The database contains data obtained from 155 separate sources which provide details of direct observations of coral disease in the field: 98 are articles from peer reviewed journals or conference proceedings; 8 are postings on the electronic coral discussion list, provided by the USA Department of Commerce National Oceanic and Atmospheric; 7 are articles published on the internet; 9 are non-reviewed conference proceedings or abstracts; 2 are popular magazine articles. Personal communications of coral disease or unpublished data, 34 in total, were included if referenced in a peer reviewed publication.

The Global Coral Disease Database was created at UNEP-WCMC and populated with records of coral disease from these sources. The occurrence of a disease on a coral species (or genus) was recorded for each location and date on which it was observed. A unique combination of coral species, disease, date and location therefore constitutes a single record. There are more than 2000 such records.

• In cases where the authors quantitatively assessed the incidence of the disease this was recorded as the percentage of colonies affected or number of affected colonies per m².
• In cases where the authors quantitatively assessed the mortality arising from disease this too was recorded as the percentage of dead colonies or number of dead colonies per m².
• In cases where the authors did not quantitatively assess incidence or mortality these have been given the non-value of 999.

The etiology of biotic diseases has been concisely reviewed by Richardson (1998). She emphasises that the procedure by which a presumed disease pathogen is demonstrated to be the causative agent, Koch’s postulates, has not been fulfilled for most coral diseases so that they should be regarded as potential disease states rather than true diseases. This applies to all diseases except aspergillosis and white plague type II.

Other authors conclude that a disease may be abiotic as well as biotic, and in the case of abiotic diseases the cause could be an environmental stressor and not a micro-organism (Santavy and Peters, 1997; Peters, 1997). Coral bleaching is widely believed to be caused by a combination of elevated water temperatures and ultra-violet radiation. In this sense bleaching is an abiotic disease because it is not usually caused by a pathogen (although a bacterium has been shown to cause bleaching in Oculina patagonica, a Mediterranean species, see Torren et al. 1998). The Global Coral Disease Database does not include records of coral bleaching.

The confusion which has been created by the many reports of new diseases during the 1990s is well known. The variety of similar names for different diseases and the uncertainty that what is being described is actually a disease contributes further to this situation. Indeed the Global Coral Disease Database contains a total of 29 differently named diseases which have been recorded in the literature. The proper names for some diseases is very controversial in some cases. Records in the Global Coral Disease Database include just the name originally given by the authors. A reference is provided for readers wishing to judge the appropriateness of any name for themselves.

Unfortunately UNEP-WCMC cannot provide copies of papers which are referenced in the Global Coral Database. People wishing to obtain copies should do so through their library service.