9. Coral Distributions and Physical Environments in Amitori Bay

The relation between coral distribution and physical characteristics was investigated for Amitori Bay, Iriomote Island, Japan. Field observations were conducted to obtain data for the coral distribution, sea temperature, sea salinity, wind speed, and river flow rate. Then, the observed data were used in ocean and wave model numerical simulations and soil particle tracking analyses to ascertain the spatial and temporal distributions of wave height and the numbers of soil particles. The main results of this study indicate that the wave height and the number of soil particles are significantly correlated with the coral distribution. Higher wave heights produce greater coverage of tabular coral and lower coverage of branching coral. A greater number of soil particles are related to less coverage of tabular coral. In contrast, the number of soil particles is not correlated with branching coral coverage. Averages of the diversity index of the coral types at the mouth and inner parts of the bay are lower than the average of the whole region, but the average of diversity index at the intermediate part of the bay with the intermediate physical disturbances is higher than the average, which supports the intermediate disturbance hypothesis.