Abstract:Like human being and other animals, corals can also be sick. Over the past 30 years, coral diseases have been widely recognized for their destructive impacts on coral reefs. To date, more than 30 types of coral diseases have been identified, but only 6 types have been determined of their specific pathogens. Here we briefly introduce the symptoms and the rates of spreading, incidencing and mortality of severn main types of scleractinian coral diseases (black-band disease, dark spots disease, white-band disease, white plague, white pox disease, yellow band disease, and bacterial bleaching), and review their influences on coral reef ecology and the relationship between coral diseases and environmental factors. Based on present understanding, the frequent occurrence of coral diseases can reduce coral cover, and which in turn can result in the shift of a coral reef from a coral-dominant community into a fleshy seaweed-dominant one. The factors that cause coral diseases include seawater temperature, pH, nutrition concentration, chemicals, dissolved oxygen concentration, and their combined influences, and the warming of global climate and the increasing of human activities are believed to have triggered the changes of the above environmental factors and the outbreak of coral diseases. It is clearly identified that the elevated seawater temperature is the essential factor in outbreak of bacterial bleaching of coral Oculina patagonica and Pocillopora damicornis. Other factors, such as enriched nutrition, exceeded organic pollutants and the changing of seawater pH values can bring physiological stress to corals, and then reduce the coral′s resistance to diseases. Coral cover, water depth and seawater disolved oxygen concentration are also observed to have influences on coral diseases, with corals at shallow water and high coral cover habitat being easily infected.