The total area of coral reefs

[Mark.Spalding at wcmc.org.uk]

As a result of its ongoing reef mapping work, which, as you may know, is  
linked to the ReefBase database, the World Conservation Monitoring Centre has  
the most comprehensive global digital reef map in the world and one thing  
we're very keen to do is re-calculate the total area of coral reefs in the  
world.  Work is currently underway preparing preliminary figures which should  
be published in a paper on marine biodiversity to be given at the 2nd  
Conference of the Parties for the Convention on Biological Diversity.  It is  
hoped to provide better figures for the Coral Reef Symposium in Panama.   

Interestingly it looks as though the figures being generated may be  
considerably smaller than those given by Smith (1978, total global area -  
600,000 sq km).  If this is indeed the case, it is not entirely surprising  
given the nature of the maps - Smith and others have tended to focus on areas  
of reefal shelf, whereas the source maps used at WCMC are largely based on  
reefs visible from the surface.  I would be very interested to know your  
comments on this, and also to track down any national or even sub-national  
projects which have accurately calculated reef areas.   

Part of this problem is the old one of "what is a coral reef?" and the  
definition may have to vary depending on whether you are interested in reefs  
for fisheries, tourism, productivity, biodiversity conservation or  
calculation of carbon budgets. 

Yours 

Mark D. Spalding                          E-mail: mark.spalding at wcmc.org.uk 

World Conservation Monitoring Centre 
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