Combined effects of three sequential storms on the Huatulco coral reef tract, Mexico

Reefs of the Huatulco area, southern Mexico, were exposed to an unprecedent ed sequence of three major storms (Olaf, Pauline, and Rick) over a 2-mo per iod (September-November 1997). The prior establishment of monitoring transe cts, as well as the timing of our surveys just I mo after the passage of Hu rricane Rick, provided an unique opportunity to document storm impacts on t hese recently described reef communities of the eastern Pacific. Considerin g the lack of prior hurricane damage to these reefs, the dominance of branc hing pocilloporid corals, and the intensity and high frequency of the 1997 storms that affected the area, it was hypothesized that storm-generated dam age patterns would be significant and consistent among the reefs of Huatulc o. However, the damage patterns documented were limited in severity and var iable in spatial distribution. Of the six reefs surveyed prior to the first storm in July-August 1997, only three showed significant decreases in live coral cover, whereas the remaining reefs showed slight, non-significant in creases in coral cover between surveys. The most common type of damage obse rved was the fragmentation of Pocillopora spp. colonies; at some locations, the density of surviving Pocillopora spp. fragments exceeded 20 m(-2). Fra gmentation of the massive coral Pavona gigantea (Verrill) was observed only at a single site. At several sites, large sections of reef framework (up t o 245 cm in diameter) still exhibiting live Pocillopora spp. colonies on th eir upper surfaces were detached and transported away from their original l ocations. Even if the immediate damage observed was significantly less than predicted in light of the physical characteristics of the storms, the long -term effects of these storms will depend on the survivorship of detached c olonies and fragments, the regeneration of damaged colonies, and the future impacts of bioerosion.