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

Reefs of the Huatulco area, southern Mexico, were exposed to an unprecedented sequence of three major storms (Olaf, Pauline, and Rick) over a 2-mo period (September-November 1997). The prior establishment of monitoring transects, as well as the timing of our surveys just 1 mo after the passage of Hurricane Rick, provided an unique opportunity to document storm impacts on these recently described reef communities of the eastern Pacific. Considering the lack of prior hurricane damage to these reefs, the dominance of branching pocilloporid corals, and the intensity and high frequency of the 1997 storms that affected the area, it was hypothesized that storm-generated damage patterns would be significant and consistent among the reefs of Huatulco. However, the damage patterns documented were limited in severity and variable 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 increases in coral cover between surveys. The most common type of damage observed was the fragmentation of Pocillopora spp. colonies; at some locations, the density of surviving Pocillopora spp. fragments exceeded 20 m−2. Fragmentation of the massive coral Pavona gigantea (Verrill) was observed only at a single site. At several sites, large sections of reef framework (up to 245 cm in diameter) still exhibiting live Pocillopora spp. colonies on their upper surfaces were detached and transported away from their original locations. 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 colonies and fragments, the regeneration of damaged colonies, and the future impacts of bioerosion.