Frequently Asked Questions

Coral Reefs

What is coral bleaching?
In healthy coral, symbiotic algae (zooxanthellae) live within the coral tissue. Algae provide the coral with food and energy and give the corals their characteristic brown colour. Stressful environmental conditions can cause the coral to expel the algae,
changing the coral colour to white. This whitening of coral is called ‘coral bleaching’. Sometimes corals can recover from bleaching, but if stressful conditions are severe, or persist for a long time, loss of algae and the nutrients they provide can lead
to coral death. Even when corals do recover, they do not always return to full health.
What can coral colour tell us about the reef?
Coral colour, or more specifically brightness and saturation, correlate with chlorophyll content and density of symbiotic algae (zooxanthellae) in coral tissue, providing a measure of coral health. Coral bleaching results from a loss of symbionts or pigmentation from stressed coral.
Why are coral reefs important?
Healthy reefs produce food for millions of people and help to protect coastal land from cyclones and storm surges. Reefs support local economies, providing employment from tourism and fishing industries. It’s our natural habitat and home to many reef animals.
How extensive really is coral bleaching?
There have been 4 global bleaching events (1998, 2002, 2016, 2017) in the last 20 years. 90% of the Great Barrier Reef shows some sort of coral bleaching.
The coral reefs are having bleaching events closer together and are not having time to recover between events.
Isn’t most of the reef already dead? Why should we even try?
The reef is not dead. Some areas have been stressed through increasing temperatures and bleaching has occurred. A white reef does not mean it is dead yet. It still has a chance to come back if the water temperature drops. We need to focus on decreasing ocean temperatures and increasing water quality to allow our corals to get healthy again.
How much can I really do as an individual?
You can choose to do nothing, or you can choose to take small easy steps that will eventually add up. For example, you can: say no to plastic, use biodegradable products, turn off powerpoints, use a bike instead of a car, switch to green energy. There are many things you can do to reduce carbon emissions and save reefs from home (link to factsheets).
What are soft corals?
Soft corals are non-reefbuilding corals, they don’t have a skeleton. If they bleach, they resolve.

CoralWatch Program

What is CoralWatch?
CoralWatch, based at The University of Queensland (UQ), integrates reef monitoring with education about reef science and conservation. CoralWatch developed a simple tool – the Coral Health Chart – that allows volunteers (‘citizen scientists’) to monitor the colour of the reef as an indicator of health.
What does CoralWatch do?
CoralWatch promotes healthy reefs by:

  • Raising public awareness / outreach about importance of reefs, threats to reefs and reef conservation;
  • Developing and distributing reef education materials for diverse audiences;
  • Engaging the global community in monitoring coral health and coral bleaching.
Who is involved with the program?
CoralWatch data gets collected by schools, dive centres, tourists, conservation groups and scientists. The Coral Health Chart is currently used in 79 countries, our biggest data contributor is Utila Dive Center in Honduras. Our member database includes people from 136 countries.
Are there CoralWatch offices all over the world?
Even though CoralWatch is a global monitoring program, we operate from just one office, in Brisbane at The University of Queensland. There are only two people working part-time with Professor Justin Marshall as project leader – so please be patient if we don’t directly respond to your email.
Can I really help monitor reef health?
There are not enough scientists to monitor all the world’s reefs. This is why we need your help! By participating in volunteer monitoring programs, citizen scientists, just like you, can help gather important data that scientists otherwise not have access to. By gathering such data, you have the opportunity to improve the evidence used to make decisions about how our reefs are managed. CoralWatch methods are simple, you don’t have to be a scientist to help science.
How can I learn more about reefs?
The best way to understand the importance and value the beauty of the reef is
through your own experience. If possible, visit the reef today – it’s an memory
you will never forget!
CoralWatch also produces a wide range of education materials for individuals and educators to share the beauty and importance of reefs. These include the ‘Coral
Reefs and Climate Change’ book and DVD, reef education packages and curriculum-linked lesson plans. Order yours today via www.coralwatch.org
How can I support the program?
A donation online will sustain our global network of volunteers and help distribute
reef education materials to communities all around the world. We also offer a wide range of corporate sponsorship packages, providing you with a way to invest in our reefs while also harnessing effective marketing opportunities. Please contact us to further discuss the possibilities.

CoralWatch Methods

What does the Coral Health Chart measure?
The Coral Health Chart consists of a series of coloured areas representing the most common colours on the reef. The brightness of the colours shows a 6-point scale represent different stages of bleaching and recovery, corresponding to varying concentrations of symbiotic algae (zooxanthellae) within coral tissues.
In the field, you simply compare the lightest and the darkest colour within a coral colony with the colours on the chart and record matching codes.
Can I use different sides of the chart when recording lightest and darkest colour scores for a single coral colony?
Yes – you should rotate the chart and find the closest match of colours for a single coral colony. For example, the lightest part of the colony may be “C2” and the darkest part can be “D4”. It is the brightness, or colour number scores, that provide an indication of coral bleaching state. The hues just make it easy for our eyes to make an accurate match.
Why can’t I measure blue corals?
The colour of purple corals is influenced more strongly by coral pigments, not symbionts/(zooxanthellae. The relationship between pigments and temperature is different to that of zooxanthellae) and temperature.
The coral colour I am looking at does not fit the colours on the chart?
It is ok if the colour of the coral you are looking at does not match exactly what is on the chart. Remember, it is the brightness of the coral colour, that indicates the degree of bleaching.
I thought the reef was colourful but it was brown?
Many corals are naturally brown and green (due to the zooxanthellae). Also many photos taken underwater use lighting that can change the appearance of the reef.
Why can’t I measure the tips of corals?
The tips of corals are naturally white, this is where they grow.
I have troubles determining the coral type? What should I do?
Coral type’ is a general morphological key that includes branching, boulder, plate and soft. Due to the dynamic nature of coral morphology some corals do not fit clearly into one category, so please pick the closest form or choose another coral. Our aim is to keep the chart and surveys as simple as possible.
Why can’t I just print out my own Chart?
The Coral Health Chart is printed on a special type of plastic with specific inks and colours that are consistent in all supplied charts. Due to the variation between printers, we supply the charts in hard copy and not electronically. Please do not reproduce the chart as using a copy invalidates the data you worked so hard to collect.
Where can I get a Coral Health Chart?
CoralWatch provides an initial chart for free. Just go here to apply for a chart. If you would like multiple copies, please use the order form in the shop.
What survey method should I use?
The Coral Health Chart can be used while diving, snorkeling or reefwalking.
You can choose a monitoring method that suits your skills, experience and location. Most people use the random survey method.
• Random survey: Ensure the corals you choose 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.
• Transect survey – select corals by following a line (transect) and record your findings every few meters. Make sure that the transect has no affect on marine life.
• Individual corals or permanent transect 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 is also useful to help relocate corals.
Any other CoralWatch monitoring tips?
1. Get to know your reef, monitor over a period of time. Assess at least 20 corals per survey.
2. Due to colour loss at depth, use a torch when diving below 5m/15 feet.
3. Use a GPS if available and record co-ordinates OR select the location using our Data Entry Apps or online data entry form.
4. Don’t forget to record your name, country, name of reef, date and time of survey, depth, water temperature and weather.
5. Corals are fragile animals, avoid touching or stepping on corals.
6. When diving, secure your equipment and make sure you’re properly weighted.

CoralWatch Data

How can I upload my data?
Transfer your survey results to our global database by using the CoralWatch website or our ‘CoralWatch Data Entry’ Apps. (Apple app or Android app)
What happens when I upload my data?
You will receive direct feedback on coral type distribution and reef colour score and if someone else has surveyed the same reef, you can compare colour scores over time. When you interpret these results, always keep in mind that some corals are naturally lighter than others. Your survey is just a snapshot in time. Regular surveys are needed to look at health over time or pick up trends of bleaching and recovery.
My email indicates a bleaching alert? What do I do?
Through a validation analysis that compared 10 years of CoralWatch data to well-established bleaching events, CoralWatch has developed an evidence-based approach classifying our data. Based on analyses, an email alert will be sent when a survey has a 70% likelihood of representing a local bleaching event.
Please take the following actions:
● Conduct additional CoralWatch surveys to confirm if a bleaching event is occurring.
● Spread the word – inspire others to help monitor your reefs (e.g Facebook, Twitter).
● Contact your local reef management group to further investigate.
How is my data used?
All the data collected is available public online and can be used for scientific analysis as well as being valuable in an educational and social context.
Up to date, 5759 Members have collected data from 227245 corals on 1894 Reefs (79 countries) during 10992 Surveys
The data gets collected and is being used by many different groups at various levels of training and involvement and the data from each group is used in different ways. The scale varies from scientific use (see Fabricius 2006) to school projects (fieldwork, reports & DVD’s). Also included are environmental monitoring groups. The system is adaptable and groups are encouraged to design their own protocols to best suit their needs. CoralWatch methods have been in referenced in many papers and reports
What kind of research questions can be answered?
There are many questions that will have to be answered in order to try and save the reefs. This is where you can help! If many people around the world, like you, participate we will be able to answer questions such as:
• Large and small scale patterns of bleaching
Do all reefs bleach during every El Niño event, or are there some reefs or zones of reef that never bleach? Do the same areas bleach every time?
• Duration and severity of coral bleaching
For what period of time are different reefs affected by bleaching events? How severely are different reefs around the world affected? Is the severity and duration dependent on previous bleaching events? Does the overall health of the reef deteriorate from one bleaching event to another?
• Large and small scale patterns of recovery
How long after the drop in water temperature does it take for a coral or reef to recover? Is recovery variable between different reefs and different coral types?
What is the difference between the data collected and reported by untrained volunteers and expert scientific teams?
Statistically speaking, there is no difference in terms of colour scores of data collected by untrained volunteers and the expert scientists. The difference comes in the identification of species, the application of the data (for instance understanding differences in coral location and morphology) and other specific protocols
Is data from around the world standardised and comparable?
Coral health data is comparable depending on the question you are asking. Data from any person can be used to add to our understanding of the trends and changes of the world’s coral reefs. It is possible for volunteer data from reefs in Florida and reefs in Australia to be compared over time and space. This real online data is also valuable as a resource to be used by students for class projects.
What are the known limitations of the data?
It is important to understand the limitations of any data set. Recognised limitations include the knowledge that species may not be well identified and that there may be trends towards collecting more visible corals than cryptic ones. If you have specific questions that you want to answer, you may have to design a particular monitoring protocol or contact other data collecting groups to obtain the information you require.