Panama bleaching

Marilyn Brandt mbrandt at
Mon Jul 29 13:37:19 EDT 2002

During the June 11-15th Atlantic and Gulf Rapid Reef Assessment (AGRRA)
expedition to the Archipiélago de Bocas del Toro in northwestern Panamá,
bleached stony corals were noted in shallow reefs near Islas Aqua,
Bastimentos and Popa, at Cayo Coral, Cayos Zapatilla and, most
dramatically, at Tobobo on the eastern side of the Península Valiente.
(please see link for photos:  However,
we observed no bleaching from June 16-28 further east on reefs located
in the western area of the Kuna Yala.

The preliminary results of our quantitative assessments are as follows:
Cayos Zapatilla A (N 9° 16.366', W 82° 3.956'), depth 12 m., live stony
coral cover  ~28%; ~23% of the stony corals that were >10 cm in diameter
(including Acropora palmata and Porites astreoides) exhibited pale to
complete bleaching.

Cayos Zapatilla B (N 9° 25.399', W 82° 19.45') depth 0.52m, live stony
coral cover ~10%; ~22% of the >10 cm stony corals (including Montastrea
annularis, Millepora alcicornis, and P. astreoides) were pale to
completely bleached. A. palmata was present but no bleaching was noted;
approximately half of these colonies were "old standing dead."

Tobobo (N 9° 6.454', W 81° 49.351' and 9° 6.374', W 81° 49.245'), 1-4 m,
live stony coral cover ~25-40%;partial to complete bleaching affected
~50% of the >10 cm corals, primarily Acropora palmata and M. complanata,
and was particularly conspicuous at <2m.

Shallow reefs in the Bocas del Toro area experienced extremely low tides
in early June (from 12 cm on June 1 to 6 cm on June 4). Seawater
temperature was unusually warm and its salinity was unusually low at
permanent reef survey sites near the Smithsonian Tropical Research
Institute¹s Bocas del Toro research station on June 12 (Arturo Dominici,
pers. comm.). Hence bleaching may have been initiated by stresses
associated with high temperatures, low salinity and exposure. Enhanced
radiation might also have contributed offshore in the Cayos Zapatilla
and at Tobobo, but is less likely closer to Bocas del Toro where
seawater is routinely discolored by the presence of dissolved organic

During the last month, bleaching has extended to depths of 5m (but no
deeper) and affected the giant anemone, Condylactis gigantea, in
addition to stony corals (Javier Jara, pers. comm.). A lens of fresh
water has been floating near the surface in the area of Bocas del Toro,
and extreme low tides (from -9 to -12 cm) occurred again from July 9 to
July 15th.

Marilyn Brandt, Judith Lang, Juan Maté, and Robert Ginsburg for the
PANAGRRA field team, which also included Jorge Andréve, Arcadio
Castillo, Cam Hernández, Ken Marks and Ryan Moyer.

Sponsored by the Royal Caribbean Cruise Lines¹ Ocean Fund and the Ocean
Research and Education Foundation. We are grateful to the Smithsonian
Tropical Research Institute, in particular the Caption and crew of the
RV Urraca and the staff at the Bocas del Toro research, station for
assistance in the field.

Marilyn E. Brandt
National Center for Caribbean Coral Reef Research (NCORE)
Rosenstiel School of Marine and Atmospheric Science (RSMAS)
University of Miami
4600 Rickenbacker Causeway
Miami, FL 33149

Ph. 305.361.4827     Fx. 305.361.4910

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