Coral bleaching in Philippine reefs: Coincident evidences with mesoscale thermal anomalies

Massive bleaching was observed in various reefs throughout the Philippines (5-21 degreesN. 116-128 degreesE), beginning early June until late November 1998. Satellite-derived SST data from NOAA/NESDIS was used to examine ther mal anomalies ('hotspots') observed in the country during this same period. Anecdotal reports from the Coral Reef Information Network of the Philippin es (PhilReefs) partners revealed the extent of bleaching in other parts of the country. The observations coincided with the occurrence of a hotspot ov er the region. Coral community studies detected significant decrease in liv e coral cover (up to 46%) and increase in dead coral cover (Lip to 49%). Th e results support the hypothesis that elevated sea temperatures was the maj or cause of the bleaching event. Some patterns of susceptibility within and across reefs, possibly due to influences of factors such as wave energy, t idal fluctuations and reef morphology, were also observed. The extent and s cale of the 1998 bleaching events in the Philippines could not be fully att ributed to small-scale anthropogenic disturbances directly affecting reefs since severe bleaching was also observed in offshore reefs. Its coincidence with the El Nino-related temperature anomalies suggests that the interacti on between human-induced and natural factors behind bleaching remains to be investigated further. This interaction is critical for reef recovery and t he discrimination between both impacts can be useful for policy and decisio n-making processes in management.