Project Details
During the early months of 1998, 2002 & 2004 many corals on the Great Barrier Reef,
Australia and many other reefs in the world changed their colouration from brown
to a brilliant white, purple or green. This ‘whitening’ of the coral is called coral
bleaching and is due to a loss of the symbiontic dinoflagellates (algae) living
within the tissue of the coral. In a healthy coral the algae supply the coral with
energy (sugars and amino acids) and in turn receive products essential to their
survival (ammonia and phosphate).
Reef flat of Heron Island, Australia in March 2001 (top) and March 2002 (bottom)
showing the extent of the bleaching in 2002 (white areas).
Simply match the colour of the coral with a colour on the CoralWatch chart. This
healthy brain coral is dark brown and has a colour score of E6.
During a bleaching event the brownish algae disappear from the tissue of the corals
leading to the observed colour change. This loss of the ‘nutrient factory’ in corals
may lead to death of the coral or the coral may slowly recover. The mass coral bleaching
event of 1998 is considered to be the most severe on record and about one-sixth
of the world’s coral colonies died!
Many stressful environmental conditions can lead to bleaching, however, elevated
water temperatures due to global warming have been found to be the major cause of
the massive bleaching events observed in recent years. As the sea temperatures cool
during winter, corals that have not starved may overcome a bleaching event and recover
their symbionts.
However, even if they survive, their reproductive capacity is reduced leading to
long-term damage to reef systems. Sea temperatures are predicted to continue to
rise and thus bleaching is expected to occur more and more frequently leading to
the death of large areas of coral reefs worldwide within a few decades!
At the University of Queensland, Australia we have recently developed a method of
coral health monitoring which uses simple colour charts, like paint colour matching
charts. This is a result of the unusual union between world leading vision and colour
experts at VTHRC (Vision, Touch and Hearing Research Centre) and world leading coral
experts at CMS (Centre for Marine Studies).
Current attempts to monitor coral bleaching often involve costly satellite-born
technologies, are restricted to locations researcher are working in and often require
sampling of live tissue for physiological analysis. Our coral reef monitoring approach
using colour charts is the first attempt to provide useful data on a relatively
large scale with the help of an inexpensive, ‘user friendly’ and non-invasive device.
The colour charts can be used by anyone, scientists, school children, tourists and
politicians. Importantly, the opportunity for everyone to participate in a global
reef-monitoring project removes the sense of hopelessness felt by many in the face
of outcomes predicted from global warming. With this monitoring program we also
aim to educate the public about coral bleaching and its devastating effect on coral
reefs.
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 (www.coralwatch.org).
The tips of this coral have lost most of their symbionts leading to a colour change
from the healthy brown (as seen between the branches) to purple and white. The Chart
cannot be used to assess purple or blue corals because of the colouration is due
to coral pigments, rather than symbionts, and the relationship between pigments
and temperature is different to that between symbionts and temperature.
Very little is known about trends of coral bleaching on a global scale. Currently
coral health monitoring mainly occurs around a few reefs that are regularly visited
by scientists. 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 in the monitoring program we will be able to answer questions
such as:
Large and small-scale pattern of coral bleaching
Based on water temperature measurements and knowledge of currents, it is possible
to predict which areas will be affected by bleaching. We hope to answer several
questions within this. Do all reefs bleach during every El Niño event, or are there
some reefs/zones of reef that never bleach? Does the same reef bleach every time?
Duration and severity of coral bleaching
How long are different reefs affected by bleaching events? How severely are different
reefs around the world affected? Is the severity and duration dependent on whether
or not a reef has bleached before? Does the overall health of the reef get worse
from one bleaching event to another?
Large - and small-scale pattern of recovery
To date most research has concentrated on the onset of bleaching rather than recovery.
With your help it will be possible to measure recovery - how long after the drop
in water temperature do different reefs recover? How long does recovery take? Is
it variable between different reefs and different coral types?
The lightest and the darkest score are recorded to allow for natural colour variation
accross the coral. The avarage score is used during the website analysis.
The website also helps you to produce graphical results like that shown to the right.
This graph highlights the different colour scores obtained for unhealthy, bleached
colours (1-3) and healthy, brown-coloured corals after recovery (2-6).
All submitted data will be analysed and made available on the project’s website.
With your help, data will be available for different regions of the world. This
will make it possible to compare the condition of many different reefs at any one
point in time, as well as the condition of a single reef over time.
With the help of the coral charts anyone in the world can monitor the health of
their local reef, or any that they visit.
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.
Other events that lead to bleaching
With your help it will be possible to monitor coral health throughout the year,
not just during bleaching events. It is important to measure the small natural fluctuations
in the coloration of healthy corals, which do happen seasonally, so that we can
immediately identify if there is a colour change outside the normal range. In this
way it will be possible to find out if there are other factors that may influence
coral health throughout the year.
The results from this project will be both supported by and provide information
for a parallel project, which will use the complex technologies of remote sensing,
vision biology and coral health through physiology website: http://www.vthrc.uq.edu.au/ecovis
follow the links to ‘Prawns in Space’.
There is no strong protocol that you must follow when using the Coral Health Charts.
We encourage you to develop your own methodology and incorporate the Charts to suit
your needs - be it research, education, or mere curiosity. Use the Charts 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!
Groups using the Charts include:
Ocean Corporation Limited is incorporating the Coral Health Charts into their Reef
Check surveys to determine and monitor the status of corals in Hong Kong. Additionally,
they are using the charts to monitor the health of coral areas currently being impacted
by nearby marine works such as dredging. Preliminary results suggest that temporal
monitoring of tagged colonies is very good for detecting small shifts in coral health
and may be useful in calculating sustainable ‘rates of work’ and subsequent ‘rest
periods’ required for recovery. Recommendations based on research using the Chart
have been submitted with the Hong Kong government.
Numerous Reef Check groups, operating in countries such as Vanuatu, Malaysia and
Australia, are incorporating the Charts into their regular surveys to provide an
additional layer of information that will help monitor reef condition.
Voyages' Heron Island Resort, Great Barrier Reef, Australia, has supported the CoralWatch
program since it’s conception. They have raised the project’s profile by including
the Charts in their popular educational reef walks and encouraging guests to donate
a little of their holiday time to monitor coral bleaching. Coral bleaching is often
the first topic of query by many visitors, and the Coral Health Chart provides a
simple, practical and effective answer to the common question “What can I do to
help?”
After 12 months of collaborative development between the University of Queensland
and local marine educators, the Reef Education Package is now available for order.
The Package includes:
- Class set (30) of Coral Health Charts
- A Guide to Using the Coral Health Chart
- A 22-page document outlining how you can use the charts in a ‘classroom’ setting
- CD containing the Guide (for editing and printing as required), Reef Fingerprint©
and Reef Transect© Microsoft Excel spreadsheets for data analysis, Virtual Reef
and Virtual Lab
- Virtual Transect poster (140 x 60cm)
- Hard copy of all images in the Virtual Reef and Virtual Lab
- Sample dive/snorkel data slate
Siebeck, UE., Marshall, NJ., Kluter, A. & Hoegh-Guldberg, O. in prep. Fine scale
monitoring of coral bleaching using a reference card.
Hoegh-Guldberg, O. 1999: Climate change, coral bleaching and the future of the world’s
coral reefs. Marine and Freshwater Research 50: 839-866.
Authors: Justin Marshall1, Ulrike Siebeck1, Ove Hoegh-Guldberg2, Kylie Jennings3,
Kylie McPherson1 & Ian Leiper1 1VTHRC, 2CMS and 3Heron Island Research Station,
University of Queensland, Australia
Contact: info@CoralWatch.org
Visit: www.CoralWatch.org