Silent Killer: What Causes This Stony Coral Tissue Loss Disease That Has Affected Over 20 Species?


A so-called “silent coral killer” is spreading in Caribbean waters and, according to the results of a recent study, it has inflicted around 22 species.

National geography reported that researchers have rushed to prevent stony coral tissue loss disease, which has killed some of the oldest and largest corals in the region.

The infected colonies developed white spots that gradually grew larger, draining the color and life of the animals.

In the most vulnerable species such as brain, pillar and star corals, infected colonies usually die within months or even weeks after infection. Florida-based coral disease specialist William Precht says it’s the worst thing he’s ever seen.

ALSO READ: Why do coral reefs turn white? Science explains

(Photo: G. Mannaerts on Wikimedia Commons)
Stony coral tissue loss disease

Stony coral tissue loss disease

Shortened to SCTLD, the stony coral tissue loss disease was first discovered in corals off Miami in the fall of 2014, the National park service reported. This disease, possibly spread by a microbe or virus, or a combination of the two, has already spread across the Florida coast and much of the northern Caribbean.

It currently exists in at least 20 countries, from Mexico to Honduras to Saint Lucia. Then, in May of this year, corals were infected with the disease in Florida’s Dry Tortugas National Park, a hotspot known for coral diversity.

As mentioned earlier, researchers, including Precht, are now rushing to find out what causes the disease, how it is spread, and how to treat it.

SCTLD may have spread slowly through water currents, but the new study published in Frontiers of marine science suggests that it can also be transmitted by merchant ships in major ports such as the Bahamas.

Essentially, the Caribbean’s corals, which form the basis of their reef ecosystems, are already threatened by warming waters from climate change, nutrient runoff and pollution, making solving the mystery much more difficult.

How SCTLD is spread and can be avoided

The emergence of SCTLD elsewhere has often been equally brutal, if not devastating. As of 2019, the disease had not yet appeared in the Bahamas, in part because the prevailing ocean current is moving north to the Florida coast.

That same year, in October, Craig Dahlgren, a marine ecologist, and his colleagues investigated about 60 miles of reef and found “no diseased corals.”

However, a month later, the team learned that the team was receiving reports that corals near Freeport had an infection identified, which later turned out to be the so-called “silent killer” disease.

Then, in another in-depth investigation in May last year, Dahlgren, with the Perry Institute of

Marine Science again examined over 60 miles of reefs and found infected corals at each site, especially brain and pillar corals. Within months, the vast majority of infected colonies were dead.

Dahlgren explained that to prevent the disease from spreading between islands, ships need to be more careful about how and when they exchange ballast water and avoid releasing it near ports and Coral reefs, which are described in a separate National Geographic report.

A related report on the hard coral tissue loss disease is featured on the Perry Institute for Marine Science YouTube video below:

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Find more news and information about coral reefs in Science Times.


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