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Using the tool

To use the tool, start by selecting the particular region you are working in, or one of the diseases listed on the right side. You can also get more information on the terminology used to describe diseases by clicking on the diagnostic features button.

What region is the coral in?
Diagnostic critera

About the tool

The GCDD Coral Disease Identification Tool for the IndoPacific and Red Sea uses standardized nomenclature and diagnostic criteria for coral diseases and other causes of coral mortality developed through a joint effort of the Coral Disease and Health Consortium (CDHC), the World Bank Coral Disease working group and numerous partners and coral disease experts. The identification of coral diseases involves a three-tiered approach to naming diseases based on field signs, identifying the causative agents, and making an etiologic diagnosis. Through application of a series of steps, a researcher can determine a common field name for a disease which reflects gross visible signs and does not require collection of the coral, or laboratory analysis involving microbiological or molecular studies. Once a common field name is identified, the nomenclature can be further refined based on a morphologic diagnosis and an etiologic diagnosis. This approach is based on techniques applied to the study of other terrestrial and marine animal diseases based on the following steps:

  1. Detection of disease through routine monitoring or random observation
  2. Description of the morphologic changes in the host associated with the disease
  3. Evaluation of morphologic changes in the host as disease progresses (e.g., pathogenesis)
  4. Determining the cause (e.g., etiology), and physiologic changes in the host as the disease progresses (e.g., pathophysiology).

This tool only assists with step 1 and 2 and allows a diver to complete a level 1 diagnosis.

Level I

Categorization of obvious gross field signs directly visible to the diver without magnification or sampling. The first step involves the identification of four easily observed descriptive categories that indicate a change in health – presence of color change, recent tissue loss, skeletal damage, and abnormal growth. By recording other gross visible signs such as the location and distribution of the lesion, condition of the affected tissue, and the extent of tissue loss it is easier to determine a common field name to describe the disease in the particular coral, and apply the same terminology to other corals (regardless of species) with similar gross visible signs. It also allows for the comparison of disease occurrence, prevalence, severity or impacts among locations or by different observers in the same or different location. This approach is used primarily for rapid assessment and routine monitoring.

Level II

Detailed examination of affected and unaffected tissue taken from the diseased coral (and compared to representative presumed healthy corals) using microscopy and histology. This approach can help identify the presence of microorganisms and describe morphological changes to the tissue. This could result in a morphologic diagnosis. The tool provided here DOES NOT allow a level II analysis.

Level III

A detailed set of field and laboratory tests to identify and confirm the presence of proposed causative agent (s), toxin, or other factor responsible for the manifestation of the disease. Microbial diseases may be determined according to Koch’s postulate – where a presumed pathogen is isolated, grown in pure culture, identified, and used to infect a presumably healthy host. If the disease signs appear, and the presence of the presumed pathogen is confirmed, and an etiologic diagnosis can be assigned. The tool provided here DOES NOT allow a level III analysis.