SAPPORO -- A great number of green algae balls known as "marimo" have been appearing on the shore of Lake Akan in Japan's northernmost prefecture of Hokkaido for the first time in eight years, proving their growth cycle.

       The moss balls were apparently blown toward the shore of the lake in the prefectural city of Kushiro by strong winds caused by a low-pressure system that crossed Hokkaido on June 4.

       It is the first time for marimo, which are designated as national natural monuments, to be washed ashore since November 2013. The Kushiro Municipal Government says their arrival points to the development cycle of marimo.

       When the spherical alga grows to certain size as a result of photosynthesis, it drifts ashore, aided by the wind and waves, then breaks down into small pieces and returns to the lake. This process is thought to repeat in cycles of five to nine years.

       The marimo lab in the municipal government's lifelong study division says it has four records of marimo washing ashore in the past. The biggest occurrence was in November 1995, when the moss balls covered some 3,900 square meters.

       Last time the marimo covered around 1,300 square meters, and this time it has been confirmed that the spherical algae which washed ashore or drifted near Churui Bay on the lake's northern shore covered some 470 square meters. Officials are continuing to investigate the phenomenon.

       Lab curator Yoichi Oyama commented, "There are concerns rising temperatures toward summer could have an effect (on the marimo), and we would like to move them back into the lake as deemed necessary in consultation with the Agency for Cultural Affairs."

       (Japanese original by Hiroaki Honma, Hokkaido News Department)

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