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| Fujiwara, Shuichi | |
| Marine Parks Center of Japan | |
| 1-3-1 Atago, Minato-ku, Tokyo 105-0002, Japan | |
| Tel: +81-3-3459-4605 Fax: +81-3-3459-4635 | |
| E-mail: marpark@blue.ocn.ne.jp |
23,509,000 Yen
(FY 1999; 7,063,000 Yen)
Aerial photographs of coral reefs were taken by a digital camera suspended in a small remote-controlled helicopter at the Sekisei Lagoon, Okinawa. In order to analyze digitized image, coverage of coral communities of corymbose Acropora at 2.5m deep and branching Montipora at 2.0m deep was surveyed using quadrat method. Mean coverage of the Acropora community dominated by A. millepora and A. nasuta was 24.1 % and of vegetation dominated by Dictyota, Cyanophyceae, encrusting and filamentous Rhodophyceae was 75.9 %. Montipora community dominated by M. digitata had 51.1 % coverage and 25.7 % in vegetation dominated by encrusting Corallinaceae. Digitized image was divided at each quadrat by image analyzer. Then mean gray value of each RGB specter bands at each quadrat was measured.
Relation between coral coverage and standard deviation/mean of RGB gray value of image was examined. The regression equation represented almost negative tendency because image of low coral coverage dominated by vegetation indicates high sd/mean. It is suggested that seaweed blade is fluctuant for water movement so image dominated by vegetation occurs unfocused image which shows high sd/mean.
Coral reef, Aerial photography, Digitized image, Image analysis, Coral coverage