Coral response during and after mass bleaching in Belize

Major coral bleaching events have occurred throughout the tropics during th e last 25 yrs. Although many reefs in the Caribbean bleached repeatedly thr oughout the 1980s and early 1990s, the reefs of Belize did not suffer a wid espread bleaching event until the summer of 1995. At the time of mass bleac hing water temperature and solar radiation were elevated and wind speeds we re low. In October-November 1995, 52% of corals surveyed were affected by b leaching, compared to only 7% in May 1996. No spatial trends were found, al though some tars had significantly different levels of bleaching at differe nt depths. A positive correlation was found between the relative abundance and the percent affected of different taxa, indicating that bleaching may a ct to increase diversity if mortality occurs. There was a significant diffe rence in the extent of bleaching between corals reported to host different clades of zooxanthellae. By May 1996, 25% of the originally bleached, tagge d specimens experienced at least partial tissue mortality. It is estimated that approximately 10% of all coral colonies experienced some partial tissu e mortality by May 1996 as a result of this bleaching event. Such bleaching -induced partial tissue mortality may decrease the structural integrity of the reef framework and decrease the ecological competitiveness of corals an d other symbiotic reef organisms.