In 2025, a new locality of brown alga Sargassum ilicifolium (Turner) C.Agardh was recorded in Okinoshima, Chiba Prefecture, Japan. This is the first clear report of this species growing naturally in Kanto district. The habitat of Okinoshima is considered to be the northern limit of the distribution of S. ilicifolium in Japan.
Hanyuda et al. (Wed,) studied this question.