Example of a Coral Health ChartCoral Health Chart

The colour charts are based on the actual colours of bleached and healthy corals. Each colour square corresponds to a concentration of symbionts contained in the coral tissue. The concentration of symbionts is directly linked to the health of the coral. All you have to do is match the colour of the coral with one of the colours in the coral health monitoring chart. You then record the matching colour codes, along with coral type (species if possible), on the website data sheet.



How to use the Coral Health Chart

  1. Choose a random coral.
  2. Look down at the coral and select the lightest area, avoiding the tips of branching corals.
  3. Hold the colour chart next to the selected area.
  4. Rotate chart until you find the closest colour match.
  5. Record the matching colour code along with coral type on the data sheet.
  6. Repeat steps 2 to 5 for the darkest area of the coral.
  7. Continue survey with other corals.
  8. When you finish, transcribe your collected data to the website data sheet & submit.

The hues on the chart represent the most common coloured corals, and help our eyes to make an accurate match. The brightness of the colours ranging from 1 to 6 are the same on every side of the chart.

Coral types

Classifying corals at the species level is very difficult, so easily identified groups are often used when recording data about coral cover or general coral health. For this purpose, coral types are described simply by the basic growth forms or shapes of coral colonies.



Branching Coral




Plate Coral



Boulder Coral



Soft Coral

The Coral Health Chart uses four coral types to classify corals. 'Branching' refers to any branching coral such as Acropora species. 'Boulder' refers to any massive or rounded corals such as some Platygyra and Porites species. 'Plate' refers to any coral that forms a plate-like formation such as tabular Acropora species, and the 'soft' category refers to corals lacking a hard skeleton, such as the Xenia species.
Due to the dynamic nature of coral morphology, these categories are not strict, as there are many forms that do not fit into one of these categories. Our aim is to keep the chart and survey as simple as possible, so if you’re experiencing difficulties when classifying your corals, please simply choose the closest coral type.

Monitoring activity

Walking or snorkelling; studying species at the surface

If snorkelling or walking alongside the coral, ensure all movements avoid contact with live coral. The Chart may be used with any living coral, remembering to avoid blue-purple varieties.

Using the Chart while reef walking

Diving: Determining symbiont density at depth

If the chart is being used for SCUBA surveys below five meters (15 feet) please use a flashlight or torch to illuminate both the chart and coral. Illumination is necessary to counter-act the changing spectral properties of water with depth. Be an AWARE diver. Be sure to secure your equipment, be properly weighted, maintain neutral buoyancy and move slowly through the water. Dive carefully to avoid any contact with the reef as reefs are extremely fragile to even the slightest touch.

Using the Chart while diving


Tips for using the Chart

  1. Get to know your reef. Fix a baseline for your area or species and monitor over a period of time. Assess at least 20 corals per trip (100+ corals are better).
  2. Use the Chart as a data collection tool to best suit your needs. We would suggest two survey techniques (to be used depending on experience & location):
  • Reef Fingerprint: Select corals randomly or along a transect. If you choose random corals, ensure they are truly random and not a collection of bleached corals. For example, take three steps or fin kicks and measure the coral closest to you. This is useful for a once-off visit to a reef or if you are not returning to exactly the same site or corals each time.
  • Individual Corals: Select a certain number of corals and monitor these specific individuals over time. Corals can be labelled or tagged using materials such as cattle tags and cable-ties but you must check with your local managing authority, regarding permits, before undertaking any tagging. A marked map or GPS device should be used to help re-locate corals.
3. The reaction of corals to various stressors may be influenced by coral type, species and/or depth and location. To address these potential differences you can:
  • Select multiple types (i.e. equal ratios of branching, boulder, plate and/or soft corals) to provide a more detailed picture of reef health.
  • Select particular species for assessment and comparison within set areas.
  • Conduct a depth comparison at, say, 3, 6 & 9 metres. Remember, a torch must be used below 5 metres (15 feet) to illuminate the Chart and corals.

Suit your own needs

There is no strict protocol that you must follow when using the Coral Health Chart. We encourage you to develop your own methodology and incorporate the Chart to suit your needs, be it research, education, or mere curiosity. Use the Chart to measure coral bleaching while on a relaxing dive, to regularly monitor corals along permanent transects for a science project, or simply to assess the current status of your local reef. Please let us know what you are doing with the Charts! Please remember to enter your data onto the website. Alternatively please email or post it to us and we will enter it on your behalf.
Your analysis will be enhanced if you're able to collect data all year-round and hence determine a baseline for your reef.

Data collection is easy and can be done by anyone!