Impact of two sequential super typhoons on coral reef communities in Palau

Typhoons generally develop in the warm tropics, but rarely damage coral reefs between the latitudes 10 degrees N and 10 degrees S because they intensify at higher latitudes. However, climate change is forcing anomalous weather patterns, and is causing typhoons to take less predictable trajectories. For the first time in 70 yr, in December 2012, a super typhoon passed near the island of Palau, located at 7 degrees N in the western tropical Pacific Ocean. A year later, another super typhoon passed over the northern reefs of Palau. This study characterized the impacts of both typhoons on coral and fish assemblages in 3 habitats (i.e. outer reefs, patch reefs, and inner reefs) and at 2 depths (i.e. 3 and 10 m). Loss of coral cover was highest on the shallow, eastern slopes (similar to 60% coral cover). Juvenile coral densities decreased along the western reef slope and on the inner reefs, where overall coral cover scarcely decreased. These results suggested a potential stock-recruitment relationship with corals on the damaged eastern reefs. Early successional corals, particularly pocilloporids, recruited 6 mo after the second typhoon. Fish communities were generally un altered by the first typhoon, except small parrotfishes, which doubled in density along the eastern reef-slope and increased on the inner reefs following the second typhoon. In combination, these findings demonstrate high spatial variability in coral loss, overall decreases in juvenile corals, and increases in herbivorous fishes on a tropical reef system that has rarely experienced large typhoon waves.