A new and significant role for marine reserves on the Great Barrier Reef has been revealed, with researchers finding the reserves reduce the prevalence of coral diseases. It's been known for some time that marine reserves are important for maintaining and enhancing fish stocks, but this is the first time marine reserves have been shown to enhance coral health on the Great Barrier Reef. 

Researchers from the ARC Centre of Excellence for Coral Reef Studies at James Cook University found that coral disease levels were four times lower inside no-take marine reserves, where fishing is banned, compared to outside reserves.

"We surveyed more than 80,000 corals around the Whitsunday Islands for six different diseases that commonly harm reef corals around the world," says study lead author, Dr Joleah Lamb from the Coral CoE.

"We found three coral diseases were more prevalent on reefs outside no-take marine reserves, particularly on reefs with high levels of injured corals and discarded fishing line. "

Wounded corals are more vulnerable to disease. Damaged tissue provides sites where pathogens and parasites can invade, particularly as coral immune responses are lowered while they heal.

Dr Lamb says once a pathogen infects a coral, tissue loss typically spreads from the point of entry.

"It's like getting gangrene on your foot and there is nothing you can do to stop it from affecting your leg and ultimately your whole body."

"Disease outbreaks can take a heavy toll, with losses of up to 95 per cent of coral cover on some reefs in the Caribbean."