More on reef area

Bob Buddemeier bob_buddemeier at
Sun Feb 16 16:05:01 EST 1997

Some comments on the reef area issue:

1.  From the standpoint of new data, project Reefbase and John McManus
(J.McManus at are the obvious contacts.

2.  As part of her work on modeling reef area, Joanie Kleypas
(kleypas at has reviewed the various reef area estimates -- there
are at least a half-dozen, ranging from 100,000 to 2-4,000,000 km2 (which
makes the Smith '78 value right about in the middle).

3.  Estimates of reef area will necessarily depend on scale, definition, and
desired application --- so,
     a.  All of the above numbers are probably right -- if you want the area
dominated by live coral and coralline alage it is somewhere in the low end of
the range, but if you want all reef-derived sedimentary structures and/or
communities containing some reef organisms, it's the higher extreme.
     b.  The Reefbase project is producing estimates that are arguably more
accurate and precise -- for the definitions and criteria they use.  That
won't make their numbers noticeably better for other purposes, although it
will probably improve the basis for other estimates.

4.  There is no one-size-fits-all "best" number --each researcher is going to
have to interpret the available data from the standpoint of his/her needs and
applications and justify an appropriate value.  What we can say is that
values for various definitions have been estimated with a probable accuracy
of better than an order of magnitude, but (my opinion here) getting below a
factor of 2-3 in the possible range is not very likely at the global scale.

This is the same conceptual problem as in previous questions about nutrient
tolerances, temperature thresholds etc. -- corals and reef communities are
both very heterogeneous classifications, so any generalizations have to be
accepted as fairly sloppy.

R. W. Buddemeier 

To: 'coral-list at'
From: Tim Adams on Sat, Feb 15, 1997 1:39
Subject: RE: info request: global coral reef coverage
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From: Tim Adams <TJA at>
To: "'coral-list at'" <coral-list at>
Subject: RE: info request: global coral reef coverage
Date: Sat, 15 Feb 1997 16:08:00 +1100
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The $1,000,000 question!

Has anyone actually yet published any information to update Smith's
estimate in 1978 (Nature 273: 225-6)? Has anyone even defined what
"coral reef coverage" actually means? (dead structural coral is almost
as important as live coral in providing fish habitat, for instance)

It is a little difficult to develop national policies and management
measures (and sustainability indicators in particular) for artisanal and
subsistence coral reef fisheries, for example, when you don't even know
this fundamental statistic for anything except a few reefs in a few
countries. And as Tanya presumably has found, it is impossible to
estimate global potentials and limits when there are so many gaps and

I would also be *very* interested in any replies to this question...

Tim Adams
South Pacific Commission
tja at

>From: 	Tanya Dobrzynski[SMTP:aoctd at]
>Sent: 	Saturday, February 15, 1997 2:46 AM
>To: 	coral-list at
>Subject: 	info request: global coral reef coverage
>Can anyone verify either of the following fisgure for global coral 
>reef coverage?  I have read most often 600,000 sq km but recently 
>heard that 230,000 sq km is a more accurate assessment.
>Thanks for your time,
>Tanya Dobrzynski
>American Oceans Campaign
>aoctd at

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