ANALYSIS OF SURVEY ON CORAL REEFS
Hiroomi Uchida* and Shuichi Fujiwara**
Distribution of hermatypic coral communities in Japan has been surveyed from 1990 to 1992 under conduct of the Environment Agency of Japanese Government.
Japanese islands stretch from southwest to northeast along the Eurasia Continent in the northwest Pacific and are influenced strongly by the Kuroshio warm current that carries huge heat and tremendous larvae and juveniles of tropical marine life.
Therefore distribution of coral communities reaches up to Tokyo Bay lying 35 degrees north latitude. But coral reefs are limited to the Ryukyu and Ogasawara Islands. That's why the two different survey methods have been used by locality.
In the non-reef region, covering northern area from 29 degrees 20 minutes, only coral communities having coverage over 5% and area over 0.1ha have been sought and researched by spot-check and manta towing methods.
In the reef region, covering southern area from 29 degrees 20 minutes, analysis of color aerial photographs at moat, and manta towing at reef margin, have been used. Ogasawara Islands have been researched by the spot check method for non-reef area because there is no moat.
Results are as follows ;
１. Total area of coral community surveyed in the reef region is approximately 3,400ha and 456ha in Ogasawara Islands. Coverage data shows that communities having coverage under 5% occupy 61.3% in the reef region.
２. Total area of coral community surveyed in the non-reef region is approximately 1,400ha.
* Kushimoto Marine Park Center
** Marine Parks Center of Japan