Use the photos below to help identify common coral diseases underwater. How healthy are the coral reefs that you dive?
5. WHITE POX DISEASE
Appearance: White pox disease can be identified by distinctive circles or patches of white, as opposed to the bands characteristic of the previous coral diseases. The bare patches are areas where the coral flesh has been consumed and the naked coral skeleton is visible.
Cause: The cause of white pox disease has yet to be definitively identified. However, a bacteria is thought to cause the disease.
Speed of infection: White pox disease consumes coral tissue at a very fast rate. Entire coral colonies can be consumed in only a few days.
Regions/Species Affected: White pox disease infects Elkhorn coral in the Caribbean and in the Florida Keys.
6. DARK SPOT DISEASE
Appearance: Dark spot disease may be identified by characteristic purple, brown, or gray patches. The disease begins at a central point and radiates outwards, consuming coral tissue as it spreads. The center of each infected patch is typically dead, with the exposed coral skeleton colonized by algae. Infected, living polyps may appear irregular in shape and/or size compared to healthy polyps.
Cause: The cause of dark spot disease has not yet been determined. The disease has been observed in the Caribbean and Western Atlantic since the late 1990's but has not been extensively studied.
Regions/Species Affected: Dark spot disease is widespread in the Caribbean and the Florida Keys. The disease is commonly observed in starlet corals, blushing star corals, and boulder star coral complexes. Dark spot disease may also be observed in massive, reef building corals in the Western Atlantic, such as brain corals and boulder star corals.
7. YELLOW BLOTCH DISEASE (YBD)
Appearance: Yellow blotch disease can be identified by pale, yellowish blotches surrounded by healthy coral. As in dark spot disease, the center of each infected patch is usually dead and colonized by algae. The size of the dead center will increase as the disease spreads outwards across the coral colony.
Cause: The cause of yellow blotch disease is still unknown.
Speed of infection: Yellow blotch disease moves across coral colonies at a rate of approximately 5 - 10 cm a year.
Regions/Species Affected: Star corals and the boulder brain coral throughout the Caribbean are affected by yellow blotch disease.
8. ASPERGILLOSIS DISEASE
Appearance: Aspergillosis disease infects sea fans and sea whips. The disease can be identified by tissue loss and the exposure of the coral skeleton. Round purple areas known as galls are commonly observed on corals infected with aspergillosis disease. These galls are used to isolate the infection from the healthy coral.
Cause: Aspergillosis disease is caused by a fungus Aspergillosis sydowii. The fungus is normally found in soil, but the spores will germinate on soft corals if the fungus falls into the water. The spores travel from Africa on dust particles. Scientists have discovered that the Caribbean receives up to one billion tons of dust from the Sahara annually.
Regions/Species Affected: Aspergillosis disease affects soft corals in the Caribbean, including species of sea fans and sea whips.
Identifying Coral Diseases Is Just the Beginning
Coral diseases affect reefs around the world. In combination with pollution, warming seas, diver impact, invasive species, hurricanes, and other threats, coral diseases are becoming more widespread. Divers can identify coral diseases using visual cues such as the shape of the infection (round, patchy, or band-like), the color of the infected polyps, and the species of the afflicted coral. Learning to identify coral diseases is interesting in its own right, but more importantly, it is an important step in working for the recovery of coral reefs. The more scientists know about the prevalence and severity of coral diseases, the more they can do to stop their spread. Keep readingWhat Causes Coral Diseases? | Common Coral Diseases 1 - 4 | Combat the spread of coral diseases