New Species of Rare Algae Discovered Near Imperial Palace; Tokyo University Professor Lauds ‘Important Discovery’

The Yomiuri Shimbun

2:00 JST, February 25, 2025

A research team announced it has discovered a new species of Kawamozuku — a rare red alga — in the basin of an artificial waterfall in Kitanomaru Park next to the Imperial Palace in Chiyoda Ward, Tokyo.

The new species, named “Kitanomaru Kawamozuku” after the park, is believed to have adapted to the artificially managed water environment. The research team, which is led by the National Museum of Nature and Science (NMNS), said a discovery of a new species of alga is rare in urban areas.

Kawamozuku grows in clear streams where there is little change in water temperature, such as springs and streams in rural areas. About 25 species have been confirmed to grow in Japan, many of which have been placed on the Environment Ministry’s red list of endangered species.

In April 2023, NMNS researcher Taiju Kitayama and other members of the research group collected the reddish-brown alga growing on the bottom of the basin as part of a study related to a biodiversity survey conducted continuously at the Imperial Palace. A DNA analysis confirmed it to be a new species of Kawamozuku.

According to the park’s administrative office, the waterfall was made in 1969. Rainwater and groundwater are circulated between the waterfall and a pond in the park with a pump, the office said.

“The discovery shows that Kawamozuku can grow in places touched by human hands, as long as the water environment is maintained,” said Mitsunobu Kamiya, a professor at Tokyo University of Marine Science and Technology who specializes in algae. “It is an important discovery, as the natural habitat of Kawamozuku is decreasing.”