Predictive modeling of coral distribution and abundance in the Hawaiian Islands

This study developed species distribution models (SDMs) of the 6 dominant Hawaiian coral species (Montipora capitata, Montipora flabellata, Montipora patula, Pocillopora meandrina, Porites compressa, and Porites lobata) around the main Hawaiian Islands (MHI). To construct the SDMs, we used boosted regression tree (BRT) models to investigate relationships between the abundance (i.e. benthic cover) of each species with a set of environmental variables for the time period from 2000 to 2009. Mean significant wave height and maximum significant wave height were the most influential variables explaining coral abundance in the Hawaiian Islands. The BRT models also identified relationships between coral cover and island age, depth, downwelled irradiance, rugosity, slope, and aspect. The rank order of coral abundance (from highest to lowest) for the MHI was Porites lobata, M. patula, Pocillopora meandrina, M. capitata, Porites compressa, and M. flabellata. Mean coral cover predicted for each species was relatively low (<= 5%) at each island and for the entire MHI except for Porites lobata around Hawaii (11%). The areas of highest predicted coral cover summed for the 6 species were Kaneohe Bay on Oahu; the wave-sheltered reefs of Molokai, Lanai, Maui, and Kahoolawe; and the Kohala coast of Hawaii. Regional-scale characterizations of coral species from these SDMs provide a framework for spatially explicit population modeling and ecological inputs to marine spatial planning of Hawaiian coral reef ecosystems.