Dozens of heavy anchors used to secure buoys and floats may be causing havoc to coral off Henoko, Okinawa Prefecture, after they became unattached and missing in a typhoon.
The anchors were placed on the seabed ahead of a project by the central government to start building an offshore site to accommodate a relocated U.S. military base.
Defense Minister Gen Nakatani disclosed during a Lower House Budget Committee on Jan. 30 that 120 anchors were being pushed along the seabed by underwater currents.
Nakatani was responding to a question from Seiken Akamine, a Japanese Communist Party lawmaker elected from the prefecture, about conditions arising from work to relocate the U.S. Marine Corps Air Station Futenma.
The anchors apparently came loose in a typhoon that churned up local waters last autumn 2014. Experts said the anchors may be causing serious damage to the seabed environment.
The government started a boring survey off the Henoko district of Nago last August to assess geological conditions there. As part of the work, it dropped 248 anchors on the seabed to secure buoys and floats.
Some of the anchors were made of layered steel plates and weigh up to 160 kilograms each.
After Typhoon No. 19 in October, half of the anchors were moving along the seabed. Traces of their movement have been spotted in 36 locations.
“The anchors could cause serious damage to the environment around the work area, especially to coral and sea plants,” said Mariko Abe, a senior member of the Nature Conservation Society of Japan, who studies the underwater environment off Nago.
“The companies that dropped the anchors on the seabed need to act responsibly and retrieve them,” she said.
The government intends to place heavier anchors on the seabed in the future. When work resumed this month, it put large concrete blocks on the seabed.