For the first time a study has shown that marine reserves enhance coral health on the Great Barrier Reef. On average the reserves had a 1-percent level of coral disease, compared to 5 percent on average outside the reserves, and even up to 9 percent in certain areas. Coral tissue damaged by discarded fishing line and other fishing-related activities is more vulnerable to disease, researchers explain, as exposed coral skeleton provides an entry point for pathogens to infect, leading to spreading tissue loss.