Diatom assemblages were studied in three strongly acidic hot springs in Akita Prefecture, northern part of Japan. Eunotia exigua and Pinnularia acidojaponica were recorded in the three springs, Fukenoyu, Tamagawa and Kawarage, with P. acidojaponica dominant in all the springs. Relative abundance of E. exigua was slightly increased in Fukenoyu, which has the highest water temperature and the lowest pH of all the springs.
