Over a Decade of Change in Spatial and Temporal Dynamics of Hawaiian Coral Reef Communities

The Hawai'i Coral Reef Assessment and Monitoring Program (CRAMP) was established in 1999 to describe spatial and temporal variation in Hawaiian coral reef communities in relation to natural and anthropogenic factors. In this study, we analyzed changes over a 14-yr period (1999 to 2012) based on data from 60 permanent reef stations at 30 sites in the main Hawaiian Islands. Overall mean statewide coral cover, richness, and diversity did not vary significantly since the initial surveys, although local variations in coral cover trends were detected. The greatest proportion of stations with significant declines in coral cover was found on the island of Maui (0.4), and Hawai'i Island had the highest proportion of stations with significant increases (0.67). Trends in coral cover at some stations varied over time due to acute (e.g., crown of thorns outbreak) and chronic (e.g., sedimentation) disturbances. Stations with increasing coral cover with the potential for recovery from disturbances were identified for possible management actions in the face of future climate change. The Hawaiian archipelago, located in the center of the subtropical Pacific, has experienced a temporary reprieve from steadily increasing temperatures over the past several decades due to a downturn of temperatures at the end of the last cycle of the Pacific Decadal Oscillation (PDO) in 1998. In 2014, however, temperatures increased dramatically in Hawai'i, resulting in a major coral bleaching event with associated mortality. Temperature models predict severe bleaching events to increase in frequency and intensity in coming decades with concomitant decline in Hawaiian corals. Trends reported in this study provide a baseline that can later be used to test this predicted decline associated with future warming.