Many thanks to Jack Sobel for his generally positive comments about Reefs at
Risk (http://www.wri.org/indictrs/reefrisk.htm). As Dr Sobel is aware the study
was an indicator based assessment. We used global maps reflecting a wide range
of factors to act as surrogate measures of threat to reefs (in the absence of
direct or comparable measures for the majority of the world's reefs). This
approach was an effort to introduce some sort of scientific objectivity into a
field otherwise dominated by more subjective opinion-based reporting.  One of
the great difficulties with using indicators is that there will always be
exceptions which the indicators are unable to predict. Dr Sobel has clearly
pointed out what may be some of the key exceptions (but subsequent arguments on
this list underline the difficulty even here), and certainly the problems with
Florida and Belize are considered on page 51 of the publication. One of the
advantages of a purely quantitative approach, however, is that we can return to
the data and ask why such apparent exceptions were not picked up, and then
re-assess the whole approach, if necessary making refinements to the methods.

Below we try and address the four particular points which Dr Sobel raises, but
before that (and please don't feel obliged to read all this!) we would make
three points:
1)  This is a GLOBAL review: as such the resolution at the level of individual
countries may be poor, but we (and that includes contributors from around the
globe representing many institutions) consider that overall it gives a pretty
good picture;
2)  The report considers "threat" rather than actual current "degradation" -
reefs may be indicated as highly threatened, but by good management or by
exceptional circumstances may still be in excellent condition;
3)  It is a first attempt. Previous efforts, which have been widely used and
have helped considerably in raising awareness about the threats to coral reefs
have been based on expert opinion, but unfortunately different experts have
different opinions while most of the world's reefs are rarely visited by
experts. Improved global datasets and possible changes to the methods may lead
to considerable refinement of the maps in future versions.

Jack Sobel's particular points:
Florida:
The Florida reefs score medium threat in two of the four threat factors and
score as high threat in none, so received an overall score of moderate risk.  In
particular -
a) Within the Coastal Development threat factor, the reefs of the Keys are just
beyond the 20 km. distance threshold for high threat from a city of over 1
million (Miami), and smaller settlements, airports and tourist resorts only
result in a classification of medium threat. 
b) Within Marine Pollution, shipping related threats resulted in a
classification of moderate threat.
c) Overexploitation - as Dr. Sobel points out, population density-based
overfishing was not evaluated for the U.S.  This exclusion was made based upon
the opinion of 20 coral reef experts who participated in the second workshop on
the Reefs at Risk methodology.  The consensus was that Malthusian-type
overfishing does not occur in wealthy countries, so these countries should be
excluded from the model, based upon per capita GDP.  As destructive fishing is
not a threat in the Keys, the Florida reefs were not found to be at risk from
overfishing.
d) Inland pollution and erosion - the watershed-based model used to predict
sediment plumes relies upon slope, land-cover type and precipitation for all
areas in the watershed.  As southern Florida is so flat, the model does not pick
up a threat from sediments in this area.  (The watershed model is better suited
to pick up threats from deforestation in hillier landscapes.) 

In this sense, Florida slipped through the net, but had we changed our indicator
criteria to include Florida as an area subject to population-density driven
overexploitation, it would have scored as high threat.  Also, had we allowed
tourism pressure to score as high risk, the Florida Keys surely would have
qualified.  Of course we could do this, but such an alteration would also bring
a number of clearly unthreatened reefs into the same high threat category.

Belize:
The reason why the reefs of southern Belize are marked as highly threatened is
due to their proximity to considerable terrestrial runoff . Clearly this runoff
has yet to impact the southern Belize reefs, and it may be that the particulars
of the coastal configuration and currents further protect these reefs, but once
again we have to look at a wider picture. In the majority of cases reefs lying
this close to such a major terrestrial input would be under considerable threat
(and this was agreed by the majority of international contributors to Reefs at
Risk).

The Lesser Antilles:
Degradation on particular reefs is already considerable in this region, but it
is of course threats not degredation we are measuring, and these are even
greater: over-exploitation, coastal development, sedimentation are all rife.
Certainly there are exceptional sites in this region, not degraded or even
threatened, but many are small, while the resolution of the study used a 4 km.
grid, so many of these would not even show up.

Over-exploitation:
Of course this can occur anywhere, what we are trying to do is pick up the cases
where it is virtually inevitable and therefore predictable using surrogate
measures. Within our modeling of overexploitation of reef resources, we examined
two broad types of threat - destructive fishing, such as blast fishing and
fishing with cyanide, and Malthusian, or subsistence type overfishing.  Areas
estimated to be under threat from destructive fishing are based upon documented
occurrences of blast or cyanide fishing, revised by our experts at a Reefs at
Risk  workshop held in Manila last Fall, attended by 20 coral reef scientists. 
Also at this workshop, the group encouraged us to estimate the demand-based
threat of Malthusian overfishing for poverty areas only, as the consensus was
that this type of fishing does not occur in wealthy areas, and that the
exclusion could be based on per capita GDP and percent of protein in the diet
from fish.  We implemented this revision to the methodology by using a maximum
of $10,000  per capita GDP per annum, and a fish consumption threshold of 50 kg.
fish per person per year.  We should have made the rational for this exclusion
clear in the report.

We are delighted with any feedback the report generates, and also hope that it
will continue to provoke discussions among reef scientists, managers and/or
politicians.

Comments from Mark Spalding (WCMC) and Lauretta Burke (WRI).





Mark Spalding
World Conservation Monitoring Centre
219 Huntingdon Rd, Cambridge, CB3 0DL, U.K.
Tel: +44 01223 277314    Fax: +44 01223 277316
e-mail: mark.spalding@wcmc.org.uk
or
Cambridge Coastal Research Unit
Department of Geography
University of Cambridge
Downing Place, Cambridge CB2 3EN
Tel: +44 (0)1223 339775
Fax: +44 (0)1223 355674
































