First signs of bleaching in Puerto Rico

Hernandez Edwin coral_giac at
Sun Jul 22 13:26:02 EDT 2001

Dear coral-listers.

This is a short notice to report that we just recorded
the first signs of bleaching in two coral species at
Carlos Rosario Beach, Culebra Island, Puerto Rico
(18°19'36"N, 65°19'56W), last Thursday, July 19, 2001.

A few colonies of Siderastrea siderea (depth: 5-10 m)
which were showing their "normal" brick reddish color
a few weeks ago in one of our permanent monitoring
sites, turned into a pale blue or lavender color
within a couple of weeks. They are also showing many
pale round spots along all of the colony surface.

In addition, about 50-90% of the surface area of
several Millepora alcicornis colonies became
completely bleached during the same period of time.

No other species have been affected so far.  During
the strong bleaching event of 1998, which affected 77%
of the coral colonies there, these species, and
particularly, these S. siderea colonies, were the
first to show signs of bleaching by mid April and
early May, 1998.  Again, these corals are the first
showing signs of bleaching this year.

Temperature is being continuously recorded at the
study site. No temperature anomalies have been
observed yet.

We'll keep an eye on these "sentinel" colonies, as
well as in other species.


Edwin A. Hernandez-Delgado, Ph.D.
University of Puerto Rico
Department of Biology
Coral Reef Research Group
P.O. Box 23360
San Juan, P.R. 00931-3360
Tel (787) 764-0000, x-4855; Fax (787) 764-2610

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