Date: Sun, 18 Oct 1998 18:17:01 +0800 (HKT) From: "Gerardo L. Ledesma" Subject: Bleaching in BELIZE 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. *..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..*..* Melanie Dotherow McField melanie@marine.usf.edu Department of Marine Science University of South Florida 140 Seventh Ave. South St. Petersburg, FL 33701