In November, Digital Journal
reported that over the past thirty years, nearly half of the Great Barrier Reef has deteriorated and collapsed. Although strong storms were primarily blamed for damaging and killing the corals, agricultural run-off was shown to prevent the coral from regenerating. Researchers had also previously believed that Furry Coral Crabs
were damaging the reef and preventing regeneration, acting in a symbiotic manner with the coral and feeding on the coral itself. The crabs were also thought to cause White Syndrome
, a deadly disease that causes lesions and tissue loss, leaving the exposed skeleton of the coral. Joseph Pollock, with James Cook University’s School of Marine and Tropical Biology and the Australian Institute of Marine Science, said
“Researchers originally speculated that they may actually cause the disease, since diseased colonies have high numbers of crabs and it is known that these crabs can eat coral tissue.”
A new study by Pollock is now showing that the crabs are beneficial to the coral. According to Phys.org
, researchers now believe that the crabs are feeding on the diseased coral and other micro-organisms that thrive on the dying and dead coral tissue. Pollock's research shows the crabs don't kill the disease, but they do significantly slow the disease progression, saying
"It slows it by about three-fold. It could be that these crabs are giving it (the coral) a bit of a chance to stay alive until potentially those water temperatures could come down or the coral could put up a defense to stop the disease progression itself."
Pollock has been studying White Syndrome coral disease at Australia's Lizard Island for approximately two years. During that time, he found that the disease was having a devastating effect on the coral in the Great Barrier Reef, causing the coral's tissue to fall off the skeleton. He compared the effects in human terms by saying
"Imagine your skin and muscle starting to fall off at your fingertips and spreading over the entire body leaving behind only skeleton."
He went on to say that the disease can kill between 2 to 3 meters or coral colonies in just a few month's times.
During his studies at Lizard Island, Pollock found the Furry Coral Crabs were strongly attracted to coral colonies plagued with White Syndrome. When a portion of the reef becomes infected with the disease, these crabs often migrated from a healthy colony to a diseased colony, thus helping to slow the disease progression throughout the reef. Excited by the discovery, he told Dawn.com
“This could be a very interesting feedback mechanism whereby these crabs help to slow coral disease on reefs.”