Twenty-five years of change in coral coverage on a hurricane impacted reef in Hawai'i: the importance of recruitment

Coral coverage was monitored 1981-2005 using a high precision method at four sites near Kahe Point, leeward O'ahu, Hawai'i by annually photographing ten 0.66 m(2) permanent plots at each site. The study began after a local storm reduced coral coverage in the area by about 50% in 1980 and included two major hurricanes in 1982 and 1992. Repeated measures ANOVA indicate significant differences among sites, time, and site-time interaction with high statistical power. Temporal changes in coral cover varied substantially among the sites, with the most stable coral coverage occurring near a thermal outfall. Although immediate impacts from hurricanes were not substantial, long-term decreases in coral coverage occurred well after the hurricanes. However, no relationships were found between coral cover and offshore wave conditions. Patterns of decline and recovery in coral cover were cyclic on a decadal time scale and significantly correlated with species and site- specific recruitment intervals of 10-12 years for Pocil-lopora meandrina and 15+ years for Porites lobata. Patterns indicated the potential importance of recruitment as a major factor affecting changes in coral coverage.