threats including pollution and increasing water temperatures.
They are hoping that the corals will be returned to the Florida Reef Tract in the future, though it is not likely to happen anytime soon since corals take time to reproduce.
The results of the efforts in this lab could determine the fate of the Florida Reef Tract and other coral reefs where the stony coral tissue loss disease has spread.