[Coral-List] Bleaching Index Methods Available

Tim McClanahan tmcclanahan at wcs.org
Sun Feb 11 01:58:24 EST 2007

Coral listers

An informal group has formed to study bleaching using standardized methods
that are similar to those originally developed by Gleason and further
modified by myself. This message is to inform you that the methods and
spreadsheets that we use are now publicly available and posted in the
following public folder "BleachDiseaseMonitoring", which is available at

The folder contains a powerpoint presentation and some scientific papers
that describe the method we use. Additionally, two spreadsheets where we
enter the data, one that is used for entering bleaching observations in the
Indian and Pacific Oceans and another used in the Caribbean are included. If
you would like to use these methods and spreadsheets to study bleaching than
you can access these tools above.

In 2005 a group of 12 coral reef scientists studied 71 sites in the western
Indian Ocean to test the effectiveness of the satellite measurements to
predict bleaching and to quantify the intensity of bleaching by sites and
taxa. These studies along with my other studies are now in a database that
contains ~38,000 colony observations from 91 sites and 48 taxa. Scientists
that have contributed towards the database are collaborating on various
coral bleaching studies and there is an interest in increasing the
collaboration to include other studies and other parts of the world.

One can join this group of collaborators by contributing their observations
entered into the above spreadsheets and sending them to me. Otherwise, the
methods and spreadsheets are freely available for your own use.

The first results of this large-scale paper are in the following

McClanahan, T. R., M. Ateweberhan, C. R. Sebastian, N. A. J. Graham, S. K.
Wilson, H. Bruggemann, and M. Guillaume. Published online. Predictability of
coral bleaching from synoptic satellite and in situ temperature
observations. Coral Reefs.  DOI : 10.1007/s00338-006-0193-7.

The following press release will be released shortly

US satellite technology need eyes and thermometers to detect climate change
effects on coral reefs
Satellites have revolutionized the way we view the Earth and have produced a
number of scientific but also household applications such as GoogleEarth.
One serious problem with viewing the Earth is that most of it is ocean, and
satellites can generally only view the surface skin of the ocean.
Nonetheless, the signal from this skin has been used to estimate the ocean¹s
temperature and presumably to predict what is happening under the water.
This has a number of useful applications, such as finding places with
unusual warm or cold temperatures, measuring changes in the oceans
temperature over time, and the effect of these changes on the ocean¹s
species and ecosystems. Unusually warm temperatures in the tropics
frequently cause corals living on reefs to lose their symbiotic algae and
color, or bleach. Coral reef scientists see coral bleaching as a sign of
stress that is increasingly being observed in recent years and considered a
harbinger of a warming planet.
The usefulness of satellite technology has resulted in the US National
Oceanographic and Atmospheric Administration to create a coral reef watch
program (http://www.coralreefwatch.noaa.gov/satellite) that is being used to
predict and warn scientists, managers of marine ecosystems, and the general
public about these coral bleaching events. The technology has proved useful
in identifying spots with the worst bleaching but, until a recent study
coordinated by the Wildlife Conservation Society¹s Tim McClanahan and
colleagues working in the western Indian Ocean, it had not been tested using
a scientific design that considered coral reefs with and without unusual
temperatures and the species of corals that are found in these reefs. A
group of 12 scientists working in 8 countries and across 35o of latitude in
the summer of 2005 reported, in an online release in the journal Coral
Reefs, that satellites were only moderately useful for predicting the
bleaching, and that the predictions were considerably improved if satellite
temperatures included thermometers in the water and even more so by the
types of coral species living in the reefs. Differences among coral species
sensitivity to warm water was almost as important as the persistence of the
warm water and the authors suggest that this is likely to be more common in
the future as corals change to accommodate a warming ocean. Consequently,
although the satellites are useful for identifying general areas where the
bleaching is occurring there is a still a need for observations in the

Tim McClanahan, PhD
Senior Conservation Zoologist
Wildlife Conservation Society
Vice President, ISRS

Download my pdf publications at

More information about the Coral-List mailing list