Unusually cold water has devastated some of the world’s most northerly coral reefs, which lie off the coast of western Japan, an environment ministry official said Wednesday
Coral bleaching in Japan
The ministry surveyed the reefs in recent months and found widespread bleaching, with between 90 to 100 per cent of each of the six spots surveyed affected. In four of the surveyed areas, researchers have reported between 85 per cent and 95 per cent of the bleached areas were now dead, said Yuto Takahashi, a ranger at the regional ministry office that conducted the survey
Meandering Kuroshio current in the Pacific
The devastation is thought to be the result of unusually cold water temperatures in the area this year, partly produced by the meandering of the Kuroshio current, he told AFP. The Kuroshio is a warm current in the northwestern Pacific Ocean, and its unusual movement away from the area brought up cold water from the depths
Unusual phenomenon
Little is known about exactly why the Kuroshio current changes its flows, but scientists have observed the meandering phenomenon six times since 1965, most recently last summer. The phenomenon results in lower water temperatures, changes the locations of fishing grounds and even affects ship navigation, according to the Japan Meteorological Agency
They are home to over 25 per cent of marine life
Coral bleaching and death is irreversible, but differs from similar events seen in other more southerly reefs. Ironically, the warming water that is bleaching corals further south could create a more stable environment for corals in northern areas. Corals make up less than one percent of Earth’s marine environment, but are home to more than 25 per cent of marine life