Bleaching in Belize

[Melanie Dotherow]

Coral Bleaching Report:

Sept. 17 - 21, 1998. Barrier reef sites at Gallows Reef, Goffs Caye and
Alligator Caye and at Calabash Caye, Turneffe Atoll all showed moderate
bleaching levels qualitatively estimated at 25-30% affected (W. Jaap and
M. McField) at depths of 14-18m.

Sept. 23 - Oct. 7, 1998. Glovers reef atoll showed higher levels of
bleaching, quantitatively measured to be 76% affected along the western
fore reef (near Baking Swash) at 12-15m. The eastern fore reef near Long
Caye and the shallow patch reefs in the lagoon were qualitatively
estimated to be between 70-80% affected (M. McField). Partial tissue
mortality was evident in some colonies by early Oct., particularly in
Acropora cervicornis and palmata, Diploria labyrinthiformis, Montastrea
annularis, Millepora complanata, and Porites porites. 

This is the second mass bleaching event in Belize, the first being in
1995. Some apparent differences between the 1995 and 1998 events:

1. While the general extent of bleaching may be comparable in 1995 and
1998, in 1995 bleaching was more evenly distributed throughout the reef,
while the severity of bleaching in 1998 appears to be greater in the
southern and northern (Ambergris) regions, compared to the central region
near Belize City. (Details of 1995 event are in press, M. McField, Bul.
Mar. Sci.)

2. The high incidence and severity of bleaching in acroporids (including
some mortality) observed thus far in the Glover's patch reefs was not
observed in 1995. Bleaching of acroporids and subsequent high mortality
(possibly associated with white line disease) was also reported from North
Ambergris Caye (G. Smith) in 1998. Acroporids were not severely affected
at either location in 1995. Overall, the  incidence of colonies
experiencing at least partial tissue mortality will likely be higher in
1998. In 1995, 10% of colonies were estimated (through a combination of
tagging studies and quantitative surveys) to have experienced at least
partial tissue mortality.

Oceanographic and climatic conditions were similar in Sept. 1995 and 1998,
with high water temperatures, low wind speeds, and exceptionally calm,
clear waters.

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Melanie Dotherow McField	melanie at marine.usf.edu
Department of Marine Science	Tel: (727) 553-1615
University of South Florida	Fax: (727) 553-1189
140 Seventh Ave. South
St. Petersburg, FL  33701