[Coral-List] About bleached vs. non-bleached sites.

Hernandez Edwin coral_giac at yahoo.com
Mon Sep 26 18:49:10 EDT 2005

Dear listers.

Hola! Regarding the interesting discussion about the
value of non-bleached sites as potential candidate
no-take MPA sites I want to add a few comments.

First, bleaching vs. non-bleaching conditions in any
given site is highly variable in time. For instance,
we have documented variable bleaching responses in
1987, 1989, 1990, 1991, 1993, 1995, 1998, 2001 and
2005 at several eastern PR coast locations that
clearly indicate that each bleaching event has been
largely variable in space and time. Therefore, we have
to proceed with caution when suggesting that
non-bleached sites in 2005 are "more important" sites
for establishing no-take MPAs than bleached sites.
Besides, as far as I'm concerned, no-take MPAs are 99%
aimed at reestablishing overexploited fish
communities, which is a social problem independent of
bleaching events.

Second, we also need to consider the benthic community
assemblage structure of any given reef before making
such a generalization. For instance, coral reefs
dominated by highly resilient coral species should be
more "resistant" to bleaching events than those where
highly susceptible species are more abundant. The
result of any given event on these two different
scenarios, even within the same geographic area, may
produce different effects. 

We are having reefs in eastern PR with approximately
50% bleaching, but do have others with >90% bleaching.
Also, shallower reef zones have been more affected in
eastern PR during the current bleaching event than
deeper reefs. Does this means that MPAs should be
established only in reefs, lets say, below 20 m in

I agree with Georgina and others in the fact that
no-bleaching should also be documented. This is
paramount to address spatial and temporal patterns.
These sites should also be somehow protected. But we
should not neglect the fact that many of those
frequently bleached locations are also extremely
important sources of coral, fish and invertebrate
propagulae, spawning aggregation sites, nursery
grounds, etc. We are also talking about the livelihood
of maybe millions of people.

Bleaching frequency is very important, but should not
be an excluding factor for determining no-take MPA
locations. Or are we giving up in our reef fisheries
and coral reef conservation and restoration efforts?


Edwin A. Hernández-Delgado, Ph.D.
Affiliate Researcher

University of Puerto Rico
Department of Biology
Coral Reef Research Group
P.O. Box 23360
San Juan, Puerto Rico 00931-3360
Tel (787) 764-0000, x-4855
Fax (787) 764-2610
e-mail: coral_giac at yahoo.com

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