is the largest

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

group in Japan, containing over 100 coral reefs and spanning about 17 by 6.5 km. Known for being above water level several times a year, most visibly around March 3, it was made a Natural Monument of Japan in 2013 as a place of Scenic Beauty. It is located about 6 km off the northern coast of Ikema Island.

Ecology

The reef contains about 300 kinds of coral.

Conservation history

The Ministry of the Environment has designated the reef as one of the 500 most important wetlands in Japan. In 2018, it was discovered that the living part of the reef had decreased by about 70% since 2008 from coral bleaching, due to rising water temperatures.

References

{{reflist Coral reefs Ryukyu Islands Natural monuments of Japan