Coral distribution and diversity in Sakiyamawan–Amitoriwan nature conservation area of Iriomote Island in Japan

Abstract

Sakiyama and Amitori bays of Iriomote Island in Japan are adjacent, but their coral distributions differ significantly. This study investigates the differences in the coral distribution and diversity between both bays from the diversity index and intermediate disturbance hypothesis (IDH) perspective. In Amitori Bay, tabular and branching corals dominate the mouth and inner part of the bay, respectively. Coral diversity is maximum in the intermediate part of the bay, realizing the IDH. In Sakiyama Bay, branching and massive corals dominate the reef edge and coast sides of the bay’s intermediate part, respectively. Coral diversity is maximum in the reef edge part of the bay, and IDH is not realized. The difference in the soil inflow and geographical characteristics between both bays significantly affects their coral distribution and diversity.