Abstract
Marine algae from Sasunohama, on the southern coast of Oshika Peninsula (38°24′N, 140°22′E), northeast Honshu, were collected monthly from April 2002 to March 2003, and the floral characteristics were analyzed. The species identified were two sea grasses and 106 species of marine algae, 17 of which belonged to Chlorophyta, 24 to Phaeophyta and 65 to Rhodophyta. The I/H value, the ratio of the number of species with isomorphic alternation of generations to heteromorphic alternation of generations (Nakahara and Masuda 1971), in Sasunohama was 1.4, whereas that in Tomarihama, adjacent to the north, was 1.2 (Agatsuma et al. 2000), and that in Matsushima Bay, adjacent to the south, was 1.8 (Takamatsu 1936). Of the fucoid species principally distributed in the warm-current floral region, five were from Sasunohama, nine from Tomarihama and 13 from Matsushima Bay. The results suggest that the algal florae in Sasunohama belong to the subarctic region.
