Japan's ocean ecosystems, including seaweed beds and coastal mangrove forests, absorb some 1.73 million metric tons of CO2 per year, according to new calculations finalized on March 5 by a research group composed of experts at universities and national research institutes.

The findings "are important for anti-global warming measures," the group stated.

The researchers combed through existing scientific papers from both inside and outside Japan to determine the total area covered by Japan's mangrove forests, seaweed beds, tidal flats and other ocean ecosystems, and then calculated how much CO2 they absorb. The group found that these systems covered 290,000 hectares of seabed as of 2013, and took up an estimated 1.73 million tons of CO2 annually.

However, Japan's seaweed forests are shrinking quickly due to worsening water quality and land reclamation.

"I would like to see these calculations spur seaweed bed preservation and restoration efforts," commented research group head and University of Tokyo professor Jun Sasaki.