In the coral reefs aerial photograph and satellite image analysis are used to investigate the distribution of coral communities and living things. These methods are effective to understand coral distribution and geographical structure of coral reefs, and show the data into two-dimensional maps. However it is not good enough to identify the exact three-dimensional shapes of coral reef structure. On the topographic map published by Geospatial Information Authority of Japan, coral reef is classified as ‘reef’. As ‘reef’ include non-coral structures as well, the outline of the structures showed by the maps are not exact, also it does not show the information of depth contours.
Under the circumstances, this study aimed for making detailed distribution maps of healthy communities of scleractinian corals and making fundamental maps of Shiraho reef of Ishigaki Island which could apply for further investigation and conservation. Two locations which had high live coral coverage were selected for making detailed map of coral distribution.
For the survey, the corrected image for distortion elimination which was made from aerial color photos (1/10,000 of the original) was used, and shapes and species composition of corals and coverage were recorded. In the next step, ortho images were made from aerial photos in areas across the entire 9 kilometer length of the North-South, for the purpose of examination of the distribution of coral reefs of Shiraho. This included coral reefs which were not included in our first detailed map. Using these outcomes, identification of topography and sediments of the coral reef became easier and it became possible to record the exact position and shapes of coral communities. Results of the survey overlaid on the ortho image using ArcGIS facilitated understanding the distribution of corals. These images were corrected for distortion elimination by aerial photographs were shown to be useful in shallow coral reef conservation.
The maps and pictures made by this study were used as a Base Map for conservation of the coral reef ecosystem which WWF coral reef protection research center collects. Moreover, this map is used also for coral reef conservation activities and marine-resources management by local people of the area.
