Bleaching Damage and Recovery Potential of Maldivian Coral Reefs

Abstract

Same-site comparisons of Maldive–Chagos reefs in the 1990s with studies before 1980 have found large losses in coral cover that were probably associated with warm El Niño events. To determine the spatial extent of this damage and potential for recovery I surveyed benthic cover, hard coral communities, and coral recruitment in previously unsurveyed sites in three reef atolls of the central Maldives in 1999, one year after the warmest recorded El Niño event of 1997–1998. Coral cover was the lowest recorded for this region, at 8%, and evidence for the local extirpation of species was found. Most reefs are presently dominated by coralline and turf algae (68%) with erect fleshy algae and sponge being higher than previously reported on Maldivian reefs. Branching coral species appeared most affected and the dominant coral genera in 1998 were massive Porites and Astreopora, whereas the original community was dominated by Acropora. Coral recruits were sufficiently abundant, at 29 ind/m 2, to insure recovery of coral cover, but the most common recruits were in genera previously reported as subordinate genera, such as Pavona (11.7 ind/m 2) and Coscinarea (4.4 ind/m 2), whereas the previously dominant branching and encrusting species ( Acropora, Montipora and Pocillopora) had recruit densities less than 0.65 ind/m 2. Unless there is significant compensation in growth and mortality there may be future changes in coral species composition and benthic cover of these reefs.